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Cover Page Inside Cover .................................................................................. 1 Association ..................................................................................... 1 Preface ........................................................................................... 1 Acknowledgements ....................................................................... 1 Members of the Steering Committee ........................................ 1 Other Companies and Organisation .......................................... 1 Companies assist in Video Production ...................................... 2
Textile Handbook
The Hong Kong Cotton Spinners Association
in collaboration with
Hong Kong Productivity Council
Supported by
Innovation and Technology Fund, Innovation and Technology Commission
Copyright© 2001
The Hong Kong Cotton Spinners Association
FIRST EDITION FIRST PRINTING – February 2001 ISBN: 962-8040-50-2 All rights reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the copyright owner.
Textile Handbook Publisher
The Hong Kong Cotton Spinners Association
Publisher’s Address
3/F., 63 Tai Yip Street, Kowloon Bay, Kowloon, Hong Kong. Tel: (852) 2305 2893 Fax: (852) 2305 2493
Editor
Hong Kong Productivity Council
Produced by Artfield Communications Company
PREFACE
Growth and competition in the Asia Pacific region, together with Hong Kong’s increasing economic interdependence with mainland China, has led to rapid relocation and expansion of the Hong Kong textiles and clothing industries in Southern China over the past decade. Effectively, Hong Kong has become a higher-value-added, design-intensive manufacturing and advanced services centre for a new industrial configuration in the South China economic region. In order to sustain the competitiveness of Hong Kong in the world textiles and clothing trade, there is a growing need for those in the trade to continuously enhance their knowledge in order to cope with the increasing market demand for sophisticated and quality textile products. This new and revised edition of The Textile Handbook, also available in CD-ROM format, is designed to meet such a need. First published in 1960 by the Hong Kong Cotton Spinners Association, The Textile Handbook has been revised every 10 years to keep up with the technological advancements in the sector and has served as an indispensable source of information in the textile field. The contents of the present edition, produced with the assistance of the Hong Kong Productivity Council and funded under the Innovation and Technology Support Programme of the Innovation and Technology Fund administered by the Innovation and Technology Commission, have been enriched to meet the needs of the industry for quality information. We are indebted to them for their support. While greatest care has been taken to ensure the accuracy of the information, there may be areas that readers might feel there is still room for improvement. In this regard, suggestion and comments from readers would be welcome.
Clement Chen Chairman of the Steering Committee ITF Project on Textile Handbook
Acknowledgements Members of the project team take this opportunity to thank all the individuals and companies that have contributed to this Textile Handbook. The project team would particularly like to record its appreciation to the Innovation and Technology Fund and its secretariat for providing the necessary funding and support, and to each of the following:
Members of the Steering Committee Mr. Clement Chen (Chairman), Tai Hing Cotton Mill, Ltd. Mr. Chi Woo Wha (Vice-Chairman), Central Textiles (Weaving) Ltd Mr. Sam Chen, East Asia Textiles, Ltd. Mr. Chu Ming Kong, Nan Fung Textiles Ltd. Dr. Clement K.M. Lam, Pacific Textiles Ltd. Mr. Peng Set Fen, Far East Cotton Ind. Ltd. Mr. Timothy Tam, Tai Hing Cotton Mill, Ltd Mr. Wong Kwong Hon, Honda Machinery Co Ltd. Mr. Eddie Yeung, Central Textiles (HK) Ltd
Other Companies and Organisation AB Carter (FE) Ltd Acordis H.K. Ltd (Tencel) Benninger FE Ltd C.D.M.(HK) Ltd (Mr. Arkin Ng) Central Textiles (H.K.) Ltd Central Textiles (Weaving) Ltd Chemtax Industrial Co., Ltd (Stoll) Cico Engineering Co., Ltd (Karl Mayer) Cotton Incoporated Cotton Technology International Du Pont China Ltd Kai Ping Ping Da Cotton Spinning Co., Ltd K & E Company Ltd (TEXparts) King March Development Ltd (Berkol) Link Dyeing Works Ltd Morrison Textile Machinery Co. Neumac Co., Ltd (Reiners + Furst)
The Hong Kong Polytechnic University –Institute of Textiles & Clothing (Professor X. M. Tao) Rieter Asia (Hong Kong) Ltd Staeubli (H.K.) Ltd Sulzer Textil Ltd Tai Hing Cotton Mill Ltd Tri-union Industrial Supplies Ltd (Kanai, Schlafhorst, Sucker-Mueller-Hacoba, Truetzschler, Zinser) Zellweger Uster
Companies assist in Video Production Central Textiles (Weaving) Ltd Lap Yick Knitting Factory Ltd Rieter Asia (Hong Kong) Ltd Sulzer Textil Ltd Tai Hing Cotton Mill Ltd Tri-union Industrial Supplies Ltd (Zinser) Win Win Industrial Co., Ltd (Shima Seiki)
To Table of Content
CONTENTS
Chapter 1
Textile Fibres
Chapter 2
Spinning Processes and Types of Yarn
Charter 3
Weaving and Woven Fabrics
Chapter 4
Knitting and Knitted Fabrics
Chapter 5
Textile Coloration and Finishing Treatments
Chapter 6
Textiles Testing and Quality Control
Appendix 1
Business Strategies for the Textile and Apparel
Appendix 2
Web Sites Related To Textiles
Appendix 3
The Hong Kong Cotton Spinners Association 2000/2001 Member List
Appendix 4
The Hong Kong Cotton Spinners Association Committee Members of 2000/2001
Appendix 5
Chairman and Vice Chairman List of the Hong Kong Cotton Spinners Association
Chapter 1 Textile Fibres ......................................... 1-2 Section 1 Fibres Commonly Used for Texilies and Clothing 1-2 1.1
Classification of Textile Fibres ........................................... 1-2
1.2
Natural Fibres ..................................................................... 1-2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7 1.2.8
1.3
Man-made Fibres ................................................................ 1-9 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7
1.4
Cotton ............................................................................. 1-2 Flax (Linen) .................................................................... 1-4 Jute ................................................................................. 1-5 Ramie ............................................................................. 1-5 Silk ................................................................................. 1-5 Wool ............................................................................... 1-6 Hair ................................................................................. 1-7 Asbestos ......................................................................... 1-8
Acetate ............................................................................ 1-9 Acrylic ............................................................................ 1-9 Nylon .............................................................................. 1-10 Polyester ......................................................................... 1-10 Rayon (Viscose Rayon) .................................................. 1-11 Spandex .......................................................................... 1-12 Olefin .............................................................................. 1-13
Microscopic Appearance of Common Textile Fibres ....... 1-14
Section 2 Fibre Properties ......................................................... 1-18 2.1
Desirable Fibre Properties ................................................. 1-18 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.1.8 2.1.9
Fibre length .................................................................... 1-18 Cross-sectional shape and surface .................................. 1-18 Straightness .................................................................... 1-18 Strength .......................................................................... 1-18 Extensibility and elasticity ............................................. 1-18 Hand feel ........................................................................ 1-19 Plasticity ......................................................................... 1-19 Absorbency .................................................................... 1-19 Abrasion resistance ........................................................ 1-19
2.1.10 2.1.11 2.1.12 2.1.13
Resiliency ....................................................................... 1-19 Lustre .............................................................................. 1-19 Density ........................................................................... 1-19 Wicking .......................................................................... 1-20
2.2
Important Characteristics and Major End-use of Textile Fibres .................................................................................... 1-21
2.3
Examples of Commercial Names and Manufacturers of Man-Made Fibres ............................................................... 1-25
2.4
Properties of Major Textile Fibres .................................... 1-30
2.5
Chemical Resistance of Fibres ........................................... 1-31
Section 3 Types of Cotton .......................................................... 1-32 3.1
Kinds and Types of Cotton ................................................. 1-32 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6
3.2
Classification of Cotton ...................................................... 1-38 3.2.1
3.3
The Features and Characteristics of the Three Principal Cotton Fibre Groups ....................................... 1-33 Structure and Properties of Cotton Fibre ....................... 1-34 Composition of Cotton Fibre .......................................... 1-35 Chemical Composition of Cotton Fibre .......................... 1-35 Physical Properties of Cotton Fibre (Upland Cotton) .... 1-36 Chemical Properties of Cotton Fibre .............................. 1-37
Classification of Upland Cotton ..................................... 1-38
Cotton Species ..................................................................... 1-44 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5
Upland Cotton ................................................................ 1-45 Sea-island Cotton ........................................................... 1-45 Peruvian Cotton .............................................................. 1-45 Asiatic Rough Cotton ..................................................... 1-45 Tree Cotton ..................................................................... 1-45
3.4
World Cotton Classification and Standard ...................... 1-46
3.5
Chinese Cotton Specification ............................................. 1-47 3.5.1 3.5.2
Chinese Cotton Grading ................................................. 1-47 . Length ............................................................................ 1-48
3.6
Indian Cotton Grading ....................................................... 1-50
3.7
Pakistan Cotton Grading ................................................... 1-51
3.8
Influence of the Fibre Characteristics of the Yarn .......... 1-51
3.9
Other Disturbing Factors in the Yarn Manufacturing Process .................................................................................. 1-53 3.9.1 3.9.2
Stickiness ........................................................................ 1-53 Cotton Contamination .................................................... 1-55
3.10 Relationship between Fibre Length, Fineness and Yarn Count to be Spun ................................................................ 1-64
Section 4 World Cotton Production ......................................... 1-65 4.1
World Cotton Production and Related Statistics ............. 1-65
4.2
The World’s Major Cotton Growing Areas ...................... 1-73 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6
China .............................................................................. 1-74 United States .................................................................. 1-75 India ................................................................................ 1-76 Pakistan .......................................................................... 1-77 Australia ......................................................................... 1-78 Republic of Uzbekistan .................................................. 1-79
Section 5 Man-Made Fibre Production ................................... 1-80 5.1
Methods of Man-Made Fibre Spinning ............................ 1-80 5.1.1 5.1.2 5.1.3 5.1.4
5.2
Wet Spinning .................................................................. 1-80 Dry Spinning .................................................................. 1-81 Melt Spinning ................................................................. 1-81 Gel Spinning ................................................................... 1-83
The Processing of Tow ........................................................ 1-84
Section 6 New Developement of Textile Fibres ....................... 1-85 6.1
Microfibres .......................................................................... 1-85 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6
Direct Spinning .............................................................. 1-85 Splittable Fibres ............................................................. 1-85 Mechanically Splittable Bicomponents .......................... 1-86 Solvent Splittable Bicomponents ................................... 1-86 Uses for Microfibres ...................................................... 1-86 Shin-Gosen ..................................................................... 1-88
6.2
Lyocell .................................................................................. 1-89 6.2.1 6.2.2
6.3
High Performance Fibres ................................................... 1-93 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6 6.3.7 6.3.8 6.3.9 6.3.10 6.3.11
6.4
TENCEL® ........................................................................................................................... 1-89 TENCEL® A100 ............................................................. 1-92
Aramids, Meta-aramid ................................................... 1-93 Para-aramid .................................................................... 1-94 Carbon Fibres — PAN and Pitch Based ......................... 1-94 Fluorocarbon Fibres (PTFE) .......................................... 1-94 Glass Fibre ..................................................................... 1-95 Melamine ........................................................................ 1-95 Polybenzimidazole — PBI ............................................. 1-95 Polyphenylenebenzobisoxazole — PBO1 ...................... 1-96 Cellulose acetate - MicroSafe ........................................ 1-96 Optical Fibres ................................................................. 1-96 Chitin, Chitosan (shells of crustacean) ........................... 1-97
Smart Technology for Textiles and Clothing .................... 1-97 6.4.1 6.4.2 6.4.3 6.4.4 6.4.5
Phase-Transition Materials and Polymer Crystals ......... 1-98 Smart Microcapsules/Microspheres ............................... 1-98 Smart Fibres for Measurement of Temperature, Moisture and Strain ........................................................ 1-99 Shape Memory Polymers ............................................... 1-99 Smart Gels and Gel Fibres ............................................. 1-100
Chapter 2 Spinning Processes and Types of Yarn 2-2 Section 1 Blowing Room Process .............................................. 2-2 1.1
Purpose of Blowing Room Process .................................... 2-2
1.2
Bale Opening ....................................................................... 2-2 1.2.1
1.3
Cleaning ............................................................................... 2-5 1.3.1 1.3.2 1.3.3
1.4
Features of Mixer and Blender ....................................... 2-9
Machine Arrangements ...................................................... 2-11 1.5.1
1.6
Purpose of Cleaning ....................................................... 2-5 Feeding System .............................................................. 2-5 Features of Some Cleaning Machines ............................ 2-6
Blending ............................................................................... 2-9 1.4.1
1.5
Features of some Automatic Bale Openers .................... 2-3
Examples of Machines Layout of Blowing Room ......... 2-11
Foreign Substance Detector ............................................... 2-13 1.6.1 The Vision Shield (Jossi) ................................................ 2-14 1.6.2 Securomat (Truetzschler) ................................................ 2-15 1.6.3 Cotton Sorter RX-CS (Barco) ........................................ 2-15 1.6.4 Optiscan (Uster) ............................................................. 2-16
1.7
Maintenance Recommendations for Opening and Cleaning Machines .............................................................. 2-17 1.7.1 1.7.2
1.8
Maintenance of Opening Room/Opening Hoppers ........ 2-17 Maintenance of Cleaners ................................................ 2-19
Trouble Shooting for Opening and Cleaning Machines .. 2-20
Section 2 Carding Process ......................................................... 2-25 2.1
Purpose of Carding ............................................................. 2-25
2.2
Carding Actions .................................................................. 2-26
2.3
Card Feeding System .......................................................... 2-27 2.3.1 2.3.2
Rieter Aerofeed U .......................................................... 2-27 Rieter UNIstore A 77 ...................................................... 2-28
2.3.3 2.3.4 2.3.5
Truetzschler Tuft Feeder Directfeed DFK ...................... 2-29 Truetzschler Sensofeed ................................................... 2-30 Truetzschler Webfeed ..................................................... 2-30
2.4
Card Clothing ...................................................................... 2-31
2.5
Card Clothing Specifications ............................................. 2-33 2.5.1 2.5.2 2.5.3 2.5.4
2.7
Card Setting Recommendations ........................................ 2-58 2.7.1 2.7.2 2.7.3
2.8
Conventional Revolving Flat Card ................................. 2-58 Rieter C51 Card .............................................................. 2-59 Truetzschler DK-803 Card ............................................. 2-60
Grinding ............................................................................... 2-61 2.8.1 2.8.2
2.9
ECC Card Clothing ........................................................ 2-33 Graf Card Clothing ......................................................... 2-36 Hollingsworth Card Clothing ......................................... 2-44 Kanai Card Clothing ...................................................... 2-48
Grinding Intervals .......................................................... 2-61 Rieter Integrated Grinding System (IGS) ...................... 2-61
New Features on Carding Machine ................................... 2-66 2.9.1 2.9.2 2.9.3 2.9.4 2.9.5
Precision Flat Setting System (Truetzschler) ................. 2-66 Flat Distance Measuring System .................................... 2-67 Webclean System (Truetzschler) .................................... 2-68 On-line Nep Counting (Truetzschler) ............................. 2-69 TREXplus (Rieter) ......................................................... 2-70
2.10 Tandem Card ....................................................................... 2-71 2.10.1 The New Twin Cylinder Card-Crosrol CST .................. 2-71 2.10.2 Technical Specification .................................................. 2-72
2.11 Production Calculations ..................................................... 2-73 2.12 Conversion of Grain Weight and Sliver Count ................ 2-74 2.13 Nep Counting ...................................................................... 2-74 2.13.1 Three Different Ways of Nep Counting ......................... 2-74 2.13.2 Nep Content of Card Web .............................................. 2-75
2.14 Uster AFIS N Application for Cotton Card Maintenance ........................................................................ 2-76 2.15 Maintenance Recommendations ........................................ 2-77 2.15.1 Lubrication Schedule ..................................................... 2-77
2.15.2 Cleaning Procedures For High Production Carding Equipment ...................................................................... 2-77
2.16 Troubleshooting ................................................................... 2-80
Section 3 Drawing Process ........................................................ 2-85 3.1
Purpose of Drawing ............................................................ 2-85
3.2
Definition of Draft ............................................................... 2-85
3.3
Drafting Zone Setting ......................................................... 2-87 3.3.1 3.3.2 3.3.3 3.3.4
3.4 3.5
Trumpet ............................................................................... 2-92 Sliver Can ............................................................................ 2-93 3.5.1 3.5.2 3.5.3
3.6
Order Specifications for Cans ........................................ 2-93 Specifications for Can’s Bottom With Casters ............... 2-94 Sliver Can Information ................................................... 2-94
Auto Levelling System ........................................................ 2-99 3.6.1
3.7
Technological Main Draft Roll Settings ......................... 2-87 Technological Break Draft Roll Setting ......................... 2-88 Draft Rolls Setting .......................................................... 2-89 Examples for Drafting System Setting of Rieters Draw Frame .................................................................... 2-91
Examples of some Auto Levelling Systems ................... 2-100
Recent Developments in Draw Frames ............................. 2-101 3.7.1 3.7.2 3.7.3
Integrated Draw Frame IDF ........................................... 2-101 CUBIcan Sliver Deposit System .................................... 2-103 Sliver Watch (Foreign Matter Detector) ......................... 2-103
3.8
Relationship between Sliver Weight and other Parameters ........................................................................... 2-105
3.9
Production Rate per Delivery Head of Draw Frame ....... 2-106
3.10 Front Roller Surface Speed in Relation to Production Rate ...................................................................................... 2-108 3.11 Relationship Between Sliver Weight and Production in Hanks and Pounds .............................................................. 2-109 3.12 Conversion of Sliver Weight to Sliver Count ................... 2-110 3.13 Maintenance of Draw Frame ............................................. 2-111 3.14 Possible Causes of Drawn Sliver Defects .......................... 2-113
Section 4 Combing Process ....................................................... 2-115 4.1
Purpose of Combing ........................................................... 2-115
4.2
Combing Preparation ......................................................... 2-115
4.3
Combing Mechanism .......................................................... 2-119 4.3.1 4.3.2
4.4
Introduction .................................................................... 2-119 Operations ...................................................................... 2-119
Combing Components Specification ................................. 2-125 4.4.1 4.4.2
Combing Cylinder .......................................................... 2-125 Top Comb ....................................................................... 2-127
4.5
Examples of Input and Output of Combing Process ....... 2-128
4.6
Advanced Development and Automation in Combing .... 2-129 4.6.1 4.6.2
4.7
Computer Aided Process Development ......................... 2-129 SERVOlap E 6/4 - L ....................................................... 2-130
Possible Faults in Combing ................................................ 2-131
Section 5 Roving Process ........................................................... 2-133 5.1
Function of Roving Process ................................................ 2-133
5.2
Drafting System .................................................................. 2-133 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6
5.3
In -feed Material ............................................................. 2-133 Total Draft ...................................................................... 2-133 Rear Draft ....................................................................... 2-134 Roller Loading ............................................................... 2-134 Top Roller Cots Grinding ............................................... 2-134 Roving Guide and Condensers ....................................... 2-134
Example of Drafting System on Speed Frame ................. 2-135 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 5.3.8 5.3.9 5.3.10
Zone Settings And Maximum Fibre Length ................... 2-136 Roller Loading ............................................................... 2-137 Top Apron Cradle System .............................................. 2-138 Opening at Apron Release Point .................................... 2-139 Top Aprons ..................................................................... 2-140 Top Roller Cots .............................................................. 2-141 Bottom Apron Nose Bar ................................................. 2-141 Rear Roving Guide ......................................................... 2-141 Rear Zone Condenser ..................................................... 2-142 Front Zone Condenser .................................................... 2-143
5.4
Roving Twist ........................................................................ 2-143 5.4.1 5.4.2 5.4.3
5.5
Flyer Speed and Roving Conditions .................................. 2-147 5.5.1 5.5.2
5.6
Relationship Between Fibre Fineness (Based On 1 Inch Fibre Length) and Twist Factor of Roving ..................... 2-144 Factors Affecting Twist Factor of Roving ...................... 2-145 Relationship Between Fibre Length and Twist Factor of Roving ........................................................................ 2-146
Flyer Speed ..................................................................... 2-147 Roving Weight ................................................................ 2-148
Bobbin Building .................................................................. 2-149 5.6.1
Bobbin Building Mechanism of Toyota Roving Frame .............................................................................. 2-149
5.7
Roving Tension Adjustment ............................................... 2-152
5.8
Horizontal Coil Density of Roving .................................... 2-153 5.8.1
5.9
Horizontal Coiling Density and Roving Count .............. 2-153
Number of Coils of Roving ................................................. 2-154
5.10 Number of Coils Per Inch of Roving ................................. 2-155 5.11 Common Defects in Roving ................................................ 2-156 5.12 Factors Affecting Roving Elongation and Remedies ....... 2-158 5.13 Machine Automation .......................................................... 2-159 5.13.1 Automatic Doffing and Bobbin Transfer System (RO-WE-MAT 670 Roving Frame, Zinser) ................... 2-159 5.13.2 Automatic Transfer System (Toyota) ............................. 2-160
Section 6 Spinning Process........................................................ 2-162 6.1
Purpose of Spinning ............................................................ 2-162
6.2
Process Flow Chart for Various Common Spinning Systems ................................................................................. 2-162
6.3
Ring Spinning ...................................................................... 2-162 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6
Drafting System ............................................................. 2-163 Draft zones ..................................................................... 2-164 Examples of Drafting System for Cotton Ring Frame ... 2-164 Top Roller Cots .............................................................. 2-172 Twisting .......................................................................... 2-179 Ring ................................................................................ 2-179
6.3.7 6.3.8 6.3.9 6.3.10 6.3.11 6.3.12 6.3.13 6.3.14 6.3.15 6.3.16 6.3.17
6.4
Open-End Spinning ............................................................ 2-218 6.4.1 6.4.2 6.4.3 6.4.4
6.5
Principle of Open-end Spinning ..................................... 2-218 Relationship between Rotor Speed, Rotor Type and Yarn Count .............................................................................. 2-224 Layout of Spinning Components ................................... 2-225 Example of Recent Development in OE Spinning ......... 2-228
AIR-JET SPINNING .......................................................... 2-230 6.5.1 6.5.2 6.5.3
6.6
Traveller ......................................................................... 2-186 Wear and Life of the Traveller and Ring ........................ 2-191 Setting of Traveller Cleaner ........................................... 2-194 Traveller Speed in m/s .................................................... 2-197 Relationship between Inside Diameter of Ring, Spindle Revolution and Traveller Circumferential Speed .......... 2-198 Relationship between Bobbin Diameter, Twist Number, Spindle Revolution, and Traveller Revolution ............... 2-199 Relationship between Inside Diameter of Ring, Bobbin Diameter and Winding Angle ......................................... 2-200 Ratio Values of Ring Diameter, Bobbin Diameter, Bobbin Length And Spindle Gauge ............................................ 2-201 High Performance Ring and Traveller ........................... 2-203 Suessen Novibra Spindle HP-S 68 and Spindle Bearing ........................................................................... 2-208 Bobbin Building ............................................................. 2-213
Processing Parameters and Fibre Characteristics for Spinning 100% Cotton Yarn ........................................... 2-231 Muratec 851 MVS Air-jet Spinning Machine ................ 2-236 Muratec 804 RJS - Roller Jet Spinning .......................... 2-236
Various Developments in Spinning ................................... 2-237 6.6.1 6.6.2 6.6.3 6.6.4
Suessen Ring-Can Spinning System .............................. 2-237 Rieter ComforSpin ......................................................... 2-238 Suessen EliTe Yarn ......................................................... 2-239 Zinser Compact Yarn ...................................................... 2-241
Section 7 Winding Process ........................................................ 2-243 7.1
Purpose of Winding ............................................................ 2-243
7.2
Knotting Mechanism .......................................................... 2-243
7.3
Air Splicing Mechanism ..................................................... 2-246
7.4
Correct Build of Ring Cops ................................................ 2-247 7.4.1 7.4.2 7.4.3
7.5
Measures to Prevent Ribbon Winding .............................. 2-251 7.5.1 7.5.2 7.5.3 7.5.4 7.5.5 7.5.6 7.5.7
7.6
Causes of Sloughing ....................................................... 2-247 Optimum Shaping of Spinning Bobbin .......................... 2-248 Balloon Breaker ............................................................. 2-250
Ribbon Winding ............................................................. 2-251 Measures to Prevent Ribbon Winding ............................ 2-252 Contact Pressure ............................................................. 2-252 Ribbon Breaker Interval ................................................. 2-253 Tension ........................................................................... 2-256 Increase (dish) ................................................................ 2-256 Drum .............................................................................. 2-257
Balloon Control and Tensioning Device ............................ 2-258 7.6.1 7.6.2
Tension Manager and Bal-Con (Muratec) ...................... 2-258 Autotense Yarn Tension Control (Autoconer338) .......... 2-259
7.7
Calculation of Package Density ......................................... 2-261
7.8
Measures Against Excessive Yarn Breakage .................... 2-263
7.9
Causes and Corrective Actions for Poor Winding ........... 2-264
7.10 Electronic Yarn Clearer ...................................................... 2-267 7.11 Conversion Graph of Peyer and UAM ............................. 2-269 7.12 Correlation Between Material and Type of Yarn by the Static Electricity Amount ................................................... 2-270 7.13 Material Setting of Uster UAM Yarn Clearer .................. 2-271 7.14 Types of Yarn Faults ........................................................... 2-271
Section 8 Twisting Process ........................................................ 2-273 8.1
Up Twister ........................................................................... 2-273
8.2
Ring Twister ........................................................................ 2-273
8.3
Two-for-One Twisting ......................................................... 2-274 8.3.1 8.3.2 8.3.3
8.4
Two-for-One Principle ................................................... 2-274 Characteristics of Two-for-One Twisting ....................... 2-275 Tritec Twister .................................................................. 2-275
Twisting Parameter ............................................................. 2-277
Section 9 Application of Information Technology in Spinning ....................................................................... 2-283 9.1
ABC-Control for Blow Room and Carding ...................... 2-283
9.2
Spiderweb : The Mill Data and Information System ...... 2-284
9.3
Barco Sycotex System ......................................................... 2-286
9.4
Uster Labdata ...................................................................... 2-286
Section 10 Special Types of Yarns ............................................ 2-287 10.1 Production of Rough-Spun (Slub and Neps) Yarn on Conventional Equipment ................................................... 2-287 10.1.1 10.1.2 10.1.3 10.1.4
Introduction .................................................................... 2-287 Machinery Settings ......................................................... 2-287 Maintenance ................................................................... 2-288 Other Considerations ...................................................... 2-288
10.2 Recommendation for Producing Linen-Look Yarn on Conventional Equipment ................................................... 2-290 10.2.1 Operating Procedures ....................................................... 2-290 10.2.2 Experiment Details ......................................................... 2-291
10.3 Slub Effect Yarn with Amsler GOE Device on OE Spinning Machine ............................................................................... 2-293 10.3.1 Function .......................................................................... 2-293
10.4 Amsler Cortex System ........................................................ 2-295 10.4.1 Features .......................................................................... 2-295
10.5 Core Spun Yarn by Plyfil Spinning System ...................... 2-297 10.5.1 Equipment for Hard Core Yarns ..................................... 2-297 10.5.2 Equipment for Soft Core Yarns ...................................... 2-298 10.5.3 The advantages of PLYfiL ............................................. 2-300
10.6 Parallel Yarn by Parafil Spinning System ........................ 2-301 10.6.1 Structure of Parallel Yarn ............................................... 2-301 10.6.2 Properties of Parallel Yarn .............................................. 2-302
Section 11 Wool Spinning Process ............................................ 2-304 11.1 Worsted System ................................................................... 2-304 11.1.1 The Worsted Spinning Process Flow .............................. 2-304 11.1.2 Scouring ......................................................................... 2-304 11.1.3 Drying ............................................................................ 2-304 11.1.4 Oiling .............................................................................. 2-305 11.1.5 Carding ........................................................................... 2-305 11.1.6 Backwashing .................................................................. 2-305 11.1.7 Combing ......................................................................... 2-305 11.1.8 Gilling ............................................................................ 2-306 11.1.9 Drawing .......................................................................... 2-306 11.1.10 Spinning ......................................................................... 2-306
11.2 Woollen System ................................................................... 2-306 11.2.1 11.2.2 11.2.3 11.2.4 11.2.5 11.2.6 11.2.7 11.2.8
Woollen Spinning Process Flow .................................... 2-306 Scouring and drying ....................................................... 2-307 Carbonizing .................................................................... 2-307 Dyeing ............................................................................ 2-307 Blending ......................................................................... 2-307 Oiling .............................................................................. 2-307 Carding ........................................................................... 2-307 Spinning ......................................................................... 2-307
Section 12 Texturing .................................................................. 2-308 12.1 Purpose of Texturing .......................................................... 2-308 12.2 False Twist Method ............................................................. 2-308 12.3 Edge-Crimped Yarns .......................................................... 2-310 12.4 Stuffer-Box Crimping ......................................................... 2-311 12.5 Air-Textured Yarns ............................................................. 2-312 12.6 Knit-De-Knit Method ......................................................... 2-313 12.7 Gear Crimping .................................................................... 2-313 12.8 Twist-Textured Yarns .......................................................... 2-313
Charter 3 Weaving and Woven Fabrics... ............ 3-2 Section 1 Warp Preparation Process ........................................ 3-2 1.1
Warping Process ................................................................. 3-2 1.1.1 1.1.2 1.1.3
Direct Beaming .............................................................. 3-2 Section Warping ............................................................. 3-2 Ball Warping ................................................................... 3-3
1.2
Warping Data ...................................................................... 3-3
1.3
Examples of Machine Settings for Warping ..................... 3-5
1.4
Recent Development in Sectional Warping Machine ...... 3-5
1.5
Defects and Possible Causes in Direct Beaming ............... 3-6
1.6
Warp Preparation for Rope Dyeing .................................. 3-9 1.6.1 1.6.2 1.6.3 1.6.4 1.6.5 1.6.6
1.7
Slasher Dyeing ..................................................................... 3-13 1.7.1 1.7.2 1.7.3
1.8
Ball Warper Specification ............................................. 3-9 Ball Warping Process Parameters ................................... 3-9 Rope Dyeing ................................................................... 3-10 Typical Recipe of Master Solution for Rope Dyeing ..... 3-11 Technical Features of Rope Dyeing Range .................... 3-12 Processing Parameters for Re-Beaming Of Rope Dyeing ............................................................................ 3-13
Warping Requirements ................................................... 3-14 Typical Recipes of Master Solution for Slasher Dyeing 3-15 Slasher Dyeing Processing Parameters .......................... 3-16
Rope Dyeing Versus Slasher Dyeing .................................. 3-16 1.8.1 1.8.2
Characteristics of Rope Dyeing ..................................... 3-16 Disadvantages of Rope Dyeing ...................................... 3-17
Section 2 Warp Sizing ............................................................... 3-19 2.1
Purpose of Warp Sizing ...................................................... 3-19
2.2
Warp Size Types and Properties ........................................ 3-19 2.2.1 2.2.2
Warp Size Types And Properties .................................... 3-19 Size Auxiliary Chemicals ............................................... 3-23
2.3
Sizing Agents and Applications .......................................... 3-25
2.4
Examples of Recipes of Sizing Solution ............................ 3-25 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5
Protein Sizes ................................................................... 3-25 Starch Sizes .................................................................... 3-25 Cellulose Ether Sizes ...................................................... 3-26 Polyvinyl Alcohol Sizes ................................................. 3-26 Acrylate Copolymer Sizes .............................................. 3-27
2.5
Comparison of the Properties of Four Types of Sizing Agent .................................................................................... 3-27
2.6
Emulsified Oil, Liquid Wax and Solid Wax ..................... 3-28
2.7
Manufacturers and Brand of Commonly Used Liquid Wax ....................................................................................... 3-28
2.8
Size Defects and Possible Causes ....................................... 3-29
2.9
Sizing Process Defects and Possible Causes ..................... 3-30
2.10
Example of Warp Tension for Cotton Yarn during Sizing .................................................................................... 3-34
2.11 Guidelines for the Sizing of Denim .................................... 3-35 2.11.1 Size Requirements .......................................................... 3-35 2.11.2 Causes of Faults in Sizing and its Solutions .................. 3-35
2.12 Recent Development in Sizing ........................................... 3-37 2.12.1 Wetsize Box SC (Sucker-Mueller-Hacoba) .................... 3-37 2.12.2 Ben-ecosize (Benninger) ................................................ 3-37
Section 3 Weaving Preparation ................................................ 3-38 3.1
Introduction ......................................................................... 3-38 3.1.1 3.1.2
Leasing ........................................................................... 3-38 Drawing-in ..................................................................... 3-38
3.2
Specifications of Heald Wires ............................................ 3-38
3.3
Specifications of Drop Wire ............................................... 3-40
3.4
Reed ...................................................................................... 3-43
3.5
Tying-in ................................................................................ 3-44
3.6
Recent Development in Weaving Preparation ................. 3-44 3.6.1 3.6.2
Quick Style Change in Weaving .................................... 3-44 The Process Flow of a QSC System .............................. 3-44
Section 4 Weaving ...................................................................... 3-47 4.1 4.2
Introduction ......................................................................... 3-47 Basic Motions of A Weaving Machine ............................... 3-47 4.2.1 4.2.2 4.2.3
Shuttle Loom .................................................................. 3-47 Shuttleless Looms .......................................................... 3-48 Useful Calculation Formulae for Weaving ..................... 3-54
Section 5 Woven Fabric Features ............................................. 3-56 5.1
Introduction ......................................................................... 3-56
5.2
Warp and Weft Yarns ......................................................... 3-56
5.3
Selvedges .............................................................................. 3-57 5.3.1 Selvedge Structure for Conventional Loom ...................... 3-58 5.3.2 Selvedge Problem .............................................................. 3-62
5.4
Yarns Per Unit Length ........................................................ 3-62
5.5
Face and Back ..................................................................... 3-63
5.6
Top and Bottom ................................................................... 3-63
Section 6 Woven Structure ........................................................ 3-64 6.1
Introduction ......................................................................... 3-64
6.2
Plain Weave ......................................................................... 3-64 6.2.1 6.2.2 6.2.3
6.3
Twill Weave ......................................................................... 3-67 6.3.1 6.3.2
6.4
Characteristics ................................................................ 3-64 Ribbed Plain Fabrics ...................................................... 3-65 Plain Weave Derivative .................................................. 3-66
Characteristics ................................................................ 3-69 Broken Twill Weave ....................................................... 3-70
Satin Weave ......................................................................... 3-70 6.4.1 6.4.2 6.4.3
Satin-Weave Fabric ........................................................ 3-71 Sateen Fabric .................................................................. 3-71 Characteristics ................................................................ 3-72
6.5
Comparison of Basic Weave Properties ............................ 3-72
6.6
Special Weave Sturctures ................................................... 3-72 6.6.1
Pile Weaves .................................................................... 3-72
6.6.2 6.6.3 6.6.4 6.6.5
6.7
Woven Pattern Design ........................................................ 3-77 6.7.1 6.7.2 6.7.3
6.8
Double-cloth Weave ....................................................... 3-75 Crepe Weave ................................................................... 3-75 Leno Weave .................................................................... 3-76 Swivel Weave ................................................................. 3-76
Introduction .................................................................... 3-77 Dobby Pattern ................................................................. 3-77 Jacquard Pattern ............................................................. 3-78
A Summary of Special Weaves and their Characteristics 3-79
Section 7 Woven Fabric Analysis ............................................. 3-81 7.1
Introduction ......................................................................... 3-81
7.2
Identification of the Construction of a Fabric ................. 3-81
7.3
Determining Yarn Counts of a Fabric ............................... 3-82
7.4
Fabric Weight ...................................................................... 3-82 7.4.1 7.4.2
Expression of Fabric Weight .......................................... 3-82 Fabric Weight Calculation .............................................. 3-82
7.5
Converting Fabric Weight from one System to Another . 3-83
7.6
Weight of Silk Fabric .......................................................... 3-84
7.7
Woven Fabric Design .......................................................... 3-84 7.7.1 7.7.2 7.7.3
7.8
Cloth Setting Theories .................................................... 3-84 Similarly Built Cloths .................................................... 3-89 Other Expression of Setting ........................................... 3-91
Fabric Cover ........................................................................ 3-92 7.8.1 7.8.2
Cover and Cover Factor (F.T. Peirce) ............................ 3-92 Cloth Cover Factor ......................................................... 3-94
Chapter 4 Knitting and Knitted Fabrics .............. 4-2 Section 1 Knitting ..................................................................... 4-2 1.1
Knitting Process .................................................................. 4-2
1.2
Weft-Knitting ...................................................................... 4-2
1.3
Weft Knitting Machines ..................................................... 4-3 1.3.1 1.3.2
1.4
Two Types of Knitting Machines Using Beard Needles 4-3 Two Types of Knitting Machines Using Latch Needles 4-4
Key Components for Weft Knitted Fabric Formation .... 4-5 1.4.1 1.4.2 1.4.4 1.4.3 1.4.5 1.4.6
Knitting Needles ............................................................. 4-5 Needle Bed ..................................................................... 4-6 Yarn Feeding .................................................................. 4-7 Cam Box ......................................................................... 4-7 Sinker ............................................................................. 4-8 Key Terms of Knitted Fabric .......................................... 4-9
1.5
Stitch (loop) Formation Sequence on a Latch Needle ..... 4-10
1.6
Types of Knitting Stitches .................................................. 4-11 1.6.1 1.6.2 1.6.3
1.7
Plain Stitch ..................................................................... 4-11 Miss Stitch (Welt or float) .............................................. 4-11 Tuck Stitch ..................................................................... 4-11
Recent Developments in Weft Knitting ............................. 4-12 1.7.1 1.7.2
Examples of Recent Developments in Flat Knitting Machines ........................................................................ 4-13 Examples of Recent Developments in Circular Knitting machines ......................................................................... 4-14
Section 2 Typical Weft-Knit Structure ..................................... 4-17 2.1
Methods Used to Represent Weft-Knitted Structures ..... 4-17 2.1.1
2.2
Three Kinds of Methods used to Represent Weft Knitted Structure ............................................................ 4-17
Single Knit Structures ........................................................ 4-18 2.2.1 2.2.2
Plain Knit. ...................................................................... 4-18 Lacoste ........................................................................... 4-19
2.3
Double Knit Structures ...................................................... 4-20 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7
2.4
Structures and Techniques Commonly Applied to Sweaters ............................................................................... 4-24 2.4.1 2.4.2
2.5
Rib .................................................................................. 4-20 Half Milano .................................................................... 4-20 Full Milano ..................................................................... 4-21 Full Cardigan .................................................................. 4-21 Half Cardigan ................................................................. 4-22 Purl Structure ................................................................. 4-22 Interlock Fabrics ............................................................. 4-24
Intarsia ............................................................................ 4-24 Designs Through Loop Transfer .................................... 4-25
Special Knit Fabrics Produced by Circular Knitting ..... 4-26 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7
High-Pile Knits ............................................................... 4-26 Knitted Terry .................................................................. 4-27 Knitted Velour ................................................................ 4-28 Fleecy Fabric .................................................................. 4-28 Coloured Stripe Fabrics .................................................. 4-29 Jacquard Fabric .............................................................. 4-30 Polar Fleece .................................................................... 4-31
Section 3 Yarn Count and Machine Gauge ............................. 4-32 3.1
Yarn Count and Machine Gauge for Circular Knit ........ 4-32
3.2
Yarn Count and Machine Gauge for Wool Knitwear ...... 4-34
Section 4 Quality and Production of Circular Kniting .......... 4-36 4.1
Pre-requisites of a Circular Knitting Machine ................. 4-36
4.2
Production Conditions for Knitting .................................. 4-37 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5
4.3
Selection of Proper Yarn Count ...................................... 4-37 Setting of the Knitting Machine. .................................... 4-37 Yarn Storage ................................................................... 4-38 Air Conditioning of the Knitting Plant ........................... 4-38 Cleaning of Knitting Machines ...................................... 4-38
Production Calculations ..................................................... 4-38 4.3.1
Introduction .................................................................... 4-38
4.4
Quality Characteristics of Ring-spun 100% Combed Cotton Yarn for Circular Weft Knitting ........................... 4-40
Section 5 Fabric Analysis ......................................................... 4-45 5.1
The Geometry of Plain Weft-knitted Fabric .................... 4-45
5.2
Stitch Density (Fabric Count) ............................................ 4-46
5.3
Cover Factor ........................................................................ 4-46
5.4
Prediction of Knitted Performance by Mathematical Model ................................................................................... 4-47 5.4.1 5.4.2 5.4.3 5.4.4
5.5
Engineering the Fabric ................................................... 4-47 Checking the Specification ............................................ 4-47 Calculations Based on K values ..................................... 4-48 Limitations of K values .................................................. 4-50
STARFISH - Engineered Knitted Program for Cotton Circular Knits ..................................................................... 4-51
Section 6 Typical Fabric Imperfections on Circular Knitting4-53 6.1
Fabric Skew ......................................................................... 4-53 6.1.1 6.1.2 6.1.3 6.1.4
6.2
Barre .................................................................................... 4-58 6.2.1 6.2.2
7.2
Definition ....................................................................... 4-53 Causes ............................................................................ 4-53 Evaluation of the Effect of Yarn, Knitting and Finishing Parameters on Skew ....................................................... 4-54 Summary ........................................................................ 4-58
Definition of Barre ......................................................... 4-58 Causes of Barre .............................................................. 4-58
Warp Knitting Machine Classification ............................. 4-61
Section 7 Warp knitting and Warp Knitted Fabrics ..............4-61 7.1
Warp Knitting ..................................................................... 4-61 7.2.1 7.2.2
Tricot Machines .............................................................. 4-62 Raschel Machines ........................................................... 4-62
7.3
Knitting Elements of Warp Knitting Machine ................. 4-63 7.3.1 7.3.2 7.3.3 7.3.4
7.4
Key Terms of Warp Knits .................................................. 4-66 7.4.1 7.4.2 7.4.3 7.4.4 7.4.5 7.4.6 7.4.7
7.5
Needle ............................................................................ 4-63 The Sinker ...................................................................... 4-64 Guides and Guide Bars ................................................... 4-64 Driving Mechanisms of Knitting Elements .................... 4-65
Course and Wales ........................................................... 4-66 Stitch Density ................................................................. 4-66 Loop Parts ...................................................................... 4-66 Open and Closed Laps ................................................... 4-67 Technical Back ............................................................... 4-67 Technical Face ................................................................ 4-67 Run-in ............................................................................. 4-68
Common Warp Knit Fabric Structures and their Characteristics .................................................................... 4-68 7.5.1 7.5.2
Tricot Fabrics ................................................................. 4-68 Raschel Fabrics .............................................................. 4-72
Chapter 5 Textile Coloration and Finishing Treatments ............................................ 5-2 Section 1 Textile Coloration and Finishing ............................. 5-2 1.1
Introduction ......................................................................... 5-2
1.2
Preparation of Cotton Goods ............................................. 5-2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7
Grey Inspection ............................................................. 5-3 Singeing .......................................................................... 5-3 Desizing .......................................................................... 5-3 Scouring ......................................................................... 5-3 Bleaching ........................................................................ 5-4 Mercerization ................................................................. 5-5 Summary ........................................................................ 5-5
1.3
Fluorescent Brightening ..................................................... 5-5
1.4
Dyeing .................................................................................. 5-6 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5 1.4.6 1.4.7 1.4.8 1.4.9
1.5
Printing ................................................................................ 5-22 1.5.1 1.5.2 1.5.3 1.5.4 1.5.5
1.6
Terminology Relating to Dyeing .................................... 5-6 Factors that Affect Dyeing ............................................. 5-7 Classification of Dyes .................................................... 5-8 Colour Formulation ........................................................ 5-10 Colour Fastness .............................................................. 5-10 Application of Pigments ................................................. 5-12 Methods of Dyeing ......................................................... 5-12 Special Dyeing Effects ................................................... 5-20 Computer Colour Matching ........................................... 5-20
General Printing Procedures .......................................... 5-23 Methods of Printing ........................................................ 5-25 Printing Effects ............................................................... 5-33 Types of Prints ................................................................ 5-33 CAD/CAM System for Textile Printing ......................... 5-35
Finishing .............................................................................. 5-36 1.6.1 1.6.2 1.6.3
Preparation ..................................................................... 5-36 Finishing ......................................................................... 5-37 Classification of Finishing ............................................. 5-37
Section 2 Common Finishing Treatments for Cotton Fabrics 5-44 2.1
Wrinkle-free Treatment of Cotton Fabrics and Garments ............................................................................. 5-44 2.1.1 2.1.2
2.2
General Considerations for Wrinkle-free Treatment ...... 5-44 Treatment Processes ....................................................... 5-45
Flame Retardant Treatment on Cotton Fabric by Precondensate/NH3 Process ............................................... 5-50 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7
2.3
Fabric Preparation .......................................................... 5-50 Precondensate Formulation ............................................ 5-50 Application ..................................................................... 5-51 Ammoniation .................................................................. 5-51 Oxidation and Process Washing ..................................... 5-53 Fabric After-Treatments ................................................. 5-54 Treatment of Cotton Blended Fabrics ............................ 5-54
Hints for Wet Processing of Cotton/Spandex Fabric ....... 5-55 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 2.3.8 2.3.9 2.3.10
Spandex in Knitted Fabric .............................................. 5-55 Relaxation ...................................................................... 5-55 Heat-Setting .................................................................... 5-56 Dyeing ............................................................................ 5-57 Drying ............................................................................ 5-58 Cotton/Spandex Woven Fabric ....................................... 5-58 Relaxation ...................................................................... 5-58 Heat-Setting .................................................................... 5-58 Dyeing ............................................................................ 5-59 Finishing ......................................................................... 5-59
Chapter 6 Textiles Testing and Quality Control .. 6-2 Section 1 Cotton Fibre Testing ................................................. 6-2 1.1
Terms Relating to the Conditioning and Testing of Textiles ................................................................................. 6-2
1.2
Recommendations for a Physical Testing Laboratory for Fibre and Yarn .............................................................. 6-3
1.3
Fibre Testing Condition ...................................................... 6-4 1.3.1
1.4
Fibre Moisture ..................................................................... 6-4 1.4.1 1.4.2 1.4.3
1.5
1.5.4
Micronaire Testing Procedure ........................................ 6-18 Calculation of Average Fibre Fineness ........................... 6-19
Fibre Maturity Testing ....................................................... 6-20 1.7.1 1.7.2 1.7.3
1.8
Staple Diagram Method - Shirley Comb Sorter ............. 6-9 Fibrograph ...................................................................... 6-11 Comparison and Evaluation of Staple Diagram and Fibrogram ....................................................................... 6-13 Staple Length Conversion .............................................. 6-17
Fibre Fineness Testing ........................................................ 6-17 1.6.1 1.6.2
1.7
Measurement of Moisture Regain .................................. 6-4 Commercial Moisture Regain Values ............................. 6-5 Relationship of Temperature and Relative Humidity on Moisture Regain of Cotton ........................................ 6-7
Fibre Length Testing Principle .......................................... 6-8 1.5.1 1.5.2 1.5.3
1.6
Ambient Laboratory Conditions for Fibre Testing ......... 6-4
Microscopic Array Method ............................................ 6-20 Differential Dyeing ........................................................ 6-21 Caustic Method .............................................................. 6-21
Fibre Strength Testing ........................................................ 6-22 1.8.1 1.8.2 1.8.3
Pressley Fibre Strength Tester ........................................ 6-22 Stelometer ...................................................................... 6-24 Pressley Index and Fibre Strength (lb/in2) Conversion Table ............................................................................... 6-25
1.9
Fibre Dust and Trash .......................................................... 6-26 1.9.1 Definition of Dust and Trash .......................................... 6-26 1.9.2 Trash And Dust Measurement By Using Shirley Analyzer ......................................................................... 6-27
1.10 Fibre Identification ............................................................. 6-29 1.11 Typical Fibre Testing Equipment ...................................... 6-34 1.11.1 1.11.2 1.11.3 1.11.4
High Volume Instrument (HVI) ..................................... 6-34 Advanced Fibre Information System (Uster AFIS) ....... 6-38 MicroDust and Trash Analyser (Uster MDTA 3) ........... 6-40 Comparison Between Uster® MDTA 3 and Uster®AFIS-T ................................................................. 6-41 1.11.5 Recommendations for Fields of Application .................. 6-43 1.11.6 Statistics on Raw Cotton Fibre Properties Determined with Uster HVI ............................................................... 6-44
Section 2 Yarn Testing ............................................................... 6-49 2.1
Yarn Conditioning .............................................................. 6-49 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5
2.2
Basis of Unscoured Yarn ................................................ 6-49 Basis of Scoured Yarn .................................................... 6-49 Preconditioning .............................................................. 6-49 Conditioning ................................................................... 6-50 Oven-Drying .................................................................. 6-50
Yarn Numbering Systems ................................................... 6-50 2.2.1 2.2.2 2.2.3
Direct and Indirect Systems ........................................... 6-50 Conversion Between Yarn Numbering Systems ............ 6-52 Yarn Diameter ................................................................ 6-52
2.3
Testing Plan ......................................................................... 6-52
2.4
Yarn Count Testing ............................................................. 6-61 2.4.1 2.4.2 2.4.3
2.5
Lea Yarn Strength ............................................................... 6-62 2.5.1 2.5.2
2.6
Instruments ..................................................................... 6-61 Sampling ........................................................................ 6-61 Testing Procedure ........................................................... 6-61
Lea Yarn Strength Testing .............................................. 6-62 Yarn Strength Conversion .............................................. 6-62
Yarn Twist Testing .............................................................. 6-65
2.7
Yarn Appearance Characteristics ..................................... 6-66 2.7.1 2.7.2 2.7.3 2.7.4 2.7.5
2.8
Tensile Properties ................................................................ 6-71 2.8.1
2.9
Count Variation .............................................................. 6-66 Mass Variation ................................................................ 6-66 Hairiness ......................................................................... 6-67 Imperfections .................................................................. 6-67 Testing of Yarn Appearance Characteristics (Uster® Yarn Testing Series) ................................................................ 6-67
Uster Tensojet ................................................................. 6-72
Classimat Defects ................................................................ 6-73
2.10 Yarn Quality Statistics of 100% Cotton Carded Ring Spun Yarns ........................................................................... 6-74 2.10.1 2.10.3 2.10.2 2.10.4 2.10.5
Yarn Quality ................................................................... 6-74 CLASSIMAT Defects .................................................... 6-77 Imperfections .................................................................. 6-77 Tensile Properties ........................................................... 6-78 HV Tensile Properties .................................................... 6-81
2.11 Standard Tolerances for Yarn Spun on the Cotton System .................................................................................. 6-85 2.11.1 2.11.2 2.11.3 2.11.4 2.11.5 2.11.6
Strength .......................................................................... 6-85 Yarn Number .................................................................. 6-85 Twist ............................................................................... 6-85 Extractable Matter .......................................................... 6-85 Appearance ..................................................................... 6-85 Uniformity ...................................................................... 6-86
2.12 New Developments in Testing ............................................ 6-86 2.12.1 Uster® Qualiprofile ......................................................... 6-86 2.12.2 Uster® Lab Expert .......................................................... 6-87
Section 3 Woven Fabric Inspection and Testing .................... 6-88 3.1
Woven Fabric Testing ......................................................... 6-88 3.1.1 3.1.2 3.1.3 3.1.4
Fabric Construction ........................................................ 6-88 Durability, Aesthetics and Environmental Resistance ... 6-91 Fabric Strength ............................................................... 6-94 Relationship Between Strip Test & Grab Test ................ 6-95
3.2
Woven Fabric Inspection System ...................................... 6-95 3.2.1 3.2.2 3.2.3
4 Point System ................................................................ 6-95 10 Point System .............................................................. 6-98 Graniteville “78” System of Visual Quality Evaluation for Woven and Knitted Fabrics ...................................... 6-99
Section 4 Knitted Fabric Inspection and Testing .................... 6-101 4.1
Knitted Fabric Testing ........................................................ 6-101 4.1.1 4.1.2 4.1.3
4.2
Fabric Construction ........................................................ 6-101 Durability, Aesthetics and Environmental Resistance ... 6-102 Fabric Strength Testing .................................................. 6-102
Knitted Fabric Inspection Systems ................................... 16-02 4.2.1 4.2.2 4.2.3
The KTA System for Circular Knitted Fabrics ............... 6-102 The KTA System for Raschel Knitted Fabrics ............... 6-104 The KTA System for Tricot Fabrics ............................... 6-107
Section 5 Fabric Quality and Performance ............................. 6-113 5.1
Quality Standard and Performance Tests for Apparel .... 6-113 5.1.2
5.2
Quality Guideline for Fabrics Containing Lycra® .................. 6-116
US Standard for Flammability .......................................... 6-120 5.2.1 5.2.2 5.2.3
Flammable Fabrics Act Standards - USA ...................... 6-120 Federal Test Method Standard 191 - Textile Test Methods .......................................................................... 6-122 Miscellaneous Tests ........................................................ 6-123
5.3
Woven Fabric Defect Description and Cause ................... 6-124
5.4
Illustrations of Woven Fabric Faults ................................ 6-129
5.5
Knitted Fabric Defect Description and Cause ................. 6-136
5.6
Illustrations of Knitted Fabric Faults ............................... 6-140
Chapter 1 Textile Fibres ........................................ 1-2 Section 1 - Fibres Commonly Used for Textiles and Clothing...............................................1-2 1.1
Classification of Textile Fibres .......................................... 1-2
1.2
Natural Fibres .................................................................... 1-2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7 1.2.8
1.3
1-2 1-4 1-4 1-5 1-5 1-6 1-7 1-8
Man-made Fibres ............................................................... 1-9 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7
1.4
Cotton ........................................................................... Flax (Linen) .................................................................. Jute ............................................................................... Ramie ........................................................................... Silk ............................................................................... Wool ............................................................................. Hair ............................................................................... Asbestos .......................................................................
Acetate .......................................................................... Acrylic .......................................................................... Nylon ............................................................................ Polyester ....................................................................... Rayon (Viscose Rayon) ................................................ Spandex ........................................................................ Olefin ............................................................................
1-9 1-9 1-10 1-10 1-11 1-12 1-13
Microscopic Appearance of Common Textile Fibres ...... 1-14
Section 2 - Fibre Production......................................... 1-18 2.1
Desirable Fibre Properties ................................................ 1-18 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7
Fibre length .................................................................. Cross-sectional shape and surface ................................ Straightness .................................................................. Strength ........................................................................ Extensibility and elasticity ........................................... Hand feel ...................................................................... Plasticity .......................................................................
1-18 1-18 1-18 1-18 1-18 1-19 1-19
2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 2.1.13
Absorbency .................................................................. Abrasion resistance ...................................................... Resiliency ..................................................................... Lustre ............................................................................ Density ......................................................................... Wicking ........................................................................
1-19 1-19 1-19 1-19 1-19 1-20
2.2
Important Characteristics and Major End-use of Textile Fibres ...................................................................... 1-21
2.3
Examples of Commercial Names and Manufacturers of Man-Made Fibres .......................................................... 1-25
2.4
Properties of Major Textile Fibres ................................... 1-30
2.5
Chemical Resistance of Fibres .......................................... 1-31
Section 3 Types of Cotton ...........................................1-32 3.1
Kinds and Types of Cotton ................................................ 1-32 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6
3.2
The Features and Characteristics of the Three .............. Principal Cotton Fibre Groups ..................................... Structure and Properties of Cotton Fibre ..................... Composition of Cotton Fibre ........................................ Chemical composition of Cotton Fibre ......................... Physical properties of Cotton fibre (Upland Cotton) ........................................................... Chemical Properties of Cotton Fibre ............................
1-33 1-34 1-35 1-35 1-36 1-37
Classification of Cotton ..................................................... 1-38 3.2.1
Classification of Upland Cotton ................................... 1-38
Back to Table of Content
Chapter 1
TEXTILE FIBRES
1-2
Textile Fibres
CHAPTER 1......... .........TEXTILE FIBRES SECTION 1
FIBRES COMMONLY USED FOR TEXTILES AND CLOTHING
1.1 Classification of Textile Fibres Textile fibre is an individual, fine, hair-like substance, which forms the fundamental element of textile yarn and fabric. Fibres are either found in nature or made by man. Natural fibres are obtained from plants, animals and minerals, while man-made fibres are produced either purely chemically (Synthetic fibres) or by modifying natural fibres by chemical means (Regenerated fibres). The classification of textile fibres is presented in fig. 1.1.
1.2 Natural Fibres 1.2.1 Cotton Cotton is the seed hair of the plant of the genus Gossypium. It is classified as natural, cellulosic, mono-cellular, staple fibre. Different kinds and types of cotton are grown in various parts of the world. Variations occur among cotton fibres because of growth conditions, including such factors as soil, climate, fertilisers, and pests. The quality of cotton fibre is based on its colour, staple, fineness, and strength. Usually, longer fibres are finer and stronger. The particular kind of cotton is often identified by the name of the country or geographical area where it is produced.
However, cotton has little lustre and has poor elasticity and resiliency. It is attacked by mildew and weakened by resin chemicals used in
Wool (sheep)
Polyolefin (olefin)
Polyvinyl derivatives
Anidex
Acrylic
Modacrylic
Nytril
Vinylal (acetalized vinyl alcohol)
Polyamide (nylon)
Fluorofibre (PTFE)
Aramid
Trivinyl
Polystyrene
Synthetic polyisoprene
Deacetylated Lyocell acetate Polyester
Modal
Cupra
Cellulose ester Acetate Triacetate
regenerated cellulose (rayon)
Other (carbon,glass, metal,ceramic)
Vegetable (arachin zein)
Regenerated protein
Natural polymer
Man-made
Animal (casein)
Rubber
Viscose
Alginate
Synthetic polymer
Poly vinylidene chloride (saran)
Chlorofibre
Segmented polyurethane (spandex)
Polyurethane
Poly vinyl chloride (vinyon)
Non segmented polyurethane
Leaf (manila, heneguen, phormium tenax, sisal)
Mineral (Asbestos)
Polyethylene Polypropylene
Novoloid
Lastrile
Bast(flax, hemp,jute, kenaf, ramie)
Vegetable
Hair (alpaca,camel,cow,goat (mohair,cashmere),horse, rabbit (angora),vicuna)
Polymethylene urea (polycarbamide)
Silk
Seed(cotton, kapok,coir)
Animal
Natural
Textile fibres
Textile Fibres (Source: Textiles Terms and Definition)
Textile Fibres
Figure 1.1
Textile Handbook 1-3
1-4
Textile Fibres
When dry, cotton fibre is almost entirely made up of cellulose (up to 96%). The other components, being regarded as impurities, include small amounts of protein, pectin, wax, ash, organic acids and pigment. The length of cotton is normally between 1/2 to 21/2 inches (12.7-63.5mm). Cotton has a shape like a flat twisted tube when viewed under a microscope. Cotton fibre has good strength and abrasion resistance. It is hydrophillic, absorbs moisture quickly and dries quickly, has no static or pilling problems. finishing and by acids, but is highly resistant to alkalis.
1.2.2 Flax (Linen) Flax comes from the stem of the flax plant of the species Linum usitatissimum. It is classified as a natural cellulose, bast, and multicellular fibre. When the fibre is processed into fabric it is called Linen. Flax fibre is the stem of flax plant, fibre length between 2 to 36 inches. (50.8-914.4mm) The fibres are hackled (combed) to separate the long line and short tow fibres. The line fibres are generally drafted and doubled, and then lightly twisted before undergoing a wet spinning process. This produces strong, fine yarn. The short tow fibres are carded and drafted and then spun using a dry spinning method. Dryspun yarns have a heavier count and are used for furnishing fabrics, heavy apparel and household textiles and knitwear. Flax is lint-free because of the absence of very short fibres. It has excellent strength, especially when wet. It has poorer drape and resiliency than cotton but is more hydrophillic, and therefore good for hot weather. Major flax producing countries are Australia, Austria, Belgium, Czechoslovakia, France, Germany, Ireland, Scotland, and the former USSR. The highest quality flaxes come from Belgium, Northern France and the Netherlands.
Textile Handbook 1-5
1.2.3 Jute Jute is the common name given to fibre extracted from the stems of plants belonging to the genus Corchorus. It is yellowish-brown in colour, which is classified as natural, bast, and long staple fibre. People all over the world have used jute for most of their packaging requirements. Demand for jute goods reached a peak between the two world wars, but since then the industry has experienced strong competition from bulk handling paper sacks and more recently synthetic fibres like polypropylene and polyethylene. The bulk of the world jute is grown in Bangladesh and India. Both countries are large-scale manufacturers of jute goods. A small amount of jute is also grown in China and some African countries. Jute is commonly used in making sacks and bags and woven into fabric for carpet backing.
Ramie is a bast fibre from a plant known as reha, and China grass; it is obtained from a tall shrub grown in Southeast Asia, China, Japan, and Southern Europe. The fibre is stiff, more brittle than linen, and highly lustrous. It can be bleached to extreme whiteness. Ramie lends itself to general processing for textile yarns, but its retting operation is difficult and costly, making the fibre unprofitable for general use. Ramie is seldom used for garments worn next-to-the-skin because it can cause a prickle and itchy sensation to the human skin, particularly when the skin is moistened such as during humid summer. It has poorer drape and resiliency than cotton. Since it has hydrophillic property similar to linen, it was used to produce fabric, called “Summer Cloth”, to be worn in summer in China.
1.2.5 Silk Silk is a continuous strand of protein filament cemented together forming the cocoon of silk worm Bombyx mori. The silk worm forms silk by forcing two fine streams of thick liquid out of tiny openings in its head. On contact with air, the streams of liquid harden into filaments. Silk is classified as a natural, protein filament fibre.
Textile Fibres
1.2.4 Ramie
1-6
Textile Fibres
Silk classification depends whether it comes from cultivated or wild silk worms. The cultivated silk worms, which solely live on mulberry leaves, produce the finest lustrous fibres, and these fibres are known as real silk fibre. The wild silk worms which are not cultivated, feed on the leaves of other trees such as oak and cherry, and produce brown, much thicker and less lustrous fibres. These fibres are known as tussah silk and are used for heavier, rough-textured fabrics. Duoppioni is made when two silk worms make their cocoons at the same time, thus joining together in one cocoon. Silk has excellent drape, lustre and luxurious hand. It is hydrophillic and with little problem in static, wet strength is 15% less than dry. It has poor resistance to prolonged exposure to sunlight and can be attacked by moths. Under strong alkaline condition, silk will be weakened. Today China is the leading silk producer of the world. Other major silk producing countries include Japan, India and Italy.
1.2.6 Wool Wool is the fibre from the fleece of sheep. It is a natural, protein, multi- cellular, staple fibre. Early wool was a very coarse fibre. Its development into the soft, fleecy coat so familiar today is the result of long and continued selective breeding. The breeding of animals and the production of the wool fibre into fabric are more costly processes than the cultivation of plant fibre (e.g. cotton, linen) and their manufacture. Wool fibre is composed of proteins and organic substances with composition of Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur. All wool fibres have scales in the fibre surface. Wool fibre has good resiliency when dry, but poor when wet. It retains warmth because of slow moisture absorption and slow drying which creates no cooling effect, and its natural crimp provides an air trap for insulation. The major disadvantages of wool are felting, and it is easily attacked by moth. There are about forty breeds of sheep. Counting the cross breeds, there are over 200 distinct grades of sheep. Those that produce wool may be classified into four groupings according to the quality of the wool produced.
Textile Handbook 1-7
Class-one or Merino Wool: Merino sheep produce the best wool which is relatively short, ranging from 25-125 mm, but the fibre is strong, fine and elastic and has good working properties. Class-two wools: They are not quite as good as the Merino wool, but this variety is nevertheless a very good quality wool. It is 50-200 mm in length, has a large number of scales, and has good working properties. This class of sheep originated in England, Scotland, Ireland and Wales. Class-three wools: These fibres are of about 100-455 mm long, are coarser, and have fewer scales and less crimp than Merino and Classtwo wools. As a result, they are smoother, and therefore, they have more lustre. These wools are less elastic and resilient. Class-four Wool : These fibres are from 25-400 mm long, are coarse and hair-like, have relatively fewer scales and crimp, and therefore, are smoother and more lustrous. This wool is less desirable, with the least elasticity and strength.
Lambs wool : This is the first fleece sheared from a lamb about six to eight months old; sometimes it is referred to the first clip. This wool is of very fine quality. The fibres are tapered because the ends have never been clipped. Such fibres produce a softness of texture in fabric, and it is a popular material for sweaters.
1.2.7 Hair Hair fibres that have qualities of wool are obtained from certain kinds of animals. The hair of these animals has been so adapted by nature for the climate in which they live that the cloth produced from the fibres gives warmth with light weight. Hair fibres include camel hair, mohair, cashmere, llama, alpaca, vicuna, and angora. (rabbit hair) Camel hair is a fine and naturally water-repellent hair, which is able to protect the body in both heat and cold. Camel hair fabrics are ideal
Textile Fibres
Wool can be classified by fleece. Wool shorn from young lambs differs in quality from that of older sheep. Also, fleeces differ according to whether they come from live or dead sheep, which necessitates standards for the classification of fleeces. The typical classes of fleeces are Lamb’s Wool, Hogget Wool, Wether Wool, Pulled Wool, Dead Wool and Taglocks.
1-8
Textile Fibres
for comfort, particularly when used for overcoating, as they are especially warm but light in weight. It is divided into three grades. Grade 1 is the soft and silky light-tan underhair of from 1 1/4 to 3 1/2 inches (30-90mm), it is the choicest quality. Grade 2 consists of short hairs and partly of coarse outer hairs, ranging from 1 1/2 to 5 inches (40125mm) in length. Grade 3 consists entirely of coarse outer hairs measuring up to 15 inches (380mm) in length and varying in colour from brownish black to reddish brown. Mohair is the hair of the Angora goat, which is a smooth, strong, and resilient fibre. It does not attract or hold dirt particles. It absorbs dye evenly and permanently. Its fine silk-like lustre permits interesting decorative effects. It is more uniform in diameter than wool fibre, therefore, does not shrink or felt as readily as wool. The underhair of Cashmere goat is made into luxuriously soft woollike yarns with a characteristic highly napped finish. This fine cashmere fibre is soft, lighter in weight than wool, and quite warm ; however, because it is a soft, delicate fibre, fabrics produced from cashmere are not as durable as wool. Alpaca fibre is valued for its silky beauty as well as for its strength. The hair of the alpaca is stronger than ordinary sheep’s wool, is waterrepellent, and has a high insulative quality. It is as delicate, soft, and lustrous as the finest silk. The best selected type of alpaca is the suri which is longer, silkier, and finer and has curl throughout its length. The Angora rabbit produces long, fine, silky white hair, and comes mainly from France, Italy, and Japan. Its smooth, silky texture makes it difficult to spin, and the fibres tend to slip out of the yarn and shed form the fabric.
1.2.8 Asbestos Asbestos is fibrous mineral mined from rock deposits. Chemically, chrysotile asbestos (used in textiles) is a hydrated silicate of magnesium which contains small amounts of ferrous, ferric and aluminium oxides. The soft, long, glossy white fibres are pressed into sheets; and the best quality can be spun into yarn. Asbestos will not burn, but it will melt at a sufficiently high temperature. It is acid proof and rustproof. However, it has been found to be hazardous to health, as particles can
Textile Handbook 1-9
lodge in the respiratory system and are carcinogenic. Its use is now prohibited in many countries.
1.3 Man-made Fibres 1.3.1 Acetate
1.3.2 Acrylic Acrylic is a long-chain synthetic polymer composed of at least 85% by weight of acrylonitrile units. It was initially developed to simulate wool properties for making sweaters and blankets. The first acrylic fibre, named Orlon, was produced at Du Pont. Because of its homopolymer structure, it is almost as strong as nylon and was highly resistant to chemicals (notably acids) and to sunlight. However, it is virtually undyeable. Acrilan and Creslan are copolymer acrylic fibres, which have a more open fibre structure, and therefore disperse dyestuffs are absorbed into the fibre more readily. Some acrylic fibres are graft polymers, which are more open and less crystalline than homopolymer or copolymer. Dye receptivity is increased. Acrylic fibres are used in staple rather than filament form, mainly in knit apparel items. They are medium in tenacity, toughness, and abrasion
Textile Fibres
Acetate is a regenerated man-made fibre made from acetylation of cellulose by acetic acid. The cellulose source is similar to viscose rayon but it differs greatly in chemical nature because the acetylation of the cellulose makes it a hydrophobic character. Different degrees of acetylation will result in different fibre properties and entitlement, i.e. Secondary Acetate and Triacetate. It gives excellent drape and a luxurious hand, no pilling problem and little static, and is also inexpensive. The characteristics of acetate are quite different form those of all the other man-made fibres. One of its unique characteristics is its thermoplasticity; that is, it can be softened by the application of heat and placed or pressed into a particular shape. Creases and pleats heatset into acetate fabrics are relatively durable and are retained better than in cotton, linen, wool, silk, or rayon. It is not very absorbent and, in fact, it is one of the weakest textile fibres, weaker than any rayon.
1-10
Textile Fibres
resistance. Acrylic fibres have poor hot-wet performance. They are soft fibres with low moisture regain. They exhibit high resistance to ultraviolet light and to most chemicals to which they are commonly exposed during use.
1.3.3 Nylon Nylon is a man-made synthetic polymer, polyamide filament or staple fibre. It is a long-chain synthetic polyamide in which less then 85% of amide linkages are attached to two aromatic rings. The first nylon produced by Du Pont was nylon 6.6, so called because its chemical components contain six carbon atoms per molecule. Nylon 6 was produced from a polyamide called caprolactum, which contain 6 carbon atoms. Some other forms of nylon were also developed known as Nylon 7, Nylon 11, Nylon 6.12 and Nylon 4, 8, 10, 6.10. Nylon is produced in both regular and high tenacity strengths. Although it is one of the lightest textile fibres, it is also one of the strongest. The strength of nylon will not deteriorate with age. It has the highest resistance to abrasion of any fibre. It can take a tremendous amount of rubbing, scraping, bending, and twisting without breaking down. Nylon is one of the elastic fibres, however, such stretch nylon yarns as Helanca and Agilon have exceptional elasticity. It has excellent resilience and draping qualities. Nylon does not absorb much moisture, therefore the nylon fabric feels clammy and uncomfortable in warm, humid weather.
1.3.4 Polyester Polyester fibres are long chain polymers produced from elements derived from coal, air, water and petroleum. Polyester fibre is chemically composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic units and para substituted hydroxybenzoate units. The polyester fibres may be primarily divided into two varieties i.e. PET (polyethylene terephthalate) and PCDT (poly-1,4-cyclohexylene dimethylene terephthalate). Most of the production is PET. Modification of each of these varieties is engineered to provide specific properties. It is also possible to produce other variants of polyester. PBT
Textile Handbook 1-11
(polybutylene terephthalate) is the other polyester made by condensing terephthalic acid with butane diol and is melt spun to get the filaments.
Polyester fibres are dyed almost exclusively with disperse dyes. Because of its rigid structure, well-developed crystallinity and lack of reactive dye sites, PET absorbs very little dye in conventional dye systems. Research work has been done to improve the dyeability of PET fibres. Polymerizing a third monomer, such as dimethyl ester, has successfully produced a cationic dyeable polyester fibres into the macro-molecular chain. This third monomer has introduced functional groups as the sites to which the cationic dyes can be attached. The third monomer also contributes to disturbing the regularity of PET polymer chains, so as to make the structure of cationic dyeable polyester less compact than that of normal PET fibres. The disturbed structure is good for the penetration of dyes into the fibre. The disadvantage of adding a third monomer is the decrease of the tensile strength.
1.3.5 Rayon (Viscose Rayon) Viscose (or viscose rayon) is a man-made fibre composed of 100% regenerated cellulose discovered in 1891 and first commercial production was undertaken in 1905 by Courtaulds. It is made from cotton linters or wood pulp, usually obtained from spruce and pine trees. Initially viscose was called ‘Artificial silk’ and later named as ‘rayon’ because
Textile Fibres
Fabrics made of PET polyester yarn should be given compressive shrinking and heat setting to obtain dimensional stability to subsequent finishing processes and washing. PCDT polyester fabrics need not be initially heat-set because they are inherently stable. Both forms of polyester fabrics can be permanently pressed since they are thermoplastic and hold their shape exceedingly well. Polyester fibres are subject to the accumulation of static electricity. In general, PET polyester filament yarns used for tires and industrial purposes are extremely strong. The abrasion resistance of polyester fibre is exceptionally good, being exceeded only by nylon among all of the commonly used fibres. However, the abrasion resistance of low-pilling types, including those of PCDT polyester, is of a lower order that is generally similar to wool. As polyester fibres do not have a high degree of elasticity, its strength, abrasion resistance, and stability make it very suitable for sewing thread.
1-12
Textile Fibres
of its brightness and similarities in structure with cotton (Sunray & Cotton). The other two regenerated cellulose fibres are cuprammonium (Cupro®) and polynosic (Modal). In the USA these three regenerated cellulose fibres are still referred to collectively by the generic term rayon. But the International Standardisation Organisation (ISO) prefers the name viscose and defines viscose as regenerated cellulose obtained by the viscose process. The name viscose was derived from the word viscous, which describe the liquid state of the spinning solution. Viscose rayon is weak, with high elongation at break and a low modulus. It loses 30 to 50% of its strength when wet, and needs careful laundering. It also shrinks appreciably from washing. Viscose rayon is one of the most absorbent of all textiles. It is more absorbent than cotton or linen and is exceeded in absorbency only by wool and silk. A variation of rayon is classified as high wet modulus (HWM) rayon or polynosic rayon. This type of rayon is launderable.
1.3.6 Spandex Spandex is an elastomeric fibre, that is it has superior elasticity. It is capable of being stretched over 7 times its length and returning immediately to its relaxed state upon release of tension. Spandex may be described as being molecularly composed of a chain-like arrangement of soft, stretchable segments of polyurethane linked together for reinforcement by hard segments. There are two members of the spandex group - the polyester segmented and the polyether segmented. The polyester spandex fibres are more resistant to oxidation and oil absorption. Polyether spandex fibres are more resistant to detergents and mildew. In 1958 DuPont was the first to introduce to the trade man-made elastic fibre under the Lycra trademark. This synthetic elastic fibre overcomes the product deficiencies such as stress-strain properties, denier range and mouldability of rubber yarn. Elastic fibres have contributed to improvement in fashion, freedom of motion and the comfort and fit in modern clothing. For example, the Lycra® Soft family of products was developed to provide added comfort while responding to movements without tension.
Textile Handbook 1-13
Since the introduction of synthetic elastic fibre, the major application area was in the replacement of rubber in waistbands and foundation garments. This was followed by expansion into underwear and swimwear, and later continued into hosiery, sportswear ready-to-wear, diapers, shoes, upholstery and technical applications. Spandex fibre is available as filament in a variety of deniers ranging from 20-5400. Deniers of 20-210 are used in lightweight support hosiery and of 140-560, in men’s hosiery. Coarse deniers of 70-2240 are used in panty hose tops, swimwear, and foundation garments. Spandex fibre may be delustered and white in colour; it can also be transparent when used for fine knit products.
1.3.7 Olefin
Olefins are used for making indoor/outdoor carpeting and bathroom floor covering because of their low specific gravity. Important apparel end uses are athletic clothes, exercise suits, and underwear because of its excellent wicking action.
Textile Fibres
Olefin is a manufactured fibre in which the fibre-forming substance is any long-chain synthetic polyethylene, propylene, or other olefin unit, except amorphous ( noncrystalline) polyolefins. It is a very lightweight fibre possesses very good strength and abrasion resistance. It possesses a unique combination of low moisture absorbency and exceptional wicking of water, which are advantages in providing comfortable apparel in certain circumstances. Olefin is almost completely hydrophobic. Such moisture properties are sought for active sportswear fabrics, particularly sweatshirts, socks, and warm-up suits, because water is moved away from the skin. This fibre also has excellent sunlight resistance and weatherability, and can be washed or drycleaned easily. However, because olefin is sensitive to perchloroethylene, the most frequently used drycleaning solvent, generally, petroleum solvent should be specified if necessary.
1-14
Textile Fibres
1.4 Microscopic Appearance of Common Textile Fibres
Longitudinal View
Cotton
Linen
Jute
Ramie
Cross-sectional View
Textile Handbook 1-15
Longitudinal View
Cross-sectional View
Silk
Wool
Textile Fibres
Angora
Acetate
1-16
Textile Fibres
Longitudinal View
Acrylic
Nylon
Polyester
Rayon
Cross-sectional View
Textile Handbook 1-17
Longitudinal View
Cross-sectional View
Olefin (Polyethylene)
Spandex Textile Fibres
1-18
Textile Fibres
SECTION 2
FIBRE PROPERTIES
2.1 Desirable Fibre Properties Fibres usually are grouped and twisted together into yarn and the yarns are then used to make woven and knitted fabrics. A fibre’s structure contributes to the performance characteristics of a fabric made from it. The properties are determined by a fibre’s physical attributes, chemical composition and molecular formation.
2.1.1 Fibre length Fibres which can be measured in length are called staple fibres, while fibres of infinite length are called filament fibres. For staple fibres, the longer the fibre length the better the quality of yarn being spun.
2.1.2 Cross-sectional shape and surface These determine the bulk, texture, luster and hand feel of the fibre. For example, round shape fibres do not pack as well as flat fibres (which results in bulkier products) and they have a smoother, and more slippery hand.
2.1.3 Straightness Fibres may be straight, twist, coiled, or crimped, and this affects the performance properties such as resiliency, elasticity, and abrasion resistance. For example, crimp on fibre inverse resiliency, bulk, warmth, elongation and absorbency.
2.1.4 Strength Fibre strength contributes to yarn strength and eventually affects fabric durability. It is usually expressed as tenacity (gram per tex).
2.1.5 Extensibility and elasticity This is the ability to increase in length when under tension and then return into the original length when released. Fibres that can elongate at least 100% are called elastometric fibres.
Textile Handbook 1-19
2.1.6 Hand feel This is affected by its shape, surface and configuration. The terms such as soft, crisp, dry, silky, or harsh are used to describe the hand feel.
2.1.7 Plasticity A thermoplastic fibre melts or softens when heat is applied. Thus, permanent creased and pleats can be made on fabrics containing thermoplastic fibres.
2.1.8 Absorbency This is the ability to take in moisture. It is expressed as a percentage of moisture regain (M.R.). M.R. is the amount of water a bone-dry fibre will absorb from the air under 20°C and 65% R.H.. Fibres which absorb water easily are called hydrophilic, while those which only absorb a small amount are called hydrophobic.
This is the ability to resist wear form rubbing; fibres that have high breaking strength and abrasion resistance are more durable.
2.1.10 Resiliency This is the ability of a material to spring back to shape after being distorted. It is closely related to wrinkle recovery.
2.1.11 Lustre This refers to the light reflected form a surface. Various characteristics of a fibre will affect the amount of luster produced. The cross-sectional shape, lengthwise appearance, yarn type, weave and finish used will affect the amount of lustre.
2.1.12 Density A fibre of low density can produce a thick and lofty, but still relatively lightweight fabric.
Textile Fibres
2.1.9 Abrasion resistance
1-20
Textile Fibres
2.1.13 Wicking This the ability of a fibre to transfer moisture form one section to another. Usually the moisture is along the fibre surface. The wicking propensity of a fibre is usually based on the chemical and physical composition of the outer surface; a smooth surface reduces wicking action. A hydrophilic fibre such as cotton possesses good wicking action, while a hydrophobic fibre such as polypropylene also possesses good wicking action when it is in an extra thin filament form. This property is especially desirable for sportswear; body perspiration is transported by wicking action along the fibre surface to the outer surface of the cloth thus providing improved comfort.
Textile Handbook 1-21
2.2 Important Characteristics and Major End-use of Textile Fibres Fibre ACETATE
ACRYLIC
COTTON
Luxurious appearance Crisp or soft hand Wide range of colours; dyes and prints well Excellent drapeability and softness Shrink, moth, and mildew resistant Low moisture absorbency, relatively fast drying No pilling problem, little static problem Most acetate garments require dry-cleaning Light-weight, soft, warm for winter wearing Dyes to bright colours with excellent fastness Outstanding wickability Machine washable, quick drying Resilient; retains shape; resists shrinkage, & wrinkles Flexible aesthetics for wool-like, cotton-like or blended appearance Excellent pleat retention Resistant to moths, oil and chemicals Superior resistance to sunlight degradation Static and pilling can be a problem
Major end-uses Apparel - Blouses, dresses, linings, special occasion apparel, Home Fashion - Draperies, upholstery, curtains, bedspreads
Apparel - sweaters, socks, fleece, circular knit apparel, sportswear, childrenswear Home Fashion - Blankets, throws, upholstery, awnings, outdoor furniture, rugs/floor coverings
Apparel - protective clothing, Does not melt military helmets, protective Highly flame-resistant vests High strength Others - hot-gas filtration fabrics, structural composites High resistance to stretch Maintains its shape and form at high for aircraft and boats, sailcloth, tires, ropes and cables, temperatures mechanical rubber goods, marine and sporting goods. Apparel - Wide range of Comfortable wearing apparel: blouses, Soft hand shirts, dresses, childrenswear, Absorbent activewear, separates, swimwear, suits, jackets, skirts, Good colour retention, prints well pants, sweaters, hosiery, Machine-washable, dry-cleanable neckwear. Home Fashion - curtains, Good strength draperies, bedspreads, Drapes well comforters, throws, sheets, towels, table cloths, table mats, Easy to handle and sew napkins.
Textile Fibres
ARAMID
Characteristics
1-22
Textile Fibres LINEN
Comfortable Good strength, twice as strong as cotton Hand-washable or dry-cleanable Crisp hand Tailors well Absorbent Dyes and prints well Lightweight to heavyweight No static or pilling problems Fair abrasion resistant
Apparel - dresses, suits, separates, skirts, jackets, pants, blouses, shirts, childrenswear. Home Fashion - curtains, draperies, upholstery, bedspreads, table linens, sheets, dish towels.
LYOCELL
Excellent strength Washable Shrink- and wrinkle-resistant Soft hand Excellent drape Absorbent Dyes and prints well
Apparel - dresses, suits sportswear, pants, jackets, blouses, and skirts.
MICROFIBERS .
Ultra fine (less than 1.0 dpf), finer than the most delicate silk Extremely drapeable Very soft, luxurious hand with a silken or suede touch Washable, dry cleanable Shrink-resistant High strength (except Rayon) Excellent pleat retention Insulates well against wind, rain and cold
Apparel - hosiery, blouses, dresses, separates, sportswear, ties, scarves, menswear, intimate apparel, activewear, swimwear, outerwear, rainwear.
MODACRYLIC
Soft Resilient Abrasion- and flame-resistant Quick-drying Resists acids and alkalis Retains shape
Apparel: Deep pile coats, trims, linings, simulated fur, wigs and hairpieces Home Fashion: Awnings, blankets. Carpets, flameresistant draperies and curtains, scatter rugs.
MOHAIR
Long, lustrous, strong fibre Luxurious Soft hand Most resilient natural textile fibre Lightweight, warms, good insulator Dyes well, brilliant colours Non-crush, -mat and -pill qualities. Resists fading
Apparel - coats, suits, dresses, sweaters, accessories, loungewear, and socks.
Home Fashion - curtains, draperies, upholstery, sheets, towels, and blankets.
Home Fashion - blankets, throws, upholstery, draperies, carpets rugs.
Textile Handbook 1-23 NYLON
POLYESTER
RAYON
Apparel - swimwear, activewear, intimate apparel, foundation garments, hosiery, blouses, dresses, sportswear, pants, jackets, skirts, raincoats, ski and snow apparel, windbreakers, childrenswear.
Strong Crisp, soft hand Resistant to stretching and shrinkage Washable or dry-cleanable Quick drying Resilient, wrinkle resistant, excellent pleat retention (if heat set) Abrasion resistant Resistant to most chemicals Because of its low absorbency, stain removal can be a problem Static and pilling problems
Apparel - essential every form of clothing, dresses, blouses, jackets, separates, sportswear, suits, shirts, pants, rainwear, lingerie, childrenswear
Lightweight, lightest fibre, it floats Strong Abrasion resistant, resilient Stain-, static-, sunlight-, and odor-resistant High insulation characteristics Resists deterioration from chemicals, mildew, perspiration, rot and weather Fast drying High wickability Colour fast, because colours are incorporated during fibre forming stage Spills can be readily wiped up Static and pilling can be a problem Ironing, washing and drying need to be done at low temperature Non-allergenic
Apparel - activewear, sportswear, jeans, socks, underwear, lining fabrics.
Soft and comfortable Drapes well Highly absorbent Dyes and prints well No static, no pilling problems Fabric can shrink appreciably if washing dry clean only rayon Washable or dry cleanable. Read the label
Apparel - Blouses, dresses, jackets, lingerie, linings, millinery, slacks, sportshirts, sportswear, suits, ties, work clothes Home Fashion - bedspreads, blankets, curtains, draperies, sheets, slip covers, tablecloths, upholstery.
Home Fashion - carpets, rugs, curtains, upholstery, draperies, bedspreads Other - Luggage, back packets, life vests, umbrellas, sleeping bags, tents.
Home Fashion - curtains, draperies, floor coverings, fibre fill, upholstery, and bedding.
Home Fashion - indoor and outdoor carpets, carpet backing, upholstery, wall coverings, furniture and bedding construction fabrics.
Textile Fibres
POLYOLEFIN (OLEFIN)
Lightweight Exceptional strength Good drapeability Abrasion resistant Easy to wash Resists shrinkage and wrinkling resilient, pleat retentive Fast drying, low moisture absorbency Can be pre-coloured or dyed in a wide range of colours Resistant to damage from oil and many chemicals Static and pilling can be a problem Poor resistance to continuous sunlight
1-24
Textile Fibres SILK
Soft or crisp hand Luxurious Drapes and tailors well Thinnest of all natural fibres Dyes and prints well Hand-washable or dry-cleanable Little problem with static, no pilling problem Only fair abrasion resistance Poor resistance to prolonged exposure to sunlight
Apparel - dresses, blouses, skirts, jackets, pants, pants, scarves, and ties.
SPANDEX
Lightweight Can be stretched over 500% without breaking Able to be stretched repetitively and still recover original length Abrasion resistant Stronger, more durable than rubber Soft, smooth and supple Resistant to body oils, perspiration, lotions or detergents No static or pilling problems
Apparel - articles where stretch is desired: athletic apparel, bathing suits, foundation garments, ski pants, slacks, hosiery, socks, belts.
TRIACETATE
Luxurious hand Excellent drapeability Resilient Excellent pleat retention Washable or dry-cleanable No pilling problem Can have static problem
Apparel - dresses, skirts, sportswear, robes, particularly where pleat retention is important
WOOL
Comfortable Luxurious, soft hand Versatile Lightweight Good insulator Washable Wrinkle-resistant Absorbent Easy to dye
Apparel - sweaters, dresses, coats, suits, jackets, pants, skirts, childrenswear, loungewear, blouses, shirts, hosiery, and scarves.
Home Fashion - curtains, draperies, upholstery.
Home Fashion - carpets, draperies, upholstery, blankets.
Textile Handbook 1-25
2.3 Examples of Commercial Names and Manufacturers of Man-Made Fibres Fibre type
ACETATE
ACRYLIC
BICOMPONENT FLUORO LYOCELL
MELAMINE MODACRYLIC
1. 2. 3. 4. 5. 6. 7.
Atlon Celanese Chromspun Dicel Estera Estron MicroSafe
Manufacturer 1. 2. 3. 4. 5. 6. 7.
Toho Rayon Co. Ltd., Japan Celanese A.G. Eastman Chemical Company British Celanese Ltd., U.S.A. Dai Nippon Celluloid Ltd., Japan Eastman Chemical Company Celanese A.G.
1. Acrilan 2. Beslon 3. BioFresh 4. Bounce-Back 5. Cashmilon 6. Creslan 7. Cresloft 8. Crylor 9. Courtelle 10. Duraspun 11. Dynel 12. Euroacryl 13. MicroSupreme 14. Orlon 15. Pil-Trol 16. So-Lara 17. The Smart Yarns 18. Toraylon 19. Ware-Dated 20. Vonnel 21. WeatherBloc
1. Solutia Inc. 2. Toho Beslon Co. Ltd., Japan 3. Sterling Fibers, Inc 4. Solutia Inc. 5. Asahi Chemical Ind. Co., Japan 6. Sterling Fibers, Inc 7. Sterling Fibers, Inc 8. Rhodiaceta Co, France 9. Courtauld Co., England 10. Solutia Inc. 11. B.I.F. Fibres., U.S.A. 12. Anic Co., Italy 13. Sterling Fibers, Inc 14. DuPont Company 15. Solutia Inc. 16. Solutia Inc. 17. Solutia Inc. 18. Toyo Rayon Co. Ltd., Japan 19. Solutia Inc. 20. Mitsubishi Vonnel Co. Ltd., Japan 21. Sterling Fibers, Inc
1. Kevlar 2. Nomex
1. DuPont Company 2. DuPont Company
1. 1. 1. 2. 3.
Resistat Teflon Fibro Lyocell by Lenzing Tencel
1. 1. 1. 2. 3.
BASF Corporation DuPont Company Acordis Cellulosic Fibers, Inc. Lenzing Fibers Corporation Acordis Cellulosic Fibers, Inc.
1. 1. 2. 3.
Basofil Dynel Kanekalon SEF Plus
1. 1. 2. 3.
BASF Corporation B.I.F. Fibres, U.S.A Kanefushi Chemical Industry, Japan Solutia Inc.
Textile Fibres
ARAMID
Trade names
1-26
Textile Fibres Mitsubishi Rayon Co., Ltd, Japan Fuji Spinning Co Ltd, Japan Tejin Co Ltd, Japan Daiwa Spinning Co Ltd, Japan Toho Rayon Co Ltd, Japan Toyobo Co Ltd, Japan Lenzing Fibers Corporation Lenzing Fibers Corporation
MODAL
NYLON 6
1. Anso 2. Caprolan 3. Dry Step 4. Eclipse 5. Enkalon 6. Grilon 7. Hardline 8. Hydrofil 9. Matinesse 10. Micro Touch 11. Nylon 6ix 12. Bayer-Perlon (Dorlon) 13. Powersilk 14. Shimmereen 15. Silky Touch 16. Softglo 17. Sportouch 18. Stay Gard 19. Tru-Ballistic 20. Ultra Touch 21. Zefsport 22. Zeftron 200
1. Honeywell Inc 2. Honeywell Inc 3. Honeywell Inc 4. Honeywell Inc 5. British Enkalon Ltd, England 6. Fibron S.A. Ems/Format, Switzerland 7. Honeywell Inc 8. Honeywell Inc 9. BASF Corporation 10. BASF Corporation 11. BASF Corporation 12. Farbenfabriken Bayer 13. BASF Corporation 14. BASF Corporation 15. BASF Corporation 16. BASF Corporation 17. BASF Corporation 18. Honeywell Inc 19. Honeywell Inc 20. BASF Corporation 21. BASF Corporation 22. BASF Corporation
1. Amilon 2. Antron 3. Assurance 4. Avantige 5. Cantrece 6. Cordura 7. Durasoft 8. Duratrek 9. DyeNAMIX 10. Hytel 11. Micro Supplex 12. Natrelle BCF
1. Toyo Rayon Co Ltd, Nagoya 2. JapanDuPont Company 3. DuPont Company 4. DuPont Company 5. DuPont Company 6. DuPont Company 7. Solutia Inc. 8. Solutia Inc. 9. Solutia Inc. 10. DuPont Company 11. DuPont Company 12. DuPont Company
NYLON 6.6
Hipolan Junlon Polycot Polyno Toholon Tufeel Modal by Lenzing Modal Micro
1. 2. 3. 4. 5. 6. 7. 8.
1. 2. 3. 4. 5. 6. 7. 8.
Textile Handbook 1-27
NYLON 6.6
NYLON 6/6.6
PBI
13. Nippon Rayon Co Ltd, Japan 14. Solutia Inc. 15. Solutia Inc. 16. DuPont Company 17. DuPont Company 18. DuPont Company 19. Solutia Inc.
1. Wellon 2. Wellstrand
1. Wellman, Inc. 2. Wellman, Inc.
1. Alpha 2. Condesa 3. Courlene 4. Essera 5. Impressa 6. Innova 7. Marves 8. Meraklon 9. Propex 10. Spectra 1000 11. Spectra 900 12. Spectra Fusion 13. Spectra Guard 14. Spectra Shield 15. Spectra Shield Plus 16. SpectraFlex 17. Telar 18. Trace
1. American Fibers and Yarns Company 2. American Fibers and Yarns Company 3. British Celanese Ltd 4. American Fibers and Yarns Company 5. American Fibers and Yarns Company 6. American Fibers and Yarns Company 7. American Fibers and Yarns Company 8. Montedison (Montefibre), Italy 9. American Fibers and Yarns Company 10. Honeywell Inc 11. Honeywell Inc 12. Honeywell Inc 13. Honeywell Inc 14. Honeywell Inc 15. Honeywell Inc 16. Honeywell Inc 17. American Fibers and Yarns Company 18. American Fibers and Yarns Company
1. PBI Logo
1. Celanese Acetate A.G.
20. DuPont Company 21. Solutia Inc. 22. Solutia Inc. 23. Solutia Inc. 24. Solutia Inc. 25. Solutia Inc.
Textile Fibres
OLEFIN
13. Niplon 14. No Shock 15. OPTA 16. Stainmaster 17. Supplex 18. Tactel 19. Traffic Control Fiber System 20. Ultramirage 21. Ultron 22. Wear-Dated 23. Wear-Dated Assurance 24. Wear-Dated Freedom 25. Wear-Dated II
1-28
Textile Fibres POLYVINYL CHLORIDE FIBRE (PVC)
1. 2. 3. 4.
Avsico Vinyon, HH Dynel Fibravyl Rhovyl
1. 2. 3. 4.
American Viscose Corporation Union Carbide Corporation Societe Rhovyl, France Societe Rhovyl, France
POLYVINYLIDENE CHLORIDE FIBRE (PVDC)
1. 2. 3. 4. 5.
Kurehalon Saran Verel Velon Permalon
1. 2. 3. 4. 5.
Kureha Kasel Co. Ltd. Dow Chemical, U.S.A. Tennessee Eastman Co., U.S.A. Firestone Ind. Products., U.S.A. Pierce Plastic Inc., U.S.A.
POLYESTER
1. A.C.E. Polyester 2. Avora FR 3. Celbond 4. Colorfine 5. Comforel 6. ComFotrel 7. Coolmax (CM) 8. Corebond 9. Corterra Fibers 10. Dacron 11. Dacron Microfiber 12. Diolen 13. DSP 14. ESP 15. Fiberbrite 2000 16. Fillwell 17. Fillwell II 18. Fillwell Plus 19. Fortrel 20. Fortrel BactiShield 21. Fortrel EcoSpun 22. Fortrel EcoSpun2 23. Fortrel MicroSpun 24. Fortrel Plus 25. Fortrel Spunnaire 26. Fortrel Spunnese 27. Hollofil 28. Kuraray 29. Loftguard 30. Microloft 31. MicroMattique 32. Microselect 33. Microtherm 34. Nature Tex 35. Polyguard 3D
1. Honeywell Inc 2. KoSa 3. KoSa 4. Martin Color-Fi, Inc. 5. DuPont Company 6. Wellman, Inc. 7. DuPont Company 8. DuPont Company 9. KoSa 10. DuPont-Akra Polyester, LLC 11. DuPont-Akra Polyester, LLC 12. Acordis Industrial Fibers, Inc. 13. Honeywell Inc 14. KoSa 15. Honeywell Inc 16. Wellman, Inc. 17. Wellman, Inc. 18. Wellman, Inc. 19. Wellman, Inc. 20. Wellman, Inc. 21. Wellman, Inc. 22. Wellman, Inc. 23. Wellman, Inc. 24. Wellman, Inc. 25. Wellman, Inc. 26. Wellman, Inc. 27. DuPont Company 28. Kurashiki Rayon Co. Ltd., Japan 29. KoSa 30. DuPont Company 31. DuPont Company 32. DuPont Company 33. KoSa 34. Martin Color-Fi, Inc. 35. KoSa
Textile Handbook 1-29
RAYON
1. 2. 3. 4.
Fibro Galaxy Viscose by Lenzing Viscose FR by Lenzing
1. 2. 3. 4.
Acordis Cellulosic Fibers, Inc. Acordis Cellulosic Fibers, Inc. Lenzing Fibers Corporation Lenzing Fibers Corporation
CUPRAMMONI UM RAYON
1. 2. 3. 4.
Bemberg Bemsilkie Cuprama Cupresa
1. 2. 3. 4.
J.P. Bemberg A.G., Germany Asahi Chemical Ind. Co. Ltd., Japan Farbenfabriken Bayer A.G., Germany Farbenfabriken Bayer A.G., Germany
POLYESTER
SPANDEX
SULFAR
TRIACETATE
1. Clearspan 2. Dorlastan 3. Estane 4. Glospan 5. Lycra 6. Spanzelle 7. Vyrene 8. Roica 9. Espa 10. Texlon
1. Globe Manufacturing Co. 2. Bayer, A.G., W. Germany 3. B.F. Goodrich Chemical Co. Ltd. 4. Globe Manufacturing Co. 5. DuPont Company 6. Courtaulds, U.K. 7. U.S. Rubber Co. 8. Asahi Chemical Industry Co.Ltd 9. Toyobo Co.Ltd 10. Tongkook Corporation, Korea
1. Ryton
1. American Fibers and Yarns Company
1. 2. 3. 4. 5.
1. 2. 3. 4. 5.
Arnel Courpleta Rhonel Trialbene Tricel
Celanese Corp. of America., U.S.A. Courtaulds., U.S.A. France Rhodiaceta, France British Celanese Ltd., U.K.
Textile Fibres
48. Wellene
36. DuPont Company 37. DuPont Company 38. KoSa 39. Honeywell Inc 40. Honeywell Inc 41. Nan Ya Plastics Corporation, America 42. I.C.I Ltd, England 43. Toyo Rayon Co. Ltd., Japan 44. Teijin Ltd,. Japan 45. DuPont Company 46. DuPont Company 47. Farbwerke Hoechst A.G. West Germany 48. Wellman, Inc.
36. Quallofil 37. Qualloform 38. Serelle 39. Stay Gard 40. Substraight 41. Tairilin 42. Terylene 43. Teteron 44. Tetolon 45. Thermastat 46. Thermoloft 47. Trevira
(3)
Good
132
Good Fair-Excel. Fair Fair Good 1.32 Fair 0.8-2.0
20%
No
(2)
Fair
260
Good Fair Fair Good Poor 1.52 Good 3.5-6.0
+10%
No
(2)
Poor
150
Fair Good Good Good Poor 1.54 Good 3.0-5.0
+10%
No No
15%
Poor Excel. Fair Good Fair 1.30 Fair 2.4-5.1
135
Good
90
65
75
20
99
20-40
3
3-10
Silk 11%
(2)
Wool 131/2%
Flax 12%
Cotton 81/2%
Yes
30%
Good Excel. Poor Good Fair 1.32 Fair 1.2-1.5
177
Excel.
Excel. Good Fair Fair Good 1.14-1.19 Poor 2.0-3.5
150
Excel.
(3)
92
35-45
No
Yes
30-50%b 20%
Fair Good Fair Good Poor 1.48-1.54 Good 1.2-3.0
177
Fair
(2)
95
48-65 (4)
15-30
25-45
Man-made Cellulosic Acetate Viscose Rayon 1.5% 11% 6.5%
note:(a) Softening temperature. (b) HWM (high wet modulus) rayon has much higher wet strength than viscose rayon.
Properties Absorbency (% M.R.) Elongation at break (%) (21oC, 65% RH) Elastic recovery (%) at 21oC, 65%RH (% strain) Mildew resistance Heat resistance temperature (oC) Sunlight resistance Hand feel Abrasion resistance Pilling resistance Resiliency Specific Gravity Static resistance Strength (g/denier) Strength loss when wet (approx.%) Thermoplastic
Natural
2.4 Properties of Major Textile Fibres
Yes
0.10%
Excel. Poor Poor Excel. Excel. 2.54 Excel 9.5
315
Excel.
(33)
100
Yes
0
Poor Fair Excel. Poor Good 1.14 Poor 2.5-7.3
150
Excel.
(5)
82-100
Yes
0
Good Fair Excel. Good Excel. 0.91 Good 2.5-3.5
75
Excel.
(3)
96
Yes
0
Good Fair Good Very poor Excel. 1.38 Very poor 3.0-6.0
120
Excel.
(50)
81
19-55
30-100
3-4 16-75
Olefin 0.4%
Nylon 01-0.1%
Acrylic Glass 0% 2.8-4.8%
Man-made non-cellulosic
Yes
Fair Poor Good Excel. Excel. 1.21 Excel. 0.07-1.0
175a
Excel.
99
400-700
Polyester 1%
1-30
Textile Fibres
CHEMICAL AGENT INORGANIC ACIDS Dilute Concentrated
Acrylic Glass Nylon Olefin Polyester Spandex
Swells Swells Degrades easily Degrades Dissolved Saponifics § Swells (loses tenacity)
Resistant Resistant Degrades easily Attacked (hot) Resistant Resistant
Degrades ε
OXIDIZING ALKALIES Dilute Concentrated AGENTS
Degrades
Degrades in conc. bleach
REDUCING AGENTS
* Degrades in 96% sulfuric acid. ↑ In concentrated nitric and sulfuric acids ε In concentrated sulfuric acid.
§ Reverts to cellulose. Destroyed by hot sulfuric acid # Not damaged by hypochlorite or peroxide bleaches
Attacked (strong agents) # Degrades (hot) Resistant Resistant (hot) Resistant Resistant Dissolves ↑ Do not bleach Fairly resistance Poor Good Good Resistant Fair Resistant Moderate Slowly oxidized Resistant Resistant Resistant Degrades (hot) Resistant Resistant * Resistant Good to most acids Good to most alkalies
= =
Textile Fibres
Cotton
Hydrolyzed (hot) Hydrolyzed (hot) Oxidized conc. Hydrolyzed Flax (linen) Hydrolyzed Resistant Resistant Wool Dissolved Silk Fairly resistant Acetate Decomposed Resistant (conc) Disintegrates Rayon Disintegrates (hot) (cold)
FIBRE
2.5 Chemical Resistance of Fibres
Textile Handbook 1-31
1-32
Textile Fibres
SECTION 3 - TYPES OF COTTON 3.1 Kinds and Types of Cotton Cotton, the purest form of cellulose found in the nature, is the seed hair of the plants of the genus Gossypium. It is classified as natural, cellulosic, mono-cellular, staple fibre. Cotton has been cultivated for more than 5000 years. Different kinds and types of cotton are grown in various parts of the world. Variation among cotton fibres occur because of growth conditions including such factors as soil, climate, fertilizers, and pests. The quality of cotton fibre is based on its colour, staple, fineness, and strength. Usually, the longer fibres are finer and stronger. The particular kind of cotton is often identified by the name the country or geographical area where it is produced. Though many species of cotton are grown commercially, they may be conveniently divided into three principal groups. The first group (Gossypium hirsutum) form the bulk of the world crop and has been developed for extensive use in the United States as American Upland cotton. The staples length (i.e. average fibre length) varies from 23 - 33 mm. The second group (G. barbadense) has staple lengths varying from 33 to 45 mm. In the United States, it is known as American Pima. This group also includes high quality fine cottons such as the Egyptian, Sudanese and Sea Island varieties commonly referred to as Extra Long Staple (ELS) cotton (up to 60 mm). The third group (G. herbaceum and G. arboreum) embraces cottons of shorter staple length, about 13 - 25 mm, commonly produced in various Asian countries. Major cotton producers at the present time are China, the USA, India, Pakistan, Uzbekistan; other countries producing small but not insignificant quantities include Brazil, Turkey, Mexico, Egypt and Sudan. At present the four largest exporters of cotton in the world are the USA, Uzbekistan, Franch-zone Africa and Australia.
Textile Handbook 1-33
3.1.1 The Features and Characteristics of the Three Principal Cotton Fibre Groups Coarse staple Asiatic Cotton Small Shape as a pike 5 to 7 deeply split Triangular shape or small heart shape Yellow, white, red, always have red spots at the base. Long and slightly pointed Opening is small or smooth 3-4 Small Fluffy
26
13
Growing period 120-140 (number of days)
135-160
100-125
Productivity Colour Fibre fineness Fibre length (mm)
High White Fine 23-33
Low Grayish white Short and thick 13-25
Fineness (m/gm) Fibre diameter (µm) Fibre width (µm) Convolution (turns/ cm) Single fibre strength (gm) Breaking length (km) Range of yarn tex
4500-7000 15-19 28-25 50-80
Medium Creamy or light brown Long and fine 33-45 6500-9000 12-15 14-22 100-120
3-5
4-6
4-7
20-28
28-40
Below 21
10-60
4-12
Above 28
Medium staple Upland Cotton Crop Large Stem Wide triangle Leaf blade 3 to 5 slightly split Humber of lobes Heart shape, length Shape of bud is longer than width Creamy white,no red Colour of petal spots at the base Shape of boll Oval Boll surface Smooth Locules 4-5 Seed Big Seed appearance Fluffy and some sleek Homo-chromosome 26 number
2500-4000 16-22 20-32 30-60
Remark: 1. For long staple cotton, the development is to mix cross of Upland cotton and Seaisland cotton. 2. Medium staple gradually replaces coarse staple cotton.
Textile Fibres
Fibre Long staple Sea-island Cotton Large Long and gradually sharp 5 to 7 deep split Heart shape,length and width are equal Yellow,red spots at the base Long and slightly pointed Opening is large 3-4 Big Sleek or fuzz
Item
1-34
Textile Fibres
3.1.2 Structure and Properties of Cotton Fibre The mature cotton fibre forms a flat ribbon-like structure that resemble a bicycle inner-tube from which the air has been removed, varying in width between 12 to 20 micrometer. It is highly convoluted and the number of convolutions varies between 4 to 6 per mm, reversing in direction about every millimeter along the fibre. Cotton fibres have a fibrillar structure. Their morphology exhibits three main features: primary wall, secondary wall and lumen. The primary wall consists of a network of cellulose fibrils covered with an outer layer of pectin, protein and wax. The wax renders the fibre impermeable to water and aqueous solutions unless a wetting agent is used. Although the primary wall accounts for only 5% by weight of the fibre, it contains most of the non-cellulosic constituents. The secondary wall constitute the bulk of a mature fibre and consists of cellulose fibrils arranged spirally around the fibre axis. Composition of a typical cotton fibre is given table 3.1.3. The actual composition depends on the type of cotton, growing conditions and maturity.
Figure 3.1.2 Schematic diagram of cotton Fibre structure. Primary wall (approx. 0.1µ thick) Secondary lameliae (approx. 0.4µ thick)
Winding (approx. 0.1µ thick)
Lumen
Textile Handbook 1-35
3.1.3
Composition of Cotton Fibre Constituent Cellulose Protein Pectin Wax Ash Other substances
Proportion of dry weight (%) 94.0 1.3 1.2 0.6 1.2 1.7
3.1.4 Chemical composition of Cotton Fibre Chemical analysis of cotton fibre is given in the following table. 44.4% 6.2% 49.4% (C6H10O5)n 10000-15000 2000000
Textile Fibres
Carbon Hydrogen Oxygen Chemical structure Crystallinity Molecular weight
Element composition
1-36
Textile Fibres
3.1.5
Physical properties of Cotton fibre (Upland Cotton) Properties
Fibre length Fibre diameter Fibre circumference Fibre width Fibre cross-section area Lumen cross-section area Special area Cell wall thickness Convolution Fibre fineness Single fibre tenacity Elongation at break Breaking Length Relative strength Strength per specific area Initial modulus Moisture regain Specific density Thermo hydrometer Thermal transmissivity Exposure strength Friction coefficient
Birefringence Compression resistance Compressional resilience Torsional rigidity Shearing strength Breakdown voltage Mass specific resistance Dielectric constant
(mm) (µm) (µm) (µm) (µm2) (µm2) (1/µm) (µm) (Convolutions/cm) (m/gm) (gm) (%) (km) (gm/tex) (kg/mm2) (gm/tex) (%) (gm/cm3) (calorie/gmoC) (kcal/mhroC) (strength drops 50%xhr) (cotton with cotton) (cotton with leather) (cotton with steel) (ne-no) (%) (%) (dyne/cm2) (108dyne/cm2) (Kvolt/mm) (Ωgm/cm2) 0 (60Hz,20 C and 65%R.H.)
Applicable range 23-33 15-19 50-56 18-25 85-145 11-27 0.33-0.42 5-8 50-80 4500-7000 3-5 7-12 20-28 2.0-3.5 30-40 68-93 7.0-9.5 1.50-1.55 0.315-0.319 0.05(0oC) 940 0.22-0.29 0.28-0.35 0.26-0.33 0.040-0.043 80-84 38 0.04-0.06 12.9 4.5 2.29x107 7.7
Textile Handbook 1-37
3.1.6 Chemical Properties of Cotton Fibre Chemical treatment Reaction to Water Hydrolysis reaction
Acidity reaction
Alkaline reaction
Oxidization reaction
Reaction to heat Reaction to micro organism
Dye ability Reaction with organic solvent
Fibre swells, but not dissolves in water, cross section enlarges about 40-50% and length increases 1-2%, absorbent fibres absorb water greatly. Hydrolyses in acidic aqueous solution or high temperature acidic solution, polymerization degree drops and strength decreases. Corrodes in sulphuric acid or hydrochloric acid, dissolves in high temperature dilute acid and in cool concentrate acid. However the reaction with organic acid such as formic acid is not strong. The acidity reaction changes with different temperature, concentration and different time phase. Stable reaction in dilute alkaline solution at constant temperature. Can be mercerized at 18% NaOH bath and becomes alkaline cellulose in concentrate alkaline treatment. Fibre will be oxidized in oxidization agent and under long period of steam treatment. Molecular chains break and fibre decomposes. Cellulose structure is destroyed while exposing under sun light. The ultra violet beam is the strongest, it lowers down the degree of polymerization of cellulose, therefore, fibre strength decreases and cotton fibres become fragile. Fibre strength decrease 40% while exposing under sun for 100 days. Moisture absorbed evaporates at 100 o C; fibre dehydrates at 160oC, decays at 240oC and carbonizes at 400-450oC. The moisture regain of fibre with micro-organism is greater than 9% at R.H. above 75%, cellulose structure decomposes and cotton fibre can be attacked by mould easily and greatly. The dye absorption rate of cotton is very strong; it can be easily dyed with normal dyes. Cellulose fibre does not dissolve in organic solvent, only symbiotic materials of it will be dissolved. Fibre swells very slightly at benzene and petrolatum, therefore, these solvent are used for measuring fibre weights.
Textile Fibres
Reaction to Light
Reaction
1-38
Textile Fibres
3.2 Classification of Cotton The term “cotton classification” refers to the application of standardized procedures for measuring those physical attributes of raw cotton that affect the quality of the finished product and/or manufacturing efficiency. In the United States, laws were passed authorizing the United States Department of Agriculture (USDA) to develop cotton grade standards and offer cotton classification services. USDA classification currently consists of determinations of fibre length, length uniformity, strength, micronaire, colour, preparation, leaf, and extraneous matter. Research and development for the technology to rapidly measure other important fibre characteristics, such as maturity, stickiness and short fibre content, continues.
3.2.1 Classification of Upland Cotton a) Instrument Determination Measurements for the following quality factors are performed by high-volume precision instruments, commonly referred to as “HVI” classification. (i) Fibre Length Fibre length is the average length of the longer fibres (upper half mean length). It is reported in both l00ths and 32nds of an inch (see conversion chart 3.2.1a(i)). It is measured by passing a “beard” of parallel fibres through a sensing point. The beard is formed when fibres from a sample of cotton are grasped by a clamp, then combed and brushed to straighten and make parallel the fibres.
Textile Handbook 1-39
Table 3.2.1a (i)
Upland Length Conversion Chart
Inches 0.79 & shorter .80-.85 .86-.89 .90-.92 .93-.95 .96-.98 .99-1.01 1.02-1.04 1.05-1.07 1.08-1.10
32nds 24 26 28 29 30 31 32 33 34 35
Inches 1.11-1.13 1.14-1.17 1.18-1.20 1.21-1.23 1.24-1.26 1.27-1.29 1.30-1.32 1.33-1.35 1.36 & longer
32nds 36 37 38 39 40 41 42 43 44 & longer
(ii) Length Uniformity Length uniformity is the ratio between the mean length and the upper half mean length of the fibres and is expressed as a percentage. If all of the fibres in the bale were of the same length, the mean length and the upper half mean length would be the same, and the uniformity index would be 100. However, there is a natural variation in the length of cotton Fibres, so length uniformity will always be less than 100. Table 3.2.1a (ii) tabulation can be used as a guide in interpreting length uniformity measurements. Table 3.2.1a (ii) Length Uniformity Measurements Degree of Uniformity Very High High Intermediate Low Very Low
HVI Length Uniformity Index (Percent) Above 85 83-85 80-82 77-79 Below 77
Textile Fibres
Fibre length is largely determined by variety, but the cotton plant’s exposure to extreme temperatures, water stress, or nutrient deficiencies may shorten the length. Excessive cleaning and/or drying at the gin may also result in shorter fibre length.
3.3
Cotton Species .................................................................... 1-44 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5
3.4
Upland Cotton : ............................................................ Sea-island Cotton : ....................................................... Peruvian Cotton : ......................................................... Asiatic Rough Cotton : ................................................. Tree Cotton : .................................................................
1-45 1-45 1-45 1-45 1-45
World Cotton Classification and Standard ..................... 1-46 3.5.1
3.5 3.5.2
Chinese Cotton Grading ............................................... (Souice: China National Standad GB 1103-1999 Upland Cotton) ............................................................. Chinese Cotton Specification ....................................... Length ..........................................................................
1-47 1-47 1-47 1-48
3.6
Indian Cotton Grading ...................................................... 1-50
3.7
Pakistan Cotton Grading .................................................. 1-51
3.8
Influence of the Fibre Characteristics of the Yarn (Source: Zellweger Uster) .................................................. 1-51
3.9
Other Disturbing Factors in the Yarn Manufacturing Process ................................................................................. 1-53 3.9.1 3.9.2 3.10
Stickiness ...................................................................... 1-53 Cotton Contamination .................................................. 1-55 Relationship between Fibre Length, Fineness and Yarn Count to be Spun ................................................. 1-64
Section 4 - World Cotton Production ........... ........... 1-65 4.1
World Cotton Production and Related Statistics ............ 1-65
4.2
The World’s Major Cotton Growing Areas ..................... 1-73 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6
China ............................................................................ United States ................................................................ India .............................................................................. Pakistan ........................................................................ Australia ....................................................................... Republic of Uzbekistan ................................................
Back to Table of Content
1-74 1-75 1-76 1-77 1-78 1-79
1-40
Textile Fibres
(iii)
Fibre Strength
Strength measurements are reported in terms of grams per tex. A tex unit is equal to the weight in grams of 1,000 metres of fibre. Therefore, the strength reported is the force in grams required to break a bundle of fibres one tex unit in size. The table 3.2.1 a(iii) tabulation can be used as a guide in interpreting Fibre strength measurements. Table 3.2.1 a(iii) Fibre Strength Degree of Strongth
HVI Strength (grams per tex) 31 & above 29-30 26-28 24-25 23 & below
Very Strong Strong Average Intermediate Weak
Strength measurements are made on the same beards of cotton that are used for measuring fibre length. The beard is clamped in two sets of jaws, one-eighth of an inch apart, and the amount of force required to break the fibres is determined. Fibre strength is largely determined by variety. However, it may be affected by plant nutrient deficiencies and weather. (iv)
Micronaire
Micronaire is a measure of Fibre fineness and maturity. An airflow instrument is used to measure the air permeability of a constant mass of cotton Fibres compressed to a fixed volume. Table 3.2.1a(iv) can be used as a guide in interpreting micronaire measurements.
Textile Handbook 1-41 Table 3.2.1a (iv)
3.4 and below
Relationship of Micronaire Readings to Market Value
3.5-3.6
3.7-4.2 Premium
4.3-4.9
5.0 and up
Base Range Discount Range
Micronaire measurements can be influenced during the growing period by environmental conditions such as moisture, temperature, sunlight, plant nutrients, and extremes in plant or boll population. (v) Colour
The colour of cotton Fibres can be affected by rainfall, temperatures below freezing, insects and fungi, and by staining through contact with soil, grass, or the cotton plant’s leaf. Colour also can be affected by excessive moisture and temperature levels while cotton is being stored, both before and after ginning.
Textile Fibres
The colour of cotton is determined by the degree of reflectance (Rd) and yellowness (+b). Reflectance indicates how bright or dull a sample is, and yellowness indicates the degree of colour pigmentation. A three-digit colour code is used. The colour code is determined by locating the point at which the Rd and +b values intersect on the Nickerson-Hunter cotton colourimeter diagram for Upland cotton.
1-42
Textile Fibres Figure 3.2.1 a(v)
(vi)
Nickerson-Hunter cotton colourimeter diagram for Upland cotton
Trash
Trash is a measure of the amount of non-lint material in the cotton, such as leaf and bark from the cotton plant. The surface of the cotton sample is scanned by a video camera and the percentage of the surface area occupied by trash particles is calculated. Although the trash determination and classer’s leaf grade (see below) are not the same, there is a correlation between the two as shown in the table below.
Textile Handbook 1-43 Table 3.2.1 a(vi)
Trash Measurement
Trash Measurement (4-yr. Avg.) (% area)
Classer’s Leaf Grade 1 2 3 4 5 6 7
0.12 .20 .33 .50 .68 .92 1.21
b) Classer Determinations
(i) Colour Grade There are 25 official colour grades for American Upland cotton, plus five categories of below grade colour, as shown in Table 3.2.1b (i) Colour tabulation below. USDA maintains physical standards for 15 of the colour grades. The others are descriptive standards. Table 3.2.1b (i)
Colour Grades of Upland Cotton Effective 1993
Colour Grades of Upland Cotton Effective 1993 White
Light Spotted
Spotted
11* 12 Good Middling 21* 22 Strict Middling 31* 32 Middling 41* 42 Strict Low Middling 51* 52 Low Middling 61* 62 Strict Good Ordinary 71* Good Ordinary 81 82 Below Grade * Physical Standards. All others are descriptive.
13 23* 33* 43* 53* 63* 83
Tinged 24 34* 44* 54* 84
Yellow Stained 25 35 85
Textile Fibres
Although USDA provides instrument measurements of colour and trash, the traditional method of classer determination for colour, leaf, and extraneous matter remains useful to the cotton industry and continues to be included as part of the official USDA classification.
1-44
Textile Fibres
(ii) Leaf Grade The classer’s leaf grade is a visual estimate of the amount of cotton plant leaf particles in the cotton. There are seven leaf grades, designated as leaf grade “1” to “7,” and all are represented by physical standards. In addition, there is a “below grade” designation which is descriptive. Leaf content is affected by plant variety, harvesting methods, and harvesting conditions. The amount of leaf remaining in the lint after ginning depends on the amount present in the cotton prior to ginning, and on the type and amount of cleaning and drying equipment used. Even with the most careful harvesting and ginning methods, a small amount of leaf remains in the cotton lint. From the manufacturing standpoint, leaf content is all waste, and there is a cost factor associated with its removal. Also, small particles cannot always be successfully removed and these particles may detract from the quality of the finished fabric. (iii) Preparation Preparation is a term used to describe the degree of smoothness or roughness with which the lint is ginned. Various methods of harvesting, handling and ginning cotton produce differences in roughness or smoothness of preparation that sometimes are very apparent. (iv)
Extraneous Matter
Extraneous matter is any substance in the cotton other than Fibre or leaf. Examples of extraneous matter are bark, grass, spindle twist, seedcoat fragments, dust, and oil. The kind of extraneous matter, and an indication of the amount (light or heavy), are noted by the classer on the classification document.
3.3 Cotton Species Basically, cotton can be divided into American Cotton and Asiatic cotton, and each can be further sub-divided into five categories.
Textile Handbook 1-45
3.3.1 Upland Cotton : There are too many species in this category; an American, Dugger, classified it into eight types: • • • • • • • •
Cluster type: cotton fibre clusterly grown together in one region. Semi-cluster type: not too dense as cluster type. Rio-grande type: such as Trice Early type: the bolls mature early as type King. Big boll type: bolls are larger as type Acala and Long star. Long limb type: stems are longer Long staple type: fibre is longer like type Dolfose Intermediate type: like Stoneville
3.3.2 Sea-island Cotton :
3.3.3 Peruvian Cotton : Originally grown in South America, and the Egyptian crop belongs to this category.
3.3.4 Asiatic Rough Cotton : Grown in China, Japan, India and Pakistan, also known as coarse cotton. Productivity is going down and it is gradually being replaced by medium cotton.
3.3.5 Tree Cotton : Cultivated in India and Africa; being typically a large shrub, it has different varieties. Improved varieties are making this crop, obsolete.
Textile Fibres
Origin from South Carolina, Georgia, Florida of southeast America and West Indies, suitable for cultivation in a sea-island environment. It is the longest and silkiest among the cotton. Recently, a complex cross of other species has been proceed.
10
ZZ
Z
9
U
7
Y
O
6
8
I
E
4
5
A
3
2
1
Below grade
7th
6th
5th
4th
3rd
2nd
1st
Egyptian Cotton
yellowish
Middling Fair (M.F.) Strict Good Middling (S.G.M.) Good Middling (G.M.) Strict Middling (S.M.)
Fair (F.)
Extra (E) Fully Good to Extra (F.G. to E.) Fully Good (F.G.) Good to Fully Good (G. to F.G.) Good Middling (G) (M) Fully Good Fair To Good (F.G.F. to G.) Fully Good Fair (F.G.F.) Strict Low Middling (S.L.M.) Fully Good Fair to Good (F.G.F. to G.) Good Fair Low Middling (G.F.) (L.M.) Fully Fair to Good Fair (F.F. to G.F.) Strict Good Ordinary (S.G.O.) Fully Fair (F.F.) Good Ordinary Fair to Fully Fair (G.O.) (F. to. F.F.)
Grading Chinese American Upland Staple cotton (White) Symbol
TIPO 9
TIPO 8
TIPO 7
TIPO 6
TIPO 5
TIPO 4
TIPO 3
TIPO 2
TIPO 1
Brazilian cotton1
No. 8
No. 7
No. 6
No. 5
No. 4
No. 3
No. 2
No. 1
No. 5
No. 4
No. 3
No. 2
No. 11/2
No. 1
L.M.2
S.L.M.2
M.2
S.M.2
G.M.2
M.2
S.M.2
G.M.2
L.M.2
S.L.M.2
M.2
S.M.2
G.M.2
American American Peruvian Peruvian American cotton Upland cotton Upland cotton Upland cotton cotton (Gray) (Tinged) (Spotted) (Tanguis) (Pima)
Remarks: 1. Brazilian cotton, standard grading is lower than American Upland Cotton grading, so for simplification American Upland Cotton grading system is used for Brazilian Cotton. 2. American colour grade, i.e. spotted, grey, tinged is classified according to the difference between each whiteness degree.
Below grade
Low grade cotton
Medium grade cotton
Top grade cotton
Grade
3.4 World Cotton Classification and Standard 1-46
Textile Fibres
Textile Handbook 1-47
3.5 Chinese Cotton Specification 3.5.1 Chinese Cotton Grading (Souice:China National Standad GB 1103-1999 Upland Cotton) Grade
Table 3.5.1 (1)
Chinese Cotton Grading Saw Gins
Roller Gins Grade
1st
2nd
4th
5th
6th
7th
Maturity
Colour
Ginning Quality
Maturity
Colour
Ginning Quality
W h i t e o r Roots and White or creamy, good trash are rare creamy, good lustre with pale Excellent lustre with yellow pale yellow
Neps, trash and linters are few
White or creamy, good lustre with some pale yellow
N e p s , trash and linters are few
White or creamy, lustre, some y e l l o w spotted
Neps, trash and linters are not many
Greyish white with l i t t l e Average contamination
N e p s , trash and linters are increasing
Greyish white with Poor pale yellow, increased contamination with linters High content Greyish of trash white or Very poor g r a y i s h yellow, contaminated and linters Greyish Dark grey, high High content All immature, yellow, high contamination of trash damaged and Extremely contamination contaminated cells, Extremely and linters. poor and linters. high content of poor trash
N e p s , trash and linters are more
White and fine in early and middle stage, fibre cells Excellent are big and thick, only few are pale yellow, little trash. White and good in early and middle stage, some raining spotted and some Good semi-mature cells, few trash White in early and middle stage, good and white in late stage, cells are Fair random in size, some raining spotted and some immature, more trash Fair in early and middle stage, white in late stage, cells are small, some Average frosting greyish and some immature, much trash Poor white in late stage and immature in early and middle Poor stage, high trashes
W h i t e o r Roots and creamy, good trash are rare lustre with some pale yellow W h i t e o r Roots and c r e a m y , t r a s h slightly pale increases yellow, lustre, more in pale yellow or yellow spotted Greyish white Roots and w i t h l i t t l e trash become contamination higher
Greyish white with pale y e l l o w , increased in contamination with linters All immature and G r e y i s h greyish white in y e l l o w , late stage, high Very poor contaminated content of trash and linters
Roots and trash are high
Good
Fair
High level of neps, trash and linters High level of neps, trash and linters
Textile Fibres
3rd
Seed
1-48
Textile Fibres Table 3.5.1 (2) Grading Parameters Ginning quality Grade Maturity Tenacity Index (not strength (not Roller gin less than) less than) Seed coats Linters % Impurities cN/tex % ( n o t (not more per 100 gm (not more more than) than) than) 0.4 1,000 0.3 20 1st 1.6 0.4 1,200 0.3 19 2nd 1.5 0.6 1,300 0.5 19 3rd 1.4 0.6 2,000 0.5 18 4th 1.2 0.6 3,000 0.5 18 5th 1.0
Saw gin Linters % (not more than) 0.4 0.4 0.6 0.6 0.6
20-30 20-30 20-30 20-30 20-30
Remarks: 1.Impurities include leaf , trash, fuzzy seeds, linters, lint hair butts, dust and neps. 2.The standard of ginning is the quality standard of roller ginned cotton. 3.For tenacity strength, gauge setting is 3.2 mm. Calibrated by ICC (International cotton calibration) cotton.
3.5.2 Length a) Each increment of cotton staple length (here called length) is 1mm. The grading is as follows: 25mm
from 25.9mm or below;
26mm
from 26.0 to 26.9mm;
27mm
from 27.0 to 27.9mm;
28mm
from 28.0 to 28.9mm;
29mm
from 29.0 to 29.9mm;
30mm
from 30.0 to 30.9mm;
31mm
ranges from 31.0mm and above.
b) Length standard 28mm is the acceptable staple length. For grade 5 cotton, a length longer than 27mm is counted as 27mm. For grade 6 and 7, length is counted as 25mm. Remark: The 1mm increment system commenced in 2000. 1999 cotton length standards were counted according to GB1103-1972 standard.
Textile Handbook 1-49
c) Micronaire Micronaire is divided into A,B,C classes, B is the standardlevel.
Micronaire grading is shown in table 3.5.2c:
Table 3.5.2c Below 3.4 3.5-3.6
Micronaire Value 3.7-4.2
4.3-4.9 Above 5.0
Class A Class B Class C
Remark:This system commenced in 2000. d) Moisture regain
e) Trash Content Standard trash content for roller gin is 3.0% and for saw gin is 2.5%.
Textile Fibres
The standard moisture regain is 8.5%, and the maximum moisture regain range is 10.5%.
Textile Fibres
1-50
3.6 Indian Cotton Grading Table 3.6
India Cotton Grading
Standard Descriptions with Basic Grade & Staple in millimeters (in inches) based on 2.5 Span length (By-law 66 A (a) (4))
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.** 13. 14. 15. 16.
17. 18.** 19. 20.** 21. 22.
23. 24.
(a) (b)
(a) (b) (a) (b) (a) (b)
(a) (b)
(a) (b) (a) (b) (a) (b) (a) (b) (a) (b) (c) (d)
Bengal Deshi Bengal Deshi Waged V-797 Laxmi/Hampi 197/3/ Virnar 197/3/ Virnar Gaorani (A) Gaorani (B) A.K.235/277 R.G.J.-34 CJ-73 Jayadhar Y-1 Y-1 Digvijay G-12 A-51-0 L-147 (Berar) R.G.F.-414 including Agatti and H-777 S.G.F.-414 including Agatti and H-777 1007 1007 H-4 H-4 Laxmi Shankar 4 (Hybrid 4) Shankar 4 (Hybrid 4) MCU-5 Varalaxmi (A) Varalaxmi (B) Varalaxmi (C) Varalaxmi (D) DCH-32 Suvin
-
-
Fine Extra Superfine Fine 19mm. (24/32") Fine 21mm. (27/32") Fine 21mm. (27/32") Fine 21mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 22mm. (28/32") Fine 23mm. (29/32") Fine 23mm. (29/32") Fine 23mm. (29/32") Fine 24mm. (30/32") Fine 24mm. (30/32") Fine 25mm. (31/32") Fine
- 25mm. (31/32") - 26mm. (1") - 26mm. (1") - 27mm. (12/32") - 28mm. (13/32") - 28mm. (13/32") - 30mm. (16/32") - 31mm. (17/32") - 33mm. (19/32") 34mm. (1 10/32") 34mm. (1 10/32") 35mm. (1 12/32") 36mm. (1 13/32") 36mm. (1 13/32") 40mm. (1 18/32")
Fine Fine Fine Fine Fine Fine Fine Fine Fine Fine Fine Fine Fine Fine Fine
Textile Handbook 1-51
3.7 Pakistan Cotton Grading Table 3.7
Pakistan Cotton Grading
Variety
Staple length
Micronaire value
Pressley tensile 1000 lb/sq in
UPLAND VARIETIES PUNJAB B-557
1-1/32
4.45
92.9
MNH-93 NIAB-78 MS-84
1-1/8 1-1/32 1-1/4
4.47 4.46 3.90
94.0 92.5 91.3
SLH-41
1-1/32
4.40
95.8
SIND M-4 M-100 NT
15/16 1-113
3.3-4.5
85.0 85.0
TH-1101
1-1/8 1-1/8 1-3/16 1-1/16
4.3 4.0-4.4
90.0 92.7 96.1 89.0-90.0
DESI VARIETIES PUNJAB D-9
3/8-5/8
7.5
80.0
Ravi
3/8-5/8
8.0
-
SIND TD- 1 SKD-10/19
11/16 3/8-5/8
10.0-10.2 9.6-10.2
79.5 -
3.8 Influence of the Fibre Characteristics of the Yarn (Source: Zellweger Uster) The quality characteristics of a yarn are very much dependent on the following quality factors of the raw material (see table 3.8 (1) and 3.8 (2)). Examples of the influence of fibre characteristics on yarn are given in the same two tables.
Textile Fibres
H-59-1 (Qallandavi) S-59-1 (Sarmast) K-68/9
3.5-4.0 3.3-3.7 3.5-3.7
1-52
Textile Fibres
Example 1:
The influence of individual fibre characteristics on a certain yarn characteristics.
Table 3.8 (1) The influence of the fibre characteristic on the yarn breaking force.
Example 2:
Various interrelationships between the fibre and yarn quality characteristics
Table 3.8 (2) Relationship between fibre and yarn properties for ring-spun yarns
Textile Handbook 1-53
Example 3 : Influence of the variation in fibre characteristics on the yarn characteristics. The following are some examples of the variation in fibre characteristics on the tenacity of rotor-spun yarn: • An increase or decrease in fibre tenacity of approx. 1 cN/tex results in an improvement or a downgrading of the yarn tenacity by 0.5 cN/ tex. • An increase or decrease in fibre length of approx. 1 mm (2.5% span legnth, HVI-value) results in a change of 0.4 cN/tex in the yarn tenacity. • An increase or decrease in fibre length of approx. 1 mm (50% span length, HVI-value) can even result in a change of 0.8 cN/tex in the yarn tenacity.
Apart from those measurable fibre characteristics, there are other factors which are difficult to measure but which can downgrade the spinning process and the resulting yarn quality. These factors refer to stickiness and contamination (foreign matter) in the raw material.
3.9.1 Stickiness “Sticky cotton” is a term to describe cotton lint which sticks to moving machinery parts and causes problems in yarn manufacturing. a) Causes Stickiness on cotton lint can be caused by secretions from insects (honeydew) or natural plant sugars resulting from nectaries on the cotton plant or cellulose precursors in the cotton boll. It has been estimated that most sticky cotton problems are related to insect honeydew contamination on cotton lint. However, problems do occasionally arise because of natural sugars on cotton lint.
Textile Fibres
3.9 Other Disturbing Factors in the Yarn Manufacturing Process
1-54
Textile Fibres
(i) Natural Sugars These natural sugars are produced by leaf and floral nectaries on the cotton plant as well as sugars present on Fibre from newly opened bolls. Stickiness due to natural sugars usually disappears on storage. This stickiness is uniformly deposited on the lint and is often less of a problem in high rainfall production areas of the cotton belt. (ii) Insect Honeydew Insect honeydew is most often caused by aphids, whiteflies and mealy bugs, all members of the insect order Homoptera. Of these, the whitefly most often causes stickiness. These insects ingest plant juices, extract proteins and other nutrients from these plant juices, and then expel excess sugars in the form of honeydew. These sticky liquid droplets subsequently fall on leaves or lint after boll opening. In view of these manufacturing problems, mill trials were run and industry contacts were made to determine recommendations for control. The results of this work follow. b) Processing Recommendations The processing of sticky cotton during yarn manufacturing may be improved by introducing or adjusting some conditions in cotton bale storage and/or the yarn preparation stages. The following list of items is presented to assist the manufacturer in processing. These items can be evaluated individually or in combination with each other. (i) Fibre Storage Store suspect or identified bales with the sticky condition for an ageing period. (ii) Opening/ Blending • Incorporate a minimum number of suspect bales in each laydown blend. • Distribute contaminated bales throughout the mix. • Optimize blending conditions to assure an even distribution through the blend mix.
Textile Handbook 1-55
• Introduce a lubricant in fog form at the end of the hopper conveyer to minimize sticking problems. • Reduce relative humidity below 50%, or a workable level, in opening, picking, and carding. (Note: Reduced humidity conditions may be required and could be beneficial in drawing. combing, and spinning.)
(iii) Carding • Reduce or adjust rate of production of card to optimise processing of Fibre. • Reduce pressure on crush rolls of card, while continuing to maintain sufficient crushing action for dried trash. • Replace and adjust card crush roll blade as necessary, and Roll blade may require more frequent cleaning during processing.
3.9.2 Cotton Contamination Foreign matter, stickiness and seed-coat fragments in raw cotton continue to be among the most serious problems affecting the cotton spinning industry world-wide. This is the conclusion to be drawn from the “Cotton Contamination Survey 1999” which has just been released by the International Textile Manufacturers Federation (ITMF). The survey is carried out every other year. In the 1999 report, 87 growths were evaluated by 283 spinning mills located in 24 countries.
Textile Fibres
• Improvements may be experienced by sparingly spraying the card crush rolls with lubricant twice each shift. (Some U.S. mills used “Pam”, a spray product to prevent fry pan sticking and in made by Boyle-Midway Household Product Inc., as the lubricant.)
Textile Fibres
1-56
Table 3.9.2 (1) Participation Participation in 1999 Survey Country Australia Austria Belgium Brazil Czech Republic Egypt France Germany Greece Hungary India Indonesia Italy Japan Korea Rep. Madagascar Morocco Portugal South Africa Spain Switzerland Taiwan Turkey USA Total *
Number of respondents (participating companies) 2 1 5 11 14 1 3 14 4 11 69 16 14 10 8 1 5 2 6 6 7 13 15 43 283
Divided among 87 cotton descriptions
Number of samples (evaluations) 2 2 23 59 78 25 25 146 10 21 301 117 129 84 53 1 25 27 29 22 53 69 62 162 1,501*
Textile Handbook 1-57 Table 3.9.2 (2)
Source of Contamination
Number of Samples: 1,501 Degree of contamination (%) NonSource of contamination existent/ Moderate serious insignificant 14 woven plastic 6 1 Fabrics made of 80 11 plastic film 5 2 84 17 jute/hessian 8 3 75 19 cotton 5 4 76 17 woven plastic 8 5 Strings made of 75 16 plastic film 6 6 78 19 jute/hessian 11 7 70 19 cotton 6 8 75 29 leaves,feathers,paper,leather,etc. 61 10 9 Organic matter 23 sand/dust 7 10 Inorganic matter 70 14 rust 4 11 82 12 metal/wire 4 12 84 18 5 13 Oily substances/chemicals grease/oil 77 5 rubber 1 14 94 11 stamp colour 3 15 86 3 tar 1 16 96 15 6 Average of 1-16 79 No(%) Yes(%) No(%) Yes(%) Stickiness Seed-coat fragments 38 20 62 80
All Countries/ All growths
Year 1989 1991 1993 1995 1997 1999
Degree of Contamination
Summary 1989-1999 Degree of contamination (%) Non-existent/ Serious Moderate insignificant 9 86 5 11 85 4 11 85 4 13 82 5 13 82 5 15 79 6
Stickiness (%)
Seed-coat fragments (%)
21 27 26 20 23 20
0 34 36 39 32 38
Textile Fibres
Table 3.9.2 (3)
Textile Fibres
1-58
Table 3.9.2 (4)
Ranking 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
The Most Contaminated Descriptions
Description India Pakistan India India India India India India Turkey Sudan Turkey Turkmenistan India Egypt Tajikistan Mexico Iran Turkey China Uzbekistan Uzbekistan Tanzania Turkmenistan Turkey Tajikistan Tanzania Mexico Mali Uganda
F-414 AmSeed AFZAL J-34 India-Others Shanker-4/6 H-4 LRA DCH Cukurova/South Barakat Turkey-Others Long Staples MCU-5 Giza Long Staples Mexicali Iran Izmir Xinjiang Long Staples Medium Staples Mwanza Medium Staples Antalya Medium Staples Coastal Juarez Mali Uganda
Degree of contamination (%)* Number of Non-existent/ Moderate Serious samples** insignificant 36 51 52 57 59 59 59 61 65 66 68 68 68 69 71 72 73 73 74 75 76 78 78 79 79 80 82 83 83
53 23 32 27 25 26 28 26 27 28 18 18 22 23 12 24 15 22 19 17 19 15 20 13 17 17 13 14 14
11 26 16 16 16 15 13 13 7 6 14 14 10 8 17 4 12 5 7 8 5 7 2 8 4 3 5 3 3
* Average degree of contamination by each of the 16 pre-indicated contaminants ** Minimum: 5 samples
6 9 31 38 54 26 38 40 18 14 12 6 43 45 11 6 9 23 10 17 66 8 18 5 25 7 11 39 8
Textile Handbook 1-59
Table 3.9.2 (5)
Ranking
Description Israel Zimbabwe Argentina Sudan Australia Cameroon Israel Spain USA USA Syria USA USA USA South Africa Zambia Burkina Faso Benin USA Paraguay USA USA USA Chad Senegal Brazil Ivory Coast Togo Greece
Acala Zimbabwe Argentina Acala Australia Cameroon Pima Spain Memphis Territory USA-Others Syria Texas High Plains California EL Paso South Africa Zambia Burkina Faso Benin Arizona Paraguay Pima South Eastern Rio Grande Valley Chad Senegal South Brazil Ivory Coast Togo Greece
1999
Degree of contamination (%)* Number of Non-existent/ Moderate Serious samples** insignificant 95 94 94 92 92 90 90 90 89 88 88 88 88 88 88 88 87 87 87 87 86 86 86 85 85 84 84 84 83
5 5 5 8 7 9 8 7 9 11 10 10 9 9 9 31 11 10 10 7 11 11 8 13 12 15 12 12 15
0 1 1 0 1 1 2 3 2 1 2 2 3 3 3 9 2 3 3 6 3 3 6 2 3 1 4 4 2
* Average degree of contamination by each of the 16 pre-indicated contaminants ** Minimum: 5 samples
14 34 19 9 55 10 11 26 59 5 37 37 75 22 13 5 37 34 30 7 59 38 11 28 11 12 32 18 41
Textile Fibres
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
The Least Contaminated Descriptions
1-60
Textile Fibres
Table 3.9.2 (6)
Ranking 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
Descriptions Most Affected by Stickiness
Description Sudan Sudan Mexico Tanzania India Cameroon Chad Pakistan USA USA Mali Mexico Senegal Uzbekistan Turkmenistan Benin Togo USA Tajikistan Uzbekistan India India South Africa Burkina Faso USA Iran India China Turkey
Acala Barakat Mexicali Coastal DCH Cameroon Chad AmSeed AFZAL Arizona USA-Othera Mali Juarez Senegal Long Staples Long Staples Benin Togo California Long Staples Medium Staples MCU-5 H-4 South Africa Burkina Faso Texas High Plains Iran India-Others Xinjiang Antalya
1999
Affirmative replies (%)*
Number of samples**
78 71 67 57 53 50 46 44 40 40 38 36 36 35 33 29 28 27 27 24 23 23 23 22 22 22 21 20 20
9 14 6 7 40 10 28 9 30 5 39 11 11 17 6 34 18 75 11 66 43 23 1 37 37 9 38 10 5
* Percentage of replies 18 indicating the existence of stickiness ** Minimum: 5 samples
Textile Handbook 1-61
Table 3.9.2 (7) Descriptions Least Affected by Stickiness
Ranking
Turkey Israel USA Paraguay Zambia Spain USA Greece USA Argentina India Israel Brazil Australia Zimbabwe USA Syria Turkey Egypt India Tanzania Uganda Tajikistan Turkmenistan Turkey India India USA Ivory Coast
Izmir Pima Rio Grande Valley Paraguay Zambia Spain Memphis Territory Greece South Eastern Argentina Shankar-4/6 Acala South Brazil Australia Zimbabwe El Paso Syria Cukurova/South Giza J-34 Mwanaz Uganda Medium Staples Medium Staples Turkey-Others F-414 LRA Pima Ivory Coast
Affirmative replies (%)* 0 0 0 0 0 4 5 5 5 5 7 7 8 9 9 9 11 11 13 13 13 13 16 17 17 17 18 19 19
* Percentage of replies indicating the existence of stickiness ** Minimum: 5 samples
Number of samples** 23 11 1 7 5 26 59 41 38 19 54 14 12 55 34 22 37 18 45 31 8 8 25 18 12 6 38 59 32
Textile Fibres
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
Description
1999
Textile Fibres
1-62
Table 3.9.2 (8) Descriptions Most Affected by Seed-Coat Fragments
Ranking 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
Description India Turkey Pakistan India Turkmenistan India India Sudan Tanzania Turkey India Turkey Sudan Tajikistan India India Turkey Egypt India Togo Brazil Uganda Mexico Mail Greece Uzbekistan Cameroon USA Zambia
DCH Cukurova/South AmSeed AFZAL F-414 Long Staples LRA J-34 Barakat Mwanza Antalya MCU-5 Turkey-Others Acala Long Staples India-Others Shankar-4/6 Izmir Giza H-4 Togo South Brazil Uganda Mexicali Mali Greece Long Staples Cameroon USA-Others Zambia
1999
Affirmative replies (%)*
Number of samples**
85 72 67 67 67 66 65 64 63 60 58 58 56 55 53 52 52 51 50 50 50 50 50 46 41 41 40 40 40
40 18 9 6 6 38 31 14 8 5 43 12 9 11 38 54 23 45 26 18 12 8 6 39 41 17 10 5 5
* Percentage of replies indicating the existence of seed-coat fragments ** Minimum: 5 samples
Textile Handbook 1-63
Table 3.9.2 (9)
Ranking
Description Australia USA USA Turkmenistan Burkina Faso Israel USA South Africa Benin Zimbabwe Tajikistan USA Chad Uzbekistan USA Syria Spain Mexico Ivory Coast Paraguay Tanzania China USA USA Iran Israel Senegal USA Argentina
Australia Rio Grande Valley El Paso Medium Staples Burkina Faso Acala Arizona South Africa Benin Zimbabwe Medium Staples California Chad Medium Staples South Eastern Syria Spain Juarez Ivory Coast Paraguay Coastal Xinjiang Mmphis Territory Texas High Plains Iran Pima Senegal Pima Argentina
Affirmative replies (%)*
Number of samples**
5 9 14 17 19 21 23 23 24 24 24 25 25 26 26 27 27 27 28 29 29 30 32 32 33 36 36 37 37
55 11 22 18 37 14 30 13 34 34 25 75 28 66 38 37 26 11 32 7 7 10 59 37 9 11 11 59 19
* Percentage of replies indicating the existence of seed-coat fragments ** Minimum: 5 samples
Textile Fibres
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29.
Descriptions Least Affected by Seed-Coat Fragments 1999
1-64
Textile Fibres
3.10 Relationship between Fibre Length, Fineness and Yarn Count to be Spun a) Fibre length in relation to yarn court to be spun Carded Cotton
Fibre length (in)
Warp
Weft
10S
10S 10-20S 20-30S 14-20S 30-36S 20-30S 36-45S 30-36S 45-60S 36-50S 60-80S 50-70S Carded Cotton
1/2-5/8 5/8-3/4 3/4-7/8 7/8-1 1-1-1/8 1-1/8-1-3/8 1-1/4-1-3/8
10-14S
Fibre length (in)
Warp
Weft 40S 40-70S 70-100S
30S
1-1-1/8 1-1/8-1-3/8 1-1/4-1-3/8
30-60S 60-70S
b) Fibre fineness and length in relation to yarn count to be spun Yarn Court Range
Fibre length
Fineness (m/g)
mm
in.
Nm
Ne
2200 2400 2600 3000 3400 3800 4200 4600 5000 5500 6000 8000
18 20 22 24 26 28 30 32 34 36 38 40
3/4
24 30 36 44 56 74 100 128 160 200 250 340
14 18 22 26 32 44 60 76 94 120 150 200
7/8 1 1-118 1-114 1 38 1 12
Textile Handbook 1-65
SECTION 4
WORLD COTTON PRODUCTION
4.1 World Cotton Production and Related Statistics Table 4.1(1)
World Cotton Production, Yield, Supply And Utilization (in Thousand 480-lb. Bales, MY 1990/91-1999/2000) (1) (1) Ending Beginning Total ConStocks Production Imports Supply sumption Loss Exports Stocks
25,347 27,812 37,747 35,403 27,609 29,899 35,760 38,189 40,772 41,743
87,069 95,754 82,507 77,051 85,859 93,065 89,593 91,629 84,535 86,358
30,653 29,077 26,875 27,717 30,528 27,538 28,939 26,290 25,159 26,651
143,069 152,643 147,129 140,171 143,996 150,502 154,292 156,108 150,466 154,752
85,518 85,745 85,549 85,298 85,543 96,644 89,013 88,388 85,216 88,193
749 29,560 683 28,468 1,071 25,520 509 26,771 245 28,385 341 27,757 253 26,845 298 26,650 (138) 23,645 211 26,479
27,812 37,747 35,403 27,609 29,899 35,760 38,189 40,772 41,743 39,869
Notes : (1) Beginning with 1970/71, world import and export totals were expanded to include trade among the 12 countries of the former Soviet Union and the 3 Baltic States. (2) Estimate (3) Forecast
Source: USDA/FAS Jan-2000
Textile Fibres
Yield Marketing 1,000 Kg/ year Hectares Ha 1990/91 33,155 572 1991/92 34,787 599 1992/93 32,631 551 1993/94 30,710 546 1994/95 32,176 581 1995/96 35,936 564 1996/97 33,818 577 1997/98 33,815 590 (2) 1998/99 (3) 32,971 558 1999/2000 32,610 577
1-66
Textile Fibres
Table 4.1(2)
Cotton Production, Supply and Distribution by Country MY 1999/2000 (1,000 480 lb Bales)
Beg. Stocks Afghanistan 13 Albania 53 Algeria 22 Angola 7 Argentina 798 Armenia, Rep. 2 Australia 1,206 Austria 49 Azerbaijan; Republic 122 Bangladesh 41 Belarus 5 Belgium-Lux. 20 Benin 166 Bolivia 26 Brazil 1,446 Bulgaria 18 Burkina 115 Burma 41 Cambodia 1 Cameroon 86 Canada 23 Cen. African Rep. 10 Chad 68 Chile 39 China 17,433 Colombia 90 Costa Rica 12 Cote d’’Ivoire 234 Cuba 10 Cyprus 1 Czech Republic 61 Denmark 4 Dominican Rep. 2 Ecuador 26 Egypt 520
Prod. 100 1 0 20 550 0 3,100 0
ImportsTotal Supply 0 113 34 88 130 152 0 27 35 1,383 5 7 0 4,306 140 189
Dom. Loss* Use 75 0 35 0 130 0 15 0 400 9 5 0 200 0 125 0
Exports Ending Stocks 25 13 0 53 0 22 5 7 500 474 0 2 2,800 1,306 10 54
145 70 0 0 625 40 1,900 30 600 130 0 300 0
0 700 35 210 0 0 2,000 70 0 2 5 0 350
267 811 40 230 791 66 5,346 118 715 173 6 386 373
40 750 30 200 10 10 3,800 100 25 105 5 45 350
0 1 0 0 0 0 0 0 0 0 0 0 0
120 0 5 15 600 35 0 0 550 25 0 270 0
107 60 5 15 181 21 1,546 18 140 43 1 71 23
75 375 0 17,600 160 4 750 2 1 0 0 3 15 1,075
0 0 100 150 195 10 0 40 1 260 15 15 115 100
85 443 139 35,183 445 26 984 52 3 321 19 20 156 1,695
5 15 100 20,500 340 14 130 45 2 250 15 18 120 900
0 0 0 0 2 0 0 0 0 5 0 0 0 23
60 350 0 1,200 10 0 575 0 0 0 0 0 0 375
20 78 39 13,483 93 12 279 7 1 66 4 2 36 397
Textile Handbook 1-67 Table 4.1(2)
Cotton Production, Supply and Distribution by Country Prod.
ImportsTotal Supply 1 130 163 0 140 153 70 20 112 0 50 73 0 500 678 0 10 13 0 620 692 70 15 103 1,750 20 2,132 3 140 177 10 0 18 2 12 17 0 600 718 0 85 110 13,000 450 18,132 17 2,500 2,705 600 0 781 40 60 127 0 110 147 125 40 233 1 1,350 1,465 0 1,250 1,576
Dom. Loss* Use 130 0 120 0 90 0 50 0 480 20 10 0 560 0 70 0 600 5 145 0 10 0 15 0 550 0 80 3 13,000 0 2,400 50 600 0 100 0 110 0 100 0 1,300 10 1,250 0
Exports Ending Stocks 0 33 20 13 0 22 0 23 0 178 0 3 60 72 15 18 1,100 427 0 32 0 8 0 2 50 118 0 27 200 4,932 0 255 20 161 0 27 0 37 75 58 10 145 0 326
350 30 5 1 130 0 0 0 60 30 0 950 600 0 1 150 0 10 5 250
80 60 110 1,550 45 30 10 70 60 35 400 15 2,450 10 210 10 17 1 4 210
240 0 0 35 80 70 0 30 0 5 0 925 200 0 0 140 0 9 1 115
0 40 105 1,600 0 100 10 100 0 10 425 0 2,100 10 210 5 17 0 0 70
408 100 140 1,995 144 114 13 110 73 43 471 1,237 3,146 19 239 190 22 12 8 469
0 0 0 0 0 0 0 0 0 0 0 0 25 0 0 0 0 0 0 0
88 40 30 410 19. 14 3 10 13 3 71 297 471 9 29 40 5 2 3 144
Textile Fibres
Beg. Stocks El Salvador 32 Estonia 13 Ethiopia 22 Finland 23 France 178 Georgia, Rep. 3 Germany 72 Ghana 18 Greece 362 Guatemala 34 Haiti 8 Honduras 3 Hong Kong 118 Hungary 25 India 4,682 Indonesia 188 Iran 181 Iraq 27 Ireland 37 Israel 68 Italy 114 Japan 326 Kazakhstan, Rep. 58 Kenya 30 Korea, North 30 Korea, South 394 Kyrgyzstan, Rep. 14 Latvia 14 Lebanon 3 Lithuania 10 Madagascar 13 Malawi 3 Malaysia 46 Mali 287 Mexico 446 Moldova, Rep. 9 Morocco 28 Mozambique 35 Netherlands 5 Nicaragua 2 Niger 3 Nigeria 149
1-68
Textile Fibres Table 4.1(2)
Cotton Production, Supply and Distribution by Country
Beg. Stocks Norway 8 Pakistan 1,711 Panama 1 Paraguay 54 Peru 61 Philippines 77 Poland 17 Portugal 285 Romania 92 Russia 142 Senegal 9 Singapore 8 Slovakia 23 Somalia 1 South Africa 97 Spain 215 Sri Lanka 16 Sudan 56 Sweden 10 Switzerland 66 Syria 674 Taiwan 227 Tajikistan, Rep. 72 Tanzania 84 Thailand 376 Togo 92 Tunisia 38 Turkey 583 Turkmenistan 659 Uganda 24 Ukraine 64 United Kingdom 110 United States 3,939 Uruguay 5 Uzbekistan, Rep.615 Venezuela 25 Vietnam 65 Yemen 4 Yugoslavia 52 Zaire 5 Zambia 52 Zimbabwe 146 World Total 41,743
Prod. 0 8,000 0 325 185 5 0 0 0 0 85 0 0 7 230 550 5 375 0 0 1,400 0 435 185 30 375 10 3,950 1,200 100 0 0 16,953 0 5,300 50 30 65 1 15 100 460 86,358
ImportsTotal Dom. Loss* Supply Use 15 23 15 0 500 10,211 7,300 25 5 6 5 0 0 379 40 0 170 416 320 0 160 242 170 0 325 342 325 0 735 1,020 750 0 200 292 200 0 1,000 1,142 1,000 0 0 94 20 0 55 63 0 0 75 98 60 0 5 13 12 0 155 482 350 0 250 1,015 540 5 35 56 40 0 0 431 60 0 25 35 25 0 150 216 150 0 0 2,074 415 0 1,450 1,677 1,425 0 0 507 90 0 0 269 50 0 1,350 1,756 1,300 46 0 467 15 0 125 173 130 0 1,400 5,933 5,100 0 0 1,859 150 0 0 124 10 0 150 214 50 0 90 200 90 0 75 20,967 10,200 (33) 10 15 10 0 5 5,920 850 0 150 225 200 0 250 345 275 0 0 69 25 0 100 153 100 0 15 35 30 0 0 152 65 0 0 606 175 15 26,651 154,752 88,193 211
Exports Ending Stocks 0 8 700 2,186 0 1 275 64 35 61 0 72 0 17 0 270 0 92 0 142 50 24 55 8 10 28 0 1 40 92 230 240 0 16 270 101 0 10 5 61 1,000 659 4 248 355 62 125 94 0 410 325 127 0 43 200 633 850 859 85 29 100 64 0 110 6,400 4,400 0 5 4,100 970 5 20 0 70 40 4 0 53 0 5 20 67 270 146 26,479 39,869
Textile Handbook 1-69
* Loss for countries outside of the United States reflects cotton lost or destroyed while in the marketing channel. For the United States, loss reflects the difference between stocks as reported by the Bureau of the Census and implicit stocks based on supply plus total use. A negative “loss” is a positive number. Source: USDA/FAS Jan-2000 Table 4.1(3)
Cotton Area, Yield, and Production World and Selected countries and Regions
Region and Country
Textile Fibres
1998/99 1999/00 1998/99 1999/00 1998/99 1999/00 1,000 1,000 1,000 1,000 Ha Ha KG/Ha KG/Ha Bales Bales WESTERN HEMISPHERE United States 4,324 5,415 701 682 13,918 16,953 Brazil 800 850 572 487 2,100 1,900 Mexico 229 160 951 816 1,000 600 Argentina 650 325 301 368 900 550 Colombia 55 60 673 581 170 160 Paraguay 140 175 451 404 290 325 Peru 60 85 617 474 170 185 Guatemala 2 2 327 327 3 3 Nicaragua 4 4 544 544 10 10 Venezuela 30 30 363 363 50 50 Others 75 60 316 279 109 77 TOTAL 6,369 7,166 640 632 18,720 20,813 EUROPE Greece 412 425 926 897 1,753 1,750 Spain 97 110 1,084 1,089 483 550 Others 18 18 399 399 33 33 TOTAL 527 553 937 919 2,269 2,333 AFRICA Egypt 280 275 816 851 1,050 1,075 Sudan 150 225 363 363 250 375 Zimbabwe 320 300 359 334 528 460 South Africa 137 137 381 366 240 230 Tanzania 250 250 118 161 135 185 Cameroon 180 180 435 363 360 300 Nigeria 300 280 218 194 300 250 Chad 420 420 156 194 300 375 Others 2,625 2,684 333 334 4,013 4,118 TOTAL 4,662 4,751 335 338 7,176 7,368
1-70
Textile Fibres Table 4.1(3)
Cotton Area, Yield, and Production
ASIA AND OCEANIA China FSU-12 Uzbekistan Turkmenistan Others India Pakistan Turkey Australia Syria Israel Burma Thailand Afghanistan Others TOTAL FOREIGN TOTAL WORLD TOTAL
4,459 2,500 1,485 475 540 9,300 2,900 757 562 272 30 180 14 60 379 21,413 28,647 32,971
3,900 2,465 1,500 475 490 8,700 3,000 730 450 240 15 180 15 60 375 20,130 27,185 32,600
1,011 575 674 435 423 298 473 1,107 1,274 1,232 1,706 157 498 363 499 573 537 558
983 668 769 550 471 325 581 1,178 1,500 1,270 1,814 157 435 363 493 604 556 577
20,700 6,600 4,600 950 1,050 12,727 6,300 3,850 3,289 1,539 235 130 32 100 868 56,370 70,617 84,535
17,600 7,560 5,300 1,200 1,060 13,000 8,000 3,950 3,100 1,400 125 130 30 100 849 55,844 69,405 86,358
Note: Total may not add because of rounding. Harvest season begins August 1. Bales of 480 lb. Net. Source: Production estimates & Crop Assessment Division, FAS,USDA. January 2000 Table 4.1(4)
World Cotton Supply, Use, and Trade 1994/95 - 1999/2000 (Season Beginning August 1) In 1,000 480 lb. Bales 1994/95 1995/96 1996/97 1997/98 1998/99 1999/2000 Estimate Forecast Production
World Total China, People’s Rep. United States India Pakistan Uzbekistan, Rep. Franc-Zone Africa (2/) Turkey Others
85,859 19,900 19,662 11,148 6,250 5,778 2,656 2,886 17,579
93,065 21,900 17,900 13,250 8,200 5,740 3,144 3,911 19,020
89,593 19,300 18,942 13,918 7,323 4,813 3,665 3600 18,032
91,629 21,100 18,793 12,337 7,175 5,228 4,320 3,651 19,025
84,535 20,700 13,918 12,727 6,300 4,600 4,050 3,850 18,390
86,358 17,600 16,953 13,000 8,000 5,300 4,140 3,950 17,415
Textile Handbook 1-71
World Total China, People’s Rep, India United States Pakistan Turkey EU-1 5 S,E, Asia (1) Others World Total S,E, Asia (1) EU-15 Mexico Brazil Korea, South Taiwan Turkey Others
World Total China, People’s Rep India United States Pakistan EU-15 Brazil Australia Others
88,388 20,800 12,675 11,349 7,187 5,000 5,349 3,987 22,041
85,216 19,800 12,472 10,401 7,000 4,600 4,952 4,280 21,711
88,193 20,500 13,000 10,200 7,300 5,100 4,862 4,545 22,686
26,290 3,945 4,613 1,480 1,884 1,322 1,209 1,450 10,387
25,159 4,340 4,101 1,488 1,360 1,472 1,375 1,139 9,884
26,651 4,746 4,132 2,100 2,000 1,600 1,450 1,400 9,229
26,650 7,500 4,570 3,617 2,710 1,345 34 905 5,969
23,645 4,344 3,800 3,621 3,000 1,399 681 1,150 5,650
26,479 6,400 4,100 3,706 2,800 1,425 1,200 1,000 5,848
40,772 16,855 4,174 3,887 1,521 1,582 1,486 1,102 10,165
41,743 17,433 4,682 3,939 1,711 1,484 1,446 1,206 9,842
39,869 13,483 4,932 4,400 2,186 1,590 1,546 1,306 10,426
(1) Includes Indonesia, Malaysia, Philippines, Singapore, Thailand, and Vietnam. (2) Includes Benin, Burkina, Cameroon, CAR, Chad, Cote d’lvoire, Mali, Niger, Senegal, and Togo. Note: Totals may not add due to rounding. Source: USDA/FAS Jan 2000
Textile Fibres
World Total United States Uzbekistan, Rep, Franc-Zone Africa (2) Australia EU-15 China, People’s Rep, Syria Others
Consumption 86,644 89,013 20,600 21,350 11,747 13,120 10,647 11,126 7,200 7,000 4,363 4,735 5,149 5,265 4,426 4,412 22,512 22,005 Imports 30,528 27,538 28,939 4,310 4,584 4,503 4,930 4,748 4,792 580 695 950 1,612 1,768 2,386 1,747 1,661 1,504 1,114 1,380 1,300 1,083 519 1,355 15,152 12,183 12,149 Exports 28,385 27,757 26,845 9,402 7,675 6,865 5,006 4,524 4,550 2,682 2,798 3,308 1,345 1,466 2,384 1,353 1,676 1,545 183 21 10 568 567 670 7,846 9,030 7,513 Ending Stocks 29,899 35,760 38,189 8,878 13,202 14,755 4,032 5,053 4,679 2,650 2,609 3,971 1,692 1,358 1,818 1,615 1,611 1,464 1,931 1,485 1,257 433 747 947 8,668 9,695 9,298 85,845 21,000 10,545 11,198 6,750 3,904 5,535 4,416 22,195
1-72
Textile Fibres Table 4.1(5)
MY 1991/92 1992/93 1993/94 1994/95 1995/96 1996/97 1997/98 1998/99 (3) 1999/2000 (4)
New Independent States (NIS) Supply and Demand Marketing Years 1991/92 - 1999/2000
Beginning Stocks 3,414 3,629 2,712 2,163 2,122 2,469 1,774 1,867 1,802
Production 11,065 9,146 9,378 8,778 8,260 6,588 7,108 6,600 7,560
Imports
Exports
Internal1 Internal2 Internal1 Internal2
5,450 3,530 3,535 2,969 1,820 1,550 1,700 1,375 1,505
50 20 10 20 45 45 80 30 50
5,450 3,530 3,535 2,969 1,820 1,550 1,700 1,375 1,505
3,300 5,550 6,012 5,974 5,048 4,755 4,345 4,225 4,465
Consum- Ending ption Stocks 7,600 3,629 4,538 2,712 3,925 2,163 2,865 2,122 2,910 2,469 2,573 1,774 2,750 1,867 2,470 1,802 2,580 2,367
(1) Reflects only trade among the 12 countries of the former Soviet Union and three Baltic States. (2) Reflects NIS trade with external trading partners. (3) Estimate. (4) Projection. Notes: (i)
: Adding internal and external trade will provide a total trade figure.
(ii)
: Ending stocks may include any loss that has occurred.
(iii) :The NIS includes: Armenia, Azerbaijan, Byelarus, Estonia, Georgia, Kazakstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, Uzbekistan. Source: USDA/FAS/COTS Jan-2000
Textile Handbook 1-73
4.2 The World’s Major Cotton Growing Areas
Figure 4.2
World’s Cotton Growing Areas
Textile Fibres
1-74
Textile Fibres
4.2.1 China Table 4.2.1 a (000) 480-pound bales Year Beginning Stocks 95 8,878 96 13,202 97 14,755 98 16,855 99 17,433
Produc- Imports Total Supply tion 21,900 3,045 33,823 19,300 3,613 36,115 21,100 1,834 37,689 20,700 359 37,914 17,600 150 35,183
Mill Use 20,600 21,350 20,800 19,800 20,500
Exports Ending Stocks 21 13,202 10 14,755 34 16,855 681 17,433 1,200 13,483
SUR* 64.02% 69.08% 80.90% 85.12% 62.13%
Source: USDA-Foreign Agriculture Service *
Stocks-to-Use Ratio: Calculated by dividing Ending Stocks by Total Use (Use & Exports)
Figure 4.2.1b
China
Textile Handbook 1-75
4.2.2 United States Table 4.2.2a Year Beginning Stocks 95 2,650 96 2,609 97 3,971 98 3,887 99 3,939
(000) 480-pound bales
Produc- Imports Total Supply tion 17,900 408 20,958 18,942 403 21,954 18,793 13 22,777 13,918 443 18,248 16,953 75 20,967
Mill Use 10,647 11,126 11,349 10,401 10,200
Exports Ending Stocks 7,675 2,609 6,865 3,971 7,500 3,887 4,344 3,939 6,400 4,400
SUR* 14.24% 22.07% 20.62% 26.71% 26.51%
Source: USDA-Foreign Agriculture Service *
Stocks-to-Use Ratio: Calculated by dividing Ending Stocks by Total Use (Use & Exports)
Figure 4.2.2b
United States
Textile Fibres
1-76
Textile Fibres
4.2.3 India Figure 4.2.3(a)
(000) 480-pound bales
Year Beginning Produc- Imports Total Stocks Supply tion 95 3,385 13,237 85 16,707 96 4,163 13,918 40 18,121 97 4,679 12,258 145 17,082 98 4,174 12,727 429 17,330 99 4,682 13,000 800 18,482
Mill Use 11,977 12,367 12,675 12,472 13,200
Exports Ending SUR* Stocks 567 1,190 312 176 100
4,163 4,564 4,095 4,682 5,182
33.19% 33.67% 31.53% 37.02% 38.96%
Source: USDA-Foreign Agriculture Service *
Stocks-to-Use Ratio: Calculated by dividing Ending Stocks by Total Use(Use & Exports)
Figure 4.2.3b
India
Textile Handbook 1-77
4.2.4 Pakistan Table 4.2.4a
(000) 480-pound bales
Year Beginning Produc- Imports Total Stocks Supply tion 95 1,692 8,200 122 10,014 96 1,358 7,323 279 8,960 97 1,818 7,175 120 9,113 98 1,521 6,300 925 8,746 99 1,711 8,200 500 10,411
Mill Use 7,200 7,000 7,187 7,000 7,400
Exports Ending Stocks 1,433 1,358 119 1,818 380 1,521 10 1,711 700 2,286
SUR* 15.73% 25.54% 20.10% 24.41% 28.22%
Source: USDA-Foreign Agriculture Service *
Stocks-to-Use Ratio: Calculated by dividing Ending Stocks by Total Use (Use & Exports)
Figure 4.2.4b Pakistan
Textile Fibres
1-78
Textile Fibres
4.2.5 Australia Table 4.2.5a Year Beginning Stocks 95 433 96 747 97 947 98 1,102 99 1,206
(000) 480-pound bales
Produc- Imports Total Supply tion 1,970 3 2,406 2,792 1 3,540 3,059 1 4,007 3,289 0 4,391 3,100 0 4,306
Mill Use 193 209 195 185 200
Exports Ending Stocks 1,466 747 2,384 947 2,710 1,102 3,000 1,206 2,800 1,306
SUR* 45.03% 36.52% 37.93% 37.86% 43.53%
Source: USDA-Foreign Agriculture Service *
Stocks-to-Use Ratio: Calculated by dividing Ending Stocks by Total Use (Use & Exports)
Figure 4.2.5b
Textile Handbook 1-79
4.2.6 Republic of Uzbekistan Table 4.2.6a Year Beginning Stocks 95 956 96 1,304 97 822 98 635 99 603
(000) 480-pound bales
Produc- Imports Total Supply tion 5,740 5 6,701 4,813 5 6,122 5,228 5 6,055 4,600 5 5,240 5,300 5 5,908
Mill Use 873 750 850 825 850
Exports Ending Stocks 4,524 1,304 4,550 822 4,570 635 3,812 603 4,200 858
SUR* 24.16% 15.51% 11.72% 13.00% 16.99%
Source: USDA-Foreign Agriculture Service *
Stocks-to-Use Ratio: Calculated by dividing Ending Stocks by Total Use(Use & Exports)
Textile Fibres
Section 5 - Man-Made Fibre Production ................ 1-80 5.1
Methods of Man-Made Fibre Spinning ........................... 1-80 5.1.1 5.1.2 5.1.3 5.1.4
5.2
Wet Spinning ................................................................ Dry Spinning ................................................................ Melt Spinning ............................................................... Gel Spinning .................................................................
1-80 1-81 1-81 1-83
The Processing of Tow ....................................................... 1-84
Section 6 - New Developement of Textile Fibres ... 1-85 6.1
Microfibres ......................................................................... 1-85 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.1.6
6.2
TENCEL® ................................................................... 1-89 TENCEL® A100 .......................................................... 1-92
High Performance Fibres .................................................. 1-93 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6 6.3.7 6.3.8 6.3.9 6.3.10 6.3.11
6.4
1-85 1-85 1-86 1-86 1-86 1-88
Lyocell ................................................................................. 1-89 6.2.1 6.2.2
6.3
Direct Spinning ............................................................ Splittable Fibres ........................................................... Mechanically Splittable Bicomponents ........................ Solvent Splittable Bicomponents ................................. Uses for Microfibres .................................................... Shin-Gosen ...................................................................
Aramids, Meta-aramid ................................................ Para-aramid .................................................................. Carbon Fibres - PAN and Pitch Based ......................... Fluorocarbon Fibres (PTFE) ........................................ Glass Fibre ................................................................... Melamine: Basofil (BASF) .......................................... Polybenzimidazole — PBI ........................................... Polyphenylenebenzobisoxazole — PBO ...................... Cellulose acetate - MicroSafe (Celanese Acetate) ....... Optical Fibres ................................................................ Chitin, Chitosan (shells of crustacean) .........................
1-93 1-94 1-94 1-94 1-95 1-95 1-95 1-96 1-96 1-96 1-97
Smart Technology for Textiles and Clothing ................... 1-97 6.4.1 6.4.2
Phase-Transition Materials and Polymer Crystals ....... 1-98 Smart Microcapsules/Microspheres ............................. 1-98
6.4.3 6.4.4 6.4.5
Smart Fibres for Measurement of Temperature, Moisture and Strain ...................................................... 1-99 Shape Memory Polymers ............................................. 1-99 Smart Gels and Gel Fibres ........................................... 1-100
Back to Table of Content
1-80
Textile Fibres
SECTION 5
MAN-MADE FIBRE PRODUCTION
5.1 Methods of Man-Made Fibre Spinning The earliest man-made fibre was proceed using the wet spinning method. Through this process, fibre is produced by spinning liquids in a coagulating or regenerating bath. The second method is dry spinning, which has been applied to the production of other fibres from solutions of fibre-forming materials in suitable volatile solvents. Melt spinning is another method applied to the production of thermoplastic and relatively high melting point polymers.
5.1.1 Wet Spinning The equipment required for wet spinning consists of a supply tank for the spinning solution, pump, filter, spinneret, and coagulating bath. Viscose rayon is the fibre that is spun in greatest quantity using this method. High tenacity rayons and polynosic (cotton-like) rayons are produced in a similar way, with different formulae for the composition of the coagulating bath and varying stretching techniques. Calcium alginate and polyvinyl chloride are other fibres in this category. Most acrylic fibres such as acrilan and courtelle are wet spun.
Figure 5.1.1 Wet spinning
Textile Handbook 1-81
5.1.2 Dry Spinning Cellulose acetate is produced by the dry spinning method. The dope is filtered between the pump and spinneret; the hot air enters the drying chamber at 100°C and removes the solvent, leaving the filament. A certain degree of stretch is imparted between spinneret and take-up roller that gives some molecular orientation and higher tenacity. Cellulose triacetate and Orlon, which is a polyacrylonitrile fibre, are also spun this way.
Figure 5.1.2
Dry spinning
Textile Fibres
5.1.3 Melt Spinning Melt spinning is used for the production of nylons, polyester and polyolefins. The polymer chips are first washed with a solvent such as alcohol, acetone, or water to remove most impurities. It is then melted and extruded through small orifices of a spinning nozzle to form fibres. The amount of molten polymer in the sump is kept to a minimum to prevent the possibility of decomposition and changes in the degree of polymerization arise. The filaments are extruded, solidify,
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Textile Fibres
and pass through a cooling chamber in which they are cooled by a current of cold air. In the case of nylon, this is followed by a steaming process that moistens the fibres; polyester fibres are moistened by passing them over moist rollers or discs. It is also essential that water and air bubbles should be absent from the material being proceed. Nylon is cold drawn by about 400%; polyester is hot drawn by about 500%. For high tenacity polyester, yarns may be stretched more than this. Melt spinning has the advantage of needing no chemical baths or solvent recovery systems. Glass fibre and Spandex yarns are produced in a rather similar way. Figure 5.1.3
Melt spinning
Textile Handbook 1-83
5.1.4 Gel Spinning Gel spinning is defined as a spinning method for high strength fibres through a gel-like state as intermediate substance. In gel spinning, the degree of polymerization is the most critical property; therefore, for polyethylene the ultra-high molecular weight above 600,000 g/ mol is used. A relatively high-concentration polyethylene solution must be prepared as uniformly as possible, because any in-homogeneity will remain as a defect in the final fibre structure and reduce the final mechanical properties of the fibres. In addition, essential to the formation of high strength fibres, is control of this entanglement. This can be controlled either by dilution in an appropriate solvent or morphological control through the crystallization process. The extruded solution is substantially cooled down by a gas or a liquid cooling medium. Polyvinylalochol (PVA) polymer and polyacrylonitrile (PAN) can also be processed by gel spinning. Figure 5.1.4
Schematic diagram of (1) gel spinning process, (2) technical points of gel spinning process.
Textile Fibres
(1)
(2)
PROCESS
DEFECT REMOVAL
1 Dissolution Process Homogeneous soulution of ultra-high molecular weight PE
2
3
Chain end entanglement
Spinning Process Gel-like as-spun fiber Crystallization control
Entanglement
Drawing Process High draw-ratio drawing
Folded chains Amorphous content
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Textile Fibres
5.2 The Processing of Tow A tow is a collection of thousands of parallel, continuous filaments of man-made fibres in rope form, processed so that individual filaments are cut, or broken, into staple fibres of suitable length, which are processed into yarn on conventional spinning machinery. Rather different procedures are adopted for the cutting of different types of fibre. Viscose rayon may be cut when wet immediately after coagulating and drawing; it is then washed, given suitable purifying chemical treatments, and dried. Alternatively it can be drawn, purified, and dried before cutting. Other man-made tows have similar treatments appropriate to their properties; thermoplastic fibres such as polyesters are drawn, crimped, heat set, and cut. Tow-to-top is the method, which eliminates the conventional spinning process, such as opening, carding, and combing operations. The tops are introduced into the drawing operation. Two-to-top converters can either be operated by stretch breaking or by cutting. The stretch breaking system has a pair of sharp teeth gear-like wheels that intermesh but do not touch. All filaments are broken in turn as they pass through the wheels, so the fibre length is more uniform. Fibre cutting systems take a tensioned tow, and cut it on the bias using a rotating upper roller, around which spiral knives are wound. These spiral cutting edges are pressed with great force against a lower, smooth anvil roller. By this means, fibres are cut to uniform length, the fibre length being equal to the pitch of the cutting spirals. Tow to top have the advantage over cut-staple processing in that further opening, carding, drawing, and combing operation are avoided, the yarns made from them are more uniform and stronger, and they can be spun to finer counts.
Textile Handbook 1-85
SECTION 6
NEW DEVELOPMENT OF TEXTILE FIBRES
6.1 Microfibres One of the most important developments in recent years has been the technology to extrude extremely fine filaments (less than 1.0 denier) while maintaining all of the strength, uniformity and processing characteristics expected by textile manufacturers and consumers. These “microfibres” are even finer than luxury natural fibres, such as silk.
Microfibres are made primarily by three methods; direct spinning, mechanical splitting and solvent splitting.
6.1.1 Direct Spinning The direct spun route to microfibres is the most economical and is used by all major producers. Most offer direct spun filament microfibres in the 0.7 to 0.9 denier range. A few like DuPont, Toyobo and Unitika supply fibres as low as 0.3 dpf. Microdenier staples down to 0.5 dpf are available from several suppliers and Kuraray even sells a 0.4 dpf staple. Fibres in this range are extremely difficult to process on textile equipment. Deniers in the 0.7 range can be carded at commercial rates (25 to 36 kg/hr) with proper card clothing and good card maintenance.
6.1.2 Splittable Fibres Fibres below 0.3 dpf, usually called ultrafine or super microfibres, are made by spinning conventional deniers and during later processing are split into individual fibres. This can be done by direct spinning of homopolymer fibres having weak points that subsequently split when the fabric is brushed, abraded or subjected to high velocity gas or water as in the DuPont Spunlace® process. For example, if a 1.2 dpf
Textile Fibres
Microfibre is defined as a fibre of less than 1.0 denier (i.e. 9000 metres of fibre weigh less than one gram). It can be extruded by reducing the polymer output at the spinneret and drawing with a large draw ratio. It is classified into two types: continuous filament type and random (staple) type. Their designed characteristics are extreme softness, high flexibility and smoothness.
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Textile Fibres
hexalobal hollow fibre is split, each segment will be 0.2 dpf. However, this method usually leads to a mixed denier product since it is difficult to control the splitting of all segments.
6.1.3 Mechanically Splittable Bicomponents When two incompatible or partially compatible polymers are spun through the same spinneret capillary, subsequent working easily separates the fibres. This could be during drawing, relaxing or bombardment with a gas (e.g., interlacing) or liquid (e.g., hydraulic needling). After separating into individual strands, both components are part of the final fabric. A frequently used variety is the segmented pie or citrus type with alternating polymer segments (PET/Nylon, PET/PP). After splitting, the fibres can have sharp edges which are not possible in monocomponent spinning. This can enhance fabric aesthetics.
6.1.4 Solvent Splittable Bicomponents In this variation of the bicomponent route, the segments are separated by dissolving one of the components. The solvent can be administered at any stage after spinning, but most practically during fabric finishing. The most commercially successful use of this technology is the “islandsin-the-sea” variety used for suedes and leather-like application. Multiple fibres are spun into an expendable matrix or sea. During fabric finishing, the sea is dissolved leaving the fine filaments. Typical compositions use PET as the islands and polystyrene or PVA as the dissolvable sea. Toray has perfected the technology and is producing deniers in the 0.05 dpf range for eyeglass wipes. Deniers in the 0.15 to 0.3 range are used for suede-like fabrics like Ecsaine® and Hilake® (Ultrasuede® in the U.S.). Kuraray has succeeded in producing 0.0001 denier ultra microfibre by this technology for an artificial leather called Sofrinau®.
6.1.5 Uses for Microfibres The lower bending rigidity, high surface area and greater number of fibres per unit weight enable the production of fabrics which, are softer, quick drying, have greater cover and cooler hand. Consider, for example, the advantages of polyester microfibre when used in outerwear. A raincoat or jacket made from 100% microfibre will be much lighter and more comfortable than one made from conventional fibres. Since the small filaments pack closely together, they provide a wind barrier to prevent loss of body heat and assuring
Textile Handbook 1-87
Coolmax
Polypropylene
Acrylic
Nylon
Wool
Moisture Management Tests
Cotton
Table 6.1.5 (1)
Textile Fibres
comfort on chilly days. This close packing of fibres, together with polyesters’ natural resistance to wetting also gives the fabric the ability to repel rain. The non-wetting surface of the fibres causes water to form beads (like rain on a newly-waxed car). These beads are much larger than the spaces between the yarns and water is effectively locked out. And this is done without the need for chemical treatments or coatings which can make the fabric heavier and less able to “breathe”. Fabrics from microfibres, on the other hand, breathe well. Although the spaces between the yarns are too small to be penetrated by liquid water, they are ample for the passage of moisture vapour, leaving the wearer dry and comfortable. For example, DuPont CoolMax™ is a high-performance fabric that can help the athletic performance of the people who wear it. Using DuPont’s proprietary Dacron® fibres, CoolMax™ moves sweat away from the body to the outer layer of the fabric. This is due to the unique shape of the fibre with four channels on the surface; they speed moisture faster to the outer surface (see Fig. 6.1.5 (2)). In moisture management tests, garments made with CoolMax™ dried almost completely in 30 minutes. Cotton, by comparison, remained wet nearly 50%).
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Textile Fibres Table 6.1.5 (2)
Unique Shape of Coolmax
Tetra-channel fibre pulling moisture away from skin. Even though microfibres are more expensive, the high fashion market segments love these products because they imitate silk at a fraction of the cost. Microfibres have been combined with other fibres. DuPont has promoted Lycra 3D®, a stretch knit yarn with a microfibre surface and Lycra® core. Polyester and Nylon Microsupplex® jackets, worsteds, suedes, athletic wear, and denims are even important in fibrefill due to superior insulation. Polypropylene, acrylics and rayon microfibres are primarily used in blends with the PET and nylon fibres. An important new rapidly growing market is in spunbondeds, particularly polyester/ PP fabrics like ComforMax I B®. Apart from application in the apparel industry, polyester type microfibres are good for making wiping cloth, owing to the large number of very fine filaments on the surface. They are also very good in absorbing grease. Polyester microfibre is an excellent material for wiping cloth to clean spectacle lenses.
6.1.6 Shin-Gosen This word was introduced by the media in Japan during the latter half of 1988 to describe a completely new generation of textiles based on synthetic fibres. Micro, random and a combination of all availability technologies, were used to produce these fibres, which have a different quality and performance from those of ordinary fibres. Shin-Gosen is classified into four types : new silky, new worsted, dry touch, and peach skin based on the hand feel of fabrics.
Textile Handbook 1-89 Figure 6.1.6
Classification of technologies to impart the various types of hand feel to Shin-gosen.
Cross-sectional shape Mircrocrater Twist Dry touch New silky
Polymer modification Bicomponent spinning Caustic reduction Fabric heat treatment
Shin-gosen Peach Skin New worsted Micro fibre Direct spinning Bicomponent spinning and separation
Thick and thin yarn Multi-feed false twist Air-texturing or twist
6.2 Lyocell Lyocell is a cellulose fibre obtained by an organic solvent spinning process where:
6.2.1 TENCEL® TENCEL® is the registered trademark of Acordis Fibres (Holdings) Ltd. It is a 100% cellulosic fibre. It is produced from natural cellulose derived from wood pulp using a solvent-spinning process which is designed to minimise environmental impact. A solvent, an amine oxide, is used to dissolve the cellulose directly into a very viscous solution. After filtration, the solution is extruded to yield fine filaments, from which the solvent is subsequently removed by washing, The resulting tow is dried and cut to staple fibre.
Textile Fibres
• “organic solvent” means a mixture of organic chemicals and water, • “solvent spinning” means dissolving and spinning without the formation of a derivative.
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Textile Fibres Figure 6.2.1(1)
The Process Route
Wood Pulp Amine Oxide Dissolve Filter Evaporate Extrude Purify
Wash Dry Fibre
TENCEL®, as a cellulosic fibre, absorbs moisture and is fully biodegradable. Table 6.2.1 (2)
Stress and Strain Comparison Between TENCEL® and other Fibres TENCEL®
Viscose
Titre (dtex)
1.7
1.7
Dry Tenacity (cN/tex)
Cotton
Polyester 1.7
38 - 42
22 - 26
20 - 24
55 - 60
Dry Elongation (%)
14 - 16
20 - 25
7-9
25 - 30
Wet Tenacity (cN/tex)
34 - 38
10 - 15
26 - 30
54 - 58
Wet Elongation (%)
16 - 18
25 - 30
12 - 14
25 - 30
TENCEL® fibre is available commercially in a range of dtex viz 1.1, 1.4, 1.7, 2.4 and 3.3 dtex. It is also available in a range of staple lengths suitable for short staple spinning systems, and in longer staple lengths for worsted and woollen spinning systems. On short staple spinning systems, a wide range of yarn counts can be created in 100% TENCEL®. For example, yarns can be produced from the 1.7dtex fibre in the range Nm 10 - 60 (Ne 6 - 36); Nm 30 100 (Ne l8 - 60) from the 1.4 dtex fibre, Much finer yarns are possible with the 1.1 dtex fibre, e.g. Nm160 (Ne100).
Textile Handbook 1-91
a) Fibrillation Fibrillation is the longitudinal splitting of a single fibre into microfibres of 1 to 4 microns in diameter. The splitting occurs as a result of wet abrasion against fabric or metal. The fibrils are so fine that they can become almost transparent, giving a white or ‘frosty’ appearance to finished fabric. In cases of extreme fibrillation, the micro-fibrils become entangled, giving a pilled appearance.
b) Using fibrillation
Fibrillation can be used both in piece dyeing of fabric and in garment washing/dyeing to produce characteristic softness and drape aesthetics.
Figure 6.2.1 b (1)
TENCEL® fibre
Textile Fibres
Fibrillation can occur in the wet processing of fabrics and garments in TENCEL®. The microfibres generated can be used to create a variety of interesting touch and feel aesthetics. A peach skin effect, which can also withstand repeated domestic washing at 40°C, is possible, providing the fibrillation is developed such that the fibrils cannot become long and entangled.
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Textile Fibres Figure 6.2.1 b (2) Fibrillated TENCEL® fibre
Figure 6.2.1 b (3)
Fibrillation in a fabric in TENCEL®
6.2.2 TENCEL® A100 Tencel A 100 is a new Tencel fibre which possesses all the properties of Tencel. The most distinctive property of Tencel A 100 is that it does not fibrillate. This makes dyeing and finishing much easier and economical. Tencel A 100 has been used predominantly in knitted fabric production but on a relatively small scale. a) TENCEL® Al00 attributes • • • • • • •
Characteristic drape and fluidity of TENCEL® Full, soft handle Fibrillation-free fabric surface Subtle surface lustre Deep, clear colour Excellent print definition Pronounced stitch definition
b) TENCEL® A100 performance • Superior dye uptake and retention • High tear strength: twice that of cottons (in wovens) a High burst strength in knitted fabrics
Textile Handbook 1-93
• Excellent laundering performance • Retention of 3D character in wash and in wear Applications c) TENCEL® A100 Applications • Knitwear and jersey • Yarn - and piece-dyed wovens • Unfinished fabrics for garment processing Table 6.2.2 c Comparison of Fibre Properties between Tencel and Other Fibres fibre properties fibre TENCEL®Al00 TENCEL
®
38-40
26-32
Dry Water Wet extension modulus inhibition (cN/TEX) (%) (%)
11-16
10-14
950
70-85
1,100
65-70
40-44
36-38
13-15
14-16
18-44
21-53
3-10
25-50 700
75-80
900
55-70
Modal
32-34
19-21
13-15
14-16
Polynosic
34-42
25-34
10-13
13-15
Polyester
31-53
31-53
45-55
60-280
6.3 High Performance Fibres High performance fibres are driven by special technical functions that require specific physical properties unique to these fibres. They usually have very high levels of at least one of the following properties: tensile strength, operating temperature, limiting oxygen index and chemical resistance.
6.3.1 Aramids, Meta-aramid: Nomex (DuPont), TeijinConex (Teijin) Meta-aramids are perhaps the best-known and most widely used specialized Fibres. Nomex is a familiar fibre to many. Meta-aramids are best known for their combination of heat resistance and strength, at reasonable cost. In addition, meta-aramid fibres don’t ignite, melt or drip.
Textile Fibres
Cotton
Dry Wet Dry tenacity tenacity extension (cN/TEX) (cN/TEX) (%)
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Textile Fibres
6.3.2
Para-aramid: Kevlar (DuPont), Twaron (Akzo), Technora (Teijin)
Due to their highly oriented, rigid molecular structure, para-aramid fibres have very high tenacity, high tensile modulus and high heat resistance. Para-aramid fibres have similar operating temperatures to meta-aramid fibres, but have 3-7 times higher strength and modulus, making them ideal for reinforcement and protective type applications. The special high modulus of para-aramids allows them to be used in cut-resistant and ballistic applications. The so-called “bulletproof vest” worn by law enforcement was made possible with development of Kevlar and is perhaps the most famous application for the para-aramids, but now only one of a multitude of uses.
6.3.3 Carbon Fibres. PAN and Pitch Based: Numerous U.S., European and Asian producers The different categories of carbon fibres based on modulus, tensile strength, raw material and final heat treatment temperature. Some are rigid and brittle and used in composites; others are soft and supple and used in apparel. In the carbonization process, temperature exposures range from 1,000-2,000°C, each different level of exposure creating a different property for the fibre. For example, high-modulus type is processed at 2,000°C, at 1,500°C for high-strength type and at 1,000°C for low-modulus and low-strength type. The main carbon fibres are made from polyacrylonitrile (PAN) base or are pitch based, and are well known for their composite-reinforcement (i.e., golf clubs) and heat-resistant end uses. Many, especially the pitch-based materials, are considered “engineering” materials more than textile products, and are often used in specialized composites, e.g. aerospace.
6.3.4
Fluorocarbon Fibres (PTFE): Teflon (DuPont), Toyoflon (Toray)
PTFE (polytetrafluoroethylene) fibres offer a unique blend of chemical and temperature resistance, coupled with a low friction coefficient. Since PTFE is virtually chemically inert, it can withstand exposure to extremely harsh temperature and chemical environments. The fibre’s low friction coefficient, as well as its low tensile strength, makes it difficult to process, and difficult to blend with other fibres. Due to its excellent ultraviolet and chemical resistance, PTFE sewing thread is ideal for a number of protective and outdoor applications. PTFE is familiar to most people as the breathable, porous membranes laminated
Textile Handbook 1-95
to fabrics to create Gore-Tex, (W. L. Gore) for high-performance wearing apparel.
6.3.5 Glass Fibre Glass fibre is the “grandfather” of high- performance fibres, being one of the first manmade fibres to be commercialized (late ’30s). Glass is an inorganic fibre, which is neither oriented nor crystalline. It is widely used in woven-fabric form for reinforcing thermoplastic composites in products ranging from circuit boards to boat hulls. Hightemperature filtration is another volume use. Glass is the most widely produced and used fibre in the high-performance arena, and is the least expensive. But since it is basically a glass rod, it has its limitations, especially in abrasion resistance and brittleness.
6.3.6
Melamine: Basofil (BASF)
6.3.7
Polybenzimidazole — PBI: PBI (Celanese)
Polybenzimidazole is an organic fibre with excellent thermal resistant properties and a good hand. PBI does not burn in air and does not melt or drip. High Limiting Oxygen Index (LOI) coupled with good chemical resistance and good moisture regain make PBI an excellent fibre for fire-blocking end uses, such as safety and protective clothing and flame-retardant fabrics. Its physical properties are relatively low, but PBI processes on most types of textile equipment. It blends well with other materials such as carbon and aramid fibres, most often for performance and cost reasons. PBI has had significant success in the firemen’s apparel market where, blended in a 60-40 para-aramid-PBI mixture, it has become the standard “premium” material. PBI’s characteristic gold colour blends well with other materials for a pleasing appearance.
Textile Fibres
Basofil recently entered the high-temperature fibre market. It’s the newest fibre to be fully commercialized. Based on melamine chemistry, Basofil offers a high operating temperature and a high Limiting Oxygen Index, and typically targets the hot-gas filtration and safety and protective apparel markets. Because of its variable denier and staple length, low tensile strength and difficulty in processing, Basofil is generally blended with stronger fibres such as aramids. It is more often used in needled products, or yarns made from wrapped spinning techniques.
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Textile Fibres
6.3.8
Polyphenylenebenzobisoxazole — PBO: Zylon (Toyobo)
PBO is another new entrant to the high-performance organic fibres market. Toyobo’s Zylon is the only PBO fibre in production. PBO has outstanding thermal properties and almost twice the tensile strength of conventional para-aramid fibres. Its high modulus makes it an excellent candidate for reinforcement of composites. Its high LOI gives PBO more than twice the flame retardant properties of metaaramid fibres.
6.3.9 Cellulose acetate - MicroSafe (Celanese Acetate) Cellulose acetate staple fibre and filament yarn, both called MicroSafe® fibre, feature in Microban antimicrobial protection. MicroSafe® provides continuous inherent control of the growth of a broad spectrum of bacteria, as well as fungi, mould and mildew in products. The antimicrobial protection contributes to a more hygienic product; inhibits the growth of odor-causing bacteria and mildew in products so that they stay fresher longer; and is engineered to last the life of the product. MicroSafe® fibre can be blended with other fibres to create a wide range of fabric types to fit many applications. It brings the naturallike qualities of acetate-comfort, breathability, softness and luxury-to the fabric blend, both enhancing natural fibres and complementing manufactured fibres.
6.3.10 Optical Fibres Optical fibres are classified into three groups according to the types of core material, quartz, multi-component and plastic optical fibres (POF). The quartz optical fibre is used for long distance optical communication including public trunk lines. The multi-component optical fibre is used for middle-distance communication, of 1-2 km, including local area networks (LAN) in plants and fibrescopes. The glass optical fibre has shortcomings because it is expensive, brittle and hard to process. Advantages of plastic optical fibre (POF) are that it is inexpensive, flexible, light and easy to process, though the transmission loss is higher than in glass optical fibre. The material of both the core and sheath of the plastic optical fibre require high transparency. Generally, Polymethylmethacrylate (PMMA) and Polycarbonate (PC) are used as the core material. Since the refractive index of the sheath material should be lower than that of the core
Textile Handbook 1-97
material, fluoroplastics including polyvinylidene fluoride, Teflon FEP, Teflon AF, fluorinated methacrylate and fluorinated polycarbonate are used as the sheath material.
6.3.11 Chitin, Chitosan (shells of crustacean) Chitin and chitosan are natural ingredients which can be abundantly found in the shells of crustaceans, such as crabs, lobsters and prawns. These extremely safe, nontoxic materials both as bandaging materials which accelerated up the healing of wounds and as animal drugs. Chitosan films and chitin paper interact comfortably with the human body, and experiments on animals have also proved that these new materials attain the same or even greater effects than antibiotics against suppuration caused by bacterial infection.
6.4 Smart Technology for Textiles and Clothing Smart materials and structures are the materials and structures which can sense and react to environmental conditions or stimuli. According to the manner of reaction, they can be divided into three categories: passive smart, active smart and very smart. Passive smart materials can only sense the environmental conditions or stimuli; active smart materials will sense and react to the conditions or stimuli; very smart materials can sense, react and adapt themselves accordingly. An even higher level of intelligence can be obtained from those intelligent materials/structures capable of responding to or being maturally activated or pre-programmed to perform a function. Such materials and structures are the results of a successful marriage of traditional textiles/clothing technology with modern technologies such as new materials, wireless communication, artificial intelligence, and biology. The following are some of available smart materials suitable for textiles and clothing, classified according to their principles:
Textile Fibres
Chitopoly was first created by Fuji Spinning from an ultra-fine chitosan powder. Chitogreen is a new anti-microbial material for the next generation. The positive mechanism of Chitogreen is that the fabric attracts germs with an electrostatic power, then the cell membrane of the seized germs is destroyed. A major characteristic of Chitopoly and Chitogreen is their long lasting effectiveness. Since the chitosan ingredient is fixed in the textile itself, its performance and effectiveness remain the same even after repeated washings.
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Textile Fibres
6.4.1 Phase-Transition Materials and Polymer Crystals Phase-transition (solid-liquid) materials, such as inorganic salt hydrates and polyethylene glycols, exhibit high enthalpy changes at their phase change temperatures. Polymer crystals are compounds that exhibit large changes in enthalpy and entropy, not because of phase change but because of solid-to-solid transition due to decrystallization or crystallization. The application of these materials has led to the invention of temperature-adaptable fabrics with enhanced cooling when the ambient temperature increases and enhanced warmth when the ambient temperature decreases. One problem associated with the technology is that adhesion of these materials to fibres is poor, and thus the treatments by normal application techniques such as pad-dry-cure are not durable in laundry. Various methods for improvement have since been developed. The first approach is to make microcapsules containing these phase transition materials or polymer crystals, which has resulted in commercial products in the forms of powder and slurry, with a wide range of transition temperatures for various applications. The second approach is to design and manufacture a polymeric fibre with a certain molecular weight distribution. Functional groups can be grafted onto the ends of the molecules or blended into the fibre, hence phase transition occurs on the side chains of the polymer or its surface. Compared with other methods, the advantages include better adhesion and good handle as the main chains are not affected by the grafted groups at the ends of molecules. The third approach is to develop hollow fibres filling them with smart materials, and then sealing the fibres. A number of research groups around the world have been working on acrylic, polyester and nylon fibres since the1980s, and some prototypes have been developed.
6.4.2 Smart Microcapsules/Microspheres Cells, the basic units in life, possess many functions, such as multiplication, excitation and control, and the abilities of self-diagnosis, self-repair, self-adjustment. Membranes of cells can exchange information with, and transfer energy to and from the environment, and have capacities for protection. Smart microcapsules and microspheres are recent developments which attempt to mimic the functions of natural cells. Smart microcapsules have been designed and fabricated by controlling their chemical compositions, size and distribution, physical and chemical properties as well as response characteristics to light, electricity, magnetism, temperature, pH values and pressure.
Textile Handbook 1-99
6.4.3 Smart Fibres for Measurement of Temperature, Moisture and Strain
6.4.4 Shape Memory Polymers Many polymers exhibit shape memory behaviour: they can remember one (one-way) or two (two-way) or reverse (reverse) status of configurations below and above their respective glass transition temperatures. Wool, polypropylene, polyoxymethylene, trans-polyisoplyne and polyurethane have this effect to various extents. By adjusting its glass temperature around certain temperatures, say room temperature, one can introduce substantial changes in specific volume, gas permeability, mechanical properties, dielectric and optic properties. A typical example of its application is a smart fabric Diaplex with invisible pores which can open and close with temperature change by using shape memory polyurethane.
Textile Fibres
In parallel with rapid developments in the area of optical fibre communications, smart fibre sensors have also attracted much attention and experienced fast growth in recent years. An optical fibre normally consists of a core surrounded by a cladding whose refractive index is slightly smaller than that of the core. Inside the fibre core, light rays incident on the core-cladding boundary at angles greater than the critical angle undergo total internal reflection and are guided through the core without refraction. By modifying the reflective index of the core via masked exposure of intense UV pulse generated by a laser, smart fibre optic sensors have been made and integrated into a number of textile structures such as yarns, fabrics and composites, in the laboratories of the Hong Kong Polytechnic University. Fibre optic sensors, with the dimension of a textile yarn and flexibility, are capable of measuring internal strain and temperature, humidity, gas content etc. A number of such sensors can be multiplexed along a single optical fibre using wavelength-, frequency-, time- and polarization-division techniques to form one-, two- or three-dimensional pseudo distributed sensing systems. Fibre based moisture sensors are also available.
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Textile Fibres
6.4.5 Smart Gels and Gel Fibres Smart polymeric gels change their structures and physical and chemical properties according to environmental stimuli. For instance, when subject to external stimuli such as changes in pH values, moisture, temperature, light intensity and electric field, or composition of solution, the gels undergo a sudden phase change. Noticeably, super-absorbent gel powders have been used for nappies and inconvenience pads. For textile and clothing applications, it is more desirable to have such materials which have fibre forms under normal conditions and will remain so when wet. In this regard, a few new super-absorbent bicomponent fibres made via conjugate spinning are now commercially available. The core of the fibre has a normal fibre-forming polymer such as polyester or nylon, while the sheath comprises the gel which will swell up to 300-400% of its original volume when wet, and generates a considerable amount of heat upon absorption.
Chapter 2 Spinning Processes and Types of Yarn ...................................................... 2-2 Section 1 - Blowing Room Process ............................ 2-2 1.1
Purpose of Blowing Room Process ................................... 2-2
1.2
Bale Opening ...................................................................... 2-2 1.2.1
1.3
1.4
A
1.3.1 1.3.2 1.3.3
Purpose of Cleaning ..................................................... 2-5 Feeding System ............................................................ 2-5 Features of Some Cleaning Machines .......................... 2-6
A
Blending .............................................................................. 2-9
A
Features of Mixer and Blender ..................................... 2-9
Machine Arrangements ..................................................... 2-11 1.5.1
1.6
Features of Some Automatic Bale Openers ................. 2-3
Cleaning .............................................................................. 2-5
1.4.1
1.5
Example of Machines Layout of Blowing Room: ....... 2-11
Foreign Substance Detector .............................................. 2-13 1.6.1 The Vision Shield (Jossi) .............................................. 1.6.3 Cotton Sorter RX-CS (Barco) ...................................... 1.6.2 Securomat (Truetzschler) .............................................. 1.6.4 Optiscan (Uster) ...........................................................
1.7
A
2-14 2-15 2-15 2-16
Maintenance Recommendations for Opening and Cleaning Machines ............................................................. 2-17 1.7.1 1.7.2
1.8
A
Maintenance of Opening Room/Opening Hoppers ...... 2-17 Maintenance of Cleaners .............................................. 2-19
Trouble Shooting for Opening and Cleaning Machines ............................................................................. 2-20
Section 2 - Carding Process ..................................... 2-25 2.1
Purpose of Carding ............................................................ 2-25
2.2
Carding Actions ................................................................. 2-26
A
2.3
Card Feeding System ......................................................... 2-27 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5
Rieter Aerofeed U ........................................................ Rieter UNIstore A 77 .................................................... Truetzschler Tuft Feeder Directfeed DFK .................... Truetzschler Sensofeed ................................................. Truetzschler Webfeed ...................................................
2-27 2-28 2-29 2-30 2-30
2.4
Card Clothing ..................................................................... 2-31
2.5
Card Clothing Specifications ............................................ 2-33 2.5.1 2.5.2 2.5.3 2.5.4
2.7
Conventional Revolving Flat Card ............................... 2-58 Rieter C51 Card ............................................................ 2-59 Truetzschler DK-803 Card ........................................... 2-60
Grinding .............................................................................. 2-61 2.8.1 2.8.2
2.9
2-33 2-36 2-44 2-48
Card Setting Recommendations ....................................... 2-58 2.7.1 2.7.2 2.7.3
2.8
ECC Card Clothing ...................................................... Graf Card Clothing ....................................................... Hollingsworth Card Clothing ....................................... Kanai Card Clothing ....................................................
Grinding Intervals ........................................................ 2-61 Rieter Integrated Grinding System (IGS) .................... 2-61
New Features on Carding Machine .................................. 2-66 2.9.1 Precision Flat Setting System (Truetzschler) ................... 2.9.2 Flat Distance Measuring System ..................................... 2.9.3 Webclean System (Truetzschler) ...................................... 2.9.4 On-line Nep Counting (Truetzschler) .............................. 2.9.5 TREXplus (Rieter) ...........................................................
2-66 2-67 2-68 2-69 2-70
2.10 Tandem Card ...................................................................... 2-71 2.10.1 The New Twin Cylinder Card-Crosrol CST ................ 2-71 2.10.2 Technical Specification ................................................ 2-72
2.11 Production Calculations .................................................... 2-73 2.12 Conversion of Grain Weight and Sliver Count ............... 2-74 2.13 Nep Counting ..................................................................... 2-74 2.13.1 Three Different Ways of Nep Counting ....................... 2-74
A
2.13.2 Nep Content of Card Web ............................................ 2-75
2.14 Uster AFIS N Application for Cotton Card ..................... 2-76 Maintenance ....................................................................... 2-76 2.15 Maintenance Recommendations ....................................... 2-77 2.15.1 Lubrication Schedule ................................................... 2-77 2.15.2 Cleaning Procedures For High Production Carding Equipment .................................................................... 2-77
2.16 Troubleshooting .................................................................. 2-80
Back to Table of Content
Chapter 2
SPINNING PROCESSES AND TYPES OF YARN
2-2
Spinning Processes and Types of Yarn
CHAPTER 2.........
.......SPINNING PROCESSES AND TYPES OF YARN SECTION 1
BLOWING ROOM PROCESS
1.1 Purpose of Blowing Room Process Opening and picking of cotton necessitates several steps to get the cotton from a tightly packed bale containing trash and other foreign matter, and ready for the carding operation. These steps include separating the cotton into particles small enough to facilitate cleaning and reforming the tufts into a sheet suitable for carding. Since the feeding of cotton is done from the original bales, this operation includes the blending or mixing of the various fibre properties to be contained in the final yarn and fabric. For synthetic material, the opening and beating points should be minimized to as few as possible.
1.2 Bale Opening
A
At the very beginning, automatic feeding of cotton is generally accomplished by the use of a circular bale picker or a continuous rectangular bale opener. This picker or opener is designed to receive the layers of cotton directly from the bale and to break these layers into small lumps. To ensure evenness in blending, usually the lay-out of the cotton bales should have the same height level. Lying bales of material on a conveyor belt is a special idea on today’s continuous bale opener. Figure 1.2
Continuous Rectangular Bale Opener
Textile Handbook 2-3
1.2.1 Features of Some Automatic Bale Openers a) Truetzschler Blendomat BDT 019 One to eight groups of bales can be allocated to form one to three opening lines
•
Can process on either one or both sides of the track
•
Can accommodate up to 180 bales with a working width of 2300mm.
•
Traverse speed can be controlled between 6-13 m/min.; production rate is up to 1500kg/hr.
b) Truetzschler Blendomat BDT 020 •
Works on a continuous basis with bale replenishment done either automatically or manually. New bales are brought into the working zone on a conveyor belt
•
Fibres strip off at an inclined angles, blending takes place in adjacent bales and from various layers from the different bales
•
A reserve belt attached with a bale carriage is used for the continuous supply
•
Microcomputer control of the operation is a standard option
Figure 1.2.1b
Truetzschler Blendomat BDT 020
Spinning Processes and Types of Yarn
•
2-4
Spinning Processes and Types of Yarn
c) Rieter UNIfloc A11 •
Alignment is performed automatically, bales are opened parallel down to the last tuft
•
Laydown up to 2 x 130 bales
•
Alternate take off for 4 assortments
Figure 1.2.1c (1)
Rieter UNIfloc A11
Figure 1.2.1c (2)
Rieter UNIfloc A11
Textile Handbook 2-5
1.3 Cleaning
A
1.3.1 Purpose of Cleaning
Measures of cleaning efficiencies have been facilitated either by the use of the Shirley Analyser, Uster AFIS or Uster MDTA3. They are laboratory instruments used to separate cotton or waste into its lint and non-lint (trash) components. By computing the percentage of trash or non-lint content in the sample, the cleaning efficiency and over beating effect of the processing can be determined.
1.3.2 Feeding System
A
It is generally understood that the handling, cleaning, and metering of cotton is facilitated by having the cotton particles as small as is practical. To handle cotton over longer distances, blowers or fans are usually used; for shorter distances, condensers have been very satisfactory. These condensers operate on the principle of a suction or vacuum produced by a radial-type fan, drawing through a perforated screen section. This type of condenser is adaptable for use with a number of different types of cleaning and distribution systems.
Spinning Processes and Types of Yarn
The purpose of the cleaning machines is the opening of larger particles of cotton and the removal of large motes, pieces of trash, and other heavy foreign matter in the cotton. The main action of cleaning machines is to beat the cotton which tends to be carried upward. In addition, any air motion is upward. This air motion is quite important; it sets up a definite suction through the machines. During the beating about of the opening action, the cotton is repeatedly thrown against the inner casing, and the heavy particles, which are exposed, are thrown off, passed through the openings, and settled outside the beater chamber. Many types of cleaning machine have grid bars underneath the beaters which can be adjusted externally while the machine is in operation to allow and control the amount and type of droppings to drop out.
2-6
Spinning Processes and Types of Yarn Figure 1.3.2
Condenser and Chute Feed attached to Cleaner
1. High-capacity condenser LVSA 2. Feed chute BS 3. Cleaner CLEANOMAT CVT1
1.3.3 Features of Some Cleaning Machines a) Truetzschler Cleanomat CXL •
Specially developed for high production rate, a working width of 1600 mm processes cotton at up to 800kg/hr.
•
4 roll cleaner with fully spiked roll, coarse saw tooth roll, medium saw tooth roll and fine saw tooth roll.
•
Use of direct suction over a conventional system with grid bars and waste chambers is an advantage in processing sticky cotton.
Figure 1.3.3 a
Truetzschler Cleanomat CXL
Cleaner CLEANOMAT
Textile Handbook 2-7
b) Rieter UNIclean B 11 •
Combined cleaning and de-dusting, raw material is guided over the integrated dusting filter; dust, fibre fragments and pepper trash are stripped off mechanically.
•
Material passes 7 times over the cleaning grid.
•
Amount of waste and cleaning intensity is controlled by the Varioset software.
Rieter UNIclean B 11
c) Rieter UNIflex B 60 •
Fine cleaner for natural fibres
•
Its maximum production capacity is 500 kg/hr. (1100 lb/hr)
•
Without additional components it can be used as a feeding machine for cards
Spinning Processes and Types of Yarn
Figure 1.3.3 b
2-8
Spinning Processes and Types of Yarn Figure 1.3.3 c Rieter UNIflex B 60
d) Truetzschler Dustex DX
A
•
Material is fed into the Dustex DX at high speed by a fan, and is equally distributed over a perforated plate through two distribution flaps.
•
Fine and micro dust comes off through the perforated plate and is then led to a filter unit via a dust removal pipeline.
•
The integration of this machine in a cleaning line is particularly recommended in OE spinning mills for rotor spun and air-jet yarns.
Figure 1.3.3 d
Truetzschler Dustex DX
Textile Handbook 2-9
1.4 Blending Nowadays, blending or mixing of cottons is accomplished by the use of a multi-blender. These machines have 6 to 8 rooms, and the more rooms the machine has, the better the blending results. There are two openings in each room, one at the top and one at the bottom. Cottons are deposited into each room in a sequential order through the top opening and dropped onto a conveyor belt from the bottom opening. The conveyor belt carries tufts of cotton from different rooms towards a stripping roller which further beats cottons into fine and small particles.
a) Rieter UNImix B •
A smooth air stream simultaneously feeds fibre tufts into six vertical filling chutes
•
Ensures an instantaneous blend of every bale is deposited uniformly in all six chutes
•
Material is pneumatically compacted and dust is eliminated
•
After a deflection of 90o, fibre layers placed on top of each other are formed and opened into small tufts by an upright lattice, working in a vertical direction
•
A stripper roller throws excess material back into the blending chamber
Figure 1.4.1 a
UNImix B
Spinning Processes and Types of Yarn
1.4.1 Features of Mixer and Blender
2-10
Spinning Processes and Types of Yarn
b) Rieter UNIblend A80 •
Can be delivered with two to eight blending modules, each with a production capacity of up to 300 kg/hr (660 lb/hr)
•
The maximum production is 1000 kg/hr (2200 lb/hr)
•
Combines precise dosing with homogeneous blending in one single machine
•
Possibility of splitting lines after the machine into as many as four different card lines with each receiving a different blend ratio of the same components
Figure 1.4.1 b
Rieter UNIblend A80
c) Truetzschler Multimixer MPM 6 •
Uses direct suction at the blending duct underneath the opening rolls
•
No conveyor belt
•
Works on the basis of a closed air circulation, i.e. the transport air entering the machine also feeds the material to the flowing machine
•
Trouble free operation of the mixing process is ensured by an integral control
Textile Handbook 2-11 Figure 1.4.1 c
Truetzschler Multimixer MPM 6
1. Feed funnel 2. Closing flap 3. Mixing chamber 4. Feed duct 5. Light barrier
8. Delivery rolls 9. Opening rolls 11. Blending duct 13. Material suction funnel
1.5 Machine Arrangements In the past there was an almost limitless number of opening combinations. Today there are still many opening combinations designed to meet the needs of each combination of plant and type of cotton to be handled. In spite of the different combinations of needs, to some extent there appears to be a general trend toward standardization of opening lines.
1.5.1 Example of Machines Layout of Blowing Room: a) Cotton Carded Ring-Spun Yarn
Figure 1.5.1 a Cotton Carded Ring-Spun Yarn
Spinning Processes and Types of Yarn
7. Perforated plate
2-12
Spinning Processes and Types of Yarn
b) Cotton OE-rotor Yarn Figure 1.5.1 b
1. 2. 3. 4. 5. 6.
Cotton OE-rotor Yarn
Automatic Bale Opener BLENDOMAT BDT 020 High-Capacity Condenser LVSA B Multi-Mixer MPM 10 High-Capacity Condenser LVSA B Multi-Mixer MCM 4/ Cleaner CLEANOMAT CVT 4 Dedusting Machine DUSTEX DX
c) Cotton Coarse Count OE-rotor and Carded Ring Yarn Figure 1.5.1 c
Cotton Coarse Count OE-rotor and Carded Ring Yarn
1. Automatic Bale Opener BLENDOMAT BDT 019 2. High-Capacity Condenser 3. Waste Feeder AS 4. Double - roll Cleaner AXI-FLO AFC 5. Station for Separating Foreign Matter SECUROMAT SC 6. Multi-Mixer MPM 8 7. Dedusting Machine DUSTEX DX
Textile Handbook 2-13
d) Production of Cotton Combed Yarn Figure 1.5.1 d
Production of Cotton Combed Yarn
1.6 Foreign Substance Detector Spinning mill problems associated with foreign matter in cotton have increased during the past years. In developing countries with their low labour costs, it is not uncommon to employ up to 100 persons per shift for contaminant screening. However, in high labour cost regions, automated systems are the only sensible alternative. For example, magnets located after the automatic bale opener or cleaner would pick up any tramp iron particles which might be picked up with the cotton at the feeding bale. Newly developed foreign substance detectors are also recommended to be arranged in the blowing room for high quality bleached white or raw white yarn. Over the last few years, the number of suppliers of such systems has increased continuously. The main differences between the technical solutions can be found in the areas of the material feed and the sensor technology.
Spinning Processes and Types of Yarn
1. Automatic Bale Opener BLENDOMAT BDT 019 2. High-Capacity Condenser LVSAB 3. Double-roll Cleaner AXI-FLO-AFC 4. Waster Feeder AS 5. Station for Separating Foreign Matter SECUROMAT SCF 6. Multi-Mixer MPM 6/ Cleaner CLEANOMAT CVT 4 7. Dedusting Machine DUSTEX DX
2-14
Spinning Processes and Types of Yarn
1.6.1 The Vision Shield (Jossi) The system employs 2 ultrafast CCD colour line cameras with digitised image processing to catch the colours of the passing cotton tufts and transfer the collected data through a fibreglass cable to the image processing unit. The resolution and photorealistic real-colour processing guarantees the differentiation between cotton and contamination. The system uses fuzzy logic software to detect contamination with very little colour difference to cotton. Immediately after detection, the pneumatic ejection eliminates the detected contamination. The ejected contaminants can be collected by an optional automatic evacuation which consists of a fan with a control box and collector cart. In combination with a foreign-fibre cleaner at the cone winder the result will be a high quality yarn, almost free of foreign fibres. With this combination a production rate of up to 1000 kg/hr is possible. Without a foreign-fibre cleaner, a production rate of 400 kg/hr is normal.
Figure 1.6.1
The Vision Shield Compact
Textile Handbook 2-15
1.6.2
Securomat (Truetzschler)
To detect foreign fibres, tuft is guided through a rectangular duct. Electronic cameras operating with front and back lighting scan the tufts from both sides of the duct. Characteristic features for detecting foreign parts and foreign fibres are colour, size, geometry, transparency and reflection. Detected foreign fibre tufts are diverted into a waste box via a separation flap.
Figure 1.6.2 Securomat
1.6.3 Cotton Sorter RX-CS (Barco) The Cotton Sorter RX-CS employs four line cameras to scan the cotton through illuminated glass windows. Condemnations can be described as a deviation in colour and size. The line cameras interpret colour deviation as colour level deviations. Tolerances in colour are defined by means of threshold levels. Objects with a colour value below this limit being marked as contaminant.
Spinning Processes and Types of Yarn
The Securomat SC can be equipped with special individual sensors such as metal detectors for metal particles and spark sensors for burning material and sparks. All sensors are connected to a single point of separation.
2-16
Spinning Processes and Types of Yarn
The ejection of the contaminant is performed by a mechanical flap that is positioned in the outfeed pipeline located a few metres from the detection unit. On request, the ejector valve can be completed with spark detection and metal detection.
Figure 1.6.3
Cotton Sorter RX-CS
1.6.4 Optiscan (Uster) The tufts are released from the chute feed onto a conveyor belt, which, together with the machine frame, forms a tapered channel. At the narrowest point of this channel, there is a two-line sensor array with 64 fibre-optic cables and microprocessor controlled colour sensors, which continuously monitor the flow of tufts. As soon as an object which deviates from the colour of the cotton is detected, the machine control system will activate one or several of a total of eleven compressed air nozzles arranged across the width of the machine and in that way ensure a selective extraction of the contaminated tufts into the waste bin. As an option, a sensitive metal detector can be introduced in parallel to the foreign matter sensor. The metal detector is also subdivided into sections so that few good fibres are extracted together with the particles of metal.
Textile Handbook 2-17 Figure 1.6.4 Optiscan
1.7.1 Maintenance of Opening Room/Opening Hoppers a) The following routine is suggested for most hoppers: General overhaul every 12 months. •
Run stock out of hoppers.
•
Inspect the lattices, replace worn aprons, broken slats, torn canvas, etc.
•
Clean out waste, especially that packed under slats.
•
Check length of pins, number and thickness of slats. If thickness differs, no standard setting is possible.
•
Shorten or replace lattices which are too long or damaged. They should be short enough to permit future tightening.
•
Both sides of the apron should have uniform tension to prevent slippage and undue stretch.
•
Check condition of hackle comb (combing roll) and doffing rolls. Repair and replace as needed.
•
Set hackle comb (combing roll) and doffing rolls as per manufacturer’s recommendation.
•
If hoppers are equipped with grid bars under the doffing roll, the grid bars should be removed, cleaned, and deburred and set to proper setting.
Spinning Processes and Types of Yarn
1.7 Maintenance Recommendations for Opening and Cleaning Machines (Source: Cotton Incorporated)
2-18
Spinning Processes and Types of Yarn
•
Check condition of bearings and shafts. Replace as needed.
•
Check condition of all belts and pulleys. Replace and adjust as needed.
•
Check condition of all guards and covers before replacing.
Note: After the hopper is back in production, check tuft size and production rate.
b) Maintenance of Top Feed Bale Plucker (i) Daily Cleaning and Inspection Clean and check power supply chain. (ii) Weekly - Clean safety lights and deflectors. - Clean control cabinet. - Clean the duct (inside and outside). - Clean all motors, removing any lint from the fan covers. - Clean the milling head and inspect for damage and loading. - Clean fibre from the track. (iii) Monthly - Clean external sheet metal casing. - Clean all roller chains. (Check for proper tension.) - Clean all V-belts. (Check for proper tension.) - Clean and check counting mechanism. - Check run time of bale plucker. (This should be no less than 85%.) (iv) Every 6 Months - Clean and check gears, motors and brakes. - Clean counter weight guides. (v) Yearly - Clean and check telescopic tube. - Clean and check suction pipes. - Clean and check cover-belt guide and sliding block.
Textile Handbook 2-19
1.7.2 Maintenance of Cleaners a) General overhauling frequency every six months. Remove all guards and covers.
•
Take out and clean feed rolls, gears; smooth out nicks, dents, and replace worn parts.
•
Check beater bearings and shafts, clean old grease from bearing and housing and renew.
•
Inspect, renew, and polish damaged or rounded beater pick. Evaluate the possibility of turning beater to obtain new working edge.
•
Take out grid bars, clean, deburr, straighten and polish.
•
Set beater to feed roll on cleaners equipped with feed rolls.
•
Set cut-off plate to beater on cleaners equipped with cutoff plates.
•
Line grid bar brackets and replace bars.
•
Set grid bars to beater and grid bar angle,
•
Adjust all safety latches.
•
Check all belts, replacing any that are worn.
•
Adjust all belts for proper tension.
•
Check condition and replace all guards and covers.
•
After cleaner is back in production, check waste percent.
Note: Cleaners equipped with Kirschner beaters should have beater lags replaced every six months.
b) Maintenance of Multiple Wire Wound Roll Cleaners Multiple wire wound roll cleaners can range from two to four wire wound rolls with mote knives on the first roll, and sometimes on the second roll, with other cleaning points throughout the multiple roll system. The feed should be adjusted to run 85 to 90 percent of the time for better cleaning and to reduce fibre damage.
Spinning Processes and Types of Yarn
•
2-20
Spinning Processes and Types of Yarn
(i) Weekly - Clean control cabinet. - Clean gear and drive motors. - Clean lights and deflectors on safety barriers. - Clean by suction inside waste compartment. - Clean all suction points. (ii) Monthly - Clean interior frame walls. - Clean all roller chains; check tension. - Clean and check all gears. - Clean interior roller covers. - Clean all V-belts and check for proper tension. (iii) Every 6 Months - Clean all gear and drive motors. - Clean and check all servo-drives. Note: Wire on all rolls must be sharp and free of damage.
1.8 Trouble Shooting for Opening and Cleaning Machines Table 1.8
Trouble Shooting
TROUBLESHOOTING 1.8.1 OPENING HOPPERS a. Hoppers Feeding Large Clumps Probable Cause
Solution
1. Comb bar or combing roll set too far form lift apron.
1. Set comb bar or combing roll close to lift apron.
2. Comb bar or combing roll too slow.
2. Speed up comb bar or combing roll as needed.
Textile Handbook 2-21 b. Hopper Production Not Equal 1. Set comb bars or combing rolls the same on each hopper.
2. Surface speed of lift apron not equal.
2. Check tension on lift and bottom aprons.
3. Comb bars or combing rolls running at different speeds.
3. Check all pulleys and belts.
4. Different type pins on lift apron.
4. Check pins on all lift aprons for height, length, number of pins per row, and diameter.
5. Different type of comb bars or combing roll.
5. Check teeth on comb bars or pins on combing rolls.
6. Hoppers being fed unevenly.
6. Maintain a consistent level of stock in hoppers at all times.
c. Hoppers Stop Too Often 1. Hoppers too full.
1. Don’t overfill hoppers.
2. Comb bars or combing roll set too far from lift apron.
2. Set comb bars or combining rolls closer to lift apron.
3. Lift apron speed too fast
3. Slow lift apron to desired speed.
d. Hoppers Running Too Much 1. Hopper choked
1. Remove choke and start hopper
2. Belt broken on hopper.
2. Repair or replace belt.
3. Hopper level too low.
3. Maintain proper level in hopper.
e. Lift or Horizontal Apron Too Slow 1. Apron too loose.
1. Adjust apron tension.
2. Choke in apron.
2. Remove choke and check tension on apron.
3. Belts loose.
3. Check for loose belt and adjust.
f. Drive Motor Overheating 1. Hopper chokes.
1. Remove choke and restart.
2. Bearing bad on hopper.
2. Check all bearings and replace any bad bearing.
3. Motor going
3. Have motor checked by an electrician.
Spinning Processes and Types of Yarn
1. Comb bars or combing rolls not properly set.
2-22
Spinning Processes and Types of Yarn g. Lift or Horizontal Apron Rubbing the Sides 1. Apron not adjusted properly.
1. Adjust apron as needed.
2. Choke in apron.
2. Remove choke and check adjustment.
3. Bearing bad on apron shaft.
3. Replace bad bearing and readjust apron.
4. Apron inside belt broken.
4. Repair or replace apron.
5. Guide pulley slipped on apron shaft.
5. Adjust pulley as needed.
6. Apron too wide for hopper.
6. Replace with proper apron.
h. Losing Good Fibre Under Hopper 1. Seal bad under lift and horizontal apron.
1. Replace seal and reset.
2. Screen under lift apron damaged.
2. Check screen for damage and replace as needed.
3. Horizontal apron damaged.
3. Check apron; repair or replace as needed.
l. Hopper Noisy 1. Pulley loose.
1. Check pulleys; adjust and replace if damaged.
2. Gears worn.
2. Replace as needed.
3. Gears need lubrication
3. Lubricate gears with proper lubrication.
4. Bearing bad on hopper or motor.
4. Check and replace bearing as needed.
5. Guards and covers loose.
5. Check for loose guards and covers, making sure they are not touching the pulleys.
6. Hopper choked up.
6. Unchoke hopper as needed.
1.8.2 TOP FEED BALE PLUCKER a. Frequent Feeder Stopping 1. Cards out of production.
1. Check to see if all cards are in production.
2. Feeder taking too much fibre from each bale.
2. Adjust feeder to take off less fibre from each bale.
3. Bales not allowed to bloom.
3. Bales should be opened and allowed to set for 8 to 24 hours before feeding.
Textile Handbook 2-23 1.8.3 CLEANING EQUIPMENT a. Cleaner Removing too little waste 1. Adjust grid bars to a greater angle.
2. Grid bar dirty.
2. Remove grid bars; clean and replace.
3. Grid bars set too far from beaters.
3. Set grid bars to manufacturer’s recommendations.
4. Beater speed too slow.
4. Increase goods to manufacturer’s recommendations.
5. Lint built up under grid bars.
5. Check condition of grid bars; check the amount of air pulling up through the grid bars - too much air will cause lint buildup.
b. Cleaner not cleaning 1. Grid bars not set properly.
1. Set angle of grid bars for maximum waste removal.
2. Too little run time.
2. Adjust feed on opening line to run at least 85% of run time.
3. Tufts too large feeding into cleaner.
3. Check opening hoppers.
4. Pulling air through step cleaners.
4. Check exit transitions. Fibre should free fall out of cleaner in an air stream for transporting.
5. Production too high.
5. C h e c k m a n u f a c t u r e r ’s recommendations for maximum production. (do not exceed).
c. Cleaner Producing Neps 1. Beaters dull
1. Check condition of beater lags, blades or pins (must be sharp and free of damage).
2. Beater not set properly to feed rolls.
2. S e t b e a t e r t o f e e d r o l l t o manufacturer’s recommendations.
3. Setting between cut-off plate to beater.
3. If cleaner is equipped with a cut-off plate, set plate to manufacturer’s recommendations
4. Production too high for cleaner.
4. C h e c k m a n u f a c t u r e r ’s recommendations for maximum production. (Do not exceed.)
Spinning Processes and Types of Yarn
1. Grid bars out of adjustment.
2-24
Spinning Processes and Types of Yarn d. Cleaners Noisy 1. Cleaner choking.
1. Stop cleaner and clean.
2. Bad bearing.
2. Check all bearings. Replace as needed.
3. Beaters out of balance.
3. Check all beaters and balance as needed.
4. Loose pulley.
4. Check all pulleys; tighten or replace as needed.
5. Guards loose.
5. Check guard and tighten as needed.
6. Pulley rubbing guard
6. Check pulleys and adjust as needed.
7. Loose beater lags
7. Check beater lags and repair as needed
1.8.4 MULTIPLE WIRE WOUND ROLL CLEANERS a. Cleaner Producing High Neps 1. Wire on rolls dull or damaged.
1. Replace wire as needed.
2. Roll not set properly.
2. S e t r o l l s t o m a n u f a c t u r e r ’s specification.
3. Run time not high enough.
3. Adjust feed to assure 85 to 90 percent run time.
b. Cleaner Not Cleaning 1. Run time too low.
1. Adjust feed to assure 85 to 90 percent run time.
2. Mote knives or baffles not set properly.
2. Adjust mote knives and baffles to manufacturer’s specification
c. Drive Motor Overheating 1. Rolls lading.
1. Check wire condition.
2. Bearing bad on cleaner
2. Check all bearings. Replace as needed.
3. Motor giving trouble.
3. Have motor checked by an electrician
Textile Handbook 2-25
SECTION 2
CARDING PROCESS
2.1 Purpose of Carding
A
In the entry part of a carding machine, the licker-in (a cylinder covered with metallic wires,) strikes against the fringe of fibre as it is fed forward, tears away tufts of fibres, and carries them forward to the main cylinder. The card cylinder is the heart of the card. All other parts are built around and adjusted to it. The cylinder consists of a large, cylinder cast-iron shell. The card flats is a series of mounted, narrow, flat clothing surfaces concentric with the cylinder. Two endless chains that move them slowly over the top of the cylinder carry them. The working flats form a practically airtight cover over the entire top of the cylinder. This prevents the formation of disturbing air currents. Normally the flats move slowly in the same direction as the cylinder but the wires’ point backward, which is opposite to the direction of the cylinder. It is between these surfaces that the fine separation of fibres is caused to occur. The doffer is a small cylinder made and clothed like the main cylinder. Metallic clothing is used for the doffer. The function of the doffer is to collect the cotton from the cylinder in a uniform fleece, which is delicately removed to form the card web. The transfer of fibre from cylinder to the slow doffer is accomplished by a stripping action, after which the film of cotton is stripped from the doffer as a web by the action of a stripper roll, and is drawn forward and gathered through a funnel-shaped opening, the trumpet plate, which shapes the web into a round sliver. Today, for all high speed carding machines, after being stripped from the doffer, the film of fibre is delivered to a conveyor belt which collects and gathers the web towards an opening, which then passing through a funnel-shaped trumpet to a pair of grooved rolls. Finally, the sliver is drawn upward to the top of the coiler and delivered into a can.
Spinning Processes and Types of Yarn
The fibres opened in the blowroom will be fed to the card for further cleaning and fibre separation. The principle of carding is to separate cotton fibres into their individual elements, thereby exposing and removing the bits of leaf, trash, and other foreign matter enclosed by the unopened fibre aggregates, and form the cleaned, disentangled fibres into slivers to feed the next process.
2-26
Spinning Processes and Types of Yarn Figure 2.1
Carding Machine (Truetzschler DK903)
2.2 Carding Actions The carding function is accomplished by the action of card clothing, a system of inclined wires, and the entire carding machine may be considered as a convenient frame to support this clothing, so that it may operate at maximum efficiency. Two surfaces covered with clothing usually work together to achieve the objective of carding. Fundamentally, there are two important actions performed with carding surfaces, carding and stripping. Carding action is accomplished when the wires of the two surfaces are inclined in opposite directions and the direction and rates of motion are point against point. This action can result from both surfaces going in the same direction, with the lower surface moving faster than the upper surface, or the action can result from both surfaces moving in opposite directions, each in the direction of inclination of the wire. Carding action causes a thorough opening of the cotton tufts by tensioning and separating the fibres. Stripping action is accomplished when the wires of the two surfaces point in the same direction. With this arrangement, the action is point against smooth side. The surface which moves faster lifts the cotton away from the other wire and collects it. Stripping is used in transferring cotton from one surface to another and in removing it from a surface.
Textile Handbook 2-27 Table 2.2 Carding and Stripping Actions Showing Different Combination of Wire Points, Movement Direction and Relative Speeds
Direction
Relative Speed Movement
A
➔
B
➔
Fast
Slow
➔
Wire point
➔
Surface
Fast
Slow
Continuous material flow control for a complete spinning preparation installation from bales to card sliver has been established for some time. On modern carding feeding systems the makers have already taken care to ensure even distribution of material over the full width and very homogeneous condensing of the raw material for improved card sliver. Usually, the distribution duct terminates after the last tuft feeder. There is no excess material having to be conveyed back to the cleaner or opener. A shut-off flap in the distribution duct after the penultimate tuft feeder prevents material collecting and becoming compacted in the last tuft feeder, if the last card is stopped for any length of time. The controllable fan blows the tufts through the distribution duct into the material reserve trunks of the tuft feeder. The conveying air escapes through air outlets in the trunks. The air outlets are in the form of grids or perforated plates covered with filter fabric. One fan serving all the tuft feeders in a line extracts the dust laden exhaust air and passes it to a filter. The conveyor air thus assists the extraction of dust from the material.
2.3.1 Rieter Aerofeed U • • •
•
Aerofeed U forms flocks from the feeding machine into a homogeneous bat for the card C50. Material can be processed with a maximum production of 400 kg/hr (880 lb./hr.) per feeding machine A 7/U system controls the filling of the chute with two photocells arranged vertically to avoid running empty or over-filling. A 7/C system uses eight photocells and an invertercontrolled feed roller motor. The filling is thus held very constant and ensures a low CV%.
Spinning Processes and Types of Yarn
2.3 Card Feeding System
2-28
Spinning Processes and Types of Yarn Figure 2.3.1
Rieter Aerofeed U
1. Feed duck 2. Separator head 3. Feed Chute 4. Opening roller 5. Metering Chute 6. Extracting rollers 7. Exhaust air
2.3.2 Rieter UNIstore A 77 •
A 77 is used as a feeding machine for cards or for storage after the UNIblend.
•
The storage and opening capability of the UNIstore A 77 is in some cases required when feeding man-made fibres into the UNIblend.
•
A maximum production of up to 600 kg/hr (1300 lb/hr.)
Figure 2.3.2
Rieter UNIstore A 77
1. Material input 2. Dust and air extraction 3. Opening and feeding unit 4. Material output 5. Air to filter unit
Textile Handbook 2-29
2.3.3 Truetzschler Tuft Feeder Directfeed DFK The delivery roll of the tuft feeder is identical to the feed roll of the card
•
There are no faulty drafts caused by false or not optimal settings, therefore the evenness of the feeding is considerably improved
•
The air outlet combs, with direct and permanent suction, are positioned right in front of the feed roll of the cardhere the web is formed
•
The feed tray has been separated into 5 segments which are individually spring-born
Figure 2.3.3 Tuft Feeder Directfeed DFK
1. Feed trunk 2. Air outlet combs 3. Upper trunk 4. Feed roll 5. Segmented tray 6. Opening roll 7. Fan 8. Bottom trunk 9. Air outlet combs
Spinning Processes and Types of Yarn
•
2-30
Spinning Processes and Types of Yarn
2.3.4 Truetzschler Sensofeed •
The web is guided to the transfer point between feed roll and 1st licker-in roll via 10 spring elements
•
Each spring element exactly adjusts itself to the momentary mass of the web to be fed, i.e. if mass variations in the web occur, the spring elements are deflected differently
•
The deflections of all 10 spring elements are processed to become one signal for the short wave regulation, therefore it is possible to avoid thickness variations and obtain better sliver evenness
Figure 2.3.4
Sensofeed & Webfeed
1. Feed roll 2. Feed table 3. Measuring lever with measuring plates 4. Pre-opening segments 5. Clearing units 6. 1st Webfeed roll 7. 2nd Webfeed roll 8. 3rd Webfeed roll
2.3.5 Truetzschler Webfeed •
This system consists of three opening and cleaning rolls in series arrangement
•
The first WEBFEED roll runs at a clearly lower speed than the only licker-in roll of conventional cards
•
The effect of nep reduction prior to the cylinder is unique
•
Each licker-in roll is equipped with direct suction, which prevents a build up of sticky particles, therefore cotton containing honey-dew can be processed without any problem
Textile Handbook 2-31 Figure 2.3.5 Licker-in system WEBFEED
There are two general classifications of card clothings: fillet and metallic. Fillet card clothings consists of foundation and wire, and are continuous strips of clothing 1-1/2 inches to 2 inches wide. Card flats are special fillets about 40 inches long mounted on cast-iron slats to enclose the upper portion of the card cylinder. Metallic clothing is somewhat like licker-in or garnet clothing, and consists of a steel band with teeth punched in one side and a thick rib on the other. The advantage of metallic clothing is that it does not require frequent grinding and stripping like fillet clothing. The tapered shape of the metallic wire points permits easy transfer of fibres without retaining them as cylinder and doffer wastes. The choice of the clothing depends not only on the raw material being carded, but also to a considerable extent on the card involved. Usually, the clothing makers have developed special equipment for mounting the saw tooth wire, and have worked out sets of rules which go a long way to assuring successful operation. Modern mounting equipment ensures proper guidance and unrolling of the wire, and guarantees proper alignment, firm positioning and constant pressure between turns. Special importance is attached to uniform tension. The winding on speed may be adjusted to anywhere between 0 to 40m/min.
Spinning Processes and Types of Yarn
2.4 Card Clothing
2-32
Spinning Processes and Types of Yarn
Cylinder and doffer clothings need grinding after mounting, to ensure that all points have the right shape for good carding performance. A distinction is made between grinding in newly mounted clothings and subsequent regrinding. At least 90% of all points should be touched by the grinding stone when grinding-in. The grinding roller must be exactly parallel to the cylinder on the card. This prevents hollow grinding, which impairs quality. Grinding metallic clothings much more difficult than fillet ones, because the metal tooth cannot yield under the grinding pressure. Normally the grinding intervals depend on the amount of material put through. They are also governed to a very large extent by the hardness of the clothing wire, i.e. its points. The first regrind should be postponed as long as possible. Generally, doffer regrind intervals can be attained amounting to many times the cylinder interval.
Textile Handbook 2-33
2.5 Card Clothing Specifications 2.5.1 ECC Card Clothing a) Licker-in Wires Licker-in wire designs for the processing of 100% cotton, cotton/man-made blends and 100% man-made. Rib thickness is determined by the groove, except where interlocking licker-in wire is required.
Number Grooved 6STL 8SN 6STM
4SAM R110 R111 R115 Interlocking B8TR/6STL B8TR/4SAL BSTR/SSN B8R10 B8R5 B12 R10 B12 R5 B16T/250/70 B16T/195/70
Licker-In Wire Specification
Total height Rows per Pitch Angle (mm) Inch (mm)
ppsi
5.65 5.65 5.50
8 8 8
5.65 4.80 5.10
80 90 80
36 42 40
5.50 5.50 5.50 5.50
8 8 8 8
5.10 5.10 5.10 7.60
85O 78O 85O 90O
40 40 40 27
5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00
8 8 8 8 8 12 12 16 16
5.30 5.30 4.70 5.30 5.30 2.70 2.70 2.50 1.95
80O 85O 90O 80O 85O 80O 85O 70O 70O
38 38 43 38 38 113 113 161 206
O O O
b) Millennium Cylinder Wire Millennium teeth are positioned on the rib surface with a minimimum free blade area (B) (see Figure 2.5.1.b (1). The Micro Tooth Depth concept provides that even the smallest fibre bundlecan be carded. Figure 2.5.1b(1)
Millennium Teeth
Spinning Processes and Types of Yarn
Table 2.5.1 a (1)
2-34
Spinning Processes and Types of Yarn Table 2.5.1b(2) Millennium Specification
Dedicated designs for super high production carding of all types of fibres. Number
Total height (mm) 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00
5511 5595 5585 5586 5686 5672 5676 5572 5666
Rib (mm) 0.40 0.40 0.40 0.50 0.50 0.50 0.65 0.65 0.65
Pitch (mm) 1.50 1.70 1.90 1.50 1.50 1.80 1.30 1.40 1.50
Angle 55O 55O 55O 55O 60O 60O 60O 60O 60O
ppsi 1075 950 850 860 860 720 760 720 660
c) Doffer wires Doffer Wires have been developed with added strength and durability to combine with the Millenium cylinder wires for all super high production applications. Table 2.5.1c
Number 5635 5640 8635 8641 8640 8326
Doffer Wire Specification
Total height (mm) 3.70 3.70 4.00 4.00 4.30 5.00
Rib (mm) 0.90 0.90 0.80 0.80 0.80 0.90
Pitch (mm) 2.00 1.80 2.40 2.00 2.00 2.20
Angle
ppsi
60o 60o 60o 60o 63o 60o
358 398 350 403 403 326
Also available in striated form for cotton and synthetic applications: 5635R1 5640R1 8635R1 8641R1 8326R
3.70 3.70 4.00 4.00 5.00
0.90 0.90 0.80 0.80 0.90
2.00 1.80 2.30 2.00 2.20
60o 60o 60o 60o 60o
358 398 350 403 326
Textile Handbook 2-35
d) Tops The Ecco series of tops covers carding requirements at all levels of production on every type and grade of fibre. Special finish is standard on this series. Plattflex is used where little or no flat strip is desirable. Table 2.5.1d
Number
Top Wire Specification
Total height (mm)
Angle
ppsi
27 30 24 27 27 30 30 50 27 30 27 30
75O 70O 75O 75O 75O 70O 70O 75O 75O 75O 80O 80O
332 443 276 332 370 443 480 516 370 480 267 393
e) Regrinding cycle in relation to Nep count Curves (2) and (3) indicate the effect of regrinding the wire after a 20% increase in Nep count. Note that MILLENNIUM wires run significantly longer from start up to the first regrind, and between regrinds, compared to conventional wires. Too high a Nep count acceptance limit (1) can allow excessive wear of the points which cannot be rectified by grinding. Table 2.5.1.e Grinding Cycle in Relation to Nep Count
Spinning Processes and Types of Yarn
CLIPPER33 7.50 CLIPPER4-4 8.00 ECCO300 7.50 ECCO330 7.50 ECCO400 7.50 ECCO440 8.00 ECCO500 8.00 FINO 42 7.50 ECCO 400A 8.00 ECCO 500A 8.00 PLATTFLEX HD 7.90 PLATTFLEX 400 7.50
Rows per Inch
2-36
Spinning Processes and Types of Yarn
2.5.2 Graf Card Clothing a) Metallic Wire Figure 2.5.2 a (1)
Metallic wire
> 50kg/h
15-50kg/h
< 15kg/h
1.5-3.0 dtex >3.0 dtex
Licker-in
Doffer
Cylinder
Doffer
N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9
R-2520-x0.7 O-2515-x0.9 R-2525-x0.6 R-2525-x0.6
E-5510-x... E-5510-x... D-5505-x... D-5505-x... C-5500-x... D-5505-x... E-5510-x... E-5510-x... V.E-5010 ... 8 V.E-5010 ... 8 V.E-5010 ... 8 V.D-5005...8 V.D-5005...8 V.C-5000...8 V.D-5005...8 V.E-5010 ... 8
R-2030-x0.5 R-2030-x0.5 P-2030-x0.4 N-4025Bx0.9 N-4025Bx0.9
R.2030-x0.6 R-2030-x0.6 R-2030-x0.5 R-2525-x0.6 R-2520-x0.7 O-2515-x0.9 R-2525-x0.6 R-2525-x0.6 R-2525-x0.6 R-2525-x0.6 R-2525-x0.5 R-2525-x0.5 N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9 N-4025Bx0.9 N-4025BX0.9
<1.0 dtex
Recycled Fibres
Cylinder
combed
BlendsCo/MMF 1.0-1.4dtex
R-2520.x0.6 R-2520.x0.6 R-2520-x0.6 R-2520-x0.6 R-2515-x0.7 O-3215-x0.9 R-2520-x0.6 O-4025.x0.9 O-4025-x0.9 O-4025-x0.9 N-4020-x0.85R N-4020-x0.85R N-4020-x0.86R N-4020-x0.85R
Carded
Ring-spun
Man-made fibres-MMF
Cylinder Doffer
Rotor-spun
Cotton-Co
Application of Metallic Card Clothing
Spinning Processes and Types of Yarn
Production
Table 2.5.2.a (2)
Textile Handbook 2-37
2-38
Spinning Processes and Types of Yarn
b) Border Wires Figure 2.5.2 b
Border Wires
c) Top Flats
Figure 2.5.2 c (1) PRIMATOP
• Primatop PT 35/0 350 p.p.s.i. Used for yarns up to Nm 35 (coarse, short staple cotton and medium fine synthetic fibres) PT 43/0 430 p.p.s.i. Used for yarns from Nm 35 - 70 (medium cotton and fine synthetic fibres) SPACETOP 520 p.p.s.i Used for yarns
Figure 2.5.2 c(2)
RAPPOTOP
• Rappotop HS 30/0 300 p.p.s.i. Used for recycling HS 40/0 400 p.p.s.i. Used for yarns from Nm 35 - 70 HS 50/0 500 p.p.s.i. Used for yarns of Nm 50 and finer
Textile Handbook 2-39 Figure 2.5.2 c (3)
DIAMANT/PICCO-DIAMANT
• Diamant/Picco-diamant DI/PD 24/0 240 p.p.s.i. Used for synthetic fibres DI/PD 33/0 330 p.p.s.i. Used for synthetic fibres of 1.5 - 3.0 dtex
•
M-Top
The M-Top represents a Metallic Flat Clothing for the processing of synthetic fibres. Compared to the conventional flexible flat clothing, it is designed to withstand extreme strain and therefore is most suitable for very high production rates. MT 32/0 320 p.p.s.i. MT 42/0 420 p.p.s.i
Spinning Processes and Types of Yarn
of Nm 50 and finer (fine, long staple cotton)
> 50kg/h
15-50kg/h
< 15kg/h
Production
PT 43/0
PT 35/0 PT 43/0
PRIMATOP
MT 42/0
PT 43/0 HS 40/0
PT 43/0 HS 40/0
PRIMATOP RAPPOTOP DIAMANT/PICCODIAMANT
RAPPOTOP DIAMANT/PICCODIAMANT M-TOP
PT 43/0 HS 5010
PT 43/0 HS 40/0
HS 40/0
PT 43/0 PT 35/0
>3.0 dtex
DI/PD 24/0 DI/PD 24/0
PT 35/0
<1.0 dtex 1.5-3.0 dtex
Man-made fibres-MMF
PT 35/0
MT 32/0
MT 32/0
DI/PD 33/0 DI/PD 24/0
PT 35/0
PT 35/0 SPACETOP PT 43/0 PT 35/0 HS 5010 HS 40/0 DI/PD 33/0 DI/PD 24/0
combed
Ring-spun
Cotton-Co
Carded
Rotor-spun
Application of Top Flats
PRIMATOP RAPPOTOP DIAMANT/PICCODIAMANT
Table 2.5.2 c (4)
PT 43/0
PT 43/0 HS 4010
PT 43/0 HS 40/0
BlendsCo/MMF 1.0-1.4dtex
MT 32/0
HS 30/0
HS 30/0
Recycled Fibres
2-40
Spinning Processes and Types of Yarn
Textile Handbook 2-41
d) Stationary flats
Figure 2.5.2 d (1)
Figure 2.5.2 d (2)
Carding segment with 3 stationary Flats FD14 above the Licker-in for pre-carding and protection of the flat clothings
Figure 2.5.2 d (3)
Carding segment with 3 Stationary Flats FD 64 above doffer, with mote knife and suction hood to improve the nep and trash elimination as well as fibre parallelisation
Spinning Processes and Types of Yarn
Licker-in screen with pre-opening segments bar with 2 Stationary Flats FD 6
2-42
Spinning Processes and Types of Yarn Figure 2.5.2 d (4)
Carding segment with 6 Stationary Flats FD 64 above doffer to improve the nep elimination as well as fibre parallelisation
e) Replacement Clothings and Systems Figure 2.5.2 e (1)
• Below licker-in • Conversion of carding segments
Figure 2.5.2 e (2)
• C-Cleaner II • Truetzschler DK760
Textile Handbook 2-43 Figure 2.5.2 (3)
• Rieter TREX-System
• Clothing clipped on to cast iron or aluminium bar
• Replacement of Clothings: Below licker-in
FD 6: 60 p.p.s.i. FD 9: 90 p.p.s.i
Above Licker-in
FD 14: 140 p.p.s.i.
Above Doffer
FD 24: 240 p.p.s.i. For manmade fibres FD 64: 640 p.p.s.i. For cotton
Spinning Processes and Types of Yarn
Figure 2.5.2 (4)
2-44
Spinning Processes and Types of Yarn
2.5.3 Hollingsworth Card Clothing a) Licker-in Wire Table 2.5.3 a Licker-in Wires Specification Groove
Base
Angle
Pitch
Teeth Per Inch Heigth
072403981
1.10
5
6.35
4.00
5.72
072403503
1.10
l0
5.08
5.00
5.72
072403463
1.10
10
4.32
5.88
5.72
072403982
1.20
5
6.35
4.00
5.72
072402007
1.20
10
5.08
5.00
5.72
072403319
3.18
5
5.08
5.00
5.00
072403445
3.18
10
5.08
5.00
5.00
072403244
3.18
10
4.61
5.50
5.00
072404221
3.18
15
4.23
6.00
5.00
072456322
1.59
20
2.49
10.20
5.00
072456323
1.59
20
1.95
13.00
5.00
(o)
Inter Lock
b) Cylinder Wires Table 2.5.3 b Cylinder Wires Specification Wire No.
Base
Height
Angle
Teeth Per Inch PPSI Application
072451001
0.95
2.50
10
15.87
424
Synthetic.
072403775
0.60
2.50
10
15.87
672
Synthetic
072403876
0.80
3.00
10
15.87
504
Blends
072451007
0.80
2.50
15
16.00
508
Synthetic
072403855
0.60
2.50
15
15.87
672
Synthetic
072403250
0.65
2.25
20
15.28
597
Universal
072456128
0.80
2.50
20
17.54
557
Universal
(o)
Textile Handbook 2-45 0.80
2.50
20
20.00
635
Universal
072403443
0.60
2.50
20
15.99
677
Universal
072403401
0.50
2.50
20
16.00
813
Universal
072403490
0.50
2.50
20
15.87
806
Pima
072451006
0.60
2.50
20
20.00
847
Universal
072403297
0.60
2.50
20
22.00
931
Cotton
072455820
0.65
2.25
25
15.99
625
Universal
072403742
0.60
2.50
26
17.24
730
Universal
072404118
0.60
2.50
30
17.24
730
Universal
072403781
0.60
2.50
30
20.00
847
Cotton
072456250
0.50
2.50
30
17.25
876
Cotton
072403832
0.50
2.00
30
17.25
876
Cotton
072403681
0.50
2.54
30
20.00
952
Clean Cotton
072403408
0.50
2.50
30
19.59
995
Clean Cotton
072402701
0.50
2.50
35
16.00
813
Universal
072403767
0.50
2.50
35
15.37
781
Cotton
072404015
0.50
2.50
35
16.95
861
Cotton
072404014
0.50
2.00
35
16.95
861
Cotton
072404201
0.50
2.00
40
18.87
958
For production
low shoulder
of 50-90 kg/h
072456088
0.50
2.00
45
15.39
781
OE
072456338
0.40
2.00
40
14.88
945
Cotton
Spinning Processes and Types of Yarn
072451008
2-46
Spinning Processes and Types of Yarn
c) Doffer Wires Table 2.5.3 c Doffer Wires Specification Wire No.
Base
Height Angle Teeth Per Inch PPSI Remark
072403879
1.00
4.00
25
13.70
348
072403886
0.90
4.00
25
14.09
398
072456373
0.90
4.00
25
13-02
367
(OB 174)/04217
072403980
0.90
4.00
30
13.34
376
No Serration
072455606
0.90
5.00
30
12.50
352
For C4 Cards
072404084
0.81
4.00
30
11.91
372
Serration
072403212
0.80
4.19
30
12.20
387
3212 / 4.19
072404216
0.90
4.00
35
16.91
336
072403996
1.00
4.00
35
12.04
306
Rieter/Serration
072404179
0.90
4.00
35
12.04
370
Rieter
(o)
Serration
d) Top Flat Wires Table 2.5.3 d
Top Flat Wires Specification
Type
Technical Specifications
Application
H29-E
290 PP Sq.in-wire25x29-
for 100% clean waste or waste blended
height 7.5mm
with very dirty cotton; also for synthetics
290 PP Sq.in-wire 27 x 31-
for very dirty cotton or synthetics
H29-LS
height 7.5 mm H35 H35 - LS H42
350 PP Sq. in - wire 28 x
for dirty cotton (coarse micronaire) and
32 - height 8 mm
fine synthetics
350 PP Sq. in - wire 27 x
same as H35 but for production rate over
31 - height.7.5 mm
20kg / hr
420 PP Sq. in - wire 28 x
for cotton ( medium micronaire ) fairly
32 - height 8 mm
clean
Textile Handbook 2-47 H43 - LS
430 PP Sq. in - wire 28 x 32
for production rates over 20kg / hr
- height 7.5 mm H46 H46 - LS H50-R
for clean cotton ( fine + medium
- height 8 mm
micronaire)
460 PP Sq. in - wire 27 x 31
same as H46 but for production rates
- height 7.5 mm
over 20kg / hr
500 PP Sq. in - wire 28 x 32
for good quality cotton, fine micronaire,
- height 8 mm
specially for combed yarn
390 PP Sq. in - wire 26 x 30
for high production cards (Truetzschler)
- height 7.5 mm
- medium type cotton
e) Recommendation of Wires For Various Applications Table 2.5.3 e Recommendation list Wire Type
OE
Cylinder
072404201 072403832
072403681 072403443
072403443
072404015 072456250
072403832 072451008
072451008
072404217 072404217
072404217 072403980
072403886
072403980 072403212
072403212 072403212
072403980
Licker-in
072402007 072402007
072402007 072403981
072403981
Flat Tops
H35
H50
H35/ H27
Doffer
Clean Cotton Combed
H42/ H50
Chemical
H43
Blends
Spinning Processes and Types of Yarn
H39F
460 PP Sq. in - wire 28 x 32
2-48
Spinning Processes and Types of Yarn
2.5.4 Kanai Card Clothing a) Cylinder Wire • New Powerful • Powerful • H Type Figure 2.5.4a (1)
New Powerful (PAT. PENDING)
Figure 2.5.4a (2)
Powerful (JP PAT.NO. 1689009)
Figure 2.5.4a (3)
H Type
b) Doffer Wire Figure 2.5.4.b
Doffer Wire
Textile Handbook 2-49
c) Taker-in Wire Figure 2.5.4 c Taker - in Wire
• Stripping Wire • Control Roller Wire • Base Wire
Figure 2.5.4 d (1)
Stripping Wire (Type: HU11DH)
Figure 2.5.4 d (2)
Control Roller Wire (Type: EU15GH)
Spinning Processes and Types of Yarn
d) Other Wires
2-50
Spinning Processes and Types of Yarn Figure 2.5.4 d (3)
Base Wire (Type: BW5.5)
e) Dimension of Metallic Wires Figure 2.5.4 e Use
Dimensions of Metallic Wires
Type
A mm B mm C mm Xo
Teeth Point /25.4mm /(25.4mm2)
New Powerful CC73-NPD 2.8 Cylinder Wire CC86-NPD 2.8 CC58-NPI 2.8 CC65-NPI 2.8 CC73-NPI 2.8 CC69-NPK 2.8 CM54-NPN 2.8
0.5 0.5 0.85 0.85 0.85 0.65 0.6
0.63 0.5 0.7 0.63 0.63 0.7 0.75
63 63 68 68 68 70 73
18 17 16 16 18 19 16
726 864 581 645 726 690 542
CC30-P0l Powerful Cylinder Wire CC39-P CC58-P CC65-P CC73-P CT58-P CT61-P CC65-E CC73-E CU58-P H Type CM46AH Cylinder Wire CM54AH
2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 2.8 3.0 3.0
0.85 0.85 0.85 0.85 0.85 0.5 0.8 0.85 0.5 0.85 1.2 1.0
1.1 0.85 0.7 0.63 0.63 0.7 0.75 0.63 0.63 0.7 1.0 0.85
75 80 68 68 68 80 80 70 68 73 77 77
13 13 16 16 18 16 18 16 18 16 18 18
300 388 581 645 726 581 610 645 726 581 457 538
Doffer Wire
4.0 4.0 4.0 4.5 5.0
2.2 2.2 2.2 3.0 3.0
0.85 0.85 0.85 0.8 0.85
60 63 65 63 60
13 13 13 13 12
388 388 388 412 359
Taker-In Wire TC45KH TC50KH TM40KH0l TM45KH
5.6 5.6 5.6 5.6
3.5 3.5 3.5 3.4
* * * *
80 80 90 85
4.5 5 4 4.5
-
Worker Wire
4.0 4.0
2.2 2.2
1.2 1.0
70 68
8 13
169 330
3.0
1.1
1.5
65
10
169
DU39-0 DU39-3 DU39-5 DM41GH DC3601H
WM17DH WM33DH
Stripper Wire SM17AH
Textile Handbook 2-51
f ) Top Flat Wires • VS-type and VL-type tops • T-type tops • Powerful X-type tops • Krestop Table 2.5.4.f (1)
VS-type and VL-type TOPS TW PAT. NO. 36042 P
0.5D
Setting Structure
10 x 4
Spinning Processes and Types of Yarn
Designation Wire Wire diameter Points count D’/D D’/D mm in2 VL -300 25/29 0.530/0.380 300 VS VL -350 26/31 0.480/0.330 350 VS VL -400 26/31 0.480/0.330 400 VS VL -450 27/32 0.430/0.305 450 VS VL -500 28/33 0.405/0.280 500 VS VL -550 30/35 0.355/0.230 550 VS
2-52
Spinning Processes and Types of Yarn Table 2.5.4.f (2) T-type Tops Designation Wire Wire diameter Points count D’/D D’/D mm in2 T-350
27/30
0.430/0.355
350
T-400
28/31
0.405/0.330
400
T-450
28/31
0.405/0.330
450
T-500
30/33
0.355/0.280
500
T-550
30/33
0.355/0.280
550
Table 2.5.4.f (3)
P
0.6D 0.65D 6 x 45 0.65D -0.7D
Powerful X Type Tops
Designation
Wire Wire diameter Points count D’/D D’/D mm in2
Powerful X 280
0.71/0.255 280
• Setting Structure of Top Wires Table 2.5.4.f (4-1)
Setting structure 6 x 4.5
Setting Structure
6 x 4.5
Textile Handbook 2-53 Setting structure 10 x 4
Table 2.5.4.f (4-3)
VS type T type
Spinning Processes and Types of Yarn
Table 2.5.4.f (4-2)
Table 2.5.4.f (4-4) Powerful X
Type N
1 516
W1 916
inch
inch
a
b
20.5
32.6
25.8
38.8
c VL VS X Other
6.3 6.4 4.0 6.3
VL VS X Other
6.7 6.8 5.4 6.7
d
N
26.4
9.5
32.5
9.5
2-54
Spinning Processes and Types of Yarn
Table 2.5.4.f (5) Krestop Specification Product range KV S-350 KV S-400 KV S-450 KV S-500 KV S-550 KV S-600
KVL-350 KVL-400 KVL-450 KVL-500 KVL-550 KVL-600
g) Basis for Selection of Kanai’s Card Clothing Specification • Cylinder Card Clothing Table 2.5.4.g (1)
Cylinder M.C.C.
• Doffer Card Clothing Table 2.5.4.g (2) Doffer M.C.C.
Textile Handbook 2-55
• Taker-in Card Clothing Table 2.5.4.g (3) Taker-in Wire
Spinning Processes and Types of Yarn
• Top Wire Table 2.5.4.g (4)
Top Wire
h) Recommendation for Selection of Card Clothing Table 2.5.4.h (1) For Conventional Card Production: up to 25lbs/hr (Cyl.:180-250rpm) Tops Staple range Micronaire Cyl. Dof. Ta-in Range Short Cotton 7/8" - 15/16" 4.9-5.9 CC58-NPI DU39.5 TC45KH VS-400 Dirty 4..0-4.4 M e d i u m 1"-1 1/8" CC65-NPI DU39-5 TC45KH VS-450 Cotton Clean 3.0-3.9 Long Cotton 1 3/16"CC69-NPK DU39-5 TC50KH VS-450 Fine 1 1/2" Material
2-56
Spinning Processes and Types of Yarn Table 2.5.4.h (2) For Semi Hi-Speed Card
Production: up to 70lbs/hr (Cyl.:250-300rpm) Tops Staple range Micronaire Cyl. Dof. Ta-in Range Short Cotton 7/8" - 15/16" 4.9-5.9 CC65-NPI DU39.5 TC50KH VS-400 Dirty M e d i u m 1"-1 1/8" 4..0-4.4 CC73-NPI DU39-5 TC50KH VS-450 Cotton Clean Long Cotton 1 3/16"-1 1/2" 3.0-3.9 CC73-NPK DU39-5 TC50KH VS-450 Fine
Material
Table 2.5.4.h (3) For High-speed Card
Production: up to 70lbs/hr (Cyl.:300-650 rpm) Tops Staple range Micronaire Cyl. Dof. Ta-in Range Short Cotton 7/8" - 15/16" 4.9-5.9 CC73-NPI DU360IH TC50KH VS-400 Dirty 4..0-4.4 CC86-NPI DU360IH TC50KH VS-450 M e d i u m 1"-1 1/8" Cotton Clean Long Cotton 1 3/16"-1 1/2" 3.0-3.9 CC86-NPK DU360IH TC50KH VS-450 Fine Material
Table 2.5.4.h (4) For Tandem Card (OE Spinning) Use Breaker Production: Up to Finisher 70 lbs Production: Over 70 lbs Table 2.5.4.h (5) Use Breaker
Cyl.
Dof.
Ta-in.
Tops.
CC30-P01
DC360IH
TC45KH
VS-350
DC360IH
TC45KH
VS-400
CC73-NPD CC86-NPD
For Tandem Card (Ring Spinning) Cyl. CC39-P
Production: Up to CC73-NPD 70 lbs Finisher Production: Over CC86-NPD 70 lbs
Dof.
Ta-in.
Tops.
DC360IH
TC45KH
VS-400
DC360IH
TC45KH
VS-450
Textile Handbook 2-57
2.6 The Trumpet • The bore of the trumpet controls the amount of condensation of the sliver. For every weight of sliver, there is a corresponding bore for the trumpet. • The coiler trumpet should be 1.12 times the trumpet diameter. • Certain long staple, low micronaire cotton may require an even larger hole than recommended because of coring (the tendency to form core/ sheath geometry).
Table 2.6
Trumpet Size to be Used
Grain Sliver 40 45 50 55 60 65 70
Diameter Trumpet Hole Recommended Minimum 0.160 0.175 0.185 0.190 0.200 0.210 0.220
0.140 0.150 0.160 0.167 0.175 0.182 0.190
Note: the above does not apply to a card equipped with an autolevelling device.
Spinning Processes and Types of Yarn
• Sizing of the trumpet should be done with a tapered reamer. Check with standard trumpet gauge from discharge end of trumpet.
2-58
Spinning Processes and Types of Yarn
2.7 Card Setting Recommendations 2.7.1 Conventional Revolving Flat Card Figure 2.7.1
Setting points for revolving flat card
3
Setting Points 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Feed Roll to Plate Feed Plate to Licker-in Licker-in to Cylinder Back Plate Top Bottom Flats Back Intermediate Intermediate Intermediate Front Front Plate Top Bottom Doffer to Cylinder Take Off Roll Top To Doffer Bottom
Max.
Min.
.005 .029 .010 .034 .034 .034 .034 .034 .034 .034
.003 .010 .007 .022 .022 .007 .007 .007 .007 .007
.064 .064 .007 .080 .100
.022 .022 .003 .034 .054
Textile Handbook 2-59
16 17 18 19 20 21 22 23 24
Calender Roll Screen
Front Middle Back Basket to Licker-in Nose to Licker-in Trumpet Card Hole Diameter Coiler Arch to Cylinder (Not Shown)
.015 .250 .062 .029 .034 .125 .250 .250 .034
.003 .125 .029 .017 .017 .034 .150 .150 .015
2.7.2 Rieter C51 Card Cotton and blends (With TREXplus). Basic settings
Figure 2.7.2 Cotton and blends (with TREXplus). Basic settings
Spinning Processes and Types of Yarn
Note: Setting expressed in inches
2-60
Spinning Processes and Types of Yarn
2.7.3 Truetzschler DK-803 Card Figure 2.7.3
(1) & (2) Truetzschler DK-803 Card
Textile Handbook 2-61
2.8 Grinding 2.8.1 Grinding Intervals
An example of re-sharpening intervals for Graf HP-clothings and flexible flat clothings are shown in table 2.8.1. Table 2.8.1
Intervals for Graf HP - Clothings
Finished product / Yarn
1st re2nd resharpening sharpening interval interval
3rd resharpening interval
4th resharpening interval
Combed Yarn
90 t
170 t
240 t
300 t
350 t
Carded Yarn
100 t
190 t
280 t
350 t
400 t
OE Yarn
130 t
250 t
340 t
430 t
500 t
Replacement
Note: t=ton
The recommended guide values may vary in either direction, depending on quality requirements and contents of trash and sand. If Graf CUTTY-SHARP clothing is used, the re-sharpening intervals (with TSG) and therefore the lifetime of the clothings, is extended by approximately 30%.
2.8.2 Rieter Integrated Grinding System (IGS) a) Rieter IGS is an automatic grinding device permanently mounted on the cylinder and top flats. IGS classic features a grindstone which moves across the cylinder clothing under automatic control during production. This process is performed 400 times during the planned life cycle of the clothing, and not only every 80 to 100 times, as is the case with manual grinding.
Spinning Processes and Types of Yarn
The grinding intervals may vary depending on yarn-count and required quality standard. For highest quality requirements for fine yarn counts, it has proven most efficient to determine the re-sharpening intervals on the basis of the maximum permissible number of neps (standard to be set by each mill individually). In case of preventive re-sharpening service, the intervals need to be calculated.
2-62
Spinning Processes and Types of Yarn Figure 2.8.2 a (1) IGS- classic
IGS-Top is installed permanently over the returning flats after the flats cleaning unit. More than 100 grinding cycles per clothing life cycle are performed automatically during production. The flats rod are raised one after the other by spring force and pressed against the rotating grinding brush. Short, hard bristles grind the points of the flats pins. Longer, softer bristles keep the lateral edges sharp.
Textile Handbook 2-63 Figure 2.8.2a (2) IGS-Top
b) Operating principle The IGS consists of an aluminum profiled section that serves as support, and a grindstone following a linear path and stabilized by spring pressure. The parameters needed for the grinding operation can be entered while programming the card. The program calculates the grinding schedule by distributing the prescribed 400 grinding cycles in an optimal curve over the useful life of the clothing. (One movement of the grindstone to and fro = 1 cycle)
Spinning Processes and Types of Yarn
Figure 2.8.2a(3) Quality Improvement with IGS
2-64
Spinning Processes and Types of Yarn Figure 2.8.2b (1)
Mounting the grinding apparatus
-
The drive and connections must be on the right-hand side of the machine.
-
Place the grinding apparatus (2) underneath the machine, Hold it up evenly on both sides and insert the screws (1) (M8x50).
-
Attach the covers to the fastening points.
-
Connect the pneumatic hose and insert the electric plug.
-
Each time the apparatus (2) is mounted and dismantled, it must be tested.
c) Useful life of the grindstone Default setting ex works is 450 tons. This corresponds with the recommendations of the wire suppliers. This value can be altered according to the experience in the mill. Depending on the programmed value the optimal grinding plan, with the respective grinding cycles, will be calculated.
Textile Handbook 2-65
The program can show: 60.1 Production since the last grinding of IGS cylinder xxxt
60.2 Production since last reclothing of cylinder xxxt
The display shows the amount produced since the last grinding cycle. The display shows the amount produced since the last change of clothing.
60.8 Next IGS cycle on Grinding cycles:yyy Budget:zz zzz
xxxt
Budget: The total number of grinding cycles available. Grinding cycles already completed. After changing the clothing reset the data screens 60.1, 60.2 and 60.8 to <<0>>.
d) Changing the prescribed amount of production per clothing The amount to be produced with a clothing before it needs changing can be altered at any time. The program then calculates the number of grinding cycles remaining on the basis of this new input. For example : The new value is increased by more than 50%, e.g. from 400 t to 600 t, the grindstone must be changed.
e) Replacing the grindstone After using the drum clothing, the grindstone must be replaced. This is essential to guarantee the optimal sharpening of the teeth on the new clothing.
Spinning Processes and Types of Yarn
The next grinding cycle takes place after the amount displayed.
2-66
Spinning Processes and Types of Yarn Figure 2.8.2.e
Fitting the grindstone
Fitting the grindstone: -
The bevelled edge (3) of the grindstone (2) must lie against the direction of rotation the drum.
-
Hold the grindstone (2) tight while tightening the screw (1). If it should move while the screw is being tightened, the diaphragm underneath might be damaged.
-
The screw (1) must be tightened as much as possible without twisting the grindstone (3).
2.9 New Features on Carding Machine 2.9.1 Precision Flat Setting System (Truetzschler) The precision flat setting system PFS is a new, patented system for setting the distance between the revolving flats and cylinder. The adjustment is made centrally. At each side of the card, an actuator is turned manually or by motor. That way, the distance of all flat bars in working position towards the cylinder is widened or reduced. In the case of a manual adjustment, a scale shows the actual setting in relation to the basic setting. In the case of an adjustment by motor, the position is chosen and shown on the display of the machine control.
Textile Handbook 2-67 Figure 2.9.1 (1) Manual adjustment
Adjustment by motor
2.9.2 Flat Distance Measuring System FLATCONTROL FCT is a system for measuring the distance between the main cylinder and flat. For the measurement, three normal flats are replaced by the FLATCONTROL measuring flat. The sensors of the measuring flat determine the distance to the cylinder clothing when the cylinder is running at normal operating speed. The microcomputer within the measuring flat stores all measuring values automatically. After a series of measurements the values are transferred to a portable PC and graphically represented.
Spinning Processes and Types of Yarn
Figure 2.9.1 (2)
2-68
Spinning Processes and Types of Yarn
2.9.3 Webclean System (Truetzschler) The Truetzschler WEBCLEAN system consists of 8 carding segments and 3 intensive cleaning units, 2 strips of carding segments are integrated into one compact cassette, the Twin Top. They all together form the Twin Top System TTS. The Twin Top cassettes need not be readjusted after dismantling. Each cleaning unit is made up of a mote knife with suction hood. These cleaning units separate smallest trash particles and seed coat fragments. Thorough dedusting is a side-effect of the permanent suction. Figure 2.9.3 WEBCLEAN system
1. Flat cleaning device 2. Revolving flat 3. Mote knives with suction hoods 4. Twin Top segments 5. Suction hoods 6. Cylinder cover 7. Doffer cover
Textile Handbook 2-69
2.9.4 On-line Nep Counting (Truetzschler) NEPCONTROL NCT is to monitor the card slivers for their nep level during running production.
- temporary checking with one NEPCONTROL NCT for a group of cards - permanent checking with one NEPCONTROL NCT at each card
Figure 2.9.4 On-line Nep counting
Spinning Processes and Types of Yarn
An electronic camera films the web under the take-off roll. The camera moves along the whole working width of the card in a special, fully closed profile. The pictures are evaluated regarding neps and trash particles by a computer directly flanged to the profile. This measuring principle largely follows the visual web inspection. NEPCONTROL NCT can be used basically in two different ways:
2-70
Spinning Processes and Types of Yarn
2.9.5 TREXplus (Rieter) The TREXplus which is available as an option for cotton applications is a further development of the TREX-System Five carding units and a guiding element separate trash, dust and short fibres in the precarding zone so that these can be transported away from the associated mote knife into the extraction system. In the post-carding zone the remaining, tiny trash and dust particles are removed from the carding process by a combination of five carding elements, one guiding element and two mote knives. The selective removal of impurities in the cotton is evident right up to the yarn. Comparisons have shown that thin places, thick places and neps are clearly reduced by the TREXplus without having to pay for this with an excessive waste level.
Textile Handbook 2-71 Figure 2.9.5 TREXplus
The origins of Tandem carding in the 1960’s were for the production of high-quality ring spun yarn. The benefits of Tandem carding include higher cleaning efficiency, higher nep reduction, a greater degree of fibre individualisation and “parallelisation”, better fibre blending, and the use of lower grade (and therefore less expensive) raw materials to produce high quality yarns. In the case of rotor spinning, Tandem carding was found to increase the productivity of rotor spinners and the quality of rotor yarn due to the factors mentioned above. The additional benefit of the very low level of micro-dust in Tandem carded sliver has the effect of reducing rotor trash accumulation and therefore reducing end-break rates and rotor cleaning frequency. However, a Tandem card is more difficult to maintain than a single card due to its relative complexity, particularly in the centre-section.
2.10.1 The New Twin Cylinder Card-Crosrol CST The CST has the following specific features: • Web transfer from the breaker to finisher cylinders by direct stripping of the breaker doffer by the finisher taker-in.
Spinning Processes and Types of Yarn
2.10 Tandem Card
2-72
Spinning Processes and Types of Yarn
• Maintenance access to all four sides of both the breaker and finisher sections is achieved by integral built-in motorised separation with the feed chute remaining in situ Figure 2.10.1
Crosrol CST
2.10.2 Technical Specification Production rates: up to 100kg/hr (220lb/hr) Speed Ranges: Taker-in (breaker) 660-1500 rpm Breaker Cylinder 425-770 rpm (typically 500 rpm) Finisher Cylinder 425-770 rpm (typically 640-770 rpm) Doffers 40-120 rpm Taker-in (finisher) 120 rpm Feed Rate: 340-930g/m(11-30oz/yd) Sliver weight: 3.5-7.0g/m(50-100grain/yd) Delivery speed: up to 350 m/min (380 yd/min) Lap width: 965 mm (38 in) Number of flats: Breaker 89 revolving 33 working, 8 stationary - cotton Finisher 89 revolving 36 working, 5 stationary - cotton
Textile Handbook 2-73
2.11 Production Calculations Production (in lbs./hr.) = rev. x in. x yd x min. x grains x lbs. grains in. hr. min min rev. 1 60 grains 1 = RPM x πD x x x x 36 1 yd. 7000 RPM x πD x GRAIN WT. = 4200 RPM x GRAIN WT. x 6.2832 4200 RPM x GRAIN WT. = 668.45 = RPM x GRAIN WT. x 0.0015 =
RPM x GRAIN WT. x 7.854 4200 RPM x GRAIN WT. = 534.75 = RPM x GRAIN WT. x 0.00187
Production (for 2 1/2” roller) =
RPM x GRAIN WT. x 9.4248 4200 RPM x GRAIN WT. = 445.6 = RPM x GRAIN WT. x 0.00224
Production (for 3” roller) =
Note: 1. D = Diameter of Calender Roll 2. Production at a Card of 3" Calender Roll = RPM x GRAIN WT. x 0.00224 x1.1 3. Production at a Card of 4" Calender Roll = RPM x GRAIN WT.x 0.003 x1.1
Spinning Processes and Types of Yarn
Production (for 2” roller)
2-74
Spinning Processes and Types of Yarn
2.12 Conversion of Grain Weight and Sliver Count gr/yd Ne
tex
gr/yd Ne
tex
gr/yd Ne
tex
30 31 32 33 34 35
.278 .269 .260 .252 .245 .238
2126 2197 2268 2339 2409 2480
54 55 56 57 58 59
.154 .151 .149 .146 .144 .141
3827 3898 3968 4039 4110 4181
78 79 80 81 82 83
.107 .105 .104 .103 .102 .100
5527 5598 5669 5740 5811 5882
36 37 38 39 40 41
.232 .225 .219 .214 .208 .203
2551 2622 2693 2764 2836 2905
60 61 62 63 64 65
.139 .137 .134 .132 .130 .128
4252 4322 4394 4464 4535 4606
84 85 86 87 88 89
.009 .098 .097 .096 .095 .094
5953 6024 6094 6165 6236 6307
42 43 44 45 46 47
.198 .194 .189 .185 .181 .177
2976 3047 3118 3189 3260 3331
66 67 68 69 70 71
.126 .124 .122 .121 .119 .117
4677 4748 4819 4890 4960 5031
90 91 92 93 94 95
.093 .092 .091 .090 .089 .088
6378 6449 6520 6590 6661 6732
48 49 50 51 52 53
.174 .170 .167 .163 .160 .157
3402 3472 3543 3614 3685 3756
72 73 74 75 76 77
.116 .114 .113 .111 .110 .108
5102 5173 5244 5315 5386 5457
96 97 98 99 100 ......
.087 .086 .085 .094 .083 .....
6803 6874 6945 7016 7096 .....
Note : • tex =70.865 x gr/yd • Ne = 8.333 ÷ gr/yd
2.13 Nep Counting 2.13.1 Three Different Ways of Nep Counting • Use a 6" x 6" blackboard or glass plate to collect card web and then count the number of neps per 100 in2. • Use a template which has 34 holes, each hole is 1 in2 in area. Count the number of holes that has neps and estimate the neps per 100 in2 by using the following table.
Textile Handbook 2-75 Table 2.13 (1)
Nep Estimation
Number of holes Number of neps Number of holes that have neps that have neps per 100 in2 3 6 9 12 16 19 23 27 31 35 39 44 48 53 58 64 •
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
69 75 82 89 96 104 113 122 133 144 158 173 192 214 243 283
Take 1 gram or 10 grains of cotton web card and count the actual number of neps per gram (or grain) over a black velvet.
2.13.2 Nep Content of Card Web (Source: Textile Institute)
For convenience in comparing the behaviour of cards of different widths producing slivers of different linear density, use is commonly made of the nep count, N. The nep count is defined as the number of neps per 100 in2 of card web forming a sliver of standard hank 0.12 (4.92 ktex) on a card 40 in wide. It may be calculated from N = n x sliver hank X card width (in) 0.12 40 = 0.21 x n x sliver hank x card width (in) = 0.123 x n x card width (in) sliver linear density (ktex) where n = neps per 100 in2 of card web. neps per gram = 0.67 x n x sliver hank x card width in inches. neps per square metre of web = 15.5n.
Spinning Processes and Types of Yarn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Number of neps per 100 in2
2-76
Spinning Processes and Types of Yarn Table 2.13.2 Standard of Neps Content Grading Excellent Good Fair Poor
Neps per 100 in2 15 16-30 31-45 Above 46
Neps per gram 70 70-130 131-200 200
2.14 Uster AFIS N Application for Cotton Card Maintenance There are two ways to monitor neps in card slivers. One is to use the actual nep count per gram, another is to use card nep removal efficiency. Removal efficiency is calculated using the following formula:
% Removal Efficiency
=
(Neps in card mat) - (Neps in card sliver) x100 Neps in card mat
Neps in card mat are the neps in samples taken from cotton going into the back of the card either in lap or mat form. Neps in card sliver are the neps in samples of cotton sliver taken from the sliver can at the front of the card. Calculating the nep removal efficiency is a good way to analyze an individual card. The efficiency calculation is also very useful in comparing carding elements such as different card wire, card flats, or licker-in cylinders. This efficiency calculation is ideal for evaluating a new design of card cylinder wire. Two cards can be rebuilt, one using new wire of the old design and one using wire of the new design. These two cards can be compared for a 30 day period to determine which wire is best for the mill’s own quality requirements. This same procedure can be used to evaluate card flat wire, licker-in cylinders, and main cylinder and flat speeds.
Textile Handbook 2-77
2.15 Maintenance Recommendations 2.15.1 Lubrication Schedule The following points of a high production card should be lubricated with a good grade of low detergent oil every eight hours, as applicable, or according to manufacturer’s recommendations: • Doffer drive
• Roller chain The following points should be greased each maintenance cycle or according to manufacturer’s recommendations: • Web tension and drive gears • Coiler drive gears • Calender roll gears Units equipped with central lubrication systems are to be cycled once every eight hours of operation. Note: • Caution: Keep oil clean when filling reservoir. • Check oil flow each time maintenance requires tubing disconnection. Bleed air from line if needed. Doffer, cylinder, and Licker-in bearings should be lubricated according to manufacturer’s recommendations.
2.15.2 Cleaning Procedures For High Production Carding Equipment a) The following procedures should be completed once every 24 hours: • Cut feed out, lock stop motion in place, and leave the doffer running on 4 to 5 cards. • Pull motes and under card fly if not equipped with automatic cleaning.
Spinning Processes and Types of Yarn
• Web tension gears driving calender section
2-78
Spinning Processes and Types of Yarn
• Remove or open the following: - Back door - Side doors - Front door - Release pressure on scraper blades • Flat strip roll • Blow the following points in approximate order listed: - Four arch points where chokes sometime form - Each end of doffer shaft between shrouds and doffer ends - Under cards, from front to back - Screens, dislodging any fly accumulation on ribs - If possible, remove top clearer on calender roll and blow accumulation between rolls and trumpet - Open coiler cover and clean - Outside of card, blowing the four arch points last • Replace all covers, etc., reapply pressure to scraper blades, and put card back into production. In addition to the above, the cards should be mopped or wiped on the outside once a shift.
b) 600-Hour Maintenance Schedule The following maintenance items should be performed every 600 operating hours: • Run cotton out of card. • Clean card completely. • Run flats out — strip cylinder and doffer. • Stop card.
Textile Handbook 2-79
• Remove guard and covers. • Clean gears, sprockets, chain, and pulleys. • Check gears for wear and proper mesh. • Check sprockets for wear and proper alignment. • Check chain for wear and proper tension. • Check web roll scraper blades for wear or damage.
• Check all set points on card. • Grease or oil all lubricating points. • Clean all air cleaning equipment. • Tighten all adjustment screws. • Clean and replace all guards and covers. • Start card without cotton - check for any rubbing. • Check card drive for alignment. • Put cotton in card. • Check seating of scraper blade on web rolls. • Check card stop motions.
Spinning Processes and Types of Yarn
• Check condition of wire, cylinder, doffer, Licker-in and flats.
2-80
Spinning Processes and Types of Yarn
2.16 Troubleshooting Table 2.16 Carding Problems 2.16.1 Cylinder Loading Probable Cause 1. Contaminated stock.
Solution 1. Check opening and picking for contamination. 2. Flats set too close to cylinder. 2. Try more open flat setting. 3. Doffer not set close enough to cylinder. 3. Set doffer to cylinder on 0.005" to 0.007". 4. Back plate too close to cylinder. 4. Try more open plate setting. 5. Damaged clothing. 5. Grind, brush, or recloth. 6. Licker-in jerk in. 6. Check feed roll setting to feed plate. This setting should not exceed 0.005". 2.16.2 Licker-in Loading 1. Damaged Licker-in wire. 1. Replace Licker-in. 2. Contaminated stock. 2. Check opening and picking for 3. Licker-in wire not suited for stock being contamination. run. 3. Consult wire manufacturer. 4. Licker-in not set close enough to 4. Reset Licker-in on 0.007" to cylinder. cylinder.
2.16.3 Doffer Loading 1. Damaged wire.
1. Grind, brush, or recloth, depending on degree of damage. 2. Take-off unit improperly set. 2. Adjust take-off unit to manufacturer’s specifications. 3. Licker-in jerk in. 3. Check feed roll to feed plate. 4. Improper procedure for putting end up 4. Moisten crush roll as soon as stock starts on card. through the card. 2.16.4 Flats Loading 1. Damaged wire. 2. Improper setting of flat comb.
1. Grind, brush, or replace clothing 2. Make proper comb setting.
2.16.5 Losing Fibre off the Doffer to the Main Cylinder 1. Nose of front cylinder screen too long 1. Replace with proper length front screen. include in previous pages E1 for staple length stock being run. 2. Nose of front screen set too close to 2. Try more open setting on front of screen. cylinder. 3. Blunt doffer wire. 3. Grind doffer. 2.16.6 Heater Controls Overloaded. Drive Kicking Out on Start-Up 1. Belt too tight. 1. Adjust motor. 2. Cylinder rubbing arches. 2. Adjust arches to cylinder on 0.022" when possible.
Textile Handbook 2-81 2.16.7 Heater controls Overload on Drive, Kicking Out After Running For 1 Hour. 1. Cylinder loaded with fiber.
1. Cut feed out. Let cylinder clean out.Brush cylinder if necessary. 2. Install correct heaters.
2. Heater in control box too low. 2.16.8 Drive Belt Not Slipping on Start-Up 1. Drive belt too tight. 1. Adjust drive motor. 2. Belt dressing on belt. 2. Clean belt with cleaning fluid. (Belt should slip on cylinder pulley for 50 to 120 seconds during starting up of card.) 1. Motor mounting bracket not adjusted 1. Line and level motor bracket. properly. 2. Adjust timing pulley and main cylinder 2. Timing pulley out of adjustment. pulley. 3. Main cylinder pulley out of round. 3. Replace main cylinder pulley or turn pulley in lathe until pulley is round and true. (It is not necessary to crown the pulley.) 2.16.10 Drive Pulley Slipping in Timing Belt 1. Drive belt too loose. 1. Adjust belt tension. (Belt should slip on large cylinder pulley for 50 to 120 seconds during start-up of card. 2.16.11 Doffer Bearing Getting Hot 1. Doffer bearings not aligned. 2. Bad bearing.
1. Remove bearing caps and realign bearings. 2. Replace bearing.
2.16.12 Crush Roll Fusing Synthetic Fibre in Blends 1. Too much pressure on crush rolls
1. Pressure should be adjusted to a lower degree until the problem is eliminated.
2.16.13 Rolls Not Crushing Trash in Card Web 1. Not enough pressure between crush rolls 2. Pressure on crush rolls not being distributed evenly.
1. Adjust roll pressure according to manufacturer’s specifications. 2. Align crush rolls according to manufacturer’s specifications.
2.16.14 End Down 1. Scraper blade tagging. 2. Take-off rolls and crush rolls not set properly. 3. Draft gear not deep enough in mesh.
1. Inspect scraper blade for proper setting. Replace worn blades. 2. Set take-off rolls and crush rolls to manufacturer’s specifications. 3. Set draft gear properly.
Spinning Processes and Types of Yarn
2.16.9 Drive Belt Running Off Main Cylinder. Pulley on Start-Up
2-82
Spinning Processes and Types of Yarn 4. Web tension not correct. 5. Sliver tension from calendar roll to coiler. 6. Trumpet bore too small. 7. Doffer or cylinder loading. 8. Fiber build-up on nose of front screen. 9. Tagging under doffer cleaning hood. 10. Improper front bottom plate setting. 11. Card not properly cleaned. 12. Bad lap or batt selvage. 13. Lap or batt guides not set properly. 14. Feed roll not set properly to feed plate. 15. Split lap on lap-fed cards. 16. Calender rolls set too open. 17. Temperature and humidity. 18. Feeder and lap weight variation. 2.16.15 Neps 1. Dull or damaged doffer, cylinder, Licker-in and flat wire. 2. Cylinder loading. 3. Flats loading. 4. Plates and screens not set properly.
4. Change web tension gear to desired tension. 5. Change sliver tension gear or sprocket for best results. 6. Ream trumpet at calendar rolls and in coiler according to sliver weight. 7. Refer to problems A and C. 8. Remove screen from card, clean, deburr, or replace if damaged. Install and reset. 9. Remove hood, clean, inspect for burrs and replace. 10. Set front bottom plate to manufacturer’s specifications. 11. Card should be cleaned as instructed by manufacturer. 12. Check pickers or card feeders. 13. Re-set lap or batt guides. 14. Check feed roll bearings for wear and set feed roll to feed plate on 0.005". 15. Correct lap on card and check pickers. 16. Set calendar rolls according to sliver weight being produced. 17. Maintain proper temperature (75o to 85oF) and humidity (40% to 60%). 18. Check feeder and pickers. 1. Grind or replace wire.
2. Refer to problem A. 3. Refer to problem D. 4. Reset plates and screens to manufacturer’s specifications. 5. Licker-in to cylinder improperly set. 5. Set Licker-in to cylinder on 0.007". 6. Set flats to cylinder to manufacturer’s 6. Flats to cylinder improperly set. specifications. (For 100% cotton, set flats to cylinder on 0.010" from front to rear.) 7. Set doffer to cylinder from 0.005" to 7. Doffer to cylinder improperly set. 0.007". 8. Feed plate to Licker-in improperly set. 8. Set feed plate to Licker-in to mill’s standards. 9. Blend minimum amount of reworkable 9. Too much reworkable waste being waste with stock. processed. 10. Improper speeds on cylinder, Licker- 10. Adjust speeds according to production and stock being processed. in and flats. 2.16.16 Unevenness 1. Web and sliver tension. 2. Gears and chains not set properly.
1. Change web and sliver tension for best results. 2. Reset gears and chains to proper adjustment; replace if worn.
Textile Handbook 2-83 3. Uneven feeder batt or picker lap. 4. Feed roll not set properly. 5. Damaged clothing. 2.16.17 Improper % of Flat Strip 1. Top front plate out of adjustment. 2. Flexible bends out of adjustment. 3. Flat speed incorrect.
3. Check card feeder and picker. 4. Refer to problem 2.16.14 (14) 5. Refer to problems 1, 2, 3, and 4. 1. Set top front plate to proper setting. 2. Set flexible bends to flat pulleys to standard setting. 3. Change flat drive pulley to desired speed.
2.16.18 Improper % of Undercard Mote or Fly Waste 1. Reset screen. 2. Reset fibre retriever or mote knife. 3. Clean out plenum and pipe. 4. Reset plenum to feed roll to manufacturer’s specifications.
2.16.19 Coring of Sliver 1. Trumpet bore too small. 2. Too much pressure on calender rolls.
1. Ream trumpet according to grain weight of sliver. Refer to trumpet hole chart. 2.Adjust calender roll pressure to manufacturer’s specifications. Note: Coiler trumpet should be 0.010" larger than calender roll trumpet.
2.16.20 Uneven Selvage on Card Web 1. Choke on the nose of the front screen. 2. Lap or batt guides improperly set. 3. Bad picker lap or feeder batt selvage.
1. Clean and reset front screen. 2. Reset lap or batt guides. 3. Check pickers or feeders.
2.16.21 Stop Motion Failure to Operate 1. Stop motion not set properly. 2. Sliver wand fails to fall. 3. Sliver wand fails to latch.
1. Set stop motion as instructed by manufacturer. 2. Clean and lubricate bearing. Reset balance weight. 3. Reset the latch assembly as instructed by manufacturer.
2.16.22 Improper Web Tension 1. Improper web tension gear or sprocket. 1. Install proper tension gear or sprocket. 2. Improper calendar roll pressure. 2. Adjust calender roll pressure to manufacturer’s specifications. 3. Improper bore in calendar roll trumpet. 3. Ream calender roll trumpet according to the grain weight of sliver. (Refer to trumpet hole chart). 4. Humidity or temperature. 4. Adjust temperature to minimum 75oF, maximum 85oF. Adjust humidity to minimum 40%, maximum 60%.
Spinning Processes and Types of Yarn
1. Screen not set properly. 2. Fiber retriever or mote knife not set properly. 3. Licker-in plenum or pipe plugged. 4. Plenum improperly set to feed roll.
2-84
Spinning Processes and Types of Yarn 2.16.23 Improper Sliver Tension 1. Improper coiler tension gear or sprocket. 1. Refer to solution (2.16.16). 2.16.24 Holes in Web 1. Doffer wire loaded with trash. 2. Damaged wire on doffer or cylinder.
1. Clean doffer wire. 2. Recloth as needed.
2.16.25 Lap Jerking in at Feed Roll 1. Feed roll not set properly. 2. Feed roll bearings worn, allowing feed roll to raise up.
1. Set feed roll to feed plate on 0.005". 2. Install new feed roll bearing.
2.16.26 Belts Slipping from Cylinder to Licker-in and from Licker-in to Doffer 1. Belt too loose. 2. Bad bearing on Licker-in, doffer, calender roll or coiler. 3. Licker-in choked.
1. Replace belt and maintain 2% tension. 2. Locate bad bearing and replace. 3. Unchoke Licker-in.
Section 3 - Drawing Process ....................................... 2-85 3.1
Purpose of Drawing ........................................................... 2-85
3.2
Definition of Draft .............................................................. 2-85 3.3.1
3.3
Technological Main Draft Roll Settings ....................... 2-87
Drafting Zone Setting ........................................................ 2-87 3.3.2 3.3.3 3.3.4
Technological Break Draft Roll Setting ....................... 2-88 Draft Rolls Setting ........................................................ 2-89 Examples for Drafting System Setting of Rieters Draw Frame .................................................................. 2-91
3.4
Trumpet .............................................................................. 2-92
3.5
Sliver Can ........................................................................... 2-93 3.5.1 3.5.3 3.5.2
3.6
Auto Levelling System ....................................................... 2-99 3.6.1
3.7
Order Specifications For Cans ..................................... 2-93 Sliver Can Information ................................................. 2-94 Specifications for Can’s Bottom With Casters ............. 2-94
Examples of some Auto Levelling Systems ................. 2-100
Recent Developments in Draw Frames ............................ 2-101 3.7.1 3.7.2 3.7.3
Integrated Draw Frame IDF ......................................... 2-101 CUBIcan Sliver Deposit System .................................. 2-103 Sliver Watch (Foreign Matter Detector) ....................... 2-103
3.8
Relationship between Sliver Weight and other Parameters .......................................................................... 2-105
3.9
Production Rate per Delivery Head of Draw Frame ...... 2-106
3.10 Front Roller Surface Speed in Relation to Production Rate ..................................................................................... 2-108 3.11 Relationship Between Sliver Weight and Production in Hanks and Pounds ......................................................... 2-109 3.12 Conversion of Sliver Weight to Sliver Count .................. 2-110 3.13 Maintenance of Draw Frame ............................................ 2-111 3.14 Possible Causes of Drawn Sliver Defects ......................... 2-113 Back to Table of Content
A
Textile Handbook 2-85
SECTION 3
DRAWING PROCESS
3.1 Purpose of Drawing
A
Recently there has been a steep increase in delivery speeds, practically up to 900 m/min. These high-speed frames use synthetic cots for the top rolls.
3.2 Definition of Draft Draft is the measure of the amount the sliver is reduced as it passes through the machine. The draft on draw frames may be determined by the ratio of weights fed and delivered, and the usual draft ranges from 5.5 to 10. It is measured by the reduction in the weight per yard of the processed slivers. The draft takes place in roller drafting zones. The fibres are held firmly between the top roller and bottom roll. If the rolls are rotating and the circumference speed increases from roller pair to roller pair in the direction of the fibre flow, the fibres are pulled apart or drafted. V = Total draft Vv = Break draft VH = Main draft.
Spinning Processes and Types of Yarn
The purposes of drawing are to improve the uniformity of the slivers and to straighten the fibres in the slivers. The improvement in uniformity is due to the doubling and drafting of six to ten slivers into one. The straightening of the fibres is accomplished by drawing fibres by each other. The straightening is important because it arranges the fibres more parallel to each other and to the direction of the strand. When the fibres are well straightened, the arrangement helps in producing uniform, strong and smooth yarn. It is customary today to use two drawing processes after carding and two drawing processes after combing. For certain qualities only one drawing is applied after combing.
2-86
Spinning Processes and Types of Yarn Figure 3.2
Break - and main draft
The total draft determines the sliver count/ weight delivered. Example: With the known data: - Sliver count/weight fed: Nm = 0.20 (approx. 70.5 grains/yard) - Doublings: 6 - Sliver count/weight delivered: Nm = 0.23 (approx. 61.3 grains/yard) The total draft can be calculated as follows: Sliver count delivered (Nm) x Doublings Sliver count fed (Nm) 0.23 x 6 = 6.9 = 0.2
V=
or V= =
Sliver weight (ktex) x Doublings Sliver weight delivered (ktex) 5.0 ktex x 6 = 6.9 4.35 ktex
Textile Handbook 2-87
3.3 Drafting Zone Setting
The drafting system of a draw frame consists of steel bottom rolls with fine flutes and top rolls covered with smooth resilient material. Mostly, draw frames use a two-zone drafting system, which can be three over three, three over four, four over four, three over five or four over five. The setting of the drafting zone depends on: Influencing variable:
Determines:
Fibre length and fibre denier
Draft roll setting, draft, delivery speed and tension drafts
Sliver preparation carded, combed, drawn once or drawn twice
Draft roll setting, break draft and tension draft
Sliver weight fed, doublings, and sliver weight delivered
Draft
The quality of the slivers fed significantly influences the performance of the drawframe
3.3.1 Technological Main Draft Roll Settings a) Setting of Main Draft Zone The setting of main draft zone is affected by the staple length of the material being processed. A good manual staple diagram is sufficient to obtain the required staple length, in case no accurate diagram is available.
Spinning Processes and Types of Yarn
The setting of a drawing frame must be adjusted to suit the length of the cotton being handled. Although the cotton fibres are not uniform in length, they are longer and shorter than the setting gauge, and the drawing rolls must control as many of the fibres as possible. The imperfect control of fibres in the drawing leads to unevenness in the slivers, producing irregularities commonly known as drafting waves. As more fibres are controlled in drawing, the magnitude of the drafting waves is reduced. The unevenness of the sliver in the drawing and roving frames can be improved by doubling.
2-88
Spinning Processes and Types of Yarn
As the manual staple diagram does not consider the maximum staples, one must add 2 to 3 mm. Figure 3.3.1 Cotton staple diagram
Lmax
= maximum staple length, manual staple diagram
Lmin
= Staple length at 2.5%, measured with HVI instrument b) Recommended Main Draft Roll Setting - Cotton: Maximum staple, minus up to 2 mm L2.5% less than 27 mm: Shortest main draft roll setting L2.5% more than 27 mm: Main draft roll setting = L2.5% +8 to +10 mm - Synthetics: staple length = 38 to 40 mm: Staple length +4 to +6 mm, depending on fibre cohesion c) Function of Main Drafting Zone To control the fibres means: Holding the amount of fibres without control (floating fibres) as low as possible, and avoiding any fibre damage (breaking fibres) by a roll setting too closed.
3.3.2 Technological Break Draft Roll Setting This setting depends on: Maximum and average staple length, degree of fibre parallelization, draft resistance and draft. A simple test for a sufficiently practical setting of the break draft roll distance is: To be able to barely bend the fibres in the break drafting zone with a 2 mm feeler gauge.
Textile Handbook 2-89
3.3.3 Draft Rolls Setting The gauges “a” and “b” for the corresponding roll-distances are listed in table 3.3.3(1). Shortest setting - Break draft zone 36 mm - Main draft zone 36.5 mm
Main drafting zone
Break drafting zone
Gauge
Bottom roll distance
Gauge
a 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 10.5 11.5 12.5 13.5 14.5 15.5 16.5 17.5 18.5 19.5 20.5 21.5 22.5 23.5 24.5 25.5 26.5
A 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
b 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58
Bottom roll distance B 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88
Note: The table lists the gauges and the corresponding roll distances. There is no relationship between the gauges for the main draft zone and the gauges for the break draft zone.
Spinning Processes and Types of Yarn
Table 3.3.3 (1) Draft Roll Setting
2-90
Spinning Processes and Types of Yarn Figure 3.3.3 (2) Draft roll setting
- Select gauge a for the main drafting zone. - Select gauge b for the predrafting zone and set the bottom roll (3) parallel to the middle bottom roll (2). - After the bearing blocks are fastened, the gauges a and b should move snuggly between the bottom rolls.
Textile Handbook 2-91
3.3.4 Examples for Drafting System Setting of Rieters Draw Frame Table 3.3.4
Examples for drafting system setting of Rieter’s Draw frame
Material
Cotton, waste Cotton, carded, with high amount of short fibres Peru Tanguis. Carded, (_) = 8 doublings
34
II RSB
4-6
4.5-6 4-6
1.16 37 (1.05)
I SB
6
5
5-5.5
1.28
37.5
39
II RSB
6
5
5-5.5
1.16
37.5
42
6-8
4.3
6-8
1.28
38
41
6(8)
4.3
6 (8)
1.16 38 (1.28)
45 (42)
Spin I RSB staple approx. II RSB 34, max. approx. 39 I RSB Cotton, combed 36 1 1 16 " II RSB
Macco, combed 38-39 Egyptian, spinlab 43 staple 2.5% = 34.6mm, 50%= 18.5mm, mean = 31.0mm B l e n d 5 0 % 38/39 cotton, combed 50% PES 1.7/ 40mm B l e n d 5 0 % 38 cotton, carded, 50% Modal viscose 1.3/38 mm Rayon 1.3/40 38 mm
37-38
6
4.2
7.1
1.16
38
44
8
4.2
9.5
1.28
38
42
I RSB
8
5.3
8
1.16
40
52
I RSB
8
4.2
8.3
1.16
44
52
II RSB
8
4.2
10.5
1.28
44
49
I/II SB
8
5
8
III RSB 8
5
8
I/II SB
8
4
8
1 . 4 1 / 43/44 48/52 1.28 1.28- 44 50 1.41 46 1.41 42
III RSB 8
4
8
1.28
41
48
I SB
8
4.9
9
1.41
45
52
II RSB
8
4.7
8.3
1.41
45
51
Spinning Processes and Types of Yarn
M a x . P ro c e s s Doubling Feed Total Break B o t t o m Staple drawing ktex draft draft roll setting length & Model Break Main mm draft zone zone 4.5-6 4-6 Intimate blend 38 I SB 4-6 1.16 37 37-38 65% cotton, 35% comber noil
2-92
Spinning Processes and Types of Yarn
Acryl 1.3/ 40mm, crimped
38
I SB
PES 1.9/ 38mm, crimped
37
Sewing thread PES 1.3/38mm
38
Acryl 3.3/ 60mm, crimped, dyed
53/54
4.6
6.8
1.70
44
48
II RSB 6
4
6.7
1.70
44
48
I SB
8
4.8
8.4
1.1
43
50
II RSB 8
4.6
8
1.28
43
50
6
3.8
6.4
1.70
44
50
II RSB 6
3.6
6.4
1.70
44
49
I SB
6
5.0
6
1.70
58
65
II RSB 6
5.0
8
1.70
58
65
I SB
6
3.4 Trumpet After leaving the front roll, the drawn sliver is condensed into sliver form by passing it through a trumpet and sliver guide. The small hole in the trumpet condenses the sliver more to give it strength and to make it possible to put a large quantity of fibre in the can. The trumpet diameter to accommodate a given sliver may be calculated as for card sliver, using the same equation but with different multipliers. Hole Diameter = Multiplier grain sliver Table 3.4 (1) Tex 2830 - 3190 3190 - 3540 3540 - 3780 3780 - 4130 4130 - 4720 4720 - 5310 5310 - 5900
Trumpet Diameters Of High Speed Draw Frame (1) Sliver Weight (gr/6yds) 240 - 270 270 - 300 300 - 320 320 - 350 350 - 400 400 - 450 450 - 500
Trumpet Diameter 1st passage 2nd passage 2.8 3.1 3.4 3.7 4.1 4.5 4.9
Note: • For combing sliver, select one lower number • For acrylic sliver select one bigger number
2.4 2.8 3.1 3.4 3.7 4.1 4.5
Textile Handbook 2-93 Table 3.4 (2)
Trumpet Diameters Of High Speed Draw Frame (2)
Tex
Sliver Weight (gr/6yds)
Trumpet Diameter (mm)
3680 below 3680 - 4250 4250 - 4670 4670 - 5450 5450 above
312 below 312 - 360 360 - 396 396 - 462 462 above
d=3.0 or 3.5 d=3.5 or 4.0 d=4.0 or I = 4.5 I=5.0 - 6.0 I=6.5 or 7.0
3.5.1 Order Specifications For Cans Figure 3.5.1
Specifications For Cans
A. Diameter of cans. B. Height of cans from the floor level to the top of cans. C. Whether the cans has its sliders or casters. D. If the casters are desired, a) Kind of caster (See the attached specifications for casters). b) Position of casters (Diameter of caster position) c) D-dimension shown in Figure 3.5.1. E. In case the handles are provided, specify the number of the handles and the dimension. F. Reinforcement for automatic can changer.
Spinning Processes and Types of Yarn
3.5 Sliver Can
2-94
Spinning Processes and Types of Yarn
3.5.2 Specifications for Can’s Bottom With Casters
Table 3.5.2 Specifications for Can’s Bottom With Casters No. 1 2 3 4 5
Name of caster D mm Ball caster 32 Single wheel caster 70 Single wheel caster 95 Double-wheel caster 54 Double-wheel caster 64
H mm 30 80 110 67 84
3.5.3 Sliver Can Information a) Cans with Casters Table 3.5.3a (1)
Specification of Can with Casters
Load/ caster kg 7 30 60 40 50
Textile Handbook 2-95
d = d1 = d2 = d3 = =
Spring Specification
• Piston may not protrude from the can, used on drawing frames, • The spring forces listed are approximations, They may vary depending upon material and process. Accurate values must be established with tests. • Spring forces mentioned are valid for springs without thread displacement (with displacement 0.1 ... 15%), • The Piston top must be made slip proof. • Example: Spring force for can Card: Fn1 Drawframe 1: Fn1 Comber: Fn0 Drawframe 2: Fn0
600 x 1200 for comber: = 320 N = 320 N = 400 N = 400 N
Spinning Processes and Types of Yarn
Figure 3.5.3.a (2)
up to 600: +3 from 800: +6 d + 15mm+0 -3 d-120mm (up to d=600) d-160mm (from d=700) d+30mm max d+15mm for d=470
2-96
Spinning Processes and Types of Yarn
b) Cans (with caster) Specification for Various Materials Table 3.5.3b Specifications of Cans (with casters) for Various Materials
mm od h 400 900 1000 900 445 1000 450 1070 1100 150 1200 1070 470 1100 1150 1200 900 1000 500 1070 1100 1150 1200 900 1000 600 1070 1100 1150 1200 1270 1300 800 1000 1070 1100 1150 1200 1270 1300 1000 1070 900 1100 1150 1200 1270 1300
Spring force ( ± 5% ) Can Inches Newton (N) 1N = 0.1kg od h h(mm) Fn0 Fn1 Fn2 Fn3 Fv 16
36 40 36 40 42 44 45 48
914 1016 914 1016 1067 1118 1143 1220
18 36 40 42 44 45 48 36 40 42 44 45 48 50
914 1016 1087 1118 1143 1220 914 1015 1067 1118 1143 1220 1270
32
40 42 44 45 48 50
1016 1057 1118 1143 1220 1270
36
40 42 44 45 48 50
1016 1057 1118 1143 1220 1270
20
24
115 135 140 160 165 175 185 195 185 195 2 00 210 200 210 220 230 240 245 285 310 315 330 340 355 380 385
80 95 90 105 110 115 120 125 120 125 130 135 155 165 170 175 185 195 240 245 255 265 275 280 295 300 335 350 360 370 385 405 415 385 420 430 445 460 475 485
70 90 80 90 95 100 105 110 105 110 115 120 130 140 150 155 165 175 205 245 225 235 240 245 255 260
57 75 70 80 85 90 90 95 90 95 100 105 120 125 130 130 135 145 175 185 195 200 205 210 220 225 245 255 265 270 275 285 290 300 310 315 385 335 350 355
Piston mm od4 h4
4.5
385
50
5.5
435
50
5.5
455
50
6
485
55
8
585
60
10
780
85
11
880
100
Textile Handbook 2-97 1000 1000 40 1070 1100 1150 1200 1270 1300
40 42 44 45 48 50
450 480 495 510 530 550 585
1016 1057 1118 1143 1220 1270
Spring force
= = = = =
12
Combed cotton Cotton and rayon Blend Synthetic Pretension force
c) Cans without Casters Fig 3.5.3 c(1)
Specification of Cans without Casters
d1 d3
= = =
d+15 mm (+0 or -3) d+30 mm (max) d+15 mm for d = 470
980
100
Spinning Processes and Types of Yarn
Fno Fn1 Fn2 Fn3 Fv
345 360 370 385 385 415 425
2-98
Spinning Processes and Types of Yarn Figure 3.5.3(2)
Spring Specification
• Piston may not protrude from the can, used on drawing frames. • The spring forces listed are approximations. They may vary depending upon material and process. Accurate values must be established with tests, • Spring forces mentioned are valid for springs without thread displacement (with displacement -10 .. 15%). • The piston top must be made slip proof, • Example: Spring force for can 500 x 1200 for comber: Comber: Fno = 310 N Drawframe 2: Fno = 310 N
d) Cans (without casters) Specification for Various Materials Table 3.5.3.d
mm od h 225 250 300 350
Cans (without casters) Specification for Various Materials
Can Spring force ( ± 5% ) Newton (N) 1N = 0.1kg Inches od h h(mm) Fn0 Fn1 Fn2 Fn3 Fv
900 9 900 10 900 1000 12
36 36 36 40
914 914 914 1016
35 45 55 65
30 35 45 55
22 27 36 45
Piston mm od4 h4
3 3
210 235
50 50
3
285
50
Textile Handbook 2-99
350
400
445 450
500
600
14
15
18
20
24
Spring force
36 40 42 36 40 42 44 45 48 36 40 42 44 45 48
36 40 42 44 45 48 36 40 42 44 45 48
914 1016 1067 914 1016 1067 1118 1143 1220 914 1016 1067 11181 1143 1220
914 1018 1067 1118 1143 1220 914 1018 1067 1118 1143 1220
Fno Fn1 Fn2 Fn3 Fv
130 140 150 155 160 170 165 185 200 205 210 220 215 225 235 240 205 230 245 250 265 276 290 315 335 345 355 370
80 90 95 90 95 1000 105 110 115 120 130 140 150 155 185 165 170 180 190 160 175 190 195 205 210 220 245 255 265 275 280
70 80 85 80 90 95 95 100 105 105 120 130 130 135 140 145 150 160 165 145 160 165 170 175 185 205 220 230 235 240 245
80 70 75 85 75 80 85 90 95 90 100 105 110 120 125 125 130 130 140 130 135 140 145 150 160 170 185 195 200 205 210
3.5
335
90
4.5
385
50
5.5
435
60
5.5
455
50
6
485
55
8
586
80
= Combed cotton = Cotton and rayon = Blend = Synthetic = Pretension force
3.6 Auto Levelling System Usually an electromechanical levelling system is provided at the finisher drawing to maintain or further improve the evenness of a drawn sliver. One way of detecting unevenness of the sliver is by a pair of tongue and groove rolls. In this case the detecting element is located before the drafting zone and therefore a memory has to be applied to vary the speed of the roll in the appropriate part of the draft system (Open Loop Control).
Spinning Processes and Types of Yarn
470
900 1000 1070 900 1000 1070 1100 1150 1200 900 1000 1070 1100 1150 1200 1070 1100 1150 1200 900 1000 1070 1100 1150 1200 900 1000 1070 1100 1150 1200
2-100
Spinning Processes and Types of Yarn
Another method is to use a condenser as a measuring head in the main drafting zone. The variation of the capacitance is used to correct the draft while the uneven sliver is still in the drafting zone (Closed Loop Control).
3.6.1 Examples of some Auto Levelling Systems a) Open Loop Control Figure 3.6.1a (1)
Open Loop Control of Rieter RSB 951
In the RSB 951, the arriving sliver mass is constantly scanned at a distance of 6 mm. This means that the scanning is independent of the speed of the arriving slivers. In this way, the sliver deviations can be recorded just as precisely for the highest delivery speeds as for slow sliver feeding.
Table 3.6.1a (2) Measurement of sliver thickness with different scanning principles
Textile Handbook 2-101
b) Sliver Auto-Levelling System (SAS) Figure 3.6.1b
Toyota Sliver Auto-Levelling System
• Programming is modified so that measured value becomes nearer to actual sliver thickness by sampling data every 1 mm instead of 10mm. • Inertia moment is reduced by lightening the weight of the control gears to improve follow up function. • Pressure on T&G Rollers is increased to improve the output efficiency.
3.7 Recent Developments in Draw Frames 3.7.1 Integrated Draw Frame IDF The integrated draw frame IDF combines the carding process and the drawing process to only one processing step.
Spinning Processes and Types of Yarn
• In order to make the Servo Motor RPM reach the target RPM more quickly, the disparity of actual RPM to target RPM is corrected by emitting a control signal to the Servo Motor every 1 milli-second.
2-102
Spinning Processes and Types of Yarn
An integrated draw frame IDF is placed in front of the card instead of a conventional can changer. This draw frame consists of the draw frame unit and a round can changer. Features of IDF: • 3 over 3 two-zone drafting system • Maintenance-free servo drives • High levelling dynamics through low mass inertia • Draft up to 300 %(3-fold) • Delivery speeds up to 500 m/min • Controlled material storage unit or can changing • Truetzschler sliver sensors in the feed and delivery areas • Permanent monitoring of the sliver quality The drafting system consists of components of the Truetzschler draw frame HSR 1000. The individual top rollers are pneumatically loaded. The distances of the drafting cylinders can be adjusted via a central adjustment unit. Figure 3.7.1
IDF Draw Frame of Truetzschler
Textile Handbook 2-103
3.7.2 CUBIcan Sliver Deposit System The CUBican® system provides fully automatic can handling between finisher drawframe RSB-D 30 and the rotor spinning machine.
Figure 3.7.2
CUBIcan® sliver Deposit of Rieter
3.7.3 Sliver Watch (Foreign Matter Detector) The Sliver Watch is installed in the creel of draw frames handling the first step drawing. The purpose is to stop the draw frame if a contaminated sliver is detected, so that the operator can eliminate the contamination, thus avoiding the second step drawing and spinning spreading the contamination over many meters of yarn. Sliver Watch can also detect sliver breakage and thick places in a sliver.
Spinning Processes and Types of Yarn
The full CUBIcan® is moved by CUBIcan® changer to an intermediate can storage with eight positions. The automatic guided vehicle SERVOcan, made by Rieter’s cooperation partner Elsenmann, collects up to four cans from the storage. The central computer sets the individual exchange of empty cans for full cans on first in/first out principle on the rotor spinning machine, The build-in ROBOfeed® on the robot of the rotor spinning machine feeds slivers into the spinbox fully automatically.
2-104
Spinning Processes and Types of Yarn
a) Principle of Sliver Watch • The sliver passes through a diffuse transparent guide. Transmitters or LED’s illuminate the sealed inside of the detector. • Receivers sense the amount of light in the spherical inside of the sensor • Foreign material absorbs a fraction of the light emitted by the LED’s; this increases the signal and allows the detection. • Light is absorbed from all angles, allowing an uninterrupted view of the contamination, regardless of its position in the sliver. • The shape of the sliver guide does not compress the sliver. Figure 3.7.3b
Sliver Watch of Barco
Textile Handbook 2-105
b) Settings • The length of the contamination is the main setting. • Minimum length setting, to avoid irrelevant stops. • Filter settings are available to detect short, intensive contaminants. • Sensitivity setting based on a scale from 1 to 25.
Table 3.8 (1) Drafting Factor capability of Drawing Frame
Relationsship between Sliver Weight and Other Parameters
Quality
Feed in sliver weight
Ya r n count
Delivery speed of Draw Frame
Number of Drawing Processing
Fine Coarse High Normal High Normal Heavy Light Extra Medium High Normal More Less fine Count Sliver Light Heavy Light Heavy Heavy Light Light Heavy Light Heavy Light Heavy weight
Table 3.8 (2)
Selection of Sliver Weight in accordance with Yarn Count
Final yarn count
Recommended sliver weight gr/6yd. g/5m
Tex
Ne
Above 32
Below 18
19-25
20-30 3-19
19-29
17-23
268-354 240-325
30-60
Below 9
Above 60
15-21 11-17
155-240
212-296
Spinning Processes and Types of Yarn
3.8 Relationship between Sliver Weight and other Parameters
2-106
Spinning Processes and Types of Yarn
3.9 Production Rate per Delivery Head of Draw Frame Table 3.9 (1)
Production Rate (lb/hr)
gr/yd m/min lb/hr
100 110 120 130 140 150 160 170 180 190 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900
30
35
28.12 30.93 33.74 36.55 39.36 42.18 44.99 47.80 50.61 53.43 56.24 70.30 84.36 98.42 112.48 126.54 140.60 154.66 168.72 182.78 196.84 210.90 224.96 239.02 253.09
32.80 36.08 39.36 42.65 45.93 49.21 52.49 55.77 59.05 62.33 65.61 82.102 98.42 114.82 131.23 147.63 164.04 180.44 196.84 213.25 229.65 246.06 262.46 278.86 295.27
40
45
50
55
60
65
70
75
37.49 42.18 46.86 51.55 56.24 60.92 65.61 70.30 41.24 46.40 51.55 56.71 61.86 67.02 72.17 77.33 44.99 50.61 56.24 61.86 67.49 73.11 78.74 84.36 48.74 54.83 60.93 67.02 73.11 79.20 85.30 91.39 52.49 59.05 65.61 72.17 78.73 85.30 91.86 98.42 56.24 63.27 70.30 77.33 84.36 91.39 98.42 105.45 59.99 67.49 74.98 82.48 89.98 97.48 104.98 112.48 63.74 71.70 79.67 87.64 95.61 103.57 111.54 119.51 67.49 75.92 84.36 92.79 101.23 109.67 118.10 126.54 71.24 80.14 89.05 97.95 106.86 115.76 124.67 133.57 74.98 84.36 93.73 103.11 112.48 121.85 131.23 140.60 93.73 105.43 117.17 128.88 140.60 152.32 164.04 175.75 112.48 126.54 140.60 154.66 168.72 182.78 196.84 210.90 131.23 147.63 164.04 180.44 196.84 213.25 229.65 246.06 149.97 168.72 187.47 206.22 224.96 243.71 262.46 281.21 168.72 189.81 210.90 231.99 253.09 274.18 295.27 316.36 187.47 210.90 234.34 257.77 281.21 304.64 328.08 351.51 206.22 231.99 257.77 283.55 309.33 335.11 360.88 386.66 224.96 25 3.0 281.21 309.33 337.45 365.57 393.69 421.81 243.71 274.18 304.64 335.11 365,57 396.03 426.50 456.96 262.46 295.27 328.08 360.88 393.69 426.50 459.31 492.12 281.21 316.36 351.51 386.66 421.81 456.96 492.12 527.27 299.95 337.45 374.94 412.44 449.93 487.43 524.92 562.42 318.70 358.54 398.38 438.22 478.05 517.89 557.73 597.57 337.45 379.63 421.81 463.99 506.18 548.36 590.54 632.72
Production rate = gr/yd x m/min x 1.0936 x 60 / 7000 = x lb/hr (efficiency= 100%)
Textile Handbook 2-107 Table 3.9 (2)
Tex m/min kg/hr
2000 2500
3000 3500 4000
12.0 13.2 14.4 15.6 16.8 18.0 19.2 20.4 21.6 22.8 24.0 30.0 36.0 42.0 48.0 54.0 60.0 66.0 72.0 78.0 84.0 90.0 96.0 102.0 108.0
18.0 19.8 21.6 23.4 25.2 27.0 28.8 30.6 32.4 34.2 36.0 45.0 54.0 63.0 72.0 81.0 90.0 99.0 108.0 117.0 126.0 135.0 144.0 153.0 162.0
15.0 16.5 18.0 19.5 21.0 22.5 24.0 25.5 27.0 28.5 30.0 37.5 45.0 52.5 60.0 67.5 75.0 82.5 90.0 97.5 105.0 112.5 120.0 127.5 135.0
21.0 23.1 25.2. 27.3 29.4 31.5 33.6 35.7 37.8 39.9 42.0 52.5 63.0 73.5 84.0 94.5 105.0 115.5 126.0 136.5 147.0 157.5 168.0 178.5 189.0
24.0 26.4 28.8 31.2 33.6 36.0 38.4 40.8 43.2 45.6 48.0 60.0 72.0 84.0 96.0 108.0 120.0 132.0 144.0 156.0 168.0 180.0 192.0 204.0 216.0
4500 5000
5500
30.0 33.0 36.0 39.0 42.0 45.0 48.0 51.0 54.0 57.0 60.0 75.0 90.0 105.0 120.0 135.0 150.0 165.0 180.0 195.0 210.0 225.0 240.0 255.0 270.0
33.0 36.3 39.6 42.9 46.2 49.5 52.8 56.1 59.4 62.7 66.0 82.5 99.0 115.5 132.0 148.5 165.0 181.5 198.0 214.5 231.0 247.5 264.0 280.5 297.0
27.0 29.7 32.4 35.1 37.8 40.5 43.2 45.9 48.6 51.3 54.0 67.5 81.0 94.5 108.0 121.5 135.0 148.5 162.0 175.5 189.0 202.5 216.0 229.5 243.0
Production Rate = Tex x m/min x 60 x 10-6 = kg/hr (efficiency = 100%)
Spinning Processes and Types of Yarn
100 110 120 130 140 150 160 170 180 190 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900
Production Rate (kg/hr.)
2-108
Spinning Processes and Types of Yarn
3.10 Front Roller Surface Speed in Relation to Production Rate Table 3.10 (1) Front Roller Surface Speed in Relation to Production Rate
Front Front Roller diameter (in) Roller Speed 1-1/8 1-3/16 1-1/4 1-5/16 1-3/8 1-7/16 1-1/2 1-9/16 1-5/8 rpm .05610 .05922 .11220 .11843 .16830 .17765 .22440 .23686 .28050 .29608 .33660 .35529 .39270 .41451 .44880 .47373 .50490 .53295
100 200 300 400 500 600 700 800 900
.06233 .06545 .12466 .13090 .18699 .19635 .24932 .26180 .31166 .32725 .37399 .39270 .43633 .45815 .49866 .52360 .56099 .58905
.06857 .13713 .20570 .24726 .34283 .41140 .47996 .54853 .61709
.07168 .14336 .21503 .28673 .35841 .43010 .50178 .57346 .64515
.0748 .1496 .2244 .2992 .3740 .4488 .5236 .5984 .6732
2
.07792 .08103 .15583 .16206 .23375 .24310 .31167 .32413 .38958 .40516 .46750 .48620 .54541 .56723 .62333 .64826 .70125 .72930
.09973 .19947 .29920 .39893 .49867 .59840 .69813 .79786 .89760
(unit : hanks/8 hrs) Table 3.10 (2)
Front Roller Speed rpm 100 200 300 400 500 600 700 800 900
Front Roller Diameter (mm)
Front Roller diameter (mm) 27
28
0.0530 0.1060 0.1590 0.2120 0.2650 0.3180 0.3710 0.4240 0.4770
0.0549 0.1099 0.1649 0.2198 0.2748 0.3298 0.3847 0.4397 0.4947
32 0.0628 0.1256 0.1884 0.2512 0.3141 0.3769 0.4397 0.5025 0.5654
(unit : hanks/8 hrs) Efficiency 100%
35
40
45
50
52
0.0687 0.1374 0.2061 0,2748 0.3435 0.4122 0.4809 0.5497 0.6184
0.0785 0.1570 0.2355 0.3141 0.3926 0.4711 0.5497 0.6282 0.7067
0.0883 0.1766 0.2650 0.3533 0.4417 0.5300 0.6184 0,7067 0.7951
0.0981 0.1963 0.2944 0.3926 0.4908 0.5889 0.6871 0.7853 0.8834
0.1020 0.2041 0.3062 0.4083 0.5104 0.6125 0.7146 0.8167 0.9188
Textile Handbook 2-109
3.11 Relationship Between Sliver Weight and Production in Hanks and Pounds Table 3.11 (1)
Relationship Between Sliver Weight and Production in Hanks and Pounds
gr./yd. Production Hanks rate
4.2 8.4 12.6 16.8 21.0 25.2 29.4 33.6 37.8
4.5 9.0 13.5 18.0 22.5 27.0 31.5 36.0 40.5
4.8 9.6 14.4 19.2 24.0 28.8 33.6 38.4 43.2
5.1 10.2 15.3 20.4 25.5 30.6 35.7 40.8 45.9
5.4 10.8 16.2 21.6 27.0 32.4 37.8 43.2 48.6
5.7 11.4 17.1 22.8 28.5 34.2 39.9 45.6 51.3
6.0 6.3 12.0 12.6 18.0 18.9 24.0 25.2 30.0 31.5 36.0 37.8 42.0 44.1 48.0 50.4 54.0 56.7
6.6 13.2 19.8 26.4 33.0 39.6 46.2 52.8 59.4
6.9 13.8 20.7 27.6 34.5 41.4 48.3 55.2 62.1
65 70 75
7.2 14.4 21.6 28.8 36.0 43.2 50.4 57.6 64.8
7.8 15.6 23.4 31.2 39.0 46.8 54.6 62.4 70.2
8.4 16.8 25.2 33.6 42.0 50.4 58.8 67.2 75.6
9.0 18.0 27.0 36.0 45.0 54.0 63.0 72.0 81.0
W(gr / yd) x 840 x Hank (hk) 7000 = W x hk x 0.12
Production =
Example: 60gr/yd Sliver produces 228 hk Productions in (Ibs): 200hk 2=14.4 x 100 =1440 Ib 200hk 2=14.4 x 100 =144 Ib 8hk 2=57.6 =57.6 Ib 228hk =1641.6 Ib Table 3.11 (2) Tex kg
Km
1 2 3 4 5 6 7 8 9
2000
2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 Production
Relationship between Sliver Weight and Production Capacity in Kilometres
2500
3000
3500
2.5 3.0 3.5 5.0 6.0 7.0 7.5 9.0 10.5 10.0 12.0 14.0 12.5 15.0 17.5 15.0 18.0 21.0 17.5 21.0 24.5 20.0 24.0 28.0 22.5 27.0 31.5 (kg) = Kilometre x Tex
4000
4500
5000
5500
4.0 8.0 12.0 16.0 20.0 24.0 28.0 32.0 36.0
4.5 9.0 13.5 18.0 22.5 27.0 31.5 36.0 40.5
5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0
5.5 11.0 16.5 22.0 27.5 33.0 38.5 44.0 49.5
x 10-3
Spinning Processes and Types of Yarn
1 2 3 4 5 6 7 8 9
35 37.5 40 42.5 45 37.5 50 52.5 55 57.5 60
2-110
Spinning Processes and Types of Yarn
3.12 Conversion of Sliver Weight to Sliver Count Table 3.12
Sliver British Weight (hank (gr/yd) gram)
Conversion of Sliver Weight to Sliver Count
Tex
30 1 2 3 4 5 6 7 8 9
0.278 0.269 0.260 0.252 0.245 0.238 0.232 0.225 0.219 0.214
2126 2197 2268 2339 2409 2480 2551 2622 2693 2764
40 1 2 3 4 5 6 7 8 9
0.208 0.203 0.198 0.194 0.189 0.185 0.181 0.177 0.174 0.170
2836 2905 2976 3047 3118 3189 3260 3331 3402 3742
50 1 2 3 4
0.167 0.163 0.160 0.157 0.154
3543 3614 3685 3756 3827
Sliver British Weight (hank (gr/yd) gram)
Tex
55 6 7 8 9
0.151 0.149 0.146 0.144 0.141
3898 3968 4039 4110 4181
60 1 2 3 4 5 6 7 8 9
0.139 0.137 0.134 0.132 0.130 0.128 0.126 0.124 0.122 0.121
4252 4322 4394 4464 4535 4606 4677 4748 4819 4890
70 1 2 3 4 5 6 7 8 9
0.119 0.117 0.116 0.114 0.113 0.111 0.110 0.108 0.107 0.105
4960 5031 5102 5173 5244 5315 5386 5457 5527 5598
Note: gr/ yd x 70.865 = Tex 8.33 = English Count gr / yd
Sliver British Weight (hank (gr/yd) gram)
Tex
80 1 2 3 4 5 6 7 8 9
0.104 0.103 0.102 0.100 0.099 0.098 0.097 0.096 0.095 0.094
5669 5740 5811 5882 5953 6024 6094 6165 6236 6307
90 1 2 3 4 5 6 7 8 9 100
0.093 0.092 0.091 0.090 0.089 0.088 0.087 0.086 0.085 0.084 0.083
6378 6449 6520 6590 6661 6732 6803 6874 6945 7016 7086
Textile Handbook 2-111
3.13 Maintenance of Draw Frame Table 3.13
Maintenance of Draw Frame
Inspection item
Inspection method
DH roller
1. Surface inspection No scratches on surface...........Excellent Some scratches, but have been repaired... Acceptable Have to be replaced..........Not acceptable
Acceptable range
3. Others Bottom roller 1. Flute surface inspection
Loose joint that can be taken out................ Not acceptable The corrosion and damage of flute producing poor quality............Not acceptable
2. Vibration, eccentric Within 0.13mm (0.005in)............Excellent and damage of roller 0.13-0.25mm (0.005-0.0100in)............... neck investigation Acceptable by using caliper Over 0.25mm (0.010in)..........Not acceptable 3. Others Trumpet
The joint can be easily pushed out.............. Not acceptable Within 0.40mm (1/64in)..............Excellent 1. Trumpet hole inspection by using Over 0.40mm (1/64in).............Not acceptable caliper 2. Shape, plating and Any shape or plating damage.................... damage inspection Not acceptable
S t o p p i n g Sliver cutting and Non-stop while sliver end reaches device and sensitivity inspection roller guide............................Not acceptable Sliver cut but non-stop...........Not acceptable trumpet Top comb
Top needles damage No deformation and no weariness of top comb...Excellent inspection Some weariness, can be repaired but its function is good........................Acceptable Significant weariness, cannot be used and need repairing.............Not acceptable
Spinning Processes and Types of Yarn
2. Vibration and wear Within 0.25mm (0.010in)..........Excellent investigation by 0.25mm-0.38mm (0.010-0.015in)................... Acceptable using gauge feeler Over 0.38mm(0.015in).........Not acceptable
2-112
Spinning Processes and Types of Yarn
Clearer comb Surface inspection or Not good in function, tilting by using feeler over 1/4in. .........................Not acceptable Weariness investigation Weariness over 0.8mm (1/32in) and Coiler by feeler gauge or by movement movement over 0.25mm (0.010in).......Not acceptable Roller gear Weariness, outlook Teeth weariness, deformation and missing.......................Not acceptable inspection Roller setting 1. Roller setting difference Over standard + 1/32mm ......Not acceptable investigation by using feeler gauge
Calender roller
2. Roller bush and sliding roller gap investigation 1. Weariness of roller surface can be investigated by using screw-gauge meter and thickness gauge
Over 1/32in..........................Not acceptable
Within 0.13mm (0.055in)...........Excellent 0.13-0.38mm (0.005-0.015in)............... Acceptable Over 0.38mm (0.015in).......Not acceptable
2. Bearing weariness Within 0.8mm (1/32in)....................Excellent inspection Over 0.8mm (1/32in)...........Not acceptable Roller creel 1. Thickness can be and sliding measured by caliper bar 2. Roller creel and sliding bar investigation by using caliper
Over 3.2mm (1/8in)....................Excellent Within 3.2mm (1/8in).............Not acceptable Within 0.8mm (1/32in)...................Excellent Over 0.8mm (1/32in)...............Not acceptable
Textile Handbook 2-113
3.14 Possible Causes of Drawn Sliver Defects Table 3.14
Defect
Possible Causes of Drawn Sliver Defects
Possible reasons
Sliver weight 1. Wrong draft gear. not correct 2. Feed in sliver weight is not correct. 3. Malfunction of automatic stopping device, one feeding in sliver is missing.
Thick sliver
1. Sliver piecing is too long or highly twisted. 2. Fed in sliver is rucked.
Thin sliver
1. Missing of feed in sliver. 2. Sliver piecing is too thin.
Spinning Processes and Types of Yarn
Poor evenness, 1. Roller pressure is too low or out of function, not even on has serious two sides. thick and thin 2. Roller setting is too large or too small. places 3. Top roller seriously bent, serious damage on surface, no oiling on top roller shaft, therefore, roller is not running well. 4. Loose roller joint, weariness of roller neck, damaged roller shaft. 5. Lapping up of bottom rollers, top rollers that cause roller to become bent, roller slack and setting moved. 6. Cracked, eccentric, missing of tooth of draft change gear, gears are not well meshed and the gap between gears is too wide. 7. Poor draft distribution, front tension draft is too large. 8. Lapping of the second roller for three up four down drawing frames. 9. Fed in sliver rucked up, therefore, sliver is not under control, sliver on two sides is thin and in the middle is thick. 10. Some fed in slivers running out from the creel, perhaps the roller is too short. 11. Sliver guide is too small, or sliver guide is too high, some slivers running under the sliver guide. 12. Improper position of pressure bar, slivers are not passing through the pressure bar.
2-114
Spinning Processes and Types of Yarn
Fuzzy sliver
1. Sliver guide is too big. 2. Trumpet size is too big. 3. Sliver can is too full, substantial rubbing between sliver and plate of coiler wheel. 4. Bottom plate of sliver wheel is not polish, tube is rough. 5. Temperature is too low and dry. 6. Sliver has been drafted too much, sliver stickiness. 7. The rim of can is rough, catches fibres easily.
Fly waste
1. Carded sliver has fly waste, scattered after drafting. 2. Poor top and bottom cleaners and suction devices, especially serious for three up four down drawing frames. 3. Cleaning period is too long, machine is not stopped for cleaning, cleaning tools are not good, careless cleaning bringing flys into sliver. 4. Flys from open top drop onto the web or sliver can. 5. Sliver passage is not polished, check the roughness of the creel, fibres easily accumulated and drawn into sliver. 6. Waste accumulated inside coiler tube drawn into sliver. Contaminated 1. The oiling of top roller or coiler wheel is not proper. sliver 2. Careless handling of slivers during periodic maintenance or gear changing. 3. Carded sliver is contaminated. 4. The inside of can is not clean. 5. Sliver dropped on floor and contaminated. 6. Dust from air duct blowing onto slivers Irregular 1. Coiler eccentricity is not correct. coiling pattern 2. Can bottom plate is not leveled. 3. Tilting can or malfunction of spring can. 4. Coiler wheel and can speed is not matched.
Section 4 - Combing Process ..................................... 2-115 A 4.1
Purpose of Combing ......................................................... 2-115
4.2
Combing Preparation ....................................................... 2-115
4.3
Combing Mechanism ........................................................ 2-119 4.3.1 4.3.2
4.4
Introduction ................................................................. 2-119 Operations ................................................................... 2-119
Combing Components Specification ............................... 2-125 4.4.1 4.4.2
Combing Cylinder ....................................................... 2-125 Top Comb .................................................................... 2-127
4.5
Examples of Input and Output of Combing Process ..... 2-128
4.6
Advanced Development and Automation in Combing .. 2-129 4.6.1 4.6.2
4.7
Computer Aided Process Development ...................... 2-129 SERVOlap E 6/4 - L .................................................... 2-130
Possible Faults in Combing .............................................. 2-131
Back to Table of Content
A
Textile Handbook 2-115
SECTION 4
COMBING PROCESS
A
4.1 Purpose of Combing
A
4.2 Combing Preparation
A
As card sliver is used to feed the comb, it is necessary to arrange the carded sliver in the form of a lap. The conventional way to prepare cotton for the combing process consists of passing the carded slivers through firstly a sliver lap machine and then a ribbon lap machine. An alternative and more efficient way is passing the carded sliver through one drawing process followed by a lap former for the purpose of packing the drawing slivers into a comber lap. Table 4.2 (1) Technological Setting for Combing Method Item
SLMRLM
DF1* DF2* DF2*
DF1-SLM DF1-DF2 -RLM SLMRLM
DF1-DF2 SLM
DF1-DF2 DF3SLM
DF1UNILap
DF1UNILap -RLM
6 x 5.82
4 x 5.93 6x6
4x5 6x6 6x6
8 x 7.05
8 x 7.05
4 x 5.93 6x6
Processing
SLM* 20 x 1.47 20 x 1.57 20 x 1.03 20 x 1.03 10 x 1.03 24 x 1.72 24 x 1.72 RLM*
6 x 5.37
6 x 5.18
6 x 5.3
-
-
-
6 x 5.4
No.of Processes
2
3
4
3
4
2
3
7.9
47.3
195.0
36.7
185.4
12.1
65.5
Total Draft
Note : DF = Draw Frame; SLM = Sliver Lap machine; RLM = Ribbon Lap Machine; * means number of doubling x draft
Spinning Processes and Types of Yarn
The fundamental purpose of combing is to remove the shorter fibres and also the trash and nep which would otherwise impair the strength and appearance of the yarn. In separating short from long fibres, the long fibres are straightened to a considerable degree and made parallel to each other. Combing is used in the production of high quality fabrics, those for which fine, clean, strong yarns of lustrous appearance are required.
2-116
Spinning Processes and Types of Yarn Table 4.2 (2) Sliver Lap Roller Gauge (Source: Rieter)
Sliver Lap Grain /yd
Main Draft Zone
Pre- draft Zone
775 845 915 985
(a + 5) mm (a + 6) mm (a + 6) mm (a + 7) mm
(a + 8) mm (a + 11) mm (a + 12)mm (a + 14)m
Remark: a = 5% of staple length (mm) Table 4.2 (3)
Example of Sliver Lap Draft
C.R. - B.R. B.R.-4th R.
Total Draft 1.51
1.02
1.3
4th R.-M.R. M.R. - F.R. F.R. - 5thC.R. C.R. - L.R. 1.035
1.075
1.015
1.01
(Source: Rieter) Table 4.2 (4)
Ribbon Lap Roller Gauge
Draft Zone 1st & 2nd Roll 2nd & 3rd Roll 3rd & 4th Roll
Gauge (a + 2)mm 50 mm (a + 4)mm
Example 30mm 50 mm 36mm
a=5% of staple length mm (Source: Rieter) Table 4.2 (5)
Example of Ribbon Lap Draft
Total Draft L.R. - B.R. B.R.-3rd R. 3rd R.- 2nd.R. 2nd.R. - F.R. F.R. - C.R.1 C.R.2 - C.R.2 C.R.2 - L.R. 6.31
1.005
Table 4.2 (6) Tex Above 9.7 7.3-5.8 Below 5.8
1.34
1.0
4.42
1.005
1.005
1.01
Quality Reference of Combing Laps British Count Below 60 80-100 Above 100
Evenness % 0.90-1.10 1.05-1.15 1.10-1.20
Noils % 13-15 (below 16mm) 12-14 (below 20mm)
Textile Handbook 2-117 Table 4.2 (7) Comparison of Various Combing Preparation Systems
Parallelization
Production and combing waste ratio
Application
Sliver lap Ribbon lap 2 6 -8 120-192 12 - 19 35-43 750-840 Better
Widthwise evenness is better, no significant marks and not easily distributed. Fibre I n c r e a s e d i n Poor fibre straightening and d o u b l i n g a n d straightening and parallelization is drafting, fibre parallelization. not enough. straightening and parallelization is good. Lap weight is Can increase lap Lap weight cannot light, combing weight carefully, be increased, production rate is compared with 1 therefore, limited l i m i t e d a n d drawing process, combing production combing waste is combing waste rate and combing high. can be waste is comparatively c o m p a r a t i v e l y decreased. higher. Short processing is popular, applied because of less draw frames and spaces saving.
For high production rate and high quality, need more draw frames.
Old technology, recently not popular, especially for long staple , fine count.
Spinning Processes and Types of Yarn
2 Drawing Preparation system 1 Drawing Sliver lap Sliver lap No. of processes 2 3 6-8 Draft Drawing Sliver lap 16 -24 Ribbon lap 96-192 576-1536 Total draft Total doubling 8 - 14 34 - 65 Gram/metre 54 39-54 Lap weight Grain/yard 550-840 Below 840 Stickiness Slight Poor Lap structure Evenness Poor widthwise Improved in both evenness, lengthwise and significant marks. widthwise evenness.
2-118
Spinning Processes and Types of Yarn
Recommendation
Carefully increase sliver weight to increase fibre parallelization; use curvilinear drafting system, 8 doubling, increase top roller pressure and high draft.
Turn carded sliver upside down if possible, then two passages of drawing. This can help to lower the combing waste by 1-1.5%. Appling low draft or no draft in sliver lap can help to improve stickiness.
Apply curvilinear drafting system for ribbon lap; increasing top roller pressure can help to improve fibre parallelization, web quality and also increase lap weight.
Table 4.2 (8) Possible Defects in Combing Laps Defects
Possible reasons
Uneven lap thickness and poor irregularity in widthwise direction
1. Roller setting is too big or too small. 2. Poor top roller surface or roller bent, eccentric, and rollers are not running well. 3. Not enough top roller pressure. 4. High roller draft. 5. High tension draft. 6. Missing of feed in sliver, because of the malfunction of the automatic stopping device. 7. Sliver guiding plate is not in the centre. 8. Improper position of the sliver-guiding bar.
Periodic faults on lap
1. Weariness of draft change gear or poor meshing of gears. 2. Top rollers are not running well or due to uneven top roller pressure.
Loose lap
1. Braking mechanism is not functioning well. 2. Pressure weighting has been moved, foot brake has been choked. 3. Brake slippage because of the weariness, oiled or accumulated flies on brake lining.
Rough lap edge
1. Bobbin dimension is not regular. 2. The opening and set-up position of condensing guide plate is not correct. 3. Loosing and improper setting of lap drum gripping mechanism.
Lap size too big
1. Malfunction of full lap stopping device or it has been well set. 2. Operator’s fault.
Stickiness
1. High temperature or high humidity. 2. High draft on sliver lap. 3. High percentage of re-cycling cotton. 4. Not enough drum pressure and winding density. 5. Big gap between gripping plate and bobbin. Hairiness and stickiness due to scratched, oiled or contaminated of gripping plate. 6. Oiled or scratched condensing guide plate. 7. Too many preparation passages.
Textile Handbook 2-119
4.3 Combing Mechanism 4.3.1 Introduction
4.3.2 Operations The combing operation can be divided into seven parts, four basic and three secondary, as follows: a) Basic operations • Feeding the stock from a prepared lap. Figure 4.3.2a (1) • Combing out short fibres, foreign particles and neps; parallelizing fibres. - Nipper motion including nipper knife motion grips the fibres as a means of holding long fibres. Figure 4.3.2a (2). - Combing cylinder motion passes many rows of closely spaced needles through the fibre beard held by the nippers, as the means of removing short fibres, neps and dirt. Figure 4.3.2a (3) (4). • Detaching the combed fibres from the lap. - Bottom detaching roll motion moves the previously combed cotton backwards to the newly combed fibres which may overlap the others. Figure 4.3.2a (5) (6). - Nipper knife motion opens releasing grip on fringe of fibres. Figure 4.3.2a (7). • Piecing the fleecy tuft of combed fibres with the fibres in the returned web.
Spinning Processes and Types of Yarn
Generally, a combing machine has eight identical combing heads, each of which carries a lap which is fed forward by a pair of fluted feed rollers. The slivers produced by the individual heads are joined together on a table in two groups of four, and processed through a drafting system to form two slivers which are then coiled into separate cans. In high speed combing machines, after combing eight of the slivers are gathered together entering a high draft system to form the one and only sliver. Their nipping rate is nearly double that of the old model while the quality is improved because of the eight doubling.
2-120
Spinning Processes and Types of Yarn
- Top combing draws the back end of the detached fibres through a row of closely spaced needles, thus straightening and cleaning them, and preventing short fibres from being carried along by contact with the long fibres. Figure 4.3.2a (8). - Bottom detaching roll motion draws the newly combed fibres, which project the farthest from the lap in the nippers, away from the lap. Figure 4.3.2a (9) (10).
b) Secondary operations • Condensing the combed web into sliver and doubling the sliver on the table. • Drafting slivers from all the heads, as a narrow sheet, through a series of drawing rolls to reduce them to the required sliver weight. • Calendering and coiling puts the continuous sliver into a roving can in a uniform, regular arrangement.
Figure 4.3.2a (1)
Basic mechanisms of a combing machine
Textile Handbook 2-121 Figure 4.3.2a (2)
Spinning Processes and Types of Yarn
Figure 4.3.2a (3)
2-122
Spinning Processes and Types of Yarn Figure 4.3.2a (4)
Figure 4.3.2a (5)
Textile Handbook 2-123 Figure 4.3.2a (6)
Spinning Processes and Types of Yarn
Figure 4.3.2a (7)
2-124
Spinning Processes and Types of Yarn Figure 4.3.2a (8)
Figure 4.3.2a (9)
Textile Handbook 2-125 Figure 4.3.2a(10)
4.4.1 Combing Cylinder Combing cylinder is mounted with circular comb. There are different circular comb models depend on the staple length to be processes. • Circular comb from Graf Figure 4.4.1(1)
Primacomb 5015
For E70R - E60H - E60 - E7/6 E7/5 E7/4 Diameter of circular comb cylinder: 85 mm. Comb with 5 sections with a combing surface of 111o. Used for medium and long staple fibres exceeding 1 3/16 - 1 1/2 inches (30 38 mm).
Spinning Processes and Types of Yarn
4.4 Combing Components Specification
2-126
Spinning Processes and Types of Yarn
• Primacomb 5025 FP Figure 4.4.1(2)
Primacomb 5025FP
For E70R - E60H - E60 - E7/6 E7/5A E7/5 Diameter of circular comb shaft: 85 mm. Comb with 5 sections with a combing surface of 111o, fibre plate and staggered teeth in first section. Used for extra long staple fibres 1 1/41 5/8 inches (32 - 41 mm)
• Primacomb 5014 Figure 4.4.1 (3) Primacomb 5014
For E70R - E7/6 - E7/5 - E7/4 diameter of circular comb shaft: 85 mm. Comb with 4 sections with a combing surface of 90o. Used for short and medium staple fibres 1 1/32 - 1 7/32 inches (26 - 31 mm).
• Primacomb 4014 Figure 4.4.1 (4) Primacomb 4014
For E7/4-E7/2-E7 Diameter of circular comb shaft: 80 mm. Comb with 4 sections with a combing surface of 90o as replacement for older combs with 78o combing surface. Recommended for short, medium and long staple fibres of 1 1/32 - 1 1/2 inches (26 - 38 mm).
Textile Handbook 2-127
• Primacomb 7015 Figure 4.4.1 (5) Primacomb 7015
For new Rieter comber E62/E72 Diameter of circular comb shaft: 85 mm. Applied for cotton of 1 1/16 - 1 1/2 inches (27 - 38 mm).
Figure 4.4.2 (1)
Top Comb penetration depth
The noils percentage can be influenced by the penetration depth. -1 = smallest penetration depth (less noils) +1 = biggest penetration depth (more noils) • The maximum penetration depth possible is limited by the detaching distance adjusted.
Figure 4.4.2 (2)
Gauge Setting of Top Comb Check: - Take out all top combs. - Set circular comb shaft to 39 - Fit top comb and check distance “A”.
Minimal distances between top and circular combs
Spinning Processes and Types of Yarn
4.4.2 Top Comb
2-128
Spinning Processes and Types of Yarn
4.5 Examples of Input and Output of Combing Process Table 4.5 (1) Example one Drawing (1Hx2D)
Lap former
Comber(E7/4)
Feed in weight
300 gr/5 yd
340 gr/5 yd
980 gr/yd
Output weight
340 gr/5 yd
980 gr/5 yd
330 gr/5 yd
Doubling
8
48
4x2
Total draft
7.05
3.33
59.4
Speed of main part (diameter mm. X rpm)
Front Roller 40 x 2100
Lap Roller 470 x 54
Calender Roller 70 x 212
Delivery speed (m/mm)
263.9
79.7
46.6 x 2
Efficiency %
85%
80%
90%
Combing waste %
-
-
18
Production rate (lbs/8hr)
2288
4685
415
Lap former
Ribbon Lap
Comber(E7/5)
Feed in weight
Ne 0.12-0.18
40-60g/m
50-70g/m
Output weight
40-60g/m
50-70g/m
3-6 Ktex
Doubling
24-36
6
8
Total draft
1.5-2
4-9
93-133
Delivery speed (m/mm)
65
65
300 Nips/Min
Lap dimension and weight
230mm 12Kg 250mm 13Kg
265mm 13Kg 300mm 15Kg
Table 4.5 (2)
Example two
Efficiency %
90-94%
Combing waste %
5-25%
Textile Handbook 2-129
4.6 Advanced Development and Automation in Combing 4.6.1 Computer Aided Process Development
Figure 4.6.1 Computer aided process development
In C-A-P-D combers the mechanically defined and technologically optimum production ranges are identical. This range lies between 350 and 400 nips per minute, where the quality parameters are stable. a) Optimized technology elements This innovation in combing technology has revealed further potential in various technology elements. The newly developed Primacomb Type 7015 circular comb combines the advantages of maximum combing effectiveness with the best possible running properties.
Spinning Processes and Types of Yarn
Rieter, having had successful experience with E60H and E70R, applied the advanced C.A.P.D. (Computer Aided Process Development) technology to generate 110 billion combing nipper motion and positioning combinations. Instead of applying traditional trial and error, high speed computerized simulation technology is used to select the best combination (Figure 2.4.6 (a)) for high performance combing frames E62 and E72.
2-130
Spinning Processes and Types of Yarn Figure 4.6.1 a Reduced mechanical loading of the detaching drive at 400 nips/min
4.6.2 SERVOlap E 6/4 - L SERVOlap is a fully automatic lap transport system for the simultaneous overhead transport of eight laps from UNIlap to combers. It serves manual as well as automatic combers. The elimination of waiting times and the gentle lap treatment provide maximum efficiency and contribute to better quality. Figure 4.6.2
SERVOlap E 6/4 - L
Textile Handbook 2-131
4.7 Possible Faults in Combing Table 4.7 Fault
Possible Faults in Combing Reasons 1. Movement of ratchet gear is too much or too less, or the gap between the pawl and ratchet gear is too big. 2. Wrong feeding gear. 3. Low pressure on pawl spring. 4. Improper motion of feeding rollers, or top and bottom feed rollers are not parallel, or weariness of pawl.
Poor web patterning
1. Detaching roller timing is too early or too late. 2. Improper timing between detaching rollers and nipper. 3. Web tension is too high. 4. Bow plate setting is too late, and the last row of needles has been interfering with Fibres from the with detaching rollers. 5. Top comb setting has been moved. 6. Detaching rollers are not running well or the timing is too early.
Web patchiness and poor clarity
1. Nippers opened too early, top comb had not completed its function. 2. Damage and rust of cylinder needles. 3. Not enough combing because of lapping up of combing cylinder. 4. Accumulation of fibres or trash on top combs; breakage; missing of top comb needles. 5. Combing cylinder setting is too big. 6. Uneven gripping force of nipper unit; perhaps spring on nipper plate is cracked, or nipper plate was choked with hard particles. 7. Inching of nipper plate and detaching rollers, they are not running smooth. 8. The setting of triangular suction air and brush is too wide. 9. Diameter of top detaching rollers is too small or too hard, poor elasticity. 10. Comb waste setting has been moved.
Poor web edges
1. Improper surface treatment or glue on back detaching top rollers has worn out, or scratches on surface, or new rollers have not been adapted to the enviornment. 2. Damage of the combing cylinder needles or top comb needles on two sides. 3. Improper pressure on back top detaching rollers or roller, diameter is too small; poor elasticity. 4. The opening of the web guider of the detaching roller is too small or too big, or the height is wrongly set. 5. Speed of fan or brush is too high. 6. The setting of triangular suction plate and brush is too close. 7. Relative humidity is too low or too high.
Holes on web
1. Lapping up of combing cylinder. 2. The closing time of nippers is too early (i.e. they open too late). 3. Fluted detaching roller bent too much. 4. Top detaching rollers bent, slack, or small in diameter; poor elasticity. 5. The setting of triangular suction plate is too high, too far from brush. 6. Not enough pressure on nipper plate, cracked pressure spring. 7. Partially lapping of top or bottom detaching rollers.
Spinning Processes and Types of Yarn
Loose winding or hard winding
2-132
Spinning Processes and Types of Yarn Widthwise breakage
1. Setting of front position of nipper plate has moved. 2. Top comb setting has moved or top comb position is too low. 3. Missing of pawl taking on feed gear.
Sliver chock on table
1. Back roller gear is too large. 2. Back top roller is not running well. 3. Calender trumpets on table are too big. 4. Rough, contaminated or fluffy table.
Comb waste not regular
1. Speed of fan is too low. 2. Poor condition of brush. 3. Accumulation of flies inside combing waste passage, duct or cover become these are not polished. 4. Poor combing cylinder needles. 5. Suction duct opening is not at the proper height.
Too many long fibres in comb waste
1. Poor gripping of detaching rollers. 2. Nipper unit was choked with hard particles, and not closing tightly. 3. Poor condition of combing cylinder needles or top comb needles. 4. Too much combing waste. 5. Serious stickiness on laps or fibres; fibres of the lap are not straightened. 6. Holes on web.
Higher neps and trash in sliver
1. Low combing waste, or big difference of comb waste ratio between two sides. 2. Poor combing needles or combing setting is too wide. 3. Top comb timing is not setting well. 4. Poor lap formation or highly contaminated.
Poor regularity
1. Web piecing or poor web edges. 2. Poor top detaching rollers or top draft rollers, such as poor elasticity, eccentric, bent or slack. 3. Bent or eccentric of bottom detaching roller or bottom drafting roller. 4. Weariness or damage or not meshing of draft change gear, or the gap between axial shaft and gear is too wide. 5. Malfunction of drafting system or drafting pressure is too low. 6. Draft setting is too big or too small. 7. Tension draft of some sections is not correct. 8. Rough condenser, condenser accumulated with flies or the size of condenser is too small.
Lapping of combing lapping
1. Rust, damage of bent of combing needles. 2. The gauge of needle bars is too wide. 3. The setting of combing cylinder and brush is too wide, or are sloping down, have brush hairs poor elasticity, points scattered, and are uneven. 4. Speed of brushing is too low or air suction is not enough. 5. Lap weight is too heavy for processing long staple fibre.
Section 5 - Roving Process ........................................ 2-133 5.1
Function of Roving Process .............................................. 2-133
5.2
Drafting System ................................................................ 2-133 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6
5.3
Example of Drafting System on Speed Frame ............... 2-135 5.3.1 5.3.2 5.3.3 5.3.4 5.3.5 5.3.6 5.3.7 5.3.8 5.3.9 5.3.10
5.4
5.4.2 5.4.3
Flyer Speed .................................................................. 2-147 Roving Weight ............................................................. 2-148
Bobbin Building ................................................................ 2-149 5.6.1
5.7
Relationship Between Fibre Fineness (Based On 1 Inch Fibre Length) And Twist Factor Of Roving ..... 2-144 Factors Affecting Twist Factor of Roving ................... 2-145 Relationship Between Fibre Length and Twist Factor 2-146 of Roving ..................................................................... 2-146
Flyer Speed and Roving Conditions ................................ 2-147 5.5.1 5.5.2
5.6
Zone Settings And Maximum Fibre Length ................ 2-136 Roller Loading ............................................................ 2-137 Top Apron Cradle System ........................................... 2-138 Opening At Apron Release Point ................................ 2-139 Top Aprons .................................................................. 2-140 Top Roller Cots ........................................................... 2-141 Bottom Apron Nose Bar .............................................. 2-141 Rear Roving Guide ...................................................... 2-141 Rear Zone Condenser .................................................. 2-142 Front Zone Condenser ................................................. 2-143
Roving Twist ...................................................................... 2-143 5.4.1
5.5
In -Feed Material ......................................................... 2-133 Total Draft ................................................................... 2-133 Rear Draft .................................................................... 2-134 Roller Loading ............................................................ 2-134 Top Roller Cots Grinding ............................................ 2-134 Roving Guide and Condensers .................................... 2-134
Bobbin Building Mechanism Of Toyota Roving Frame ........................................................................... 2-149
Roving Tension Adjustment ............................................. 2-152
A
5.8
Horizontal Coil Density of Roving .................................. 2-153 5.8.1
5.9
Horizontal Coiling Density And Roving Count .......... 2-153
Number of Coils of Roving ............................................... 2-154
5.10 Number of Coils Per Inch of Roving ............................... 2-155 5.11 Common Defects in Roving .............................................. 2-156 5.12 Factors Affecting Roving Elongation and Remedies ..... 2-158 5.13 Machine Automation ........................................................ 2-159 5.13.1 Automatic Doffing and Bobbin Transfer System ........ (RO-WE-MAT 670 Roving Frame, Zinser) ................ 2-159 5.13.2 Automatic Transfer System (Toyota) .......................... 2-160
Back to Table of Content
A
Textile Handbook 2-133
SECTION 5
ROVING PROCESS
5.1 Function of Roving Process
A
The purpose of the roving operation is to reduce the sliver to a suitable size for spinning. A roving machine reduces the slivers by roller drawing, twists them slightly as needed, and winds the product accurately on a specially form of bobbin for further use in spinning.
The simplest drafting system used on the roving frames is the three roll drafting system in which three lines of rolls are running at increasing speeds. The drawing rolls of a roving machine have to be adjusted according to the staple of the material, the bulk in process, and the condition and character of the material. The settings are given as distances from roll centre to roll centre, the same principle as the drawing frame. As the staple is the most important factor in determining roll settings, it is customary to give the settings as the length of the staple plus a given distance.
5.2.1 In -Feed Material The counts of feed slivers normally used in everyday practice today are between approximately. 3.4 and 4.6 ktex (Nm 0.30 - Nm 0.22). Sliver counts in this range provide for ideal speed frame drafting. While it is possible to process feed slivers of 3 ktex or finer on speed frame drafting systems, this is not recommended due to the lack of fibre cohesion and the resultant risk of faulty drafting during sliver feed from can to drafting system. The maximum feed sliver count may not exceed 6 ktex (Nm 0.17).
5.2.2 Total Draft The amount of total draft on a four- or three-roller double apron drafting system is between 5 and 18, a range of 5-12 providing best results. Drafts greater than 12 are seldom employed as the total draft on a ring frame should be as high as possible, for yarn quality reasons. For drafts lower than 5, a speed frame should not be used, as faulty drafting may occur at such low total draft rates. For the four-roller double-apron drafting system a drafting tension of approximately 1.05 is used as a support for condensation between the roller pair I/1 and II/2 (see Figure 5.3.1(2)).
Spinning Processes and Types of Yarn
5.2 Drafting System
2-134
Spinning Processes and Types of Yarn
5.2.3 Rear Draft The task of the rear draft is to tension the fibre material in the rear zone and draw it parallel. Rear drafts of between 1.12 and 1.18 are normally used in practice.
5.2.4 Roller Loading In speed frames, the pressure stage to be set on the weighting elements is determined by the type of fibre, the fibrous mass and the amount of total draft. Basically, the greater the fibrous mass, the higher the loading pressure. For low total drafts, comparatively higher loading pressures have proved their worth.
5.2.5 Top Roller Cots Grinding Cot grinding intervals depend on the quality of the cot; the type of fibrous material; finishing agents or other additives; climatic conditions; the weighting pressure of the top roller and the top roller running time.
5.2.6 Roving Guide and Condensers It is a general practice to use roving guides and condensers on roving frames to guide flank fibres back into the fibre strand. The task of the condensers is to evenly fold flank fibres back into the fibre material. The condenser apertures should be neither too narrow nor too wide in order to avoid possible faults in the drafting process. For reasons of process reliability, closed condensers are recommended for use on speed frames, with the exception of the front zone condenser. Favourable cross-section ratios for the delivery aperture of closed condensers (height x width) of 1: 4 or 1: 5 have proved their worth. By condensing the fibre, a reduction in the spinning delta is achieved, thus improving the incorporation of the fibres into the roving. This results in the important advantages of reduced number of thread breakages (improved process reliability); increased efficiency; greater package density; and reduced fly generation. Usually, if a condenser is used between the front roll and apron, the setting should be somewhat wider.
Textile Handbook 2-135
5.3 Example of Drafting System on Speed Frame (SKF PK 1500 Series, TEX Parts) SKF series PK 1500 Weighting Arms are mainly intended for threeroller and four-roller double-apron drafting systems on cotton speed frames. They are suitable for spinning cotton, man-made fibres or blends of both types up to approximately 60mm length.
The four-roller version differs from the three-roller version in having an additional condensing zone between the roller pairs I/1 and II/2 (see Figures 5.3 (1) & (2))
Figure 5.3 (1)
Drafting arrangements PK 1500 three-roller version
Spinning Processes and Types of Yarn
The PK 1500 Weighting Arm series comprises types PK 1500-0962 604 and PK 1500-0962 602 for three-roller double apron drafting systems, and type PK 1500-0001 938, which is designed for the same applications on four-roller double apron drafting equipment.
2-136
Spinning Processes and Types of Yarn Figure 5.3 (2)
Drafting arrangement PK 1500 four-roller version
5.3.1 Zone Settings And Maximum Fibre Length
Figure 5.3.1 (1) Weighting arm
Top apron cradle
PK1500-0001 938 OH 514 PK1500-0962 604 OH 514 OH 534 OH 524 PK1500-0962 602 OH 514 OH 534 OH 524
Zone settings and maximum fibre length PK 1500 Bottom roller diameter I II III IV
28.5 28.5 28.5 28.5 30/32 25/27 30/32 -
30/32 25/27 30/32 -
1) Recommendations for the widest possible setting
Draft field mm Total HF VF VF draft min usual (1) field GFmm max. 48 45 46...50 193 49 40 60...80 189 60 40 60...80 189 76 40 70...90 189 49 40 60 40 76 40
60...80 60...80 70...90
189 189 189
Fibre length max.mm 3-nippoint 50 45 54 60 45 54 50
Textile Handbook 2-137 Figure 5.3.1 (2)
Zone settings PK 1500
Spinning Processes and Types of Yarn
5.3.2 Roller Loading Table 5.3.2
Roller Loading
Types
PK 1500 - 0001 938 PK 1500 - 0962 604 PK 1500 - 0962 602
Front I
Load stages (daN) Middle 2 Middle 3
9-12-15 20-25-30 20-25-30
15-20-25 10-15-20 10-15-20
10-15-25 -
Rear 3 Rear 4 10-15-20 15-20-25 15-20-25
2-138
Spinning Processes and Types of Yarn
a) Load adjustment Load adjustment is effected by means of an eccentric load selector activated by a special wrench (Fig 5.3.2a). Three load stages can be set on each weighting element. The three different load settings can be identified by the code colour on the eccentric load selector on the top of the guide arm. Figure 5.3.2a
Load adjustment of weighting elements PK 1500
5.3.3 Top Apron Cradle System SKF weighting arms, types PK 1500 can be fitted with short (OH 514), medium (OH 534) or long (OH 524) top apron cradles. Table 5.3.3 Top Apron Cradle Top apron cradles OH for PK 1500-0962 604 PK 1500-0962 602
PK 1500-0001 938(1)
Applications of the cradles
OH 514(2)
OH 514
Cotton and man-made fibres,alone and in blends, of up to approximately 45mm max. fibre length.
OH 534
-
Cotton and man-made fibres, alone and in blends, of up to approximately 54 mm max. fibre length.
OH 524
-
Man made fibres of up to Approximately 60mm max. fibre length.
(1) For fibre lengths up to about 50mm. (2) With diameters of the top rollers 35-33-35 mm OH 514 (short) is not to be used.
Textile Handbook 2-139
5.3.4 Opening At Apron Release Point The opening between the guide edge of the top apron cradle and the bottom apron nose bar determines the intensity with which the fibre material is controlled and guided between top and bottom aprons. In order to be able to adapt drafting conditions to good fibre control and fibre guidance corresponding to the fibrous mass present in the front zone, opening X can be regulated via the top apron distance clips.
Figure 5.3.4 (1) Opening X
Table 5.3.4 (2) Distance clips OLC in connection with SKF top apron cradle (opening X in mm)
Distance clips OLC
white 0964 104(1) grey 0964 105 black 0964 106(1) orange 0030 491 beige 0964 107 green 0964 108(1)
Top apron cradle OH 534 (middle)
OH 514 (short) Apron roller 25mm dia. 3.5 4.0 4.6 5.0 5.4 6.5
OH 524 (long)
Apron roller Apron Apron 25mm dia. roller roller 25mm dia. 33mm dia. 3.3 3.6 3.6 3.8 4.1 4.1 4.3 4.6 4.6 4.6 5.0 5.0 5.0 5.4 5.4 6.1 6.4 6.5
(1) Recommended Distance clips for PK 1500
Apron roller 33mm dia. 3.3 3.8 4.3 4.6 5.0 6.1
Spinning Processes and Types of Yarn
The opening X is adjusted via special distance clips affixed to the guide edge of the top apron cradle. To distinguish them, and to make the opening X simpler to check, the top apron distance clips have different colours (see Table 5.3.4(2)).
2-140
Spinning Processes and Types of Yarn
5.3.5 Top Aprons The dimensions of top aprons have been standardized and are determined by the type of OH top apron cradle and the diameter of the top apron roller used (see table 5.3.5) Table 5.3.5
Range of top apron cradles, top aprons and distance clips for PK 1500
Top apron cradles OH Ref. no.
Gauge Top aprons TW general mm designation
inner Top roller diaType meter Ref. no. mm
OH 514-0962 744 OH 514-0962 745 OH 514-0962 746 OH 514-0962 747
82.5 100 110 130
PR 40 PR 40 PR 40 PR 40
37.0 37.0 37.0 37.0
LP 317-0013 008 LP 317-0013 010 OLC-0964 104 LP 317-0013 01l OLC-0964 106 LP 317-0013 012 OLC-0964 108
OH 534-0962 762 OH 534-0962 764 OH 534-0962 765 OH 534-0962 766
82.5 100 110 130
PR 4010 PR 4010 PR 4010 PR 4010
43.5 43.5 43.5 43.5
LP 317-0013 008 LP 317-0013 010 OLC-0964 104 LP 317-0013 011 OLC-0964 106 LP 317-0013 012 OLC-0964 108
OH 534-0962 762 OH 534-0962 764 OH 534-0962 765 OH 534-0962 766
82.5 100 110 130
PR 407 PR 407 PR 407 PR 407
48.0(1) 48.0(1) 48.0(1) 48.0(1)
LP 317-0013 008 LP 317-0013 010 OLC-0964 104 LP 317-0013 01l OLC-0964 106 LP 317-0013 012 OLC-0964 108
OH 524-0962 753 OH 524-0962 755 OH 524-0962 756
82.5 110 130
PR 4011 PR 4011 PR 4011
52.7 52.7 52,7
LP 317-0013 008 OLC-0964 104 LP 317-0013 01l OLC-0964 106 LP 317-0013 012 OLC-0964 108
OH 524-0962 753 OH 524-0962 755 OH 524-0962 756
82.5 110 130
PR 408 PR 408 PR 408
57.2(1) 57.2(1) 57.2(1)
LP 317-0013 008 OLC-0964 104 LP 317-0013 01l OLC-0964 106 LP 317-0013 012 OLC-0964 108
(1) top apron roller diameter 33mm
Distance clip OLC Ref. no.
Textile Handbook 2-141
5.3.6 Top Roller Cots When freshly covered and ground, the rear and front top rollers of the PK 1500-0962 604 have a diameter of 28mm. The PK 1500-0962 602 is mainly used for longer fibre ranges (60mm), due to the bigger rear and front top roller diameters (35mm)
Grinding the spinning cots must not reduce the cot diameters by more than 3mm. Within this diameter reduction range, no readjustment of the weighting arm height is necessary. The cot of the apron top roller LP 317 may not be ground, as the top apron dimensions are matched to apron top rollers of fixed diameters.
5.3.7 Bottom Apron Nose Bar The bottom apron nose bar supports the bottom apron as it passes through the front zone. The recessed shape of the nose bar provides good fibre guidance and control through the double-apron unit. The three different top apron cradle sizes OH 514, OH 534 and OH 524 are to be matched up with the corresponding bottom apron nose bars.
5.3.8 Rear Roving Guide The rear roving guide 1 is to be positioned as close as possible to the rear pair of rollers (see Figure 5.3.9 (1)), When selecting the rear roving guide, take the position and type of the roving guide rail into account. If the opening widths have been correctly chosen, any tangled sliver portions will be smoothed out and the fibre material will flow unchecked.
Spinning Processes and Types of Yarn
In principle the use of a “travelling top clearer hose” is possible for all PK 1500 versions. If weighting arms PK 1500-0962 602 are used with top roller diameters of 35-25-35mm, lateral clearer roller holders should be employed. The quality and type of fibre material to be spun and running properties are decisive for the choice of cot. For top roller cots (rear, front - LP 315). Shore hardnesses of 83o are usual. As apron top roller, the LP 317 with cot is used, and SKF recommend cots with shore hardness 80o.
2-142
Spinning Processes and Types of Yarn
5.3.9 Rear Zone Condenser The rear zone condenser 2 is positioned in front of the double-apron unit (see Figure 5.3.9 (1)). The lower edge of the front aperture lies on the drafting plane. Its task is to lightly gather the fibre material before it enters the front zone or the double-apron unit and gently fold any flank fibres, which may have spread outwards, back into the sliver body. If the opening width of the rear zone condenser is too small, faulty drafting may occur. The simplest and most reliable method of checking whether the passage aperture of the rear zone condenser has been correctly selected is shown in Figure 5.3.9 (2). Figure 5.3.9 (1)
Rear and front overhang of top roller alignment of the roving guides’ respective condensers.
Figure 5.3.9(2) Correct opening width (left) and too narrow opening width (right) of condenser
Textile Handbook 2-143
5.3.10 Front Zone Condenser The use of front zone condensers in speed frame drafting systems has become generally accepted. Condensers open at the bottom have proved particularly useful.
Table 5.3.10 Matching Opening Widths of Condensers Front zone condenser. ref.no
Roving gauge
Delivery aperture width and colour of front zone condenser
KL-0998 282
680 tex to 400 tax or Nm1.5 to 2.5 (Ne0.9 to 1.48)
6 mm (yellow)
KL-0998 283
1000 tex to 680 tex or Nm 1.0 to 1.5 (Ne 0.6 to 0.9)
9 mm (colourless)
KL-0998 284 KL-0998 285
over 1000 tex or Nm 1. 0 (Ne 0.6)
12 mm (black) or 16 mm (green)
KL-0000 457
complete set
5.4 Roving Twist The purpose of roving twist is to give the relative fine strand of fibres sufficient strength to withstand the stresses of winding at the roving frame and subsequent unwinding in the spinning frame. It is a traditional procedure in the mill to keep the roving twist as low as possible so as to maintain maximum production of roving and facilitate ring frame drafting. Twisting is accomplished by the use of a flyer which is carried on the upper end of a vertical spindle. The flyer is made of steel in the form of an inverted U. One leg of the U is solid, while the other leg is tubular and serves as a passage for the rovings. There is a small guide, the presser, attached to the lower end of the hollow leg. The presser may swing in and out, with the hollow leg as a centre.
Spinning Processes and Types of Yarn
The front zone condenser 3 gathers outspread flank fibres and returns them to the sliver (see Figure 5.3.9 (1) & (2)). Subsequently the spinning delta is made smaller and roving breakages, lapping and fly generation are reduced. Particular care should be taken to match precisely the opening widths of the condensers, not only to the roving gauge but also to the fibre characteristics (see Table 5.3.10). Inhouse trials should be carried out to do this.
2-144
Spinning Processes and Types of Yarn
The fibres delivered by the front rolls of a roving frame are in the form of a thin ribbon. This ribbon is carried forward and downward to the top of the flyer. It is threaded through the top of the flyer, down through the hollow tube, wound around the presser arm and through the presser eye onto the bobbin. Each time the flyer makes one complete revolution, one twist is put into the roving. Since there is a definite rate of delivery at the front roll and a definite rate of revolution for the spindle and flyer, the two give a definite number of turns of twist for each inch of roving delivered. The amount of twist required by any roving should be judged carefully; as twist is used for strength, there should be enough so that the ends will not break in the next processing. However, if too much twist is used, the roving will not draw well in the ring spinning processing. The factors influencing the number of twists to use are the size of the roving and the length of the cotton staple. As the roving gets finer, it requires relatively more twist, while the longer the cotton staple, the less twist is needed to get the required strength.
5.4.1 Relationship Between Fibre Fineness (Based On 1 Inch Fibre Length) And Twist Factor Of Roving Table 5.4.1 Roving Count Micronaire
3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0
Relationship Between Fibre Fineness (Based On 1 Inch Fibre Length) And Twist Factor Of Roving
0.75
1.00
0.8966 0.9093 0.9219 0.9344 0.9464 0.9585 0.9705 0.9822 0.9938 1,006 1,016 1,028 1,039 1,050 1.06,1 1,072
0.9345 0.9448 0.9579 0.9707 0.9833 0.9959 1.008 1.021 1.032 1.044 1.056 1.068 1.079 1.091 1.103 1.114
1.50
2.00
3.00
4.00
5.00
6.00
1.221 1.238 1.255 1.272 1.283 1.305 1.321 1.338 1.353 1.369 1.395 1.400 1.415 1.430 1.444 1.459
1.479 1.500 1.521 1.541 1.561 1.581 1.601 1.620 1.639 1.656 1.678 1.695 1.714 1.732 1.750 1.768
1.937 1.964 1.993 2.018 2.045 2.071 2.097 2.122 2.147 2.172 2.197 2.221 2.245 2.269 2.293 2.316
2.347 2.381 2.414 2.446 2.478 2.509 2.541 2.571 2.602 2.632 2.662 2.692 2.720 2.749 2.777 2.806
2,725 2,763 2,801 2,839 2,876 2,912 2,948 2,984 3,019 3,054 3,089 3,123 3,156 3,190 3,223 3,256
3.076 3.120 3.163 3.026 3.247 3.289 3.330 3.370 3.410 3.449 3.488 3.537 3.565 3.602 3.640 3.677
Example: For fibre length 1 1/16", mic. 4.2, roving count 3, the optimum twist on the table, for fibre length 1", is 2.122. As a result, for fibre length 1 1/16", the twist multiplier is : 2.122 ÷ 1 1/16" = 2
Textile Handbook 2-145
5.4.2 Factors Affecting Twist Factor of Roving Table 5.4.2
Factors Affecting Twist Factor of Roving
Factors
Twist multiplier on roving Lower Higher
Raw cotton
Fibre length
Short
Long
Fibre fineness Temperature
Thick High
Short Low
Moisture regain of roving
Low
High
Temperature and humidity
Roving technology Roving hardness
Spinning technology
Product specification
Season
Dry
Humid
Roving weight
Light
Heavy
Fibre parallelization
Good
Poor
Winding density
Loose
Hard
Bobbin hardness
Soft
Hard
Roving strength
Low
High
Back roller pressure
High
Low
Back draft Back zone setting
High
Low
Large
Small
Carded or combed
Carded
Combed
Pure cotton or blended
Pure cotton
Blended
Knitted or piled
Knitted
Piled
Woven
Warp
Weft
Spinning Processes and Types of Yarn
Type
2-146
Spinning Processes and Types of Yarn
5.4.3 Relationship Between Fibre Length and Twist Factor of Roving Table 5.4.3 Table Relationship Between Fibre Length and Twist Factor of Roving Tex
Fibre Length (mm)
Ne 25
200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900
2.915 2.650 2.429 2.242 2.082 1.941 1.822 1.715 1.619 1.534 1.457 1.388 1.325 1.267 1.215 1.166 1.121 1.080 1.041 1.005 0.972 0.940 0.911 0.883 0.857 0.810 0.810 0.787 0.767 0.747 0.729 0.711 0.694 0.678 0.662 0.648
106.7 106.5 106.3 110.3 110.1 109.9 109.7 109.5 109.3 109.2 109.0 108.8 108.7 108.5 108.4 108.2 108.1 108.0 107.8 107.7 107.6
26
27
103.5 103.3 103.0 102.8 102.6 102.3 106.1 105.9 105.7 105.5 105.3 105.1 105.0 104.8 104.6 104.5 104.3 104.2 104.1 104.0 103.9 103.7 103.6 103.5
28
100.5 100.2 100.0 99.7 99.5 99.2 99.0 98.8 98.6 102.1 101.9 101.7 101.5 101.4 101.2 101.1 100.9 100.7 100.6 100.4 100.3 100.2 100.1 100.0 99.9 99.8 99.7
29
97.9 97.6 97.3 97.0 96.7 96.5 96.2 96.0 95.8 95.6 95.4 95.2 98.4 98.3 98.1 97.9 97.8 97.6 97.5 97.3 97.1 97.0 96.8 96.7 96.6 96.5 96.4 96.2 96.1 96.0
30
95.3 94.9 94.6 94.3 94.1 93.8 93.6 93.4 93.1 92.9 92.6 92.4 92.2 92.1 95.0 94.9 94.7 94.5 94.4 94.2 94.1 93.9 93.8 93.7 93.5 93.4 93.3 93.2 93.1 92.9 92.8 92.7
31
93.1 92.7 92.4 92.0 91.7 91.4 91.1 90.8 90.6 90.4 90.2 90.0 89.8 89.6 89.4 89.2 91.9 91.8 91.6 91.4 91.3 91.1 91.0 90.8 90.7 90.6 90.4 90.3 90.2 90.1
32
33
34
35
36
37
91.0 90.6 90.2 80.8 89.5 89.1 88.8 88.5 88.3 88.0 87.7 87.5 87.3 87.1 86.9 86.7 86.5 86.4 89.0 88.9 88.7 88.6 88.5 88.3 88.2 88.0 87.8 87.7 87.5
88.2 87.8 87.4 87.0 86.7 86.4 86.1 85.8 85.6 85.3 85.1 84.9 84.7 84.5 84.3 84.1 83.9 83.7 86.2 86.1 85.9 85.7 85.6 85.4 85.3 85.1
85.6 85.2 84.8 84.4 84.1 83.8 83.5 83.2 83.0 82.8 82.6 82.4 82.2 82.0 81.8 81.6 81.4 81.3 83.5 83.4 83.2 83.1 83.0
83.1 82.7 82.4 82.0 81.7 81.4 81.2 80.9 80.7 80.4 80.2 80.0 79.8 79.6 79.4 79.2 79.0 78.9 81.1 81.0
80.8 80.4 80.1 79.7 79.4 79.1 78..9 78.6 78.4 78.2 78.0 77.8 77.6 77.4 77.2 77.0 76.8 76.6 78.7
78.7 78.3 78.0 77.6 77.3 77.0 76.8 76.5 76.3 76.1 75.9 75.7 75.5 75.3 75.2 75.0 74.8
Remark: British Twist Multiplier = Twist Multiplier x 0.01052
Textile Handbook 2-147
5.5 Flyer Speed and Roving Conditions 5.5.1 Flyer Speed Flyer speeds up to 1,400 rpm are mechanically possible. However, the practical maximum speed may vary under some roving conditions. To produce large package roving high speed without fibre breakage, the flyer speed must be determined considering the roving conditions, including the fibre type, roving weight, twist and the amount of roving wound onto the presser.
n: No. of roving wound onto presser
: Good
: Fair
: Poor
Spinning Processes and Types of Yarn
Table 5.5.1 (1) Roving conditions and flyer speed (4-roller D-type/ carded yarn)
2-148
Spinning Processes and Types of Yarn Table 5.5.1 (2) Roving conditions and flyer speed (4-roller D-type/ combed yarn)
n: No. of roving wound onto presser
: Good
: Fair
: Poor
5.5.2 Roving Weight The weight of roving wound on a bobbin may vary according to the fibre type, flyer speed, and twist as shown in the table below. Table 5.5.2
Fibre type
Roving conditions and roving weight
Roving Thickness
Twist multiplier
Metric English Metric count count count 1.00 37 1.70 Carded yarn 0.90 39 1.53 0.76 38.5 1.29 1.04 38 1.76 Combed yarn 1.04 38.5 1.76 1.47 20 Cotton and 2.49 1.29 21 2.18 polyester blend (35 x 1.93 1.14 20 65%) 0.83 22 1.40 Polyester and rayon 1.00 18 1.70 blend (55x45%)
Flyer Roving speed weight
Twist
English count 1.23 1.29 1.27 1.23 1.26 0.67 0.68 0.68 0.72
1m
25.4 mm
rpm
kg
48 48 44 50 51 32 31 28 26
1.23 1.23 1.11 1.26 1.29 0.82 0.78 0.72 0.65
1050 1000 850 900 850 830 830 1000 800
2.1 2.0 2.0 2.0 1.9 2.6 2.7 2.4 3.0
0.58
23
0.58
730
2.8
Textile Handbook 2-149
5.6 Bobbin Building
As the roving is guided by the presser of the flyer which does not rise and fall, lay is accomplished by traversing the bobbins slowly upward and downward as the roving is being wound. Lay is measured by the number of complete coils around the bobbin per inch. The coils should be so arranged that successive coils just meet without any visible ridged effect. A traverse is one complete movement of the bobbin upward or downward. The traverse distance varies at different positions in building the bobbin in order to build a complete conical bobbin. Recently, Toyota introduced FL100 which has a microcomputer sensor to monitor roving tension and is capable to adjust the winding tension automatically to maintain an even roving strand.
5.6.1 Bobbin Building Mechanism Of Toyota Roving Frame a) Automatic Flyer Speed Control Device With Inverter By simply inputting the average flyer revolution rate and basic roving conditions such as length and weight, the computer automatically establishes the correct speed progression pattern and adjusts flyer speed via the inverter to maintain a constant centrifugal force on the roving. This results in reduced roving breakage for improved efficiency and ease of operation.
Spinning Processes and Types of Yarn
Bobbin winding is the operation of drawing the roving from the front roller, through the flyer onto the bobbin. Winding tension is controlled by the relative speeds between the surface speed of the bobbin and the delivery speed of the front rollers. The actual winding is accomplished by having the bobbin revolve faster than the flyer. As the diameter is increased, it is necessary to decrease the revolution speed to keep the winding speed (surface speed of the bobbin) equal to the delivery from the front rollers. The difficult part of the winding is to drive the bobbin at just the correct speed, in relation to that of the flyer, for each layer on the bobbin. To do this, the bobbin is driven from two sources. First, it has a constant speed equal to that of the flyer, and second, it has an added variable speed necessary to wind the material from the front rollers. Therefore, the empty bobbin must make a large number of turns to wind on the roving delivered, while at each new layer the winding revolutions of the bobbin are reduced inversely to the increase in diameter. This maintains a constant surface speed for winding the roving on the bobbin.
2-150
Spinning Processes and Types of Yarn Figure 5.6.1a
Automatic flyer speed control device with inverter
b) Cone Drumless Mechanism For High-Speed, HighQuality Roving Conventional roving frames use a cone drum belt system to control tension by mechanically changing the roving volume. By replacing this mechanism with computercontrolled, variable speed winding motors, the FL100 provides precise, fully automatic tension control. This enables both higher speed operation and superior production quality. In addition, elimination of the cone drums allows easier maintenance access at the rear side of the frame. Figure 5.6.1b Cone drumless mechanism reduces detrimental vibration for optimal operation at higher speeds.
Textile Handbook 2-151
c) Precision Sensors And Computer Control Ensure Accurate Winding Tension
Figure 5.6.1c
Precision Sensors And Computer Control Ensure Accurate Winding Tension
d) Unique Mechanism Minimizes Roving Irregularities Two separate motors are used to drive roving and winding operations. This allows winding to be halted slightly before roving, once the bobbins are full, to provide some slack between front rollers and the flyer top. Thus, by preventing excessive tension at restart, there is no irregularity in roving, even for synthetic fibres or heavy cotton. Figure 5.6.1d(1)
Roving speed
Spinning Processes and Types of Yarn
The combination of a microcomputer and CCD ‘electronic eye’ sensors accurate to 0.1 mm maintains an ideal winding tension for even the finest threads. This system also ensures uniform tension between all frames in a production group, a difficult feat with conventional manual adjustments. In addition, the computer stores settings according to various criteria-flyer speed, fibre type, etc., and automatically sets the appropriate tension, thus eliminating the need for frequent setup adjustments.
2-152
Spinning Processes and Types of Yarn Figure 5.6.1d(2)
Roving path between front roller and flyer top
5.7 Roving Tension Adjustment Table 5.7
Roving Tension Adjustment
Roving Extension Small Middle Large Bobbin Bobbin Bobbin Large
Large
Large
Large
Large
Small
Large
Small
Small
Small
Small
Small
Small
Small
Small
Small
Large
Large
Drums Belt Starting Position More towards smaller diameter More towards smaller diameter Slightly more towards smaller diameter More towards large diameter More towards large diameter Slightly more towards larger diameter
Adjustment Winding Gear number
Building Gear number
Reduce
Reduce
Reduce
Increase by proportion Increase by proportion
Increase
Increase
Increase by proportion
Reduce by proportion Reduce by proportion
Remark: Usually only adjust the belt starting position and change the appropriate building gear. In case of no satisfaction, the winding gear is then changed as necessary.
Textile Handbook 2-153
5.8 Horizontal Coil Density of Roving Table 5.8
Horizontal Coil Density of Roving
Roving Tex
10
20
5.02 4.35 3.89 3.55 3.29 3.08
4.94 4.30 3.85 3.52 3.27 3.06
4.86 4.24 3.81 3.49 3.24 3.04
Roving Tex 70 60 50 40 30 Horizontal Coiling Density 5.30 4.79 4.72 4.65 4.58 4.52 4.20 4.15 4.10 4.06 4.01 3.78 3.74 3.71 3.68 3.64 3.47 3.44 3.41 3.39 3.36 3.22 3.20 3.18 3.16 3.14 3.02 3.00 2.98 2.97 2.95
80
90
5.20 4.46 3.97 3.61 3.34 3.12 2.93
5.11 4.41 3.93 3.58 3.31 3.10 2.91
5.8.1 Horizontal Coiling Density And Roving Count The formula of Horizontal Coiling Density and Roving Count C1 r1= tex r1 = horizontal coiling density C1 = coiling constant, around 85-90; in the above table, C1=87 The formula of vertical coiling density (for reference only): Vertical coiling density = Horizontal Coiling density (from the above table) x (5.5 to 8) Usually the number of vertical coils is adjusted by experience and testing. The following factors should also be taken into account which increase the vertical coiling density. • • • • •
High pressure of roving speed. Higher roving speed Higher twist multiplier Lighter roving weight Roving with lower horizontal coiling density.
As roving volume is directly related to the coiling density, therefore, the coiling density should be adjusted accordingly while charging the roving volume.
Spinning Processes and Types of Yarn
200 300 400 500 600 700 800
0
2-154
Spinning Processes and Types of Yarn
5.9 Number of Coils of Roving Table 5.9(1) Number of Coils of Roving (Length Direction) Length Direction, coil/ inch
Roving Count Above 0.6
7x
0.7-1.0
7.5 x Hank
1.1-1.5
7.8 x
1.6-2.0
8x
2.1-2.5
8.5 x Hank
2.6-3.0
9x
3.1-3.5
9.5 x Hank
3.5-4.0
10 x Hank
4.0-8.0
11 x Hank
Hank
Hank Hank
Hank
Normally : 38 x Hank
Table 5.9(2)
Number of Coils of Roving(Radial Direction) Radial Direction, coil/ inch
Roving Count 1.1-2.0
39 x
Hank
1.1-3.0
37 x
Hank
3.1-4.0
35 x
Hank
4.1-5.0
33 x
Hank
5.1-6.0
31 x
Hank
Textile Handbook 2-155
5.10 Number of Coils Per Inch of Roving Table 5.10
Number of Coils Per Inch of Roving
Twist Multiplier 1.10
Twist Multiplier 1.20
Twist Multiplier 1.30
No. of Coils Hank Roving 6.20 23.00 6.30 23.5 6.40 24.0 6.50 24.5 6.60 25.1 6.70 25.6 6.80 26.0 6.90 26.4 7.00 26.8 7.10 27.2 7.20 27.6 7.30 28.0 7.40 28.3 7.50 28.6 8.00 29.0 9.00 29.4 10.00 29.7 11.00 30.0 12.00 30.4 30.7 31.0 31.3 31.6 31.9 32.2 32.5 32.8 33.1 33.4 33.7 34.0 34.3 34.6
No. of Coils 35.0 35.3 35.6 35.9 36.1 36.4 36.6 36.9 37.1 37.3 37.6 37.8 38.0 38.2 39.4 41.7 44.0 46.1 48.2
Spinning Processes and Types of Yarn
Hank Roving No. of Coils Hank Roving 5.6 3.00 0.40 6.1 3.10 0.45 6.5 3.20 0.50 6.9 3.30 0.55 7.3 3.40 0.60 7.3 3.50 0.65 8.1 3.60 0.70 8.4 3.70 0.75 8.7 3.80 0.80 9.2 3.90 0.85 9.6 4.00 0.90 9.9 4.10 0.95 10.2 4.20 1.00 11.0 4.30 1.10 11.7 4.40 1.20 12.4 4.50 1.30 13.1 4.60 1.40 13.8 4.70 1.50 14.4 4.80 1.60 15.0 4.90 1.70 15.6 5.00 1.80 16.2 5.10 1.90 16.8 5.20 2.00 17.4 5.30 2.10 18.0 5.40 2.20 18.6 5.50 2.30 19.2 5.60 2.40 19.8 5.70 2.50 20.4 5.80 2.60 21.0 5.90 2.70 21.5 6.00 2.80 22.0 6.10 2.90 22.5 6.20 3.00
2-156
Spinning Processes and Types of Yarn
5.11 Common Defects in Roving Table 5.11
Common Defects in Roving and their Reasons
Defects
Reasons
Poor roving evenness, has serious thickness and thinness
* Top roller pressure is not functioning. * Roller setting is too big or too small. * Top roller seriously bent, serious damage on surface, no oiling on top roller shaft, therefore rollers are not running well. * Lapping up of bottom rollers, top rollers that cause roller to bend and setting moved. * Cracked/eccentric/missing tooth of draft change gear, gears are not well meshed and the gap between gears is too wide. * Weariness of roller stand, rollers vibrate to and for while running. * Roller stand is not levelled, top roller and bottom roller are not parallel. * Roving guide traverse motion is running outside the control range of top roller and apron. * Top elastic tensor opening is too tight or chock. * Poor sliver evenness, slivers rucked up and fed in or carrying flies. * Part of draft is not suitable or roving elongation is too high. * Roving twist is too high or too low. * Flyers vibrate seriously. * Condenser is not the right size, weariness, chock or jump. * Relative humidity is too low, roving moisture regain below 6%.
Soft bobbin, rug bobbin
* Twist multiplier is too low. * Bobbin winding density is not enough. * Number of turns on presser or flyer tip is not enough, therefore, roving tension is too small. * The curvature of presser is not right. * After ends down, wait for a very long span of time to take piecing, or too much defect roving had been pulled out. * Fed in sliver is too thin. * Temperature and humidity is not well controlled, relative humidity is too low.
Textile Handbook 2-157 * Wrong ratchet gear. * Jump of Bobbin wheel. * Revert device is malfunction. * Improper tension control, too much take or loose ratchet wheel in one doff. * Shaper wheel is not well meshing, or stopping while reversing.
Slacken head, slacken bottom
* Incorrect setting of spincle, flyer and presser. * Jumping of bobbin or spindle. * Wrong shaper ratchet gear setting, tension is too high. * Pressing on inside coils. * Serious wear of bobbin wheel bottom. * Some screws on lifter shaft loose,
Soft bobbin or hard bobbin in one doff
* Shaper ratchet wheel and lifter wheel are not in good combination. * Loose cone drum belt tension. * Improper roving tension control. * Roving twist is too high or too low. * Improper temperature and humidity.
Fly waste
* Sliver has flies, clearer wastes. * Poor top and bottom clearers, clearer cloths and cleaning device, especially serious for three up four down drawing frames. * Cleaning period is too long, machine is not stopped for cleaning, cleaning tools are not good, careless cleaning bringing flies into roving. * Flies from open top drop onto sliver or roving. * Sliver passage is not polish, fibre accumulated inside, especially shoulders of flyer.
Contaminated roving
* Improper oiling on top roller, apron, top roller shaft or roller neck, spindles. * Careless handling of slivers during periodic maintenance or gear changing. * Contaminated while handling slivers and roving. * Fed in sliver is contaminated. * Roving bobbin surface is contaminated. * Roving dropped on floor and contaminated. * Operators hands are contaminated, which stain roving.
Spinning Processes and Types of Yarn
Loose shoulder
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Spinning Processes and Types of Yarn
5.12 Factors Affecting Roving Elongation and Remedies Table 5.12 Factors Affecting Roving Elongation and Remedies Factors
Results
Adjustment
Starting position of cone Higher or lower in elongation drum is not correct in small bobbin or the whole doff. Tension gear is not correct The elongation from small, medium to large bobbin varies a lot. C o n e d r u m c u r v e No matter how the starting deformed or the design is positioning of the cone drum not good belt is adjusted, the problem of elongation cannot be solved.
Adjust according to the following table.
Reduce roving twist multiplier
Reduce roving density to lower fibre cohesive force and increase elongation.
Slightly adjust the cone drum belt starting position towards small diameter
Increase roving speed
Increase the vibration of front roller and flyer tip and increase roving elongation
Increase roving twist multiplier properly
High horizontal winding density
Change vertical display of roving and significantly increase elongation.
Change lifter wheel
High temperature and high humidity
Increase frictional force between flyer and presser, and also increase elongation.
Increase roving twist multiplier properly
Variation in tension of front and rear rows
Generally the elongation of the front row is higher than the rear row
Use false twist flyer cap or mark some flutes on the top of the flyer tip.
Rough flyer tunnel
Increase roving friction and also increase elongation.
Increase flyer maintenance cycle.
Adjust according to the following table. Replace the curvature of cone drum according to the defect.
Textile Handbook 2-159
5.13 Machine Automation
Examples of automatic doffing system and automatic transfer system are given in paragraphs 5.13.1 and 5.13.2.
5.13.1 Automatic Doffing and Bobbin Transfer System (RO-WE-MAT 670 Roving Frame, Zinser) Auto-Doffing RO-WE-MAT 670
A
Fully-automatic transfer between the roving frame and the roving bobbin transfer system: When the doffing process has been completed, the full bobbins are located in the bobbin store at the rear of the roving frame. The machine is producing. Now the automatic removal of the full bobbins is carried out by the bobbin changer, Two full bobbins are removed at a time for the trolley train of the RO-WE-MAT 670. The bobbin changer exchanges these two full bobbins for two empty tubes, which are positioned in the roving bobbin transfer system.
Spinning Processes and Types of Yarn
To reduce labour requirements in roving preparation, new and more sensitive stop motions have been developed for all types of break at the front and back of the machine. These are based on light beams and photo-electric cells. Maximum labour saving could be achieved by mechanizing the highly labour-intensive operation of removing full packages from the machine, replacing them with empty bobbins, and wrapping the loose roving end into the empty bobbin surface. Modern roving frames can all be coupled with the automatic doffing system and can be replaced it with empty bobbins.
2-160
Spinning Processes and Types of Yarn
5.13.2 Automatic Transfer System (Toyota) Toyota automatic transportation system - reserved roving change system Figure 5.13.2 (1)
Automatic Transfer System (Toyota)
1. Roving frame FL16 2. Roving doffing trolley TRD 3. Reserved sections for production line 4. Reserved roving transportation device TRT 5. Ring spinning frame RY5 6. Reserved roving exchanger TRC 7. Roving ends stripper ARS-N1 8. Winding machine
The automatic transfer system is applicable to a wide combination of spindles on ring spinning frames and roving frames. • The transportation chain of the Toyota system can be separated and joined by sections, therefore the ratio of the number of spindles on ring frames to the number of spindles on roving frames is not necessary a whole number. • Because the system can be separated and joined section by section, individual transportation chains can be linked with a roving frame or a spinning frame.
Textile Handbook 2-161 Figure 5.3.2(2)
Separation and Joining of Transportation Chain
Number of spindles on ring spinning frames 432
480
720
864
960
Note:
Number of spindles on roving frames 96 108 120 96 108 120 96 108 120 96 108 120 96 108 120
Length of transportation chain (number of ring spinning spindles) 24
30
36
48
60
96
108
120
X X X X X X X X X
(X) the corresponding combination The longer the transportation chain, the easier system control will be.
X
Spinning Processes and Types of Yarn
Table 5.13.2 (3) Example of number of spindles on ring spinning frames and roving frames
SECTION 6 - Spinning Process ............................... 2-162 6.1
Purpose of Spinning .......................................................... 2-162
6.2
Process Flow Chart for Various Common Spinning Systems ............................................................................... 2-162
6.3
Ring Spinning .................................................................... 2-162 6.3.1 6.3.2 6.3.3 6.3.4 6.3.5 6.3.6 6.3.7 6.3.8 6.3.9 6.3.10 6.3.11
6.3.12
6.3.13 6.3.14 6.3.15 6.3.16 6.3.17
6.4
Drafting system ........................................................... 2-163 Draft zones .................................................................. 2-164 Examples of drafting system for cotton ring frame .... 2-164 Top Roller Cots ........................................................... 2-172 Twisting ....................................................................... 2-179 Ring ............................................................................. 2-179 Traveller ...................................................................... 2-186 Wear and Life of the Traveller and Ring ..................... 2-191 Setting of Traveller Cleaner ........................................ 2-194 Traveller Speed in m/s (Source: R&F) ........................ 2-197 Relationship between Inside Diameter of Ring, Spindle Revolution and Traveller Circumferential Speed ........................................................................... 2-198 Relationship between Bobbin Diameter, Twist Number, Spindle Revolution, and Traveller Revolution ................................................................... 2-199 Relationship between Inside Diameter of Ring, Bobbin Diameter and Winding Angle ......................... 2-200 Ratio Values of Ring Diameter, Bobbin Diameter, Bobbin Length And Spindle Gauge ............................ 2-201 High Performance Ring and Traveller ........................ 2-203 Suessen Novibra Spindle HP-S 68 and Spindle Bearing ........................................................................ 2-208 Bobbin Building .......................................................... 2-213
Open-End Spinning .......................................................... 2-218 6.4.1 6.4.2 6.4.3 6.4.4
A
Principle of Open-end Spinning .................................. 2-218 Relationship between Rotor Speed, Rotor Type and Yarn Count .................................................................. 2-224 Layout of Spinning Components ................................ 2-225 Example of Recent Development in OE Spinning ...... 2-228
A
6.5
AIR-JET Spinning ............................................................ 2-230 6.5.1 6.5.2 6.5.3
6.6
Processing Parameters and Fibre Characteristics for Spinning 100% Cotton Yarn ........................................ 2-231 Muratec 851 MVS Air-jet Spinning Machine ............. 2-236 Muratec 804 RJS - Roller Jet Spinning ....................... 2-236
Various Developments in Spinning ................................. 2-237 6.6.1 6.6.2 6.6.3 6.6.4
Suessen Ring-Can Spinning System ........................... 2-237 Rieter ComforSpin ...................................................... 2-238 Suessen EliTe Yarn ...................................................... 2-239 Zinser Compact Yarn ................................................... 2-241
Back to Table of Content
2-162
Spinning Processes and Types of Yarn
SECTION 6
SPINNING PROCESS
6.1 Purpose of Spinning In spun yarn production, spinning is the final stage of processing that produces a continuous twisted strand of fibres which has received its final attenuation.
6.2 Process Flow Chart for Various Common Spinning Systems Ring(Combed)
Ring(Carded)
Rotor
Blowing Room
Blowing Room
Blowing Room Blowing Room
Carding
Carding
Carding
Carding
Drawing
Prep Draw
st
Prep Draw
1 passage Drawing
Lap Winding
2nd passage drawing
Air - jet
Lap Winding
Combing
Combing
st
1 passage drawing
1st passage drawing
2nd passage drawing
2nd passage drawing
Roving
Roving
Ring Spinning
Ring Spinning
Winding
Winding
6.3 Ring Spinning
O.E. Spinning
Jet Spinning
A
A spinning system in which twist is inserted in a strand of fibres by using a revolving traveller. The yarn is wound on since the rotational speed of the package is greater than that of the traveller. “Carded” and “combed” refer to the methods used to make cotton and cotton-blended spun yarns. All staple fibres have to be carded to help clean and disentangle the fibres. For less costly fabrics, the fibres are carded and are delivered to drawing and spinning processing to make into yarn, while for high quality fabrics, the fibres are delivered to combing to remove short fibres, before moving to the spinning
Textile Handbook 2-163
stage. Combed fibres have longer fibres, fewer speck and dirt impurities, and are more parallel. Therefore combed yarn looks smooth and shiny and is stronger and more expensive than carded yarn. Figure 6.3
(a) Combed yarn (b) Carded yarn. Note the neps present throughout the carded yarn.
(a)
6.3.1 Drafting system The standard drafting equipment on spinning frames consists of three pairs of steel rolls, and for most systems, aprons are mounted with the middle rolls. The top rolls are held in contact with the bottom rolls by pressures of the weighting arms applied on the roll neck between the two bosses. The top rolls are usually covered with synthetic material which provides a better fibre control. The speed ratio of each pair of rolls is so adjusted that the fibres are delivered from a slowly moving pair of rolls towards a rapidly moving pair of rolls. The distance between the front and the middle rolls, and the middle and the back rolls are adjustable to accommodate different fibre lengths. The three pairs of
Spinning Processes and Types of Yarn
(b)
2-164
Spinning Processes and Types of Yarn
rolls are positioned at an inclined angle of 45o to 60o with the horizontal to permit the twist to reach up to the front rolls, so that the ends will not break down.
6.3.2 Draft zones The amount of total draft to be applied is mainly dependent on the type and composition of the fibre material and the quality of the roving. The choice of draft range depends on the desired yarn qualities and the operating conditions of the frame (ends down behaviour) In-house spinning trials should be carried out to determine the optimum draft range. The purpose of rear zone drafting is to slightly tension the roving and to feed the fibre material to the main drafting zone in a well-stretched condition. In determining the optimum rear zone draft, care should be taken for a controlled draft of the roving in the rear zone- A hard twisted roving needs a higher rear zone draft whereas too strong a loosening effect on the roving indicates a necessity for reducing the rear draft. The front zone setting depends on the types of top apron cradle being used while the rear zone setting depends on the type of fibre to be spun, the length of fibre, and also the roving twist.
6.3.3 Examples of drafting system for cotton ring frame (Source; TEXParts)
a) SKF PK 2000 Series Drafting System for Cotton Ring Frame The arms of the PK 2000 series are designed for use in 3line double apron drafting arrangements for spinning cotton, man-made fibres and blends of both up to 60mm fibre length. Weighting Arm PK 2000 Series Ref. nos. PK PK PK PK PK
2025 2025 2035 2055 2065
-
1251 1251 1251 1251 1251
331 459 784 785 786
Textile Handbook 2-165
Types PK 2035 and PK 2065 weighting arms are mainly used for spinning longer staple fibres. They are designed for this purpose for use with rear and front rollers with a diameter of 35 mm. For spinning particularly fine yarns, materials that are difficult to draft and for spinning with high total drafts, weighting arms PK 2055 and PK 2065 are recommended. The drafting arrangement of the PK 2000 series is shown in Figure 6.3.3.a Figure 6.3.3.a Drafting arrangements
Spinning Processes and Types of Yarn
Note:
(1) Without clearer roller holder on face of arm (2) In the case of PK 2035 the middle guide element is 3.5mm lower on the PK 2025.
2-166
Spinning Processes and Types of Yarn
(i) Total draft The amount of total draft to be applied is mainly dependent on the type and composition of the fibre material and the quality of the roving. With weighting arms, types PK 2025 and PK 2035 the normal total draft range for speed-frame roving is, in practice, as much as 50 (see Table 6.3.3.a(i)). If higher total drafts of up to 70 are required, it is advisable to use PK 2055 or PK 2065. In special cases, it is even possible to achieve total drafts in excess of 70 using these weighting arm types.
Figure 6.3.3.a(i): Total drafts
Draft ranges for PK 2025 and PK 2035 Rear drafts
Total drafts
1.15 - 1.3
12-20 20-35 20-40 25-45 25-50
Extremely short carded cotton Carded cotton Combed cotton Blends of cotton and man-made fibres Pure man-made fibres
Draft ranges for PK 2055 and PK 2065 Rear drafts
Total drafts
1.15 - 1.3 1.3 - 1.6 1.6 - 1.8
upto 50 50 - 70 over 70
Cotton Man-made fibres Blends
(ii) Zone Settings and Maximum Fibre Length The rear zone setting (VF) depends on the type of fibre to be spun, the length of fibre, and also the roving twist. Inhouse trials should be carried out to determine the best rear zone setting. The front zone setting depends on the type of top apron cradle being used. Figure 6.3.3.a(ii)1 shows the zone settings for the PK 2000 series weighting arms while Table 6.3.3.a(ii)2 shows the summary of the zone settings and maximum fibre length.
Textile Handbook 2-167 Figure 6.3.3.a(ii)1
Zone settings for PK 2000 Series Weighting arms
Draft field mm
Bottom roller diameter Top Weighting apron arm cradle PK 2025 OH 62 OH 2022 OH 132 OH 2042 OH 122 PK 2035 OH 62 OH 2022 OH 132 OH 2042 OH 122 PK 2055 OH 62 OH 2022 OH 132 OH 2042 OH 122 PK 2065 OH 62 OH 2022 OH 132 OH 2042 OH 122
I
II
25/27 25/27
III
HF
25/27
44 44 53 53 68 46 46 55 55 70 44 44 53 53 68 46 46 55 55 70
27/30 25/27 27/30
25/27 25/27 25/27
27/30 25/27
27/30
VF min
34
34
36
36
VF Usual1) 50...65 50...65 60...70 60...70 Max 50...65 50...65 60...75 60...75 max. 40 40 50 50 60 40 40 50 50 60
Tatal Fibre draft length field max.mm GFmm 3-nipmax. point 45 45 54 143 54 60
143
132
132
45 45 54 54 60 45 45 54 54 60 45 45 54 54 60
Note : (1) The “usual” zone settings VF are values of practical applications, recommendation is to choose the maximum settings
Spinning Processes and Types of Yarn
Table 6.3.3.a(ii)2 Summary of the different weighting arm types for cotton drafting systems
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Spinning Processes and Types of Yarn
(iii)Roller Loading Three different loads can be set for the front top roller using the eccentric load selector on the front guide arm while two different load stages can be set on the middle and rear element of weighting arms PK 2025, PK 2035 and on the middle element of weighting arms PK 2055 and PK 2065. To achieve good yarn quality, it is advisable to use the second load (14 daN) for the front top roller when processing cotton and cotton blends. Pure man-made fibres, hardtwisted rovings, and the spinning of fine yarn counts may require the third load (18 daN). For these cases, the load on the middle and rear element of PK 2025/PK 2035 pendulum arms can, if necessary, be increased to 14/16 daN and the load on the middle element of PK 2055/PK 2065 to 14 daN. If the frame is idle for long periods and soft front top rollers are used, PK 2000 series weighting arms allow a supplementary partial load reduction on the front guide element (saddle load 6 daN) in order to prevent moire effects. If the OH 2042 (OH medium) is to process relatively long fibres or to spin fine yarn in drafting systems with PK 2000 weighting arms, the high load (14 daN) should be used at the apron roller. Table 6.3.3.a(iii) shows the roller loads of the PK 2000 series weighting arms Table 6.3.3.a(iii) Weighting arms PK 2000 for cotton ring frame drafting and their roller loads Weighting arm Ref. No.
Front top roller daN
Top apron roller
Rear top roller daN
PK 2000 Series PK 2025-1251 331
(6)1)-10-14-18
PK 2025-1251 459
(6)1)-10-14-18 1)
10-14 10-14
12-16 12-16
PK 2035-1251 784
(6) -10-14-18
10-14
12-16
PK 2055-1251 785
(6)1)-10-14-18
10-14
18
10-14
18
PK 2065-1251 786 1)
Partial load reduction
1)
(6) -10-14-18
Textile Handbook 2-169
(iv)Top Apron Cradles and Top Aprons Depending on the application, SKF weighting arms of the PK 2000 Series can be fitted with 3 different top apron cradles: • Short top apron cradles OH 2022/OH 62 for cotton and man-made fibres up to 40mm length, and for blends of both
• Long top apron cradles OH 122 for man-made fibres of cut lengths up to approx. 60mm. Table 6.3.3.a(iv) shows the top apron cradles for SKF weighting arms PK 2000 together with the associated top aprons, the apron inner diameter and the recommended standard range of distance clips. Table 6.3.3.a(iv) Range of top apron cradles, top aprons and distance clips for PK 2000 weighting arms Top aprons Gauge general Tw mm designation
Inner dia-meter mm
OH 2022-1247 888 OH 2022-1247 887 OH 2022-1247 889 OH 62 -0962 841 OH 2042-1250 133 1) OH 2042-1250 134 1)
68.4 75 82.5 90 68.4 75
PR 28 PR 28 PR 28 PR 32 PR 28/13 PR 28/13
37.0 37.0 37.0 37.0 42.1 42.1
OH 132 -0963 671 OH 132 -0963 673
82.5 90
PR 32/3 PR 32/3
41.5 41.5
OH 122 -0963 495 OH 122 -0963 500 OH 122 -0963 511 OH 122 -0963 512
68.4 75 82.5 90
PR 028 PR 028 PR 032 PR 032
51.3 51.3 51.3 51.3
Top apron cradles OH Ref. No.
Distance clip2) Ref. No.
Colour
OLC-0964 118 OLC-0017705 OLC-0964 119 OLC-0964117 OLC-0964 118 OLC-0964 119 OLC-0964 117 OLC-0964 118 OLC-0964119
yellow lilac white red yellow white red yellow white
OLC-0964 118 OLC-0964 119 OLC-0017 627
yellow white grey
Note: (1) For use in weighting arms of PK 2000 series only (high load setting (14 daN) at the middle element recommended). (2) One clip per cradle is required for each type of OH. These clips are not included in standard OH supply and have to be ordered separately.
Spinning Processes and Types of Yarn
• Medium top apron cradles OH 2042/OH 132 for cotton fibres over 40mm length, man-made fibres, and blends of both up to cut lengths of 50mm
2-170
Spinning Processes and Types of Yarn
(v) Top Roller Cots Top rollers for PK 2000 weighting arms are supplied as loose boss rollers without cots as standard. If desired, SKF will also supply top rollers with ready-ground cots. The cot quality can be determined by the customer. SKF supplies the top apron roller LP 1003 with plastic sleeves as standard. If requested, the top apron roller LP 1002 with cots can also be supplied. Cots with a Shore hardness of 65˚ to 85˚ are suitable for this top apron roller. (vi) Bottom Aprons The dimensions of the bottom aprons to be used depend on the design of the substructure of the drafting system; in practice, two types of substructure are most common. • Long bottom apron system - bottom aprons are guided and pretensioned by a tensioning link. • Short bottom apron system - bottom aprons are guided by specially designed bottom apron nose bars. b) Toyota Weighting Arm α 100 Main Specifications Max. top roller gauge: 145 mm Roller pressure: Front
10daN, 14daN, 18daN/2 spindles 3-load selection with load-reducing position
Middle
10daN, 14daN/2 spindles 2-load selection
Back
12daN, 16daN/2 spindles 2-load selection
Textile Handbook 2-171 Figure 6.3.3.b
Weighting Arm α 100
The Ri-Q-Draft system has been further improved on the G 33 by the incorporation of a new bottom apron guide bridge, the Ri-Q-Bridge. The Ri-Q-Bridge guarantees optimum apron running. It is so accurately coordinated with the operation of the top apron that absolutely precise fibre guidance is achieved in the main draft. This results in a striking improvement in yarn quality and IPI values. Its main distinguishing features are: • the P 3-1 pneumatic guide arm • high-precision bottom rollers • drafts up to 80-fold • drafting system drive separate from spindle drive • drafting system powered from both sides with independent drives • torsion in the bottom rollers reduced by
1 4
• very suitable for materials which are difficult to draft (man-made fibres) • Ri-Q-Bridge for controlled fibre guidance
Spinning Processes and Types of Yarn
c) RI-Q-Draft System
2-172
Spinning Processes and Types of Yarn Figure 6.3.3.c
RI-Q-Draft drafting system
6.3.4 Top Roller Cots With reference to the cot quality, rear and front top rollers are mutually interchangeable. Determining the choice of cot depends mainly on the type of fibre to be processed and its running properties. Cots having a Shore hardness of 65o to 85o are used for rear and front top rollers today. In the case of soft cots, it is advisable to apply a low loading weight on the file front top roller if the frame is idle for longer periods. This will prevent moire formation caused by fluting. a) Berkol Top Roller Cot Specification Table 6.3.4.a
Berkol Top Roller Cot Specification
Quality
Colour
Shore A
HA66A
Red
66o
The soft all-round cot. Top feed and delivery on ring spinning machines. For top yarn quality, especially with 100% cotton. Also for blends and man-made yarns in good climatic conditions. Delivery on comber drafting systems.
Characteristics
HA65S
Brown
67o
Detaching top roller on combers and for drawframes. Minimal coating and lap formation.
HA74T
Green
74o
The all-round cot. Top feed and delivery on ring spinning machines and roving frames. For nature fibres, synthetics and blends. Minimal lap formation, abrasion-resistant, good yarn quality.
Textile Handbook 2-173 78o
For ring spinning machines, roving frames, drawframes, OE spinning machines. Minimal lap formation, extremely abrasion-resistant, withstands high mechanical stress. All-round cover.
HA80OE
Yellow
HA85S
Bordeaux 83o
HA65D
Black
68o
For texturing machines, friction machines, friction drives. Minimal swelling, abrasion-resistant.
HA75D
Black
78o
For texturing machines, friction drives. Minimal swelling, abrasionresistant.
HA90D
Black
87o
Winding machines, friction drives. Very abrasion-resistant and withstands heavy stressess.
For combing preparation, comber drafting systems, drawframes. For high stresses, minimal lap formation, abrasion-resistant.
b) Advantages of Soft Cots One Simple way of achieving better CV, thins, thicks and strength is to change from the so called hard cot (80o Shore A or above), to a mid soft (75o shore A) or soft (65o-70o Shore A) cot in the spinning operation. Two major aspects contribute to this improvement. They are frictional properties and compression. Friction Property Soft rubber typically has higher frictional properties than hard rubber and thus grips and exerts more uniform control on fibres resulting in improved yarn quality statistics. Resilience/Compression Compression and its influence contributed to the main improvement of the yarn, particularly when short, cotton
Spinning Processes and Types of Yarn
Note: Shore A hardnesses according to DIN
2-174
Spinning Processes and Types of Yarn
fibres are being spun. The softer material will compress more, resulting in contact with more flutes on the bottom steel roll and a larger contact surface which we refer to as ‘footprint”. This larger “footprint” has a threefold effect on yarn control. (i) Shorter nip to nip between cot and apron This characteristic has the highest influence on improved yarn quality when producing 100% cotton for an Nm 50 and higher. When cotton is being produced, there is always a percentage of short fibres involved even if the cotton is combed. It is common knowledge that the closer the apron nip can be set to the cot nip, more short fibres will be controlled and yarn quality statistics improved. In Figure 6.3.4.b the top cot and bottom steel roll in the upper section of the figure where a hard cot is being used shows a nip point distance of B-E. In the lower section, it is observed that by simply installing a soft cot, the nip distance has been reduced to A-E. Under this scenario, more of the shorter fibres are controlled and yarn quality statistics improved. (ii)Shorter spinning triangle In the lower half of Figure 6.3.4.b, a soft cot is used. The overhang is increased while the spinning triangle thereby reduced. This will result in less ends down and thus higher production rates and efficiency. As can be seen, the soft material has moved the overhang from point C for the hard cot to point D. (iii)Expanded “Footprint” Referring to Figure 6.3.4.b, the contact surface of the cot with the steel roll is increased from B-C on the hard cot to A-D on the soft cot. The combination of higher friction and larger “footprint” for the soft cot allows for increased control over the fibres. This is especially important when running fine counts that possess fewer fibres per cross section.
Textile Handbook 2-175 Figure 6.3.4.b Soft Cot Plus Closer Nip Point Equals improved Yarn Quality
(i) Cot Grinding • Grinding Machines Various types of grinding machines are available for specific use with textile rollers. They fall into 2 categories: -
Traverse Grinder - this type of grinder utilises a sliding (traversing) bed which carries the roller past a rotating grindstone.
-
Plunge Grinder - this type of grinder presents the roller to a revolving grinding drum which generally has a small lateral traverse motion. The whole rubber surface is in contact with the grinding media which is either a grindstone or emery covered drum.
The choice of machine is dependent on various factors; generally traverse grinder is more versatile and is lower priced. The plunge grinder is more productive when automated for large runs and is more expensive. Both types, correctly used, give the same end results.
Spinning Processes and Types of Yarn
c) Cot Grinding Specification
2-176
Spinning Processes and Types of Yarn
The following general conditions apply for the grinding of DAYtex cots: • Traverse Grinding Speeds -
Stone Surface Headstock (roller speed) Traverse
1800-2000 m/min 300-500 rpm 400-500 mm/min
Type of Grindstone Diameter Width Grade
-
200-250 mm 25-35 mm 80 grit (resin bonded)
• Plunge Grinding -
Generally speaking, unlike traverse grinding where surface finish is related to machine speed, plunge grinding is more time controlled, i.e. grinding time and polishing time.
-
Grinding time relates to the time taken to feed the roller from the initial contact of the cot with the grinding media until it reaches the required finished outside diameter (FOD).
-
Polishing time relates to the time when FOD is reached until the roller is ejected from the machine.
-
Grinding and polishing times vary according to the following:Hardness and type of rubber: Amount to be ground off wall thickness: Surface finish required.
Textile Handbook 2-177
(ii) Grinding Cycles and Tolerances • Grinding cycle Various factors influence the length of time between one grind and the next. They are: bulk of yarn being produced; roller speeds; roller pressures; type and fineness of fibre; oils and additives present on the fibre. Since conditions vary considerably, it is not possible to specify the length of time between regrinding but a guide may be taken from the following:-
-
Ring frames producing medium cotton yarn (25 Tex) approximately every 3000 hours.
-
High speed draw frames approximately every 500 hours.
Usually the grinding cycle is determined by experience on individual installations, and since grinding completely renews the cot surface, it is uneconomic to prolong the regrinding cycle. • Depth of Grinding The amount to be ground off is determined by the amount of wear on the cot. The depth should at least be such that the complete cot surface is renewed, and 0.20 mm is considered an optimum from the cot wall thickness. • Grinding Tolerances Eccentricity of finished ground cots should always be kept to an absolute minimum by the use of well maintained equipment. Centreless grinding of double boss rollers for the final grinding operation should always be used. The following general tolerances apply to most textile drafting applications. - Concentricity: Within 0.02 mm TIR - Parallelity:
Up to 40 mm Face - 0.03 mm Over 40 mm - 100 mm Face - 0.04 mm Over 100 mm - 250 mm Face - 0.06 mm
Spinning Processes and Types of Yarn
Normal Time Between Regrinding
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Spinning Processes and Types of Yarn
The amplitude of periodic variation in a yarn is proportional to the drafting roller eccentricity and increases as the draft increases. It is essential therefore to have a higher degree of roller concentricity when producing under high draft conditions. • Surface Finish (Profile) For optimum performance, in addition to concentricity and parallelity, it is essential that the ground cot surface has the required profile. Factors such as the amount ground off the cot, time for grinding/polishing, grinding machine conditions, and the type and hardness of rubber all influence the final surface profile. Tests have shown that the cot surface profile influences lap resistance and therefore cot grinding/polishing times should be determined for a particular grinding machine’s conditions and according to the cot quality being ground. As a guide, cots should ideally have a surface profile with 0.75-0.95 microns Ra., when processing fibres in the fineness range 1.5-2.5 dtex. Average Roughness Ra. DIN 4768 This is the arithmetic mean of all values of roughness profile R within the measuring length 1 m.
Figure 6.3.4.c(ii) Average Roughness
Textile Handbook 2-179
Example: SURFACE PROFILE 0.8 Ra. (ISO N6)
DAYtex 755 (65o) DAYtex 118 (75o) DAYtex 890 (85o)
Grinding Time
Polishing Time
15 seconds 15 seconds 15 seconds
2 seconds 6 seconds 5 seconds
Note: To grind to a lower surface profile, i.e. below 0.75 microns, Ra. can increase roller lap frequency.
6.3.5 Twisting Twisting is done by the spindle and traveller. Twist is inserted by threading the yarn through the traveller and the other end of the yarn revolves at high spindle speed on the circular track of the ring. As the twist is inserted, it progresses upward, through the thread guide, to the front roll and so gives the fibre ribbon enough strength to withstand the running tension. At the same time, the ring is reciprocated vertically as the frame runs. This motion causes the yarn delivered at the front roll to wind on the bobbin in an ascending and descending spiral, giving a uniform yarn package on the bobbin. As part of the general trend to increase productivity in spinning, considerable progress has been made in working towards high spinning speeds. One of the limiting factors is the allowable traveller speed. Actually, the practical limit of the traveller speed is affected particularly by the weight and shape of the traveller, the ring diameter, and the contour of the ring flange.
6.3.6 Ring The ring together with the traveller are the main elements during ring spinning and twisting. They determine to a large extent the performance and the operation conditions of the ring frame. During the operation, the ring guides the traveller which is essential for the perfect positioning of the yarn and the formation of the cop.
Spinning Processes and Types of Yarn
The above figures were obtained when grinding off 0.1 mm from the cot wall (reduction of O.D. by 0.2 mm) on a plunge type grinder.
2-180
Spinning Processes and Types of Yarn
a) Kanai Ring Flange Number and Width of Flange Ring Figure 6.3.6.a Single flange ring
Double flange ring
Ring Flange F No. 1/2
Width 2.5 mm
1
3.2 (1/8") 3.35 3.6 4.0 (5/32") 4.4 4.8 (3/16") 5.6 (7/32") 6.4 (1/4")
1-1/2 2 3 4 5
b) Popular Size of Flange Rings for Various Ring Frame Table 6.3.6.b(1)
Popular Sizes of Flange Rings for Various Ring Frame (Source: AB Carter) Dimension in mm
Make of Ring Frame a Rieter
Category Non-Reversible
b
Chinese Jing Wei/ Erfengi
Non-Reversible
c
Marzoli
Non-Reversible
d
Toyota
Single Flange
Inner Fitting Dia. Dia. 38-40 N/A 40-42 N/A N/A 38 38-42 N/A N/A 45 47.1 42 38 50.8 38-41 50.8 41-44 54 45-48/ 57.5
Outer Dia. 51 54 51 54 54 29 53 53 56 60
Full Height 8 8 10 10 10 10.8 19 19 19 19
Flange 3.2 3.2 2.5 3.2 4.0 3.2 2.5 3.2 3.2 4.0
Textile Handbook 2-181 Zinser
Single Flange
f Howa
Single Flange
e
g
Robert Arrow Platt
Figure 6.3.6.b(2)
Reversible
For RIETER
CHINESE M/C
ZINSER
For ROBERT ARROW
4.5 51 54 53 60 N/A N/A N/A
18 18 18 19 19 3/8" 3/8" 3/8"
3.2 3.2 3.2 3.2 3.2 F1 F1 F2
MARZOLI
HOWA
Spinning Processes and Types of Yarn
For TOYOTA
36-40 47 38-42 49 42-45 52 38-41 50.8 41-45 57.5 1-3/4" 2.0" 2-5/16" 2.0" 2-1/4" 2-9/16"
2-182
Spinning Processes and Types of Yarn
c) Ring Profile Shapes (Source: Reiners + Furst {R&F})
Figure 6.3.6.c Profile Shapes
EL Profile (elliptical profile)
Preferential profile shape for • flange 1 rings in the fine count range • the use of deep bow-shaped and light travellers e.g. for spinning fine combed cotton yarns • highest spindle speeds
EL-AD Profile
Special profile (anti-doffing) to avoid end breakages after the doffing. Further requirements of application comparable with El profile.
Standard Profile
K Profile
Preferential profile shape for • flange 1 rings with medium yarn counts • flange 2 rings with medium and coarser yarn counts Standard profile with enlarged traveller contact area on flange 1 rings • recommended for medium and coarser yarn counts • for the use of high bow-shaped travellers with enlarged yarn passage
Textile Handbook 2-183
d) Comparative Chart For Rings -Based On Construction (Source:AB Carter) Table 6.3.6.d Comparative Chart For Rings Carter SATIN METRO
Borgosesia Bracker RZD N/A RZD protected Thermo TB/800
Reiners + Furst Kanai Nihon Spindle N/A KS/SGL N/A CHAMPION PRIMAT SSQ-M
III
M-1000
ECO-DUR
N/A
N/A
IV V VI VII VIII IX
CROWN S-1000B N/A N/A
NCN protected STRATO/ CARAT N/A N/A B-001 N/A N/A N/A N/A N/A TITAN N/A ORBIT/ SU SU
N/A Nitro-polidur DIADUR N/A CERA-NIT N/A
N/A N/A MAXCEE XELMAT N/A RIORA
N/A N/A N/A SSQ-C N/A N/A
S-1000 N/A
e) Application of Horizontal Ring for Spinning and Twisting (Source: Kanai) Table 6.3.6.e Ring type Spin- KM ning
Application of Horizontal Ring for Spinning and Twisting
Flange Standard Suitable width i n s i d e traveller (mm) diameter range (mm) 2.5 32-50 OSS
Application Spindle revolution rpm Cotton, weft and 40s-220s 11000warp 17000 Kind of fiber
Ya r n count
KS2
3.2
40-55
OS-OS smooth Cotton, cotton/ 20s-100s 11000GS-GS smooth synthetic 18000 OSY.ZS/h.f.YS-2
KS2
3.35
40-55
KW
4.0
45-60
O.O smooth G.GS.OH.R. OSY.OY ZS/hf, YS-2 O.O smooth G.G smooth OH.OY.BZ/hf
Twist- KW2~5 4.4-6.4 ing
63.5-100 O.G.GR.LG
Cotton, cotton/ 16s-100s 11000synthetic rayon 18000 staple Synthetic fibre, 10s-30s 6000cotton, rayon 14000 staple Cotton, rayon 20s/2staple fibre, 60s/2 synthetic fibre
300010000
Spinning Processes and Types of Yarn
I II
2-184
Spinning Processes and Types of Yarn
f) Breaking-in instructions for Flange Rings (Source:AB Carter) All ring manufacturers are constantly working to develop new ring finishes that will allow rapid ring break-in but to date there are no rings available which do not require breaking-in. This is because the travellers are running on the flange of rings in a tilted position with inclined angle, which changes with the characteristic of the yarn being processed. Only after breaking-in can a proper seating for the travellers be established which will ensure optimum performance of travellers. Therefore a proper breaking-in process for new rings is an absolute necessity. An improper or insufficient breakingin process will hamper the performance of the traveller and shorten the life span of the rings. The duration of breaking-in varies in accordance to the type of finish on the rings. Some rings may require just a few traveller changes which means that the complete breakin process can be accomplished within one shift. The following table is an example which is based on the standard polished and black odized finish rings, indicating duration and total number of traveller replacements that would be determined by the condition of wear as well as the percentage of burnt travellers after replacement. Classification of travellers in terms of wear: • Burnt - these are travellers which present a deep blue or black colouring on the inside, with brown shading on the outside surface of the horn. • Worn - these are travellers which present a knife edge on one side, and an indentation on depth which is over 2/3 of the traveller thickness on the other side. • Pitted - these are travellers which present inside wear on one side only, near the flange opening (tip of horn).
Textile Handbook 2-185
• Normal - these are travellers which present an indentation of depth which are 1/3 - 1/2 of the traveller thickness without any colouring on the outside, although on the inside they may have a trace of black. Normal breaking-in : Burnt Less than 3%
Worn 5-10%
Pitted 20-30%
Normal Over 70%
Difficult breaking-in : Worn Pitted Normal More than 20% More than 30% Less than 60%
It is very important to check the condition of the travellers after each change, or at least once as indicated in the time table, during each phase of the breaking-in process, thereby ensure that the process is being followed properly. If the situation is better than the “Normal breaking-in” then it is possible to cut down the total number of traveller replacements, or to shorten the procedure of each phase. On the other hand, if the situation is comparable or worse than the ‘Difficult breakingin’, that means either the speed set up is excessive or the replacement is too long or the break-in procedure have not been followed correctly. When breaking-in new rings, never use silver plated travellers as silver would fuse with the rings at irregular micro-welding spots and block the track for travellers. Non-plated travellers are able to do a better job of breaking-in new rings than plated travellers, but they also tend to damage the rings if the breaking-in process is not followed. There are two different procedures recommended by different ring makers for the selection of traveller size (number). For example for 45T/C, Ring ID 42 maximum spindle speed projected is 17000 RPM. Travellers of No.8/0 are in used on rings of 3 years old. • To reduce the traveller size when the traveller speed is increased. In phase I at 80% of normal speed, No.8/0 travellers is suitable. In phase II at 90% speed, No.9/0 is applied, and in phase III, at 100% speed, No.10/0 is applied, By following this method, due to the compensated friction of travellers on the rings, the proper tracks are formed more slowly, and the duration of breaking-in is comparatively longer, but will result in longer life for the rings.
Spinning Processes and Types of Yarn
Burnt More than 5%
2-186
Spinning Processes and Types of Yarn
• To increase the traveller size when traveller speed increased. In phase I, at 80% of normal speed, No.10/0 traveller is being chosen. In phase II, at 90% speed, No.9/0 is applied, and in phase III, at 100% speed, No.8/0 is applied.
6.3.7 Traveller The traveller accomplishes two main tasks while running on the ring at high speeds: • it provides the fibre band or the double thread supplied by the feed rollers with the necessary torsion • it assists in winding the yarn onto the bobbin in the form of a cop with the correct tension. Steel travellers are hardened to a certain degree and polished to a mirror finish. They can be adapted in shape, weight and surface finish to the ring, the yarn type and the yarn count. a) R&F Traveller Wire Profile Figure 6.3.7.a
Wire Profiles Wire profiles preferred for yarns of cotton and rayon staple, if the hairiness is supposed to be as low as possible. Suited for average spindle speeds.
Suited for higher performance with cotton, synthetics and blended yarns. Wire profile preferred for hosiery twists.
Suited for highest performance with fine combed cotton yarns. The hairiness and end breakage values remain low.
Suited for highest performance with cotton, rayon staple, synthetics and blended yarns in the fine and medium yarn count range. Improved values of hairiness and operating time.
Textile Handbook 2-187 Wire profile preferred for core yarns as well as acrylics or synthetics. The yarn passage is made of round wire profile whereas the traveller foot at the ring contacting area has a flat or half-round wire profile which have a higher loading capacity. Therefore the achievable traveller speed is significantly higher compared to travellers of round wire. Suited for some delicate synthetic yarns or for long staple fibres in the coarser titre range. The achievable spindle speed is significantly lower compared to other wire profiles.
Table 6.3.7.b Flange
Comparative Diagram of Horizontal Steel Traveller Circle
Carter circle
Kanai
Bracker
Reiners + furst Chinese
F 1/2
KD - 3/8 EL REG KD - 1/2 EL REG RM - 3/8 E HRW
OSS OSS -
UM udr
-
OSS OSS CO
F1
PC - 5/8 EL FIR PC - 7/8 EL HR TE - 3/8 EL HR TE - 5/8 EL FIR TE - 7/8 EL FIR TE - 1 EL HR
-
Cl MM udr Cl MM udr Cl LM udr Cl LM udr Cl LM udr -
Cl hr EMT Cl hr EMT Cl hr EMT Cl hr MT
-
CD - 5/8 EL REG CD - 3/4 EL REG FT - 5/8 EL HRW FT - 3/4 EL HRW
OSY YS - 2 ZS/ hf ZS/ hf
Cl UL f Cl UL f -
Cl hd KS Cl hd KS
6802 6802
FT - 1 EL HRW M - 3/8 EL FIR M - 3/8 EL HR IMP M - 5/8 EL HRW RM - 7/8 EL HRW
Z/ hf MS/ hf MS/hf MS/ hf
C1 UM udr Cl UM udr C1 UM udr
HEI 1 hr EMT HEI 1 hr EMT HEI 1 hr EMT
WT- 1 6903 6903
Spinning Processes and Types of Yarn
b) Comparison of Horizontal Steel Traveller Circle (Source: AB Carter)
2-188
Spinning Processes and Types of Yarn
F2
-
Cl rf MT El 1 hrW El l f HW Cl f T El 1 f HW Cl r C2 C2 f C2 f
-
OSY/hf OS OY OH S G GH G G
Cl SM fr Lldr ELl f Ml f EM1 f EM1 udr Cl SH fr Cl r C2 dr C2 r C2 f C2 f
FT - 1 EL HRW FT - 1 EL HR IMP FT 1-1/2 EL HR IMP FT - 3 EL HR IMP BL - 2 EL REG
Z/ hf YZ/ hf O
C2 UM udr M2 f
C2f T
O
BL - 2 EL HRW CT 1-1/2 EL HR G - 3 EL DOFF SH - 2 EL HR SM - 2 EL HR
PK/ hf O -
M2 dr EH2 dr H2 fr EH2 dr EM2 dr
C2 hd T C2 hr T C2 rf MT C2hrTM C2 hr T
-
RM - 7/8 EL WIDE RM - 7/8 EL FIR IMPMA - 1 EL DOFF GS - 7/8 HRW G - 1 EL REG GM - 1-1/2 EL REG BL - 1 EL REG BL - 2EL HRW BL - 2 EL REG IMP G - 3 EL DOFF F 1-C CIR 3 REG IMP CIR 3 DOFF F 2-C PC - 5/8 EL HR PC - 7/8 EL HR TE - 3/8 EL HR TE - 5/8 EL HR
FO FO GS G G G
Note : The above recommendations are the closest cross matching in terms of shape and cross section of wire, but are not identical to each other and should be used as a guide line only. Final selection should be determined by actual testing results.
Textile Handbook 2-189
c) Comparison of horizontal flange traveller weight (Source:AB Carter) Table 6.3.7.c (1) ISO #
30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
467 454 441 428 415 402 389 376 363 350 337 324 311 298 285 272 253 233 214 194 168 149 130 117 104 91 84 78 71 65
Kanai Z 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1/1.5
Eadie
R&F
28
29
29
27
28 27 26 25 24 23 22 21 20
28 27 26 25 24 23,22 21 20 19
19 18 17 16 15 14 13 12/11 10 9 8 7 6 5 4 3 2 1
18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2
26 25 24 23 22 21 20 19 18 17 16 15 14 13 12/11 10 9 8 7 6 5 4 3 2
Bracker
Weight gr/ 10 g/1000 466.5 72 453.6 70 440.6 68 427.7 66 414.7 64 401.8 62 388.9 60 375.8 58 362.9 56 349.9 54 337.0 52 329.0 50 311.0 48 298.0 46 285.1 44 272.2 42 252.7 39 233.3 36 213.8 33 194.4 30 168.5 26 149.0 23 129.6 20 116.6 18 103.7 16 90.7 14 84.2 13 77.8 12 71.3 11 64.8 10
Spinning Processes and Types of Yarn
Carter
Comparison of Horizontal Flange Traveller Weight
2-190
Spinning Processes and Types of Yarn
Carter
ISO #
Kanai MS
1/0 2/0 3/0 4/0 5/0 6/0 7/0 8/0 9/0 10/0 11/0 12/0 13/0 14/0 15/0 16/0 17/0 18/0 19/0 20/0
58 52 49 45 42 39 36 34 32 31 29 27.5 26 24.3 22.7 21 19.4 18 16.2 14.6
1/0 1.5/0 2/0 2.5/0 3/0 3.5/0 4.5/0 5/0 6/0 6.5/0 7/0 8/0 9/0 10/0 11/0 12/0 13/0 14/0 15/0 17/0
21/0
1.3
19/0
22/0
11.3
21/0
23/0
9.7
24/0
24/0
8.1 26/0 6.5
25/0
28/0
Eadie
R&F
1 1/0
1 1/0 2/0 3/0 4/0
1/0 2/0 3/0 4/0
7/0
5/0 6/0 6/0 7/0
8/0 9/0 10/0 11/0 12/0 13/0 14/0 15/0 16/0
8/0 9/0 10/0 11/0 12/0 13/0 14/0 15/0 16/0
17/0 18/0
17/0 18/0
20/0 21/0 22/0 23/0 24/0
19/0 20/0
5/0 6/0
Bracker
2/0 3/0 4/0 5/0
7/0 8/0 9/0 10/0 11,12/0 13/0 14/0 15/0 16/0 17/0 18/0 19/0 20/0 22/0 23/0 24/0 25/0 26/0 27/0
Weight gr/ 10 g/1000 9 8 7 1/2 7 6 1/2 6 5 1/2 5 1/4 5 4 3/4 4 1/2 4 1/4 4 3 3/4 3 1/2 3 1/4 3 2 3/4 2 1/2 2 1/4 2 1/8 2 1 7/8 1 3/4 1 5/8 1 1/2
58.3 51.8 48.6 45.4 42.1 38.9 35.6 34.0 32.4 30.8 29.2 27.5 25.9 24.3 22.7 21.1 19.4 17.8 16.2 14.6 13.9 13.0 12.2 11.3 10.1 9.7
1 1/4 1 1/8
8.1 6.9
1
6.5
d) Selection of Traveller Number (Weight) (Source: Kanai) There are many factors and different working conditions, each of which has bearing upon the traveller number, and therefore it is very difficult to find out the correct traveller number from a particular formula. The number can be found out approximately according to experience or data of various kinds. From the following nomograph, one can easily find the optimum traveller number when the yarn count to be spun, the ring diameter to be used and the spindle revolution to be operated are given.
Textile Handbook 2-191 Figure 6.3.7.d
Nomograph of a optimum Traveller Weight
When the yarn count is cotton 40s (Ne), the ring diameter is 44mm and the spindle revolution is 14000 rpm., the traveller number will be obtained as follows: 1) Connect the spindle revolution 14000 rpm. with the ring diameter 44 mm extending to the axis A (line p) 2) Connect the intersecting point on the line-p and the axis A with the yarn count cotton 40s (Ne) (line q) 3) The point which the line q intersects the axis W shows the optimum traveller weight/ number. (OS type = 3.24 g/ 100 pcs. = No.5/0) In addition to the above, the perfect traveller selection should be made by experienced supervisors in a company’s mills according to its standard spinning conditions.
6.3.8 Wear and Life of the Traveller and Ring a) Traveller To maximize the operative time of travellers is the common goal of all spinning managers. Prolonging the change cycles of travellers, it reduces cost, and most importantly, increases production efficiency. Care should be taken that the change cycle is not extended to the point that worn or damaged
Spinning Processes and Types of Yarn
Example:
2-192
Spinning Processes and Types of Yarn
travellers are used, as the resulting deterioration of yarn quality and possible damage to rings will more than offset the savings of extending the traveller’s life. There are four primary factors for selection of proper travellers which are: Circle-Shape, Type Size -Traveller No. Profile- Cross - Section of Wire Finish-Surface Treatment But there are also other factors that determine the life span of travellers: (i) Condition of rings • Finish of rings • Time of operation • Procedure of breaking-in • History of yarn changes (ii) Property of yarn • Material processed • Twist factor • Evenness (iii) Mechanism of machine • Centering of spindle • Leveling of ring rail • Setting of traveller clearer • Size of package • Transverse distance of ring rail in relation to inner diameter of rings • Balloon control ring (iv) Operation condition • Traveller Speed • Ambient temperature All of the above mentioned factors can vary from mill to mill, thus making a direct comparison from mill to mill virtually impossible. Therefore, it is recommended that the proper change cycle of travellers be based on following criteria :
Textile Handbook 2-193
• Change of yarn quality, example CM40, by USTER standard - CV% of evenness =Goes up by 2% or more (From l3 to l5) - Neps= Increased by 30% or more (From 30 to 40) - Hairiness= Goes up by 1/2 rating or more (From 4.2 to 4.7) - Yarn strength= Decreased by 20% or more. • Number of yarn breaks-increased by over 30% (From 10 to 13) • Percentage of burnt travelers - 5% or more
A ring usually should be considered worn and due to be replaced when its nominal size of flange is reduced of 5% or more. For example, the nominal size of a Flange 1 new ring is 3.2mm, therefore, it should be replaced when it measures 3.05mm or less. It should be remembered that, due to manufacturing tolerance, some new flange 1 rings can range between 3.15mm and 3.25mm, therefore, it is important to keep record of the actual size of the rings when they are new in order to avoid misjudgment in wear determination. The main cause of ring wear is due to micro-welding points between the traveller and the ring, are consequently the longer seriously worn travellers are left operating on the ring, the more micro-welding points result and the shorter the ring life. Therefore, the selection of suitable travellers and the traveller change cycle are the prime factors related to the life and performance of the rings (this applies to rings of same quality and under same operating conditions). Some spinning mills replace the travellers only after very long intervals (say 4-6 weeks) because when they inspect the travellers after the change, they find that some travellers seem to be in an acceptable condition as regards wear, without realizing that these travellers have been mounted recently to replace those that have already burnt and flown off during the running cycle. By the same token, when suitable travellers are operating properly, with a very slow rate of wear, the fewer microwelding points appear the longer the ring life becomes.
Spinning Processes and Types of Yarn
b) Ring
2-194
Spinning Processes and Types of Yarn
Table 6.3.8.b is a guideline to compare the life of rings in months to the maximum life of the travellers in days and percentage of worn travellers found after replacement. Table 6.3.8b Estimate Life of Rings (Months) Percentage of Worn ( Burnt) Traveller
Traveller Life in Day
5 7 10 14 21 28
2.5%
5%
7.5%
10%
15%
18 24 30 36 48 72
17 16 15 14 22 20 18 16 28 26 24 22 34 32 30 28 45 42 39 36 68 64 60 56 Estimate Life of Rings (Months)
• When the maximum life of travellers is 5 days (meaning the travellers are still operating within the tolerance of yarn breakage and quality) when there is 2.5% burnt travellers, estimated life of rings is 18 months, while with 5% burnt travellers, life of rings is 17 months. • When the maximum life of travellers is 28 days, and there is 2.5% and 5% burnt travellers, then estimated ring life is 72 and 68 months respectively.
6.3.9 Setting of Traveller Cleaner (Source: R&F) Figure 6.3.9 Traveller Cleaners
The use of traveller cleaners (fluff collectors) is highly recommended, because they keep the travellers free from fibre fly. If no traveller cleaners are installed or if they are installed too far away from the ring, the traveller may be blocked by accumulating fibre fly. This results in an increase of yarn breaks. Another consequence may be rough yarns that impair the yarn quality.
Textile Handbook 2-195
Traveller cleaners being installed with the correct distance to the ring attribute much to the optimum operating results and low yarn break values. For each setting distance “E” mentioned in the table, magnetic gauges are available with the required setting distance. Table 6.3.9 (1)
Distance for Traveller Cleaners with the Use of Flange 1 Travellers Setting Distance “E” in mm
-
1.9 1.8 2.0 2.2 2.0 1.8 1.9 2.1 2.2 2.0 2.1 2.2 2.2 2.0 2.4
1.5
1.7
1.5 1.7 1.7 1.5
1.7
1.7
4 -7
8 -16
2.0 1.9 2.2 2.4 2.0 2.1 2.3 2.4 2.2 2.3 2.4 2.4 2.2 2.6 -
2.6 2.6 2.7 2.8 2.9 2.9 2.7 2.2
2.0
Traveller Type
C1f C 1 f Type -FC 1 f Type -TC 1 hd Type -TC 1 hd Type -TWC 1 hr Type -TWC 1 hr Type -EMC 1 hd Type -KMC 1 f Type -MC 1 hd Type -MC 1 hr Type -MC 1 hd Type -EMTC 1 hr Type -EMTC 1 hd Type -MTC 1 hr Type -MTC 1 hd Type -KSC 1 rf Type -MT-
20/0 4/ 0 -5 /0 -3
4 -7
8 -16
1.6 1.5 1.6 1.5
2.2 2.1 2.1 2.2 2.5 2.2 2.3 2.0 2.1 2.2 2.3 2.5 2.9
2.6 2.4 2.2 2.6 2.6 2.3 2.4 2.1 2.2 2.4 2.6 2.6 3.1
1.7 1.7 1.7 1.9
1.6 1.7 1.6 2.3
2.0 1.9 2.0 1.8 1.9 2.0 1.8 2.3 2.0 2.0 2.1 1.8 2.0 12.2 2.7
Spinning Processes and Types of Yarn
20/0 4/ 0 -5 /0 -3 EI 1 f EI 1 hd /Ell hf EI 1 hr EI 1 hr Type -TWEI 1 hd Type -EMEI 1 f Type -HEI 1 hr Type -HEI 1 f Type -W/FEI 1 hr Type -WEI 1 hd Type -WEI 1 f Type -HWEI 1 hd Type -HWEI 1 hr Type -HWEI 1f Type -CM EI 1 rf Type -HWWHEL 1 hd Type -EMTHEL 1 hr Type -EMT-
Trveller Number
Traveller Number
Traveller Type
2-196
Spinning Processes and Types of Yarn Table 6.3.9 (2)
Distance for Traveller Cleaners with the Use of Flange 2 Travellers Setting Distance “E” in mm Traveller Number
Traveller Type El 2 f El 2 hr El 2 hr Type -TWEl 2 f Type -HEl 2 hr Type -HEl 2 f Type -HWHEL 2 f HEL 2 hr C 2 f Type C 2 hd Type -TC 2 hr Type -TC 2 f Type -TMC 2 hd Type -TMC 2 hr Type -TMC 2 hd Type -TTMC 2 hr Type -TTMC 2 f Type -MTC 2 hr Type -MTC 2 hr Type -MTWC 2 r Type -TC 2 rhr Type -TMC 2 rf Type -TC 2 r Type -MTC 2 rf Type -MT-
12/0
4/0-3
4-7
8-15
16-30
1.6
1.9
2.1
2.8
3.4
1.6
2.2 1.9
2.4 2.1
3.1 2.8
3.4 3.0
1.9 1.6
2.1 1.8
2.3 2.0
2.9 2.8
3.0
1.7
1.9
2.1
2.9
3.1
1.7
1.9
2.1
-
-
1.7
2.0
2.2
2.6
3.0
2.0
2.3 2.4
2.5 2.7
2.9 3.6
3.4 -
2.0
2.5
2.8
3.4
4.1
Table 6.3.9 (3) Distance of Traveller Cleaners with the Use of Flange 2 Travellers Setting distance “E” in mm Traveller Type C 2f C 2r
12/0-5/0 1.7 2.0
Traveller Number 4/0-3 4-7 8-10 1.9 2.5 2.6 2.5 2.7 2.8 2.6 2.8 3.4
11-16 2.9 3.2 4.1
17-30 3.2 3.9 4.3
Table 6.3.10
Traveller Speed in m/s
Spinning Processes and Types of Yarn
6.3.10 Traveller Speed in m/s (Source: R&F)
Textile Handbook 2-197
2-198
Spinning Processes and Types of Yarn
6.3.11 Relationship between Inside Diameter of Ring, Spindle Revolution and Traveller Circumferential Speed (Source: Kanai) Table 6.3.11
Example:
Traveller Circumferential Speed (m/sec.)
Ring inside diameter: 50mm Spindle revolution: 17,000prm. The above diagram shows the traveller circumferential speed of 42.8 m/sec. The above diagram shows the case of 800 T/m and full bobbin.
Textile Handbook 2-199
6.3.12 Relationship between Bobbin Diameter, Twist Number, Spindle Revolution, and Traveller Revolution (Source: Kanai) Table 6.3.12
Nomograph on the delay of traveller
Spinning Processes and Types of Yarn
The nomograph is prepared from the preceding calculation formula, and shows the revolution delay of the traveller to the spindle when the yarn twisting number, bobbin or cop diameter, and spindle revolution are given. Examples: When the twist number is 15T/m., the .cop diameter is 100mmØ, and the spindle revolution is 8,000 rpm, the traveller revolution is obtained as follows: (i) Connect the cop diameter 100mmØ and twist number 15T/ m (line P) (ii) Connect the point of spindle revolution 8,000rpm, and the intersection of Line P and K axle. Extend to (Sr-Tr) axis. (Line q)
2-200
Spinning Processes and Types of Yarn
(iii)Traveller revolution is delayed, in comparison with the spindle revolution, by 1700rpm, which is the intersection value of [Sr-Tr] axle and Line q. (iv)Accordingly, the required traveller revolution number is 8000 rpm - 1700 rpm = 6300 rpm
6.3.13 Relationship between Inside Diameter of Ring, Bobbin Diameter and Winding Angle (Source: Kanai) Table 6.3 13 Relationship between Winding Angle and Bobbin diameter
R = Ring inside diameter B = Bobbin diameter = Winding angle
sin =
B R
Textile Handbook 2-201
6.3.14 Ratio Values of Ring Diameter, Bobbin Diameter, Bobbin Length And Spindle Gauge (Source: R&F) Figure 6.3 14
Ratio Values of Ring Diameter and Bobbin Diameter
Spinning Processes and Types of Yarn
2-202
Spinning Processes and Types of Yarn
Symbols: t
= spindle gauge
D = inside ring Ø d, d = mean bobbin Ø do = top bobbin Ø H = bobbin length BE = balloon ring EB = setting distance ring / balloon ring FB = yarn balloon RB= ring rail EF = setting distance top of bobbin / yarn-guide eyelet (measures in mm) Recommended values: D = t-25mm d:D in spinning: 0.48 - 0.5 or α 29o - 30o (not lower than 0.42 or (α 26o ) d:D in twisting: 0.44 - 0.5 or α 27o - 30o (not lower than 0.38 or α 22o ) H ≤ 5xD BE ~ D+2mm EB ~ 2 x D EF ~ 2 x do d: D - If the value d:D is too small, a high traveller strain occurs, and the traveller wear and end breakages increase. If the value d:D is too large, it will result in disturbances of the yarn balloon. The balloon may collapse temporarily, resulting in increased hairiness and end breakages.
Textile Handbook 2-203
H - If a too long bobbin or spindle is chosen (e.g. H = 5.5 x D), the yarn balloon will contact the tip of the bobbin. Besides increased end breakages a worse yarn quality will be registered. D and t - When choosing the ring Ø (D) the spindle gauge (t) has to be taken into consideration. Ring Ø (D) up to 85 mm. Then the ring diameter can be 25 mm smaller at maximum with regard to the spindle gauge.
Then the traveller and yarn balloon have the required freedom of movement. Inserting the traveller, repairing end breakages and exchanging the cop can be done with less disturbance. BE -The balloon ring should be 2 - 3 mm larger than the ring diameter. If the balloon ring is too big, a discharge of the yarn balloon is not possible.
6.3.15 High Performance Ring and Traveller a) Orbit Ring And Traveller System Figure 6.3.15.a(1) T-ring and Orbit-ring
Spinning Processes and Types of Yarn
Ring Ø (D) from 90 mm and above. Then the ring diameter can be chosen 30 mm smaller at maximum with regard to the spindle gauge.
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Spinning Processes and Types of Yarn Figure 6.3.15.a(2)
Surface pressure as a function of the contact surface between the ring and the traveller
Characteristics • Large contact surface between ring and traveller reduces specific surface pressure and friction (good fibre lubrication), and inclined flange form allows for considerable speed increases • Constant yarn quality and yarn breakage rate with improved performance • No fibre damages thanks to good heat conduction and enlarged yarn passage • Reduced yarn hairiness • Good guidance of the traveller, consistent yarn tension • Higher traveller life-time with the same traveller speed • Large contact surface reduces the wear and tear of the new travellers in the starting phase Recommendation for use Good results can be obtained with high yarn strength, warp twist, fine combed cotton, manmade fibres and blends.
Textile Handbook 2-205
(i) Travellers for ORBIT Table 6.3.15.a(i)
Travellers for orbit
RL: Small yarn passage, especially suitable for cotton yarn, good fibre lubrication. Possible to use for fine blends (cotton/ polyester) The travellers for ORBIT rings are used with the well-established Rapid-Strap device SFB 2.8 (681 860). SFB travellers are exclusively supplied in Strap. (ii) Traveller weights for cotton Table 6.3.15.a(ii) Guiding values with the maximum possible spindle speed
Spinning Processes and Types of Yarn
PM: For all fibre materials, large yarn passage, therefore especially suitable for man made fibres and viscose.
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Spinning Processes and Types of Yarn
Traveller weight (ISO) with ring diameter ≤ 42 mm Values depend on the spinning geometry, twist, traveller speed, fibre type, etc. Man-made fibres and blends one ISO-no. heavier Example: Ne 30, 100% combed cotton, warp twist, recommended traveller weight ISO 45. (iii)
Traveller wear and tear
Figure 6.3.15.a (iii) Visual assessment
Optimal wear Traveller weight OK
Too heavy wear in the A area Traveller is too light
Too heavy wear in the B area Traveller is too heavy
Heavy wear! If on more than 10% of the travellers : - Reduce changing cycle of travellers - Reduce spindle speed - Check the rings - Possibly change the traveller form, wire section or traveller weight
Textile Handbook 2-207
(iv) Setting of the traveller cleaner Figure 6.3.15.a(iv) Vertical traveller cleaner
“b”: “b” 1.8 mm 2.0 mm 2.2 mm
Caution: Under no circumstances should the traveller come in contact with the cleaner. The traveller number used at the end of the ring running-in program, i.e. for normal operation, should be considered. Use vertical traveller cleaners: - Excellent cleaning effect - Easy adjustability of the cleaner The centrifugal force transports the fibre fly to the outer position of the traveller.
Spinning Processes and Types of Yarn
Standard value setting Traveller ISO 12.5-40 31.5 -71 63 -125
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Spinning Processes and Types of Yarn
b) Recommended Spinning condition for MAXCEE Ring and Traveller (Source: Kanai) Fiber
18000
Spindle revolution (rpm) 20000 23000
Cotton 20s
41 Ø
Cotton 30s-40s
36-41 Ø
36 Ø
Cotton 60s- 80s
36-41 Ø
36 Ø
Cotton 100s
34 Ø
36 Ø (40s)
YS-2/ hf OSY/ hf OSS/ hf
Polyester/ cotton 40-41 Ø
36-38 Ø
36 Ø
Polyester/ rayon Rayon 20s-30s 7 Lift (inches)
6-7
6
Peripheral speed 32-39 of Traveller (m/ sec)
38-40
43
Delivery speed (m/min)
21-27
26-34
19-24
Recommended Traveller MS/ hf MS/ hf-w YS-2/ hf YS-2/ hf-w
MS/ hf MA/ hf-w ZSC/ hf
Traverller to be used: MAXCEE Traveller The MAXCEE RING can be applied to either KS2/ KSA2 or (KS/ KSA) flange. Designation example of the MAXCEE RING: KSA 14 x 57.5 Rjh MX, KS92 36 x 54 Rst MX.
6.3.16 Suessen Novibra Spindle HP-S 68 and Spindle Bearing a) HP-S 68 Spindle Design Modern spindles must be designed for spindle speeds above 25,000 rpm. The important aim is to ensure that belt or tape speeds do not increase in the same proportion as the spindle speed. The objective is therefore to reduce the wharve diameter still further. This can only be achieved by reducing the dimensions of the neck bearing and consequently the shaft diameter of the spindle upper part. Smaller spindle shaft diameters with the same bearing dimensions are however less rigid.
Textile Handbook 2-209
As mentioned above, a reduced stiffness of the spindle upper part would have a negative influence on the running performance of the spindle. Consequently, when reducing the diameter of the spindle shaft of the HP-S 68 spindle to 6.8 mm, the distance between the neck bearing and the footstep bearing is reduced at the same time. As a result the HP-S 68 spindle shaft is in fact more rigid than the shaft of conventional spindles with a diameter of 7.8 mm.
In comparison (Figure 6.3.16.a) the conventional assembly of a spindle upper part, whereby the wharve and the aluminum bush are pressed separately onto the spindle shaft. Spindle upper parts of such a design are less suitable for high spindle speeds. The shorter distance between the neck bearing and the footstep bearing places higher demands on the latter. The flexibly supported footstep bearing continuously guides the spindle upper part back to its given axis of rotation. The footstep bearing will deal with this task all the better, if the dynamic forces can be transmitted from the footstep bearing to the spindle shaft without any radial clearance.
Spinning Processes and Types of Yarn
In addition, the design of Suessen-Novibra spindle (Figure 6.3.16.a) ensures a high stiffness over the complete length of the spindle upper part. The steel spindle wharve embraces the aluminum bush, and therefore strengthens the pressfit connection between the spindle shaft and the aluminum bush.
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Spinning Processes and Types of Yarn Figure 6.3.16.a Suessen-Novibra Spindle Verus Conventional Spindle
Textile Handbook 2-211
b) Dynamic load The dynamic load of a spindle bearing mainly depends on the tube length, ring diameter, yarn count to be spun and tube quality. The design of the spindle upper part also plays a role. Upper parts with aluminum bushes exert less force than bare blade spindles. These parameters allow an estimate to be made of the dynamic load of a spindle. Depending on the load, a certain maximum spindle speed is permissible.
The load factor K is calculated according to the following formula: 2 K= b xR x Y x Tx S 100000
Table 6.3.16.b Factor b (mm) R (mm) Y T S
Key to abbreviations depending on Distance between neck bearing center and tube top Ring diameter Yarn count Tube quality Upper part design
to be determined byway of Figure 6.3.16.c (1) Figure 6.3.16.c (1) Figure 6.3.16.c (2) Figure 6.3.16.c (3) Bare blade spindle S=1.5 Spindle with aluminum bush S = 1.0
The admissible length b for the HP-S 68 spindle bearing is 320mm, and for L-HP-S 68 is 350mm. The load factors are identical for HP-S 68, NASA-HP-S 68 and NASA-FITHP-S 68.The load factors of LHP-S 68 have another limit graph.
Spinning Processes and Types of Yarn
The load factor K is determined by means of factors in functional relation to the relevant parameters. This factor K helps to decide if the HP-S 68 spindle bearing can be used for a given dynamic load, which bearing variant should be preferred and which maximum spindle speed would apply.
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Spinning Processes and Types of Yarn
c) Radial and Axial Load Due to the special geometry of the footstep bearing of the HP-S 68 spindle bearing, very high axial loads can be absorbed: Admissible radial load (permissible belt pressure):
max. 25 N
Admissible axial load with spindle stopped:
max. 500 N
Admissible load with spindle running:
Figure 6.3.16.c(1) Spindle Bearing
max. 30 N
Textile Handbook 2-213 Figure 6.3.16.c(2) Yarn Count Factor Y
6.3.17 Bobbin Building Lay refers to the spacing of the coils of yarn wound in any one layer on the bobbin. Spinning lay is similar to roving lay, but it is not practical to arrange yarns as closely as roving. The number of coils of yarn which may be arranged side by side on a bobbin depends on the yarn diameter the yarn diameter varies with the yarn count, the type of material and the amount of twist. In the cop build system, there is generally higher end breakage rate on the smaller diameter of the bobbin at the nose of the build rather than on the full diameter at the shoulder. Therefore, a high performance spinning machine will have already adopted a variable speed control system whereby a higher speed is used in spinning on the body of the bobbin than at the bottom and nose.
Spinning Processes and Types of Yarn
Figure 6.3.16.c(3) Tube Factor T
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Spinning Processes and Types of Yarn
In order to realize the advantages of automatic bobbin readying in the winding department, greater control of the dimensions and build-up of the spinning bobbin is essential: Figure 6.3.17 Bobbin Building
Dimension (a) between the highest spin point and the top of the tube must be at least 15 mm. A chase length (H) of 60mm together with a cross ratio of 2:1 are particularly favourable for high unwinding speeds. In spinning a cross ratio of 2:1 means: e.g.26 winds with ring rail moving up 13 winds with ring rail moving down; or 26 winds from top to bottom of the bobbin; and 13 winds in the opposite direction when the bobbin is unwound. The total length of yarn in both directions should not be more than 3 or 4 metres. Bobbin diameter D of a particular yarn lot should have a tolerance of only 40°¿2.5 ... 62 °¿ 2.5.
Textile Handbook 2-215
Tube length L should be within tolerances of °¿ 2.5 mm (total range 220-312 mm) The total of backwind (BW) + underwind (UW) should not exceed 1.5 metres. Examples:
BW = 1.0 m UW = 0.5m Total= 1.5m
BW =0.5 m UW =1.0 m Total=1.5m
Dimension (b) between bottom of tube and start of spin must be at least 10 mm The underwind (UW) should be distinctly separated from the base of the spinning cone (X = about 2 mm) The difference (d2 - d 1) between inside diameter at top and bottom of tube should be at least 2.5 mm (Schlafhorst Information) a) Zinser Bobbin Building Control The optimum yarn path is of critical importance for achieving excellent yarn quality and high delivery speeds, while keeping yarn break rates low. The sequence of movements of the yarn guide elements in relation to the ring rail over the entire bobbin travel is optimally coordinated on the Zinser 350 ring spinning machine to every tube length. The spinning geometry is heavily influenced by the sequence of movements and the yarn path. The ideal spinning geometry of the ring spinning machine 350 makes it possible to achieve a well-balanced yarn balloon and thus a virtually constant mean yarn tension over the entire travel of the bobbin. This has a critical effect on yarn break rates. In combination with the new ring rail motion concept, this geometry minimizes yarn breaks, even at high spindle speeds. Program-controlled bobbin winding on the ring spinning machine 350 creates ideal conditions for the subsequent winding process, facilitating higher unwinding speeds on the winding machine.
Spinning Processes and Types of Yarn
An increase of up to 2.5 metres is being considered. Bottom build of bobbin should be straight.
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Spinning Processes and Types of Yarn Figure 6.3.17.a(1) Separate movement of the yarn guide elements
The ring spinning machine 350 offers maximum productivity: the start, finish and main speeds can be adjusted and activated as standard in ten increments at the operator console. Layer control is optionally available, making it possible to optimize the yarn break rate by varying the spindle speeds in critical phases of the ring rail traverse. In phases where there is a higher probability of yarn breaks, the spinning speed is maintained at the nominal speed specified in the spinning program. In phases where the yarn break probability is low, the spinning speed is increased, thus producing higher productivity at the same time. Figure 6.3.17.a(2)
10-point spinning program for ring spinning machine 350
Textile Handbook 2-217
b) Toyota Automatic Speed Control Inverter for Ring Spindle This feature offers very precise speed control, making it possible to set the maximum speed with the minimum number of broken ends at each stage of bobbin formation. Speed can be changed while maintaining the travellers in a stable position. Average revolution speed can be increased while reducing the number of ends down. (Standard for RX220/230) Spinning Processes and Types of Yarn
Figure 6.3.17 b Spindle Speed Change Diagram
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Spinning Processes and Types of Yarn
6.4 Open-End Spinning 6.4.1 Principle of Open-end Spinning (Source: Cotton Incorporated)
The heart of the open-end process is a rotor (see Figure 6.4.1(1)), wherein fibres can be collected and then drawn off as a yarn. For short staple spinning, most rotors are 28 to 56 millimeters in diameter and may contain a shallow “U”, “V” or “T” etc., shaped fibre alignment groove around their periphery. In open-end spinning, the rotor rotation provides the twisting force. The basic difference between ring-spun yarns and open-end spun yarns is the way in which they are formed. The former produces yarn by inserting twist into a continuous ribbon-like strand of cohesive fibres delivered by the front rolls, while the latter forms yarn from individual fibres directly, by collecting them from the inside surface of a rotor by twist forces, Figure 6.4 1(1)
Rotor of an Open End Spinning System
The elements basic to production of open-end yarns are somewhat different from ring spinning (Figure 6.4.1(2)). They are: -
fibre supply, drafting system, fibre collection and alignment, twist insertion - yarn formation, and package winding.
Textile Handbook 2-219
The fibre supply used by all open-end machinery is in the form of sliver, either directly from the card or from the draw frame. Figure 6.4.1(2)
Schematic Diagram-open End Spinning
Spinning Processes and Types of Yarn
It is apparent that the total draft for a given yarn produced on an open-end machine will be greater than that of a ring frame producing the same yarn. For instance, the draft of an open-end frame producing 24/1 from 60 grain sliver would be 172.8. Open-end equipment manufacturers decided to abandon roller drafting as being too cumbersome to use to develop the high drafts required for rotor spinning. In place of roller drafting, a simple wire or pin covered cylinder several inches in diameter and about an inch wide is used (Figure 6.4.1(3)).
2-220
Spinning Processes and Types of Yarn Figure 6.4.1(3)
Combing Roll-Open End Spinning
The supply sliver is presented to the rotating teeth of the combing roll by action of a feed roll/feed plate mechanism. There is a very high draft between the feed roll/feed plate and the rotor. This high draft delivers individual fibres and/or small individual fibre groups to the rotor, where they are deposited randomly around the inside of the rotor over a period of many revolutions. This deposited fibre mass has very little fibre-to-fibre cohesiveness, and it is this fact that makes open-end spinning possible. Figure 6.4.1(4)
Drafting by Combing Roll:
Textile Handbook 2-221
Open-End Yarn Formation: in rotor spinning, the yarn is formed inside the rotating rotor from a continuous stream of individual fibres arriving from the combing roll. This spinning action can be explained as follows. Please refer to Figure 6.4.1(5), which is a schematic diagram of the inside of a rotor.
The new yarn is actually formed in Area “C” by twist collection of individual fibres. This area is known as the fibre binding zone. The point where the fibres leave the rotor surface is called the “peeling point” and is identified as Point “P.” The peeling point advances in the same direction as the rotation of the rotor, shown by Arrow “a.” The rate of advance of this point is determined by the turns per inch of twist being inserted into the yarn. One turn of twist is theoretically inserted into the yarn each time the rotor makes one complete revolution. This being the case, it becomes obvious that rotor speed and production are directly related. For example: Rotor speed = 60,000 rpm Turns per inch required = 30 60,000 = 2,000 inches per minute of yarn delivered 30
Spinning Processes and Types of Yarn
Ring “A” represents the inside groove of the rotor where the fibres are collected. Ring “A” rotates in the direction of Arrow “a” at a fixed rate. Newly formed yarn is seen at “B” and moves in the direction of arrow “b” to the yarn withdrawal tube “T”, where it is drawn out of the rotor and wound onto a cheese.
2-222
Spinning Processes and Types of Yarn Figure 6.4.1(5) Schematic Illustration Showing the Formation of Yarn Inside the Rotor
Open-end spinning is ideally suited for spinning of short fibres. A ring-frame drafting system has a minimum staple length requirement for proper fibre control to produce a quality yarn. Once control is lost, the resultant yarn spins inefficiently, and the yarn appearance is poor. Since open-end yarn is formed by twist attraction of the rapidly rotating open-end, fibre control is no problem, and therefore short staple fibre can be spun into more even and, in some cases, stronger yarn. Figure 6.4.1(6) Schematic Illustration of the Formation of Bridging or Wrapper Fibres on the Surface of Open End Yarn
Textile Handbook 2-223
Yarn Properties: the structure of open-end yarn is significantly different from ring-spun yarns. The appearance is of a strand of yarn with a high twist, inner core of fibres surrounded by a sheath of wrapper fibres containing much less twist. This difference causes varying distribution of stress across the yarn from the axis to the surface, and contributes to the uniqueness of open-end yarn, Some of the important properties of open-end yarn, compared with ring-spun yarn, are given below using the same fibre input into both: 10% to 30% weaker, higher elongation at break, more even, better abrasion resistance, less hairy, less shedding, bulkier, larger yarn packages with no knots.
Figure 6.4.1 (7) Illustration of the Surface Characteristic Differences of Ring and Open End Yarns
Spinning Processes and Types of Yarn
• • • • • • • •
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Spinning Processes and Types of Yarn
6.4.2 Relationship between Rotor Speed, Rotor Type and Yarn Count Table 6.4.2 Relationship between Rotor Speed, Rotor Type and Yarn Count
Textile Handbook 2-225
6.4.3 Layout of Spinning Components a) Rotors Table 6.4.3.a Spinning Components - Rotors
T Rotor
(Rotor with pointed groove and braced bottom)
G Rotor
(Rotor with narrow groove) • Produces yarn of higher volume, compared to the-T rotor. • Not suitable for fiber stock with high trash contents. • Danger of Moire when processing fiber stock containing microdust, especially when using small rotors.
U Rotor
(Rotor with wide groove) • Special rotor for denim yarns. Suited for Indigo-Ball warp dyeing. • Danger of Moire when processing fiber stock with high trash contents, due to partial soiling of the rotor groove. • Yarn strength lower than from the T rotor.
S Rotor
(Pointed corner rotor without rotor groove) • Suitable for cotton (including fibers with high trash contents), and for all chemical fibers. • Suitable for soft knitting yarns • Suitable for raised yarns • Little danger of Moire, including for fibers with high contents of microdust. • Low yarn strength
Spinning Processes and Types of Yarn
• Yarn structure and yarn volume similar to ring-spun yarn. • Quick circular deposit of microdust in the rotor groove; of no negative effect upon the yarn quality (self-cleaning effect). • Due to curling tendency not suitable for Indigo-Ball warp dyeing process. • Not suitable for fiber stock with high trash contents.
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Spinning Processes and Types of Yarn
K Rotor
(Rotor with shorter T groove) • Application similar to T rotor • For clean fiber stock only. This rotor is very sensitive towards soiling.
V Rotor
(Rotor with V-shaped groove) • For yarns not tending to fiber sliding, especially 100 % acrylics! (Warp-strong yarns without slashing deposits) • Very good yarn evenness • Lower yarn strength than from T rotor b) Combing Rollers
Table 6.4.3.b
spinning Components - Combing Rollers
S21
• Blends- PES/Cotton, PES/Viscose, Cotton/ Viscose,, Cotton/Acrylics • 100 % Acrylics • 100 % Cotton (limited to medium staple) • 100 % Polyester • 100 % Viscose Recommended RPM range- 8,000 ... 9,000 RPM Available Types: S21DN, S21D, S21N
B174
• Cotton • 100 % Viscose • Blends- Cotton/Viscose, Cotton/Acrylics Recommended RPM range- 7,500 ... 8,500 RPM (Check lint accumulation when running at higher speed). Available Types- B174N, B174DN, B174 (4,8) N, B174 (4,8)DN,B20N,B20DN
B174(4,8)
Textile Handbook 2-227
B20
B187
c) Withdrawal Nozzles (Navels) Table 6.4.3.c
Spinning Components - Withdrawal Nozzles (Navels)
Marking KN CG 1
Application • Smooth nozzle for spinning smooth yarns. • Prerequisite: High twist (> α 140). Use Torque Stop if possible, yet always use Navel Cleaner, in order to improve spinning stability.
KN 3
D or Y
CK3 KN 4
3 F
• Nozzle with 3 small notches for spinning yarn of limited hairiness • Better spinning stability, compared to KN nozzle. Prerequisite: Medium to high twist. With or without Torque Stop. • Nozzle with 4 notches, universally applicable. Adequate spinning stability. Yarns for knitting and weaving.
CK4
4
• Hairiness higher than from KN- and KN 3 nozzles.
KN 8
E
• Nozzle with 8 small notches, universally applicable, similar to KN 4, yet better spinning stability. • For knitting yarns of low twist. Hairiness similar to KN 4.
KN 8 R Z/L CK8R 8/-8-/8A
• Nozzle with 8 notches and knurling. • Suitable for spinning of very hairy yarn with good napping properties. • High spinning stability, allowing low yarn twist.
Spinning Processes and Types of Yarn
• 100 % Viscose • Special application- Combed Cotton (Spinning test required) Recommended RPM range-. 7,500 ... 8,500 RPM Available Type- B187DN
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Spinning Processes and Types of Yarn KN R4 G/GKN 4 R4 M KN 4 2R4 T
KS
S
KS R4 W/W-
• Smooth ceramic nozzle with whirl insert. For towel yarns (pile warp) and yarns of high hairiness. • 4-Notches nozzle with whirl insert. For spinning yarns of still higher hairiness than KN R4 with improved spinning stability. • 4-Notches nozzle with 2 whirl inserts. For extremely soft (low-twist) knitting yarns.
• Nozzle with spiral-shaped ceramic insert, produces smooth yarn types. • Good spinning stability with medium to high yarn twist. • Produces good values for yarn strength and yarn evenness, and in respect to imperfections. • Ceramic spiral-shaped nozzle with whirl insert. • Produces yarn of higher hairiness and better opacity than KS nozzle. Withdrawal nozzles for spinbox SE10 with adapter channel plates: Design of nozzles as specified above, except for magnetic fastening.
6.4.4 Example of Recent Development in OE Spinning a) Rieter AERO bearing R1 The central compressed air supply is continuously monitored; if the air pressure falls or is interrupted, the Rl turns off. This a reliable way to avoid causing damage to the bearing. The R1’s AERO-bearing works without any mechanical friction and making it completely free from wear. The layer of air from the AERO bearing thereby makes a considerable contribution to the quiet running of the bearing system. Even at the highest rotor speeds, wear-related vibration of the rotor shaft is impossible.
Textile Handbook 2-229 Figure 6.4.4.a (1) Rotor bearings of the RI with AERO-bearings and support disk bearings
b) Schlafhorst Corolab Yarn Measuring System The Schlafhorst yarn monitoring system Corolab operates on the measuring optical system using infra-red light. The transmitter sends a beam of light through the measuring field to the receiver. Simultaneously, part of this light falls upon a reference receiver. The yarn in the measuring field throws a shadow onto the receiver, whilst the reference receiver always receives 100% of the light. The amounts of light which are transmitted in each case are compared. From the difference in values Corolab measures the yarn diameter with an accuracy of 0.01mm. By this continuous comparison during yarn production, Corolab detects all irregularities in the yarn. The result of the measurement
Spinning Processes and Types of Yarn
Figure 6.4.4.a(2) Aero Beraings
2-230
Spinning Processes and Types of Yarn
is directly proportional to the yarn diameter produced, i.e. Corolab shows the actual diameter for each millimetre of spun yarn. With the digital processing of measured values, it is possible to obtain precise data on every metre of yarn produced. Faults which previously led to problems in subsequent processing such as thick places, thin places, moire and poor or incorrect sliver, are no longer able to exert a detrimental effect on quality. Figure 6.4.4.b
6.5
Corolab Measuring Principle
AIR-JET SPINNING
A sliver is drafted to a predetermined size in the draft zone and then passes into a nozzle box. Within the nozzle box, air at high pressure is released from jets set in the walls. The direction of the air current swirling in the first nozzle is opposite to that swirling in the second nozzle. Fibres protruding from the main fibre strand are made to wind around the strand by the swirling air currents in the first nozzle, giving the strand cohesion and strength. The second nozzle enhances the cohesion of the strand to give the yarn its final strength. The delivery speed of air-jet spinning can upto 400 metres per minute in the yarn count range from 5.5 - 3 0 tex. This rate of productivity is as high as 10 times that of ring spinning and twice that of open-end spinning.
Textile Handbook 2-231 Figure 6.5
Air-jet spinning.
6.5.1 Processing Parameters and Fibre Characteristics for Spinning 100% Cotton Yarn (Source: Cotton Incorporated)
Cotton Incorporated, in close co-operation with Murata, has done extensive work in developing a working knowledge of the fibre preparation procedures and parameters for successful production of 100% cotton yarns on the air-jet machine. In addition, machine design changes including a specially designed nozzle for cotton fibres, have improved the spinability, of 100% cotton yarn. a) The influence of fibre properties on air-jet spinning (i) Fibre Length The character of the roller drafting components on the air-jet spinner and structure of the yarn both require the use of long fibres to ensure adequate overlapping of core fibres and optimum wrapping of wrapper fibres.
Spinning Processes and Types of Yarn
Since its introduction in the early 1980’s, air-jet spinning and its development have been directed primarily towards synthetic and cotton/ synthetic blend spinning. Unlike other spinning methods, fine count air-jet yarns run at high production speeds, as they are twist dependent. The primary draw back of air-jet cotton yarns is their low tenacity compared to ring yarn.
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Spinning Processes and Types of Yarn
(ii) Short Fibre Content Reduction of short fibre content in cotton slivers would allow for the production of finer count yarns with fewer defects. (iii)Fibre Tenacity Stronger cotton fibres create a stronger wrapping effect around the core and, under tension, contribute more to yarn strength. (iv)Micronaire Air-jet spinning trials indicate that fibre fineness can limit count attainability and spinability. It is also important when searching for low micronaire cotton fibres to monitor the presence of immature fibres. b) Fibre processing parameters enhancing air-jet spinning (i) Opening/ Cleaning The opening action must be as gentle as possible to avoid any breakage of fibres, but it must also have the capacity to pluck or open the smallest possible cotton tufts to ensure a thorough blending action and good cleaning efficiency. It is important to clean the opened cotton efficiently with as few cleaning processes as possible to avoid overworking the fibres. (ii) Carding Proper card speed, settings and waste extraction should reduce the neps and short fibre content in the card sliver. Even card sliver should be attained through card autoleveling devices that control long and/or short term variations. (iii)Drawing Three processes of drawing tend to attain maximum fibre parallelization and the lowest possible Uster CV% of the 2nd passage drawn sliver for both carded and combed cotton. Also, optimum sliver weight required for air-jet spinning is finer than that required for ring or rotor spinning, especially for producing fine count yarns. It is preferable to equip the last process of drawing with an auto-leveling device to improve sliver uniformity over short and medium lengths.
Textile Handbook 2-233
(iv)Combing In the preparation of cotton for air-jet spinning, preferred operations include a combing process for the removal of short fibres, neps and trash, and improvement of fibre length uniformity. (v) Air-jet Spinning
In order to examine the effect of plying on air-jet yarn strength, compared to ring and rotor yarns, a trial was initiated to produce 40/2 plied yarns from the three different spinning systems for weaving. The cotton selected for this evaluation was 1 1/8 inches Acala. The average HVI properties of this cotton were as follows: Micronaire Length (UHML) Length Uniformity (%) Strength (g/Tex) Elongation (%)
4.30 1.12 inches 83.40 29.40 6.30
% short fibre content (SFC) (W) 6.60 The yarn production rates and testing results are shown in Tables 6.5. 1.b(v)(1) and 6.5.1.b(v)(2). The spinning results show that the production of air-jet yarns surpassed ring and rotor yarns by a factor of 21 and 3.3 times respectively (Figure 6.5.1.b(v)(3)). When compared to ring or rotor yarns, air-jet yarns offer a cost savings at twisting since fewer turns are required to reach the optimum strength. Also, plied air-jet yarns showed significant yarn strength improvement, as they are equal to plied rotor yarn strength and attain about 75% of plied ring yarn strength (Figure 6.5.1.b(v)(4)). These yarn samples were successfully woven into dress slack fabrics. Fabrics produced from air-jet yarns exhibited higher strength values compared to rotor yarn fabrics and attain about 88% of ring yarn fabric strength. Woven fabrics strength results are shown on Table 6.5.1.b(v)(5).
Spinning Processes and Types of Yarn
To best control the short fibres in the drafting zones, when processing 100% cotton, total draft should be kept at the lower end of the recommended range. It was found that as front roll speed is increased, a corresponding increase in nozzle pressure (N1), usually tends to optimize yarn strength. Also, spinning trials have shown that higher humidity improves air-jet yarn spinability.
2-234
Spinning Processes and Types of Yarn Table 6.5.1.b(v)(1) Yarn Spinning Results Spinning System Yarn Count (Ne) Twist Multiple Production Rate (lb/hr/unit) Adjusted Break Factor Yarn Tenacity (g/Tex) Yarn Elongation (E%) Uster Evenness (CV%) Total Imperfection
Ring 40/1 3.70 0.03 2810 16.82 5.54 14.94 290
Rotor 40/1 4.27 0.19 2133 12.32 4.80 17.88 394
MTS 40/2 Parallel — 0.63 1548 8.65 6.40 12.12 27
Table 6.5.1.b(v)(2) PLIED YARN RESULTS Yarn Type Yarn Count (Ne) Twist per Inch (T.P.I.) Twist Direction Production Rate (lb/hr/unit) Adjusted Break Factor Yarn Tenacity (g/Tex) Yarn Elongation (E%) Uster Evenness (CV%) Total Imperfection
Ring 40/2 16.33 5 0.12 3378 18.46 6.34 11.31 19
Rotor 40/2 16.33 5 0.12 2570 14.32 6.07 12.12 23
Figure 6.5.1.b(v)(3) Production Rate (lb/ hr/ unit)
MTS 40/2 12.45 5 0.15 2537 14.18 5.43 11.43 18
Textile Handbook 2-235 Figure 6.5.1.b(v)(4)
Yarn Skein Break Factor
Plied Yarn Type Tensile Strength, lbs Tear Strength, lbs Fabric Weight, Oz/yd2
Ring W* F* 101.0 84.6
Rotor W F 82.0 72.0
MTS W F 88.0 76.0
14.5
12.3
12.9 12.2 5.7
14.1 5.8
10.9 5.8
Note : *W: Warp *F: Filling 1
Greige fabric construction = 44" 84 x 72 2.26 (5.8 oz/yd2), 2 x 2 RHT. Results represent tests on fabric after preparation, dyeing, finishing and mechanical Shrinking.
Spinning Processes and Types of Yarn
Table 6.5.1.(v)(5) Woven Fabric(1) Strength
2-236
Spinning Processes and Types of Yarn
6.5.2 Muratec 851 MVS Air-jet Spinning Machine This spinner has made it possible to spin 100% cotton. • Spinning speeds of up to 400 m/min are possible. This provides a productivity 20 times that of ring spinning frames. • Development of the nozzle for cotton has made it possible to explore new products in addition to all kinds of woven and knitted goods. • Air-jet spinning is applicable to spinning from Ne 10 to Ne 50. • Produces slick yarn with virtually no hairiness. Figure 6.5 2 Muratec 851 MVS Air-jet Spinning Machine
6.5.3 Muratec 804 RJS - Roller Jet Spinning • With roller twisting, the spinning of Ne 5 to Ne 30 coarse and extracoarse count yarns is made possible. • Spinning speeds of up to 400 m/min are possible, even with coarse and extra-coarse count yarns. This provides a productivity 20 times that of ring spinning frames. • Due to the adoption of roller twisting, compressed air consumption is cut by half and a 30 - 50% energy saving is achieved compared to that of conventional spinning machines. • Produces slick yarn with virtually no hairiness.
Textile Handbook 2-237 Figure 6.5.3 RJS Spinning System
Spinning Processes and Types of Yarn
6.6 Various Developments in Spinning 6.6.1 Suessen Ring-Can Spinning System Ring-Can is a method of spinning from sliver to yarn without the roving process. The special feature of this concept is the narrow transporting tapes from the cans to the drafting system covered by skids of the same width, for the transport of sliver pairs. This way the sliver reaches the drafting system in a smooth and flattened condition, and is well prepared for drafting. On the Ring-Can false drafts are completely eliminated, even if very fine, combed draw frame slivers are used. The ring spinning frame need no longer take over the complete draft portion of the speed frame. It is possible to work with an optimum draft distribution for spinning.
2-238
Spinning Processes and Types of Yarn Figure 6.6.1 Comparison of Drafting between Ring-Can and Roving Frame
6.6.2 Rieter ComforSpin The secret of the ComforSpin process lies in the additional, pneumatic condensing zone after the main drafting process. This condensing of the drafted roving means that the marginal fibres can also be integrated properly. The result is a virtually ideal yarn structure, which no other spinning process even approaches. Figure 6.6.2(1)
Strength and elongation as functions of twist
Textile Handbook 2-239
The four main advantages of Com4® yarn in brief: • no hairiness • very high strength and elongation • very good ecological balance • unrivalled wearing comfort. Table 6.6.2(2)
H
Conv. Ring yarn 12.21 4.08 Com4 yarn 12.61 2.57 Deviation in % +3 -37
CV2D CV2D CV1D CVFS D Shape 8 mm 0.3mm 0.3mm % g/cm3 % % %
Sh
2D mm
0.94
0.169
9.41
13.16
14.94
9.20
0.85
0.53
0.56
0.154
8.61
11.28
12.98
7.28
0.85
0.63
-40
-9
-9
-14
-13
-21
0
+19
6.6.3 Suessen EliTe Yarn In the Suessen EliTe spinning system, the drafting system is followed by a condensing zone which practically eliminating the spinning triangle. The drafting process is carried out in three zones: in the pre-drafting zone the roving - or the draw frame sliver - is moderately drafted. Drafting of the fibre assembly to the required yarn count is carried out in the main drafting zone. The double-apron system, which has proved its effectiveness in millions of applications, this system, together with the smallest possible distance between the apron control line and the front roller nipping line, guarantee optimum drafting performance for fibre assemblies, consisting of carded or combed cotton, short staple synthetics, blends, wool, long staple synthetics and blends in the condensing zone. The fibre strand is orientated and condensed under tension. This function is performed by a profile tube , which is subjected to negative pressure, and which is closely embraced by a lattice apron. The apron is driven by the front top roller and glides over the profile tube, which is provided with a special coating. The exact movement of the lattice apron is at all times guaranteed because the coefficient of friction between the lattice apron and the top roller is four times greater than between the apron and the profile tube.
Spinning Processes and Types of Yarn
Spinning CVm method %
Comparison of conventional ring yarn and Com4 yarn
2-240
Spinning Processes and Types of Yarn
In the area of the lattice apron, the profile tube is provided with a slot, which begins near the vicinity of the front roller nipping line and projects beyond the delivery nipping line the front top roller and delivery top roller are connected to each other via a gear, and together constitute the so-called E-Top. The profile tube bridges the distance from roller stand to roller stand and is connected, via a centrally arranged suction tube, to the suction unit. One suction unit serves two opposite profile tubes with the required and adjustable vacuum. Consequently, the technologically very important level of negative pressure is completely independent from the length of the machine, while its magnitude from spinning position to spinning position is always identical. The suction unit, designated Vacuum Cleaner, keeps the lattice apron permanently clean and also serves to remove broken-ends The profile tube can be removed with one simple movement of the hand and be refitted after the respective top arms, including the top rollers, have been lifted upwards. The exchange of the lattice apron is also possible with the greatest of ease. Figure 6.6.3
Suessen EliTe Yarn
Textile Handbook 2-241
The standard classical High-Drafting System is followed by the autonomous EliTe Unit. Maintaining the well-established bottom roller diameters makes it possible to process carded and combed cotton, as well as synthetics and blends without restrictions. Setting Data: B=13 mm
A=13 mm
C=20mm
Diameter of Bottom Rollers: 27 - 26.5 - 27 mm Diameter of Top Rollers: as usual
6.6.4 Zinser Compact Yarn With the AIR-COM-TEX 700, the sliver emerging from the conventional 3-cylinder drafting system is taken from the nip line of the drafting system by an air flow, and condensed under suction on a perforated surface. The compacted sliver thus undergoes a substantial reduction in width prior to twist insertion. This condensation has such a favourable effect on the ratio of the width of the compacted sliver to the yarn diameter that the spinning triangle is practically eliminated. The advantages: • The condenser effect of the ring spinning machine ensures substantially reduced hairiness. • Condenser yarn is characterized by higher strength and fewer irregularities. • The yarn is characterized by low IPIs. Technical data: Range of application: Staple fibres up to 40 mm
Gauge 75mm
Spindle speed: 25,000rpm (mechanical)
Raw material: Cotton, cotton/man-made fibre blends
Ring diameter: Draft range: 38-50 mm 8-85 fold (mechanical)
Count range: Nm 20- Nm 200 (Ne 12 - Ne 120)
Tube length: 180-250mm
Number of spindles: 180-960
Spinning Processes and Types of Yarn
HV =35 mm
2-242
Spinning Processes and Types of Yarn Figure 6.6.4
Zinser AIR-COM-TEX 700
Section 7 - Winding Process .................................... 2-243 7.1
Purpose of Winding .......................................................... 2-243
7.2
Knotting Mechanism ........................................................ 2-243
7.3
Air Splicing Mechanism ................................................... 2-246
7.4
Correct Build of Ring Cops .............................................. 2-247 7.4.1 7.4.2 7.4.3
7.5
Measures to Prevent Ribbon Winding ............................ 2-251 7.5.1 7.5.2 7.5.3 7.5.4 7.5.5 7.5.6 7.5.7
7.6
Causes of Sloughing .................................................... 2-247 Optimum Shaping of Spinning Bobbin ....................... 2-248 Balloon Breaker .......................................................... 2-250
Ribbon Winding .......................................................... 2-251 Measures to Prevent Ribbon Winding ......................... 2-252 Contact Pressure .......................................................... 2-252 Ribbon Breaker Interval .............................................. 2-253 Tension ........................................................................ 2-256 Increase (dish) ............................................................. 2-256 Drum ........................................................................... 2-257
Balloon Control and Tensioning Device .......................... 2-258 7.6.1 7.6.2
Tension Manager and Bal-Con (Muratec) ................... 2-258 Autotense Yarn Tension Control (Autoconer338) ....... 2-259
7.7
Calculation of Package Density ....................................... 2-261
7.8
Measures Against Excessive Yarn Breakage .................. 2-263
7.9
Causes and Corrective Actions for Poor Winding ......... 2-264
7.10 Electronic Yarn Clearer .................................................... 2-267 7.11 Conversion Graph of Peyer and UAM ........................... 2-269 7.12 Correlation Between Material and Type of Yarn by the Static Electricity Amount ........................................... 2-270 7.13 Material Setting of Uster UAM Yarn Clearer ................ 2-271 7.14 Types of Yarn Faults ......................................................... 2-271
A
Section 8 - Twisting Process .................................... 2-273 8.1
Up Twister ......................................................................... 2-273
8.2
Ring Twister ...................................................................... 2-273
8.3
Two-for-One Twisting ....................................................... 2-274 8.3.1 8.3.2 8.3.3
8.4
Two-for-One Principle ................................................ 2-274 Characteristics of Two-for-One Twisting .................... 2-275 Tritec Twister ............................................................... 2-275
Twisting Parameter ........................................................... 2-277
Back to Table of Content
Textile Handbook 2-243
SECTION 7
WINDING PROCESS
7.1 Purpose of Winding
In most winding machines, the spinning bobbins are mounted in an approximately vertical position below the winding unit. The yarn is withdrawn over the top end of the spinning bobbin, moves through yarn guides, tensioning devices, and slub catchers before winding onto the core, The tensioning device is set to establish the correct density or firmness of the package, while the slub catchers serve to catch and break out slubs, large knots, and wild or kinky yarn.
7.2 Knotting Mechanism Figure 7.2 (1)
Types of knot
Winder’s knot Weaver’s knot
Fisherman’s knot
Spinning Processes and Types of Yarn
The need for winding arises from the fact that yarn content on spinning cops is of a discontinuous nature which requires preparation of bigger packages suitable for more economical running in the subsequent processes, namely warping, sizing, weaving and knitting. The other pre-requisite of the process is the clearing action that has taken place in winding. The removal of defects in winding not only improves the quality of the yarn, but also tends to increase production in the operations that follow. An end that breaks during warping or weaving stops the entire operation, whereas in winding only one winding position is affected.
2-244
Spinning Processes and Types of Yarn Table 7.2 (2) Comparison table of different knots Types of knot Knot size
Winder’s knot
Big
F i s h e r m a n ’s Medium knot
Knot tail
Mis-knotting Operation
Short Long
Easy Difficult
Weaver’s knot Small by knotter
Medium
Weaver’s knot by manual
Medium
Small
Table 7.2 (3)
End-use
Simple For normal yarn Acceptable F o r d r i l l , corduroy and filament yarn Medium Easy For cotton, filament and knitted yarn Easy to be S l i g h t l y For cone sewing adjusted and slow thread inspected
Frequent Knotter mis-knotting
Kinds of trouble
Causes
Tension is too high at the end of both guided yarns.
Clogging yarn around the retie pipe, suction mouth or shutter cutter.
Improper guiding of yarn.
Insufficient push of yarn guide lever. Flow on yarn path.
Bill defect
Improper yarn clamping.
Loop does not pull out of bill
Poor cut Insufficient clamping of extractors
Knotter rotation is sluggish. (Remove the knotter to check.)
Reduction in friction torque
Motion of clamp levers is sluggish Clogging of cylinder cam by waste yarn. Clogging of gear by waste yarn. Lack of oil at contact surfaces between separate rubber and extractor lever . Abrasion of friction washer. Insufficient clamping of adjust nut.
Textile Handbook 2-245 Table 7.2 (4)
Knot and knot area troubles
a) Uneven length of knot ends Causes
Trouble
Clogging of retie pipe by waste yarn. Weak clamping at rear part of knotter. Right-side extractor rise is low. Left-side extractor rise is low.
b) Yarn breakage near knot Trouble
Causes Clogging of suction mouth by waste yarn. High clamping at rear part of knotter. Tight fastening of extractors
Clogging of retie pipe by waste yarn. High clamping at front part of knotter. Tight fastening of extractors
c) Improper knots or loose knots Trouble Insufficient tightening of knot
Lapping of loops
Causes Low clamp force Extractors not tight enough.
Action Adjust Adjust
Either front or near clamp is too low.
Adjust
Clamping force of bill is low.
Adjust
Spinning Processes and Types of Yarn
Clogging of suction mouth by waste yarn. Weak clamping at front part of knotter. Right-side extractor rise is low. Left-side extractor rise is low.
2-246
Spinning Processes and Types of Yarn
d) Relation between improper knot and knotter Causes
Improper knot
* Both yarns are guided to one side of knotter as illustrated (mischanging etc.) * When the yarn is not guided to the bill opening (yarn guide lever)
Yarn C moves in direction of arrow.
* Poor cut of bill
Yarn C can be pulled out. * Two or more yarns are guided to one side (double pick finding of suction mouth or retie pipe). Yarn B and C are knotted together.
7.3 Air Splicing Mechanism Table 7.3 (1) Splicing Operation 1)Yarn take-in Push the upper and lower yarn into the splicer using the yarn guide levers, and then clamp them there. 2)Cutting of the yarn ends The upper and lower yarn cutters cut the ends of the upper and lower yarn. 3)Untwisting The cut yarn ends are sucked into the untwisting nozzle pipe and untwisted. At this time, the yarn guide lever R returns a little to allow a sufficient length of yarn to be untwisted. 4)Splicing The yarn guide lever R is pushed in again, and it pulls the yarn ends out of the untwisting nozzle. While the yarn ends are out they are held by the yarn holding lever, and a jet of compressed air from the splicing nozzle tangles and twists the yarn ends together to complete the splicing.
Textile Handbook 2-247 Figure 7.3 (2) Classification
Points to check
1) Winding speed
Is the winding speed setting suited to the yarn? Is the balloon breaker placed at the proper height?
Countermeasures Change the speed setting. The height of the balloon breaker from the head of the spinning bobbin is generally best decreased for fine yarn counts and increased for coarse yarn counts.
Is the spinning bobbin hardness too soft?
Spinning bobbins should be as hard as possible.
Broken bottom occurs. Improper treatment of yarn end. Excessive pick yarns due to miswinding in the spinning process. Excessive loosening on chase when doffing in the spinning process. Nick on bobbin head or surface. Too much coarse yarn. Wear of ring
The person in charge of the spinning section should improve the shape.
Is the spinning bobbin designed adequately for high speed winding? (sloughing)
Please refer to 7.4 (correct build of ring cops)
7.4 Correct Build of Ring Cops 7.4.1 Causes of Sloughing The causes are listed below in order of frequency. 1. 2. 3. 4. 5 6 7
Number of coils (chase length) Winding speed Height of balloon breaker Hardness of spinning bobbin Relation between balloon breaker height and number of coils Relation between winding speed and number of coils Others
42% 17% 13% 12% 4.5% 4% 7.5%
Spinning Processes and Types of Yarn
2) Spinning bobbin condition
Frequent Yarn Breakages caused by the spinning bobbin
2-248
Spinning Processes and Types of Yarn
7.4.2 Optimum Shaping of Spinning Bobbin The shape of the spinning bobbin greatly affects the winder operation (machine efficiency and work efficiency). In addition to maintaining full control over the spinning process, which is of course important, the preferred shape for spinning bobbins for use with this machine is shown below. Figure 7.4.2 (1)
Spinning bobbin shape
d3 ≥ d2 d1 = d2 + 6 mm d2= 14 - 32 mm a = 12 mm (minimum) b = 10 mm (minimum) L = 200 mm - 340 mm D = 34 mm - 75 mm H = 1.2 x D
Textile Handbook 2-249 Optimum spinning bobbin conditions
Importance of conditions Items (1), (2), and (3) affect sloughing.
(8) Coil pitch Larger coil pitches reduce the occurrence of sloughing. If the coil pitch is set lower than a certain limit (or if the number of coils is over a certain limit), sloughing increases to an abnormal level. These limits are listed in the table on the following page.
Coil pitch influences sloughing.
(9) For coil forming, the ring rail should be lowered quickly and lifted slowly.
When the Continuous Automatic Bobbin Feeder (CBF) is used, the likelihood of a range of misses increases, and for this reason, spinning bobbins meeting the requirements of items (4), (5), and (6) are desirable. Even when the CBF is not used, items (4), (5), and (6) are still important to facilitate finding of yarn ends. The other operations relate the spinning bobbin handling. In item (7), long yarn ends can cause lashing-in of waste yarn at the end of winding and yarn breakage.
Spinning Processes and Types of Yarn
(1) The dimension from bobbin top to the upper end of yarn layer should be 12 mm or more. (2) Spinning bobbin hardness should not be too low (Shore hardness of 60 o and over for cotton yarn). (3) Chase should be at least 1.2 times the spinning bobbin diameter. (4) Back winding should be 1.5 to 2 times. (5) End winding should be 3 to 5 times. _ 0.2 m is optimal (For (4) and (5), 0.8m + for the total back winding.) (6) Back wound yarn should be loosened as little as possible. (7) The yarn end at the start of winding should be as short as possible. Note: 8 to 12% of the single yarn strength is appropriate for the winding tension of this machine.
2-250
Spinning Processes and Types of Yarn
7.4.3 Balloon Breaker It is also important to control ballooning with the balloon breaker in order to minimize sloughing, a) The balloon breaker’s function The balloon breaker is used to reduce centrifugal force, tension and stretching or rubbing of the spinning bobbin on the yarn layer by intermittently breaking the balloon to enable high-speed winding of yarn. To realize maximum effectiveness from the balloon breaker, it is necessary to select a balloon breaker appropriate for the shape, position and dimensions of the spinning bobbin. b) Balloon breaker shape Balloon breakers are available in different sectional shapes including circular, triangular and square.
c) Height (installation position) of balloon breaker A low installation position is appropriate for fine yarns, and a high installation position is appropriate for coarse yarns. The choice for the installation position also depends upon whether your priority is for optimum tension control or for minimum sloughing.
Textile Handbook 2-251
7.5 Measures to Prevent Ribbon Winding 7.5.1
Ribbon Winding
How to calculate the diameter which causes ribbon winding
Diameter which causes ribbon winding (d) = drum diameter (D) x
number of drum winds number of ribbon winds on package
Table 7.5.1 Diameter at which ribbon winding occurs for each winding drum with 5 inches cheese
Spinning Processes and Types of Yarn
The ribbon winding phenomenon occurs when the ratio between the package diameter and the drum diameter is a ratio of integers, and the yarn winds in such a way that it overlaps repeatedly. In particular, when the yarn is wound on the package surface with a 1.5 or 1.0 wind, the subsequent processes are greatly affected. For example, when unwinding with the warper, ringform slips out of the ribbon winding on the package surface, and yarn breakage occurs due to tangling.
2-252
Spinning Processes and Types of Yarn
7.5.2 Measures to Prevent Ribbon Winding With surface drive type winders such as the MACH CONER, R it is difficult to completely prevent ribbon winding, but it is possible to minimize ribbon winding by adjusting the respective parts of each unit. Ribbon winding is primarily affected by the contact pressure of the cradle, and lower contact pressure is better for ribbon breaking. The following are also factors that affect ribbon winding. - Contact pressure - Ribbon breaker interval - Tension - Drum
7.5.3 Contact Pressure As shown in the graph, slipping between the package and the drum is more likely with lower contact pressure, and this improves the ribbon dispersion. Graph 7.5.3
Contact pressure vs. dispersion of ribbon winding
Conditions - Type of yarn - Winding speed - Tension - Ribbon breaker
Cotton 40’s Ne 1 000 m/min. 20 gr. Up 1.0 sec. Down 1.5 sec.
Steps to lower contact pressure • Remove cradle weight • Change the setting position of the reducer spring • Attach a cradle weight for dye winding.
Textile Handbook 2-253
7.5.4 Ribbon Breaker Interval With the MACH CONER, ribbon breaking is actively performed by turning on and off the drum motor power to periodically change the rate of drum rotation and cause slipping between the package surface and the drum surface. The on-off interval has to be set to minimize ribbon winding. Select the interval so that, at the cycle where the down interval is set longer than the up interval, the dispersion angle of the resulting ribbon is over 60°C and the number of bundles is less than 30.
A reduction ratio for the minimum drum rotation by the ribbon breaker of 80-85% is sufficient. Min.rotation Reduction ratio = x 1 00 Max.rotation
Figure 7.5.4 (1)
Dispersion angle and number of bundles
Normal interval Up interval: approx. 0.8 sec. Down interval: approx. 1.2 sec.
Spinning Processes and Types of Yarn
However, a setting combination of the up interval of 1.0 sec. or less, and the down interval of 1.8 sec or more is meaningless, because it only reduces rotation.
2-254
Spinning Processes and Types of Yarn Figure 7.5.4 (2)
Ribbon breaker mechanism
Adjustable range of ribbon breaker interval Up interval (drum motor on) : 0.5 - 2.0 sec. Down interval (drum motor off): 0.5 - 2.5 sec.
The intervals can be set by the knobs, VR1 and VR2 in the control box.
Textile Handbook 2-255
Conditions • Type of yarn • Winding speed • Contact pressure • Tension
Cotton 40’s Ne 1,000 m/min. 960 gr. 20 gr.
When up-interval is 1.0 sec.
Graph 7.5.4 (4)
When up-interval is 0.5 sec.
As the above graphs indicate, it is better to shorten the cycle for ribbon breaking based on the data for low contact pressure.
Spinning Processes and Types of Yarn
Graph 7.5.4 (3)
2-256
Spinning Processes and Types of Yarn
7.5.5 Tension Higher winding tension is more effective for ribbon breaking. Figure 7.5.5 Tension versus dispersion of ribbon winding
Conditions • Type of yarn • Winding speed • Contact pressure • Ribbon breaker
Cotton 40’s Ne 1,000 m/min. 960 gr. Up 1.0 sec. Down 1.5 sec.
7.5.6 Increase (dish) For cone packages, yarn breakage in subsequent processes due to ribbon winding tends to decrease when Increase (dish) is applied as illustrated below so as to prevent concentration of contact pressure on the larger diameter side of the package. Figure 7.5.6 Increase (dish)
Textile Handbook 2-257
7.5.7 Drum A larger number of drum winds is better to prevent ribbon winding. However depending on the yarn count, the shape of the wound package may sometimes be deformed. Figure 7.5.7 (1)
Number of Winds
Figure 7.5.7 (2) Relation Between Winding angle and Drum Lead Ratio
Spinning Processes and Types of Yarn
Drums of different lead ratio are used for cones, depending on the winding angle as shown below. Winding on a 3o 30’package with 4o 20' -9o 15' drums of 1.5:1 is not good in terms of preventing ribbon winding.
2-258
Spinning Processes and Types of Yarn
7.6 Balloon Control and Tensioning Device 7.6.1 Tension Manager and Bal-Con (Muratec) The Muratec “Bal-Con” is a balloon control device that gradually drops down over the supply bobbin as the yarn is wound off, to control ballooning. This enables high-speed winding with no loss in yarn quality, and keeps yarn damage to the absolute minimum. Compared to yarn wound on conventional winders, Bal-Con wound yarn has far less sloughing, hairiness and fluff, and fewer neps. The Tension Manager provides individual tension control for each spindle to compensate for tension fluctuation when the drum starts after joining yarn, or as winding for a supply bobbin nears its finish. To set the pressurized tension, only need to be input the type of yarn being produced, the yarn count, and the winding speed. The microcomputer in the tension manager will then pressurize the appropriate tension accordingly, This eliminates the need for troublesome setting procedures. Figure 7.6.1 (1) Bal-Con
Figure 7.6.1 (2)
Conventional balloon breaker
Textile Handbook 2-259 Figure 7.6.1 (3)
Tension Manager + Bal-Con
7.6.2 Autotense Yarn Tension Control (Autoconer338) The balloon controller evens out and reduces the yarn tension from the start of the bobbin to its end. It is set to the length and wind direction (p or q) of the bobbins. The advantage of this system is that it allows direct integration into automatic electrical control systems. The yarn tension sensor is situated in the yarn path after the clearer on each winding head, to register the actual yarn tension at the package, and provides continuous, direct measurement of the yarn tension The measured values are transmitted in a closed control loop to the tensioner, where the pressure is increased or lowered according to the information received, i.e. the yarn tension is not only measured directly but is also regulated directly by the tensioner pressure and maintained at a constant level.
Spinning Processes and Types of Yarn
Bal-Con controls yarn tension, depending upon the amount of yarn remaining on a supply bobbin, and keeps it as even as possible. This allows high-speed winding right to the end of the supply bobbin yarn, and ensures beautifully formed packages.
2-260
Spinning Processes and Types of Yarn Figure 7.6.2 (1)
Schematic overview of the Autotense yarn tension control
Figure 7.6.2 (2)
Functioning of Autotense Yarn tension control
The diagram shows the constant yarn tension progression over the bobbin unwinding cycle and the potential improvement in productivity.
Textile Handbook 2-261
7.7 Calculation of Package Density Winding density (P)
P=
W V
where
Figure 7.7 (1)
General values of density (g/cm3) for each type of yarn: Cotton, cotton/polyester mixture
: 0.42 - 0.44
Worsted
: 0.35 - 0.37
Acrylic/ cotton mixture
: 0.36 - 0.38
Loose winding
: 0.34 or less
Spinning Processes and Types of Yarn
W= Net weight of package, and πh {(D2 + Dd + d2) - (D'2 + D'd' + d'2)} V = Volume of package = 12
2-262
Spinning Processes and Types of Yarn Figure 7.7 (2)
Approximate package weight according to package density and diameter 3° 30' Package density and weight d2: 49.0 mm d1: 31.1 mm
Package diameter (Top)
Package density (g/cm 3 ) 0.30 0.35 0.40 0.45 0.50
r 150(132.1) r 200(182.1) r 250(232.1) r 300(282.1)
629 1200 1944 2859
734 1404 2268 3335
839 1601 2592 3812
944 1801 2915 4288
1049 2001 3229 4765
4° 20' Package density and weight d2: 62.0 mm d1: 40.0mm
Package diameter (Top)
Package density (g/cm 3 ) 0.30 0.35 0.40 0.45 0.50
r r r r
575 1139 1876 2784
150(128.0) 200(178.0) 250(228.0) 300(278.0)
671 1329 2188 3248
767 1519 2501 3712
863 1709 2813 4176
959 1899 3126 4639
5° 17' Package density and weight d2: 68.0 mm d1: 37.6 mm
Package diameter (Top)
Package density (g/cm 3 ) 0.30 0.35 0.40 0.45 0.50
r 150(119.6) r 200(169.6) r 250(219.6) r 300(269.6)
529 1079 1801 2694
617 1259 2101 3134
706 1439 2401 3592
794 1618 2701 4042
822 1798 3001 1191
9° 15' Package density and weight d2: 65.5 mm d1: 17.9 mm
Package diameter (Top)
Package density (g/cm 3 ) 0.30 0.35 0.40 0.45 0.50
r 150(102.4) r 200(152.4) r 250(202.4) r 300(252.4)
488 1008 1700 2564
569 1176 1984 2992
651 1344 2267 3419
732 1512 2550 3847
813 1680 2834 4274
5'' Cheese Package density and weight d: 25.0 mm
Package diameter (Top)
Package density (g/cm 3 ) 0.30 0.35 0.40 0.45 0.50
r 150 r 200 r 250 r 300
644 1160 1822 2632
752 1353 2126 3071
859 1546 2430 3510
966 1740 2734 3948
1074 1933 3037 4387
Note: The package weights in the table are calculate on the condition that the increase is 0.
Textile Handbook 2-263
7.8 Measures Against Excessive Yarn Breakage Table 7.8 (1) Classification 1 Tension
Frequent tension breakages Point to check
A. Is the tension setting proper? B. Does the tensor disc turn smoothly? C. Is the yarn path (tensor and yarn guide, etc.) free from flaws? Is the clearance adequate?
3 Drum
A. If sloughing is also frequent, check that the winding speed setting is suited to the yarn.
4 Bal-Con
Adjust the clearance to 5 to 7 times the yarn diameter. Change the preset speed.
Grind off the flaw on the drum or replace the drum.
A. Is Bal-Con aligned with a bobbin?
Align Bal-Con with a bobbin. Remove a bad bobbin.
B. Is the Bal-Con position correctly?
Adjust the Bal-Con cylinder not to go down excessively.
Frequent yarn clearer cuts Point to check
1 Frequent yarn A. Is the sensitivity setting proper’? clearer cut B. Is the time allowed after steaming too short? 2 Frequent yarn Replace the spinning bobbin with a new one to check if the sensitivity is correct clearer cut of one spindle only 3 No yarn clearer cut
Repair the flaw.
B. Check for any waste yarn on the drum brush due to a flaw on the drum nose.
Table 7.8 (2) Classification
Adjust the tension to 8 to 12% of the single yarn strength.
Countermeasures Check the count, material, sensitivity and reference length. Extend the time. If yarn breakage has not improved, replace the detection head.
A. Insert a sheet of paper into the slit of detection head.
If the cutter does not function, replace the detection head.
B. Replace the spinning bobbin with a new one.
If the cutter does not function, replace the detection head.
Spinning Processes and Types of Yarn
2 Preclearer
Countermeasures
2-264
Spinning Processes and Types of Yarn
7.9 Causes and Corrective Actions for Poor Winding Causes 1. Bulge winding
The internal compression is increased as the winding diameter is increased due to the increase in the contact pressure of the package on the drum or to the increased density of the yarn. Thus, the internal yarn layers buckle. This occurs with coarse yarn and two-ply yarn when the 1.Winding angle is too large. 2.Winding tension is excessive.
3.Contact pressure is too high.
2. Wrinkles
3. Scramble
This is caused by short traverse at the start of winding, reduced tension by slipping, or by the bulge winding (see above). 1.Inadequate tension and contact pressure. 2.Deflection of take-up tube centre. 3.Poor adjustment of contact surfaces of take-up tube and drum. 4.Excessive application of increase. 1 .Drum does not stop at yarn breakage. 2.Joining motions repeats several times. 3.Suction mouth comes in contact with package. 4.Contact pressure is too low. 5.Ribbon comes off. 6.Weak starting force of drum.
Action
1. Lower the number of drum wind from 2W to 1.5W 2. Tension release is necessary for coarse yarn or bulky yarn. 3. To reduce contact pressure, a pressure reducer is necessary.
1. Improve the tension and contact pressure. 2. Remove defective take-up tubes. 3. Correct the small diameter driving of take-up tubes for paired drums. 4. Reduce the increase 1. Replace the yarn clearer. 2. Check the joining motion and yarn path. Also check the splicer. 3. Adjust the suction mouth stopper. 4. Change the cradle weight. 5. See 6 (ribbon winding). 6. Increase the drum motor voltage. > 127V
Textile Handbook 2-265 4. Stitch
6.Ribbon winding
At the winding end of spinning bobbin or at yarn breakage, yarn end is wound on the either end of the take-up tube or wound into the package layer. 1. Liable to occur with coarse yarn, unstable yarn, elastic yarn and two-ply yarn. 2. Due to static electricity. 3. Improper gap between the drum cover and the package. 4. Excessive sloughing. 5. Excessive-surface-cut of spinning bobbin. 6. Winding speed not suited to spinning bobbin building. This is most likely to occur when the ratio of the drum diameter and package diameter is an integer. With a rotary traverse type of winder, it is not possible to completely prevent ribbon winding, but dispersing is possible. 1. Improper setting of ribbon breaker. 2. Excessive contact pressure. 3. Improper rotation of cradle. 4. Excessive moisture in spinning bobbin.
1. Set the tension properly (8 to 12% of single yarn strength). 2. Correct the flaw on the drum. 3. Replace the cradle bearing. 4. Correct the loose cradle. 5. Adjust the cradle. 6. Refer to the article for ribbon winding. 7.Remove the cause of sloughing. 8. Increase the humidity to 60% or more.
2. Increase the humidity (60% or more). 4.Remove the cause for sloughing. 5.Improve the spinning process. 6. Improve the spinning bobbin building (spinning process) or lower the winding speed.
1. Change the interval setting. 2. Lower the contact pressure by adjusting the spring of pressure reducer and cradle weight. 3. Replace the bearing of cradle if the rotation is heavy.
Spinning Processes and Types of Yarn
5. End missing
The yarn is drops off the edge of the package. 1. Inadequate tension or variation of tension. 2. Flaw near the drum nose. 3. Improper rotation of cradle bearing centre. 4. Loose cradle. 5. Improper position of drum to cone holder. 6. By ribbon winding. 7. By sloughing. 8. By low humidity (hemp, acrylic) 9. Decrease the tension variation. 10.Liable to occur at high tension with low contact pressure.
2-266
Spinning Processes and Types of Yarn 7.Stepped winding
1. Flaw on drum. 2. Flaw on drum cover. 3. Low tension. 4. Disengaged yarn from the yarn path after machine cleaning.
1&2. Check the flaw and repair by sanding. 3. Increase the tension (with dial). 4. Be careful not to blow the yarn when cleaning with air.
8. Pattern winding (small dia. Side)
1. Improper guiding of yarn to the tensor. 2. Foreign substance on tensor disc. 3. Improper rotation of tensor motor. 4. Excessive variation in unwinding tension due to improper forming of spinning bobbin.
1. Check and correct any flaw on yarn guide. 2. Clean the tensor. 3. Check the contact of tensor disc with other parts. Check for any disconnection of tensor motor connector. 4. Check and improve the spinning bobbin building.
(large dia. Side)
(besides the 1 to 4 above) 1. Low increase. 2. Improper height of balloon breaker. 3. Low tension.
l. Improve the increase.
3. Increase the tension (with dial).
9.Saddle back package
1. Over tension. 2. Low contact pressure. 3. Low increase.
1. Lower the tension (with dial) 2. Increase the contact pressure (cradle weight). 3. Improve the increase.
10.Swelled package
1. No tension is applied, covered by - Improper guiding of yarn to tensor. - Foreign substance staying on tensor disc. 2. By ribbon winding.
1. - Poor return of tensor cutter - Clean tensor disc. 2. Refer to ribbon winding.
Textile Handbook 2-267
7.10 Electronic Yarn Clearer The tables below show the main yarn clearers by each manufacturer. Refer to the catalogues or the instruction manuals supplied by each manufacturer for details. Comparison table by type Table 7.10 (1)
Applicable yarn clearer (control box) for each machine Nippon Selen
Peyer
ZAG
KC60 KC50 KC40 UPM D4 D4 C3 W3 FR YM YM YM P150 P531 P551 Seletex 68A4 700 700 800 900
7-II (Stepped √ pulley) 7-V - 7-Vss (Individual √ inverter)
√
√
√ √
√ √
√
√
√
√
√
√
√ √
√
√
√
√
√
√
Spinning Processes and Types of Yarn
ZAG
KSK
Table 7.10 (2)
Variable (per section)
Per section
Thick place
Thin place
Per section
On bus bar
On bus bar
In bus bar
In bus bar
On bus bar
On bus bar
(1) Capacitance means detection by cross-section, and “photoelectric” means detection by diameter. (2) Per group means that it is possible to set the sensitivity per group as required, and per section means that it is possible to set the sensitivity per section.
On bus bar
In bus bar
Ampblified Mounting
Solid (replaced Separate (1 amp 2 spdles, in pair) plugged-in) Separate (plugged-in)
Separate (plugged-in)
Separate (plugged-in)
√
√
√
√
√
X
Per group Variable (per gruoup)
Per section
Per section
Per section
Per section
Per group
Variable Variable (L=40cm or more) (per group)
Variable (per section)
Variable (per section)
Per section (with additional adapter)
Per group
Per section
Per section
Per section
Variable (per section)
Per group
Per group
Variable (per group)
Per group
P531, 551 Photoelectric
Photoelectric
YM700 Photoelectric
FR700 Photoelectric
P150
ZAG-Peyer
Variable (per section)
Separate (plugged-in)
Head and amplifier
UPM Capacitance
Loepfe
Variable (per gruoup)
Fixed (+50%)
X
√ √ (within _+ (15%) Separate Separate (plugged-in) (plugged-in)
Fixed
X
Per spindle (with additional adapter)
Variable (+ 50%)
Sensitivity auto-correction
Doubled Fixed (+150% upper yarn per section) at lay-in
Nep
Per section
Variable (per section)
Per section
Per section
Slub (2)
Per section
D3 Capacitance
D4
KC60
Capacitance
ZAG-USTER
Capacitance
KSK
Yarn clearer (control box) comparison
Detection system (1)
Yarn clearer
Item
Sensitvity
2-268
Spinning Processes and Types of Yarn
Textile Handbook 2-269 Table 7.10 (3)
Applicable yarn count range of each yarn clearer
Note that the data in this graph is based on theory, and may differ in actual practice.
Spinning Processes and Types of Yarn
7.11 Conversion Graph of Peyer and UAM
2-270
Spinning Processes and Types of Yarn
7.12 Correlation Between Material and Type of Yarn by the Static Electricity Amount Table 7.12
Correlation Between Material and Type of Yarn by the Static Electricity Amount Notes
Yarn
M 7.5
Cotton, Wool, Viscose
At high relative humidity: Set at 8.5 for 80 % R.H. At low relative humidity: Set at 6.5 for 50 % R.H. .
5.5
Acetate, Polyacrylo nitrile fibre
Estera, Caloran, Minalon, Exslan, Kamilon, Danelon, Torelon, Beslon, Bonnel, Nitron Vinylon, Nylon
4.5
Polyvinyl Alcohol, Polyarnid Polypropylene
Pilen, Polypro
3.5
Polyester
Ester, Tetron
2.5
Polyvinyl chloride (PVC)
Ebilon, Tebilon
Mixed fibres
For the material value of mixed fibre, the value of each fibre is calculated from the rate of mixing, then the values are added together. Examples: Polyester/wool mixtures Polyester 55%: 0.55x3.5=1.9 Wool 45%: 0.45x7.5=3.4 Material value: 5.5 approx.
Textile Handbook 2-271
7.13 Material Setting of Uster UAM Yarn Clearer Graph 7.13
Material Setting of Uster UAM Yarn Clearer
Figure 7.14 (1)
Types of yarn Faults
Spinning Processes and Types of Yarn
7.14 Types of Yarn Faults
2-272
Spinning Processes and Types of Yarn Table 7.14 (2) Faults in Cotton Yarns Faults
Appearance Nep
Seed Leaf Thick place Thin place Piecing Spinners’ waste Piecing Spinning piece-up Fly Fly waste Lint Slub Torpedo slub Cracker kink Spinners’ doubles (*100%)
Spinners’ doubles (>> + 100%) Thick yarn
Double thread Double end Lash-in Knurl Snarl Loop
Knot
Textile Handbook 2-273
SECTION 8
TWISTING PROCESS
8.1 Up Twister The yarn bobbin (feed package) is put on the spindle, which is rotated with the bobbin at high speed to insert the twist into yarn. Twisted yarn is then wound slowly on a cylinder or tube type of take-up bobbin.
8.2 Ring Twister Yarn from feed package is withdrawn slowly by the pair of feed rollers and goes through the yarn guide and wind on a ring spindle. Twists are inserted by the ring and traveller system. There are two types of twist insertion kits, ring and flyer. Figure 8.2
Ring Twister and Uptwister
Spinning Processes and Types of Yarn
Twisting is the last stage after ring spinning. Though the yarn quality has already been determined during ring spinning, processing, twisting parameters and mechanisms have their influence while producing twisted or ply yarn, such as lustre, strength, extension and balance. There are different twisting systems; the ring twister, the up-twister and the twofor-one twister. The latest development is the Tritec Twister.
2-274
Spinning Processes and Types of Yarn
8.3 Two-for-One Twisting 8.3.1 Two-for-One Principle With the Two-for-One twisting system, the thread receives two turns with one revolution of the spindle. To obtain this Two-for-One effect, the protection pot with the untwisted feed package is kept in a stationary position on the spindle rotor by permanent magnets. The yarn is unwound from the stationary feed package, passes through the hollow axle, and the yarn tension device, enters the rotating upper part of the spindle and leaves it through the opening of the spindle rotor. Between the tension device in the hollow axle and the exit in the spindle rotor, the yarn receives its first turn (1). The yarn circles around the protection pot as a yarn balloon. The second turn (2) is given within the balloon between the spindle rotor and the balloon thread guide. The apex is the eye of the balloon thread guide. Figure 8.3.1 Two-for-One twisting system
Spindle speed(r.p.m) x 2 Yarn speed =
(m / min.) Number of twists(T / M)
Textile Handbook 2-275
8.3.2 Characteristics of Two-for-One Twisting Two-for-One twisting is a textile process to improve the quality of yarn. While twisting two or more single yarns are wrapped around each other. This makes the yarn strong and smooth without chemical treatment. Quality features are: • Optimum cross-wound take-up packages for further processes,
• Higher uniformity (doubling effect), • Softer, thanks to lower bending rigidity, • Higher elastic resilience (less bulging), • Good binding of the edge fibres, • Higher wear resistance (no pilling), • Higher tear resistance, • Greater absorbency of the fibres (towels), • Less fluffing (domestic dryers and washing machines), • Allow customers to develop additional market potential for the use of twisted yarns.
8.3.3 Tritec Twister The Saurer Tritec Twister spindle consists of two contra-rotating systems on bearings. The outer system with the spindle shaft (red) and the inner system with the parallel wound feed bobbin (grey) rotate at the same speed but in opposite directions. Both systems are equipped with a cylindrical thread-guiding device. The thread comes off the bobbin due to the rotation of the inner section, and accumulates on the thread-guiding device (self regulating function). It is then drawn into the hollow spindle where both contra-rotating systems immediately give it a double twist. The thread then accumulates on the external thread-guiding device and is given a third twist before being wound up on the delivery rollers.
Spinning Processes and Types of Yarn
• Better coverage with the same yarn volume, thus less material is required,
2-276
Spinning Processes and Types of Yarn Figure 8.3.3 Tritec Twister
Maximum productivity: Low spindle rotation speeds of just 7,000 - 10,000 rpm result in an effective maximum speed of 30,000 rpm.
Textile Handbook 2-277
8.4 Twisting Parameter Table 8.4.1
Twist Factor Ratio of Ply Yarn and Single Yarn
Final Product
Quality Requirement
Ratio
High density, less hairiness, high strength
1.2-1.4
Weft
Softness and lustre
Voile
Stiff and smooth, Twist on same direction and heat setted High density and smooth, good circular shape, twist direction ZSZ
1.0-1.2 1.3-1.4
Narrow Fabric Knitted Underwear
High density, smooth and shinny
Primary Twist: 1.7-2.4 Secondary Twist:0.7-0.9 1.3-1.4
Cotton Sweater and Socks Sewing Thread
Soft shiny, few knots
0.9-1.1
High density, shiny, good strength and circular shape, few and small knots
2 Ply : 1.3-1.4 3 Ply : 1.6-1.7
High density, shinny, good strength and circular shape, twist direction SZ, few and small knots Good lustre, soft, few and small knots
1.5-1.6
High density, good recovery, good strength, twist direction ZZS
Primary Twist: 2.4-2.8 Secondary Twist: about 0.85
High density, good recovery, good elongation, high twisted
2.0-3.0
High quality sewing thread Embroidering Thread Tyre Cord
Hand-twisted Thread
0.8-0.9
Theoretically, the relationship between single yarn Twist Multiplier and ply yarn Twist Multiplier is:
2 Ply yarn: a1 = 1.41a0 3 Ply yarn: a1 = 1.59a0
a1 - Twist Multiplier of Ply yarn a0 - Twist Multiplier of Single yarn
Spinning Processes and Types of Yarn
Warp
2-278
Spinning Processes and Types of Yarn
Practically, the following condition should be followed to obtain high quality ply yarn while using low twisted single yarn. a1 > 1.41 a0 However, to have the best quality of Ply yarn by using high-twisted single yarn, their relationship should be as follows: a1 < 1.41 a0
Table 8.4.2 Twist Factor for Different Applications Usage Normal Soft Twist Extra Soft Hard Twist Extra Hard
Twist Multiplier 4.0 3.4 1.32-2.8 5.0-5.4 5.0-6.5
Textile Handbook 2-279 Table 8.4.3
Single Single Yarn Yarn Count Twist
Twist Contraction % on Same Twisting Direction Between Ply and Single Yarn Ply Yarn Twist Multiplier
350 375 400 425 450 475 500 525 550 (3.68) (3.95) (4.21) (4.47) (4.74) (5.00) (5.26) (5.53) (5.79)
Multiplier 36
24
20
16
14
10
8
6
4.95 5.1 5.25 4.8 4.95 5.1 4.65 4.8 4.95 4.5 4.65 4.8 4.35 4.5 4.6 4.25 4.4 4.55 4.05 4.2 4.3 3.95 4.05 4.2 3.8 3.9 4.0
5.5 5.65 5.85 5.35 5.5 5.65 5.2 5.35 5.5 5.0 5.15 5.3 3.85 5.0 5.15 4.75 4.9 5.05 4.5 4.65 4.8 4.4 4.5 4.65 4.2 4.35 4.45
6.1 6.3 6.45 5.95 6.1 6.25 5.75 5.9 6.1 5.55 5.7 5.9 5.4 5.55 5.7 5.25 5.4 5.6 5.0 5.15 5.3 4.85 5.0 5.15 4.65 4.8 4.95
6.75 6.9 7.1 6.55 6.7 6.9 6.35 6.5 6.7 6.15 6.3 6.45 5.95 6.1 6.25 5.8 5.95 6.15 5.5 5.7 5.85 5.35 5.5 15.65 5.15 5.3 5.45
7.4 7.6 7.8 7.2 7.35 7.55 7.0 7.15 7.35 6.75 6.9 7.1 6.5 6.7 6.85 6.4 6.55 6.7 6.05 6.25 6.4 5.85 6.0 6.2 5.65 5.8 5.95
8.1 8.3 8.5 7.85 8.05 8.25 7.6 7.8 8.0 7.35 7.55 7.75 7.1 7.3 7.5 7.0 7.15 7.3 6.6 6.8 7.0 6.4 6.6 6.75 6.15 6.35 6.5
8.8 9.0 9.3 8.55 8.8 9.0 8.3 8.5 8.7 8.0 8.2 8.4 7.75 7.95 8.15 7.6 7.8 8.0 7.2 7.4 7.6 7.0 7.2 7.35 6.7 6.9 7.65
9.6 9.8 10.1 9.3 9.5 9.8 9.0 9.2 9.4 8.7 8.9 9.1 8.4 8.6 8.8 8.25 8.45 3.65 7.85 8.05 8.25 7.6 7.8 8.0 7.3 7.45 7.65
10.4 10.6 10.9 10.1 10.3 10.6 9.8 10.0 10.2 9.4 9.7 9.9 9.1 9.3 9.6 8.9 9.1 9.4 8.5 8.7 8.9 8.2 8.4 8.6 7.9 8.1 8.3
Spinning Processes and Types of Yarn
30
320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79)
Spinning Processes and Types of Yarn
2-280
Table 8.4.4
Single Single Yarn Yarn Count Twist
Twist Contraction % on Reversed Twisting Direction Between Ply and Single Yarn Ply Yarn Twist Multiplier
350 375 400 425 450 475 500 525 550 (3.68) (3.95) (4.21) (4.47) (4.74) (5.00) (5.26) (5.53) (5.79)
Multiplier 36
30
24
20
16
14
12
10
8
7
6
320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79) 320(3.37) 340(3.58) 360(3.79)
+0.3 +0.15 0 +0.2 0 -0.15 0 -0.15 -0.3 -0.1 -0.3 -0.45 -0.25 -0.45 -0.65 -0.4 -0.6 -0.8 -0.5 -0.7 -0.75 -0.65 -0.9 -1.1 -0.85 -1.1 -1.35 -1.0 -1.25 -1.15 -1.45 -1.4 -1.65
+0.55 +0.4 +0.2 +0.4 +0.25 +0.05 +0.25 +0.05 -0.1 +0.1 -0.1 -0.3 -0.05 -0.25 -0.45 -0.2 -0.4 -0.6 -0.3 -0.55 -0.75 -0.5 -0.75 -0.95 -0.7 -0.95 -1.2 -0.85 -1.1 -1.35 -1.0 -1.25 -1.38
+0.8 +0.65 +0.45 +0.7 +0.8 +0.5 +0.5 +0.3 +0.1 +0.35 +0.15 -0.05 +0.2 -0.05 -0.25 +0.05 -0.2 -0.4 -0.1 -0.35 -0.65 -0.3 -0.55 -0.8 -0.5 -0.5 -1.05 -0.65 -0.95 -1.2 -0.85 -1.1 -1.4
+1.1 +0.95 +0.75 +1.0 +1.1 +0.55 +0.8 +0.6 +0.35 +0.6 +0.4 +0.2 +0.45 +0.2 0 +0.3 +0.05 -0.2 +0.15 -0.1 -0.4 -0.05 -0.3 -0.6 -0.3 -0.6 -0.85 -0.45 -0.75 -1.051 -0.65 -0.95 -1.25
+1.45 +1.25 +1.05 +1.3 +1.45 +0.85 +1.1 +0.9 +0.65 +0.9 +0.7 +0.45 +0.75 +0.5 +0.25 +0.6 +0.3 +0.05 +0.4 +0.15 -0.15 +0.2 -0.1 -0.35 -0.05 -0.35 -0.65 -0.2 -0.55 -0.85 -0.4 -0.75 -1.05
+1.8 +1.6 +1.4 +1.65 +1.45 +1.2 +1.45 +1.2 +0.95 +1.25 +1.0 +0.75 +1.05 +0.8 +0.5 +0.9 +0.6 +0.35 +0.7 +0.4 +0.15 +0.5 +0.2 -0.1 +0.2 -0.1 -0.4 +0.05 -0.3 -0.6 +0.15 +0.5 +0.85
-2.2 +2.0 +1.75 +2.05 +1.8 +1.55 +1.85 +1.55 +1.3 +1.6 +1.35 +1.1 +1.4 +1.1 +0.85 +1.25 +0.95 +0.65 +1.05 +0.75 +0.45 +0.8 +0.5 +0.2 +0.5 +0.2 +0.4 +0.35 0 -0.35 +0.15 -0.2 -0.2
+2.65 +2.4 +2.15 +2.45 +2.2 +1.95 +2.25 +1.95 +1.7 +2.0 +1.75 +1.45 +1.8 +1.5 +1.2 +1.6 +1.3 +1.0 +1.4 +1.1 +0.8 +1.15 +0.8 +0.5 +0.85 +0.5 +0.15 +0.65 +0.3 -0.051 +0.45 +0.05 -0.3
+3.1 +2.85 +2.6 +2.9 +2.65 +2.4 +2.65 +2.4 +2.1 +2.45 +2.15 +1.85 +2.2 +1.9 +1.6 +2.0 +1.7 +1.35 +1.8 +1.45 +1.15 +1.55 +1.2 +0.85 +1.2 +0.85 +0.5 +1.05 +0.65 +0.25 +0.8 +0.4 0
Yarn NO. 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
46
5.3 6.8 8.2 9.5 10.7 11.9 12.9 13.9 14.9 15.8 16.6 17.4 18.2 18.9 19.6 20.2 20.8 21.4 22.0 22.5 23.0
48
5.3 6.9 8.3 9.6 10.8 12.0 13.1 14.1 15.1 16.0 16.9 17.9 18.5 19.2 19.9 20.6 31.2 31.8 22.4 23.0 23.5 24.0
50
5.4 6.9 8.3 9.7 10.9 12.1 13.2 14.3 15.3 16.2 17.1 18.0 18.8 19.5 20.2 20.9 21.6 22.2 22.8 23.4 24.0 24.5 25.0
5.3 6.8 8.2 9.4 10.6 11.6 12.8 13.8 14.4 15.5 16.4 17.1 17.9 18.5 19.2 16.8 20.4 21.0 21.5 22.0
44
40
5.2 6.7 8.0 9.2 10.4 11.4 12.4 13.3 14.2 15.0 15.8 16.5 17.1 17.8 18.4 19.0 19.5 20.0
42
5.3 6.7 8.0 9.3 10.5 11.6 12.6 13.6 14.4 15.3 16.1 16.9 17.5 18.2 18.8 19.4 20.0 20.5 21.0
5.2 6.6 7.9 9.1 10.2 11.3 12.2 13.1 13.9 14.7 15.4 16.1 16.8 17.4 17.9 18.5 19.0
38
Resultant Count of Ply Yarn
5.1 6.5 7.8 9.0 10.0 11.0 12.0 12.9 13.7 14.4 15.1 15.8 16.4 16.8 17.5 18.0
36 5.1 6.5 7.7 8.9 9.9 10.9 11.8 12.6 13.4 14.0 14.7 17.4 17.9 18.5 19.0
34 5.0 6.4 7.6 8.7 9.7 10.7 11.5 12.3 13.0 13.7 14.4 14.9 15.5 16.0
32 5.0 6.3 7.5 8.6 9.5 10.4 11.3 12.0 12.7 13.3 13.9 14.5 15.0
30 4.9 6.2 7.4 8.4 9.3 10.2 11.0 11.7 12.3 12.9 13.0 14.0
28 4.9 6.1 7.2 8.2 9.1 9.9 10.6 11.3 11.9 12.5 13.0
26 18 4.5 5.5 6.4 7.2 7.9 8.5 9.0
4.8 4.7 4.6 6.0 5.9 5.7 7.1 6.9 6.7 8.0 7.8 7.5 8.9 8.6 8.2 9.6 9.3 8.9 10.3 9.9 9.5 10.9 10.5 10.0 11.5 11.0 12.0
22 20
24
14 4.2 5.1 5.8 6.5 7.0
16 4.4 5.3 6.2 6.9 7.5 8.0
Spinning Processes and Types of Yarn
Table 8.4.5 8 3.4 4.0
10 3.8 4.4 5.0
12 4.0 4.8 5.5 6.0
3.0
6
Textile Handbook 2-281
2-282
Spinning Processes and Types of Yarn
1. Ply Yarn: 1 N=
1 1 + N1 N2
N1 x N2
=
N1 + N2
N = Yarn Count N1- N2 = Individual Yarn Count
2. Three single yarns or above 1 N=
Table 8.4.6
1 1 1 + + ...... + N1 N2 N3 Twist Types for Plied Yarns and Twist Twist Direction
Process Spinning
Z
S
Z
Z
Ply Twisting
S
Z
S
Z
Z
S
ZSZ
ZZS
2nd Ply Twisting Twisting Sequence
ZS
SZ
Examples: ZS Twist - Weaving yarn, Wrapping yarn, Sail twine ZSZ Twist - Seine twine, Cable cord, Twist rope
2-282
Spinning Processes and Types of Yarn
1. Ply Yarn: 1 N=
1 1 + N1 N2
N1 x N2
=
N1 + N2
N = Yarn Count N1- N2 = Individual Yarn Count
2. Three single yarns or above 1 N=
Table 8.4.6
1 1 1 + + ...... + N1 N2 N3 Twist Types for Plied Yarns and Twist Twist Direction
Process Spinning
Z
S
Z
Z
Ply Twisting
S
Z
S
Z
Z
S
ZSZ
ZZS
2nd Ply Twisting Twisting Sequence
ZS
SZ
Examples: ZS Twist - Weaving yarn, Wrapping yarn, Sail twine ZSZ Twist - Seine twine, Cable cord, Twist rope
Section 9 - Application of Information Technology in Spinning Procsss ......... 2-283 9.1
ABC-Control for Blow Room and Carding .................... 2-283
9.2
Spiderweb : The Mill Data and Information System .... 2-284
9.3
Barco Sycotex System ....................................................... 2-286
9.4
Uster Labdata .................................................................... 2-286
Section 10 - Special Types of Yarns ......................... 2-287 10.1 Production of Rough-Spun (Slub and Neps) .................. 2-287 10.1.1 10.1.2 10.1.3 10.1.4
Introduction ................................................................. 2-287 Machinery Settings ...................................................... 2-287 Maintenance ................................................................ 2-288 Other Considerations ................................................... 2-288
10.2 Recommendation for Producing Linen-Look Yarn on Conventional Equipment ................................................. 2-290 10.2.1 Operating Procedures .................................................... 2-290 10.2.2 Experiment Details ...................................................... 2-291
10.3 Slub Effect Yarn with Amsler GOE Device on OE Spinning Machine ............................................................. 2-293 10.3.1 Function ....................................................................... 2-293
10.4 Amsler Cortex System ...................................................... 2-295 10.4.1 Features ....................................................................... 2-295
10.5 Core Spun Yarn by Plyfil Spinning System .................... 2-297 10.5.1 Equipment for Hard Core Yarns .................................. 2-297 10.5.2 Equipment for Soft Core Yarns ................................... 2-298 10.5.3 The advantages of PLYfiL ............................................ 2-300
10.6 Parallel Yarn by Parafil Spinning System ...................... 2-301 10.6.1 Structure of Parallel Yarn ............................................ 2-301 10.6.2 Properties of Parallel Yarn ............................................ 2-302
Section 11 - Wool Spinning Process ........................ 2-304 11.1 Worsted System ................................................................. 2-304 11.1.1 The worsted spinning process flow is as follows ........ 2-304 11.1.2 Scouring ...................................................................... 2-304 11.1.3 Drying ......................................................................... 2-304 11.1.4 Oiling ........................................................................... 2-305 11.1.5 Carding ........................................................................ 2-305 11.1.6 Backwashing ............................................................... 2-305 11.1.7 Combing ...................................................................... 2-305 11.1.8 Gilling ......................................................................... 2-306 11.1.9 Drawing ....................................................................... 2-306 11.1.10 Spinning ..................................................................... 2-306
11.2 Woollen System ................................................................. 2-306 11.2.1 11.2.2 11.2.3 11.2.4 11.2.5 11.2.6 11.2.7 11.2.8
Woollen spinning process flow:- ................................. 2-306 Scouring and drying .................................................... 2-307 Carbonizing ................................................................. 2-307 Dyeing ......................................................................... 2-307 Blending ...................................................................... 2-307 Oiling ........................................................................... 2-307 Carding ........................................................................ 2-307 Spinning ...................................................................... 2-307
Section 12 - Texturing ............................................... 2-308 12.1 Purpose of Texturing ........................................................ 2-308 12.2 False Twist Method ........................................................... 2-308 12.3 Edge-Crimped Yarns ........................................................ 2-310 12.4 Stuffer-Box Crimping ....................................................... 2-311 12.5 Air-Textured Yarns ........................................................... 2-312 12.6 Knit-De-Knit Method ....................................................... 2-313 12.7 Gear Crimping .................................................................. 2-313 12.8 Twist-Textured Yarns ........................................................ 2-313 Back to Table of Content
Textile Handbook 2-283
SECTION 9
APPLICATION OF INFORMATION TECHNOLOGY IN SPINNING PROCESS
9.1 ABC-Control for Blow Room and Carding
In addition, the machines in the blowroom are expected to operate without interruption, as they frequently serve a key function. If there is an interruption on a cleaning machine, in a matter of minutes 10 to 20 cards come to a standstill. As a result, the entire production can be disrupted for a long period of time. The adjustable values on a Rieter cleaning machine are “waste amount” and “intensity”. They are defined in relative sizes in the range of 1 to 10, or 0 to 1 and make up the two-dimensional VarioSet cleaning field. The “cleaning intensity”, and “relative amount of waste” cleaning parameters can be changed at the operator panel by means of the VarioSet cleaning field. The microprocessor control unit automatically adjusts the machine elements such as the feeding trough, cleaning roller and separating. ABC Control is a system which consists of a programmable logic control (plc), responsible for actual-time control of all machines and parts of the plant, as well as a visualizing system based on a PCcompatible industrial computer. This is connected via a computer network to the plc, UNIfloc, the VarioSet cleaners B 10 and B 60, and the C 50 cards.
Spinning Processes and Types of Yarn
The quality of a blowroom is often the subject of debate, and the question of which aspects are most important rarely leads to a consensus. Depending on the case and prevailing opinion, emphasis could be placed on a higher degree of cleaning, lower waste of good fibres, minimal nep accumulation or less damage to fibres,
2-284
Spinning Processes and Types of Yarn Figure 9.1 Rieter VarioSet Blowroom/Carding
9.2 Spiderweb : The Mill Data and Information System SPIDERweb is a data collection and information system for all quality and production data of the Rieter machinery. All production data are available in the form of texts, graphics or tables. On-the-spot optimisation possibilities are visible for the spinning plant. Ideally designed for Rieter equipment, SPIDERweb keeps everything under central control. Figure 9.2(1) and Figure 9.2(2) illustrate the information provided by Spiderweb. The most important advantages are: • Increase in production and improvement in quality due to specific, central and comprehensive information. • Simple operation and high flexibility through full adoption of the Windows operating philosophy.
Textile Handbook 2-285 Figure 9.2 (1)
Rotor Spin Places Events
Machine Monitored by Spider Web: Cards: C50, C51 Draw frames: SB851, SB951, RSB951, D10, D30 Combers: E7/5A, E7/6, E60, E70R UNIlap: E5/3, E30 Roving frame: F5, F10, F30 Rotor: R1, R20 Ring frame: G30, G33, K40
Spinning Processes and Types of Yarn
Figure 9.2 (2) Card Production per shift (kg)
2-286
Spinning Processes and Types of Yarn
9.3 Barco Sycotex System All BARCO and Loepfe detector systems and sensors can be integrated in BARCO SYCOTEX plant wide monitoring system. With SYCOTEX, the whole production process can be monitored starting from opening lines to draw frames, flyers, ring frames, OE machines, winders and twisters. The SYCOTEX system also allows the connection of production machines equipped with other (non BARCO) yarn quality detection or clearer systems.
9.4 Uster Labdata It is quite clear that, as a result of the combination of on-line and offline quality assurance measures, a large amount of quality data will become available on both a daily and a weekly basis. The textile mill, and particularly the laboratory, has the task of arranging this quality information in an easy-to-understand form, and of making it available to the people within the mill who require such information (Figure 9.4). Uster Labdata is an integral system to provide the flow of information and quality reports. Figure 9.4 Uster Labdata: schematic arrangement of the integral information system
Textile Handbook 2-287
SECTION 100 SPECIAL TYPES OF YARNS 10.1 Production of Rough-Spun (Slub and Neps) Yarn on Conventional Equipment (Source: Cotton Incorporated)
10.1.1 Introduction
These limitations could be largely overcome if normal raw cotton and standard yarn mill machinery were used. Rough-spun yarns may be spun using either ring or open-end spinning machines. The count range using a ring spinning frame is from 8/1 Ne to 30/1 Ne, while the open-end count range is 6/1 Ne-20/1 Ne. The “roughness” of the ring-spun yarn will be somewhat more pronounced than open-end yarn spun from the same material. The cotton selected for rough-spun yarn should be of similar quality, at least initially, to that normally spun by the mill into a given yarn. As experience is gained, it is likely that the cotton grade may be reduced.
10.1.2 Machinery Settings The rough-spun effect is achieved by altering card settings to cause fibre “rolling” on the cylinder (see table 10.1.4 card settings). This effect is essentially achieved by setting the doffer to cylinder setting and the flats to cylinder setting to 0.040 inches in each case. The effect is enhanced by also setting the licker-in to cylinder setting to 0.040 inches and by using strapless flats or slowing down the flat rotation to one or two inches per minute. If a yarn containing additional leaf and other trash is desired, under card waste as well as opening room waste may be appropriately reduced.
Spinning Processes and Types of Yarn
Many random effect yarns are made by the use of unusual raw materials such as waste, or additional machinery, such as slub attachments. In the case of the former, spinning efficiency and low yarn strengths are common problems; and the yarn character changes as the quality of the waste supply varies. In the case of the latter, additional money must be spent on machinery which may not be fully utilized as customer preferences change with time.
2-288
Spinning Processes and Types of Yarn
No other changes in machinery settings in the card room or spinning room are required. It is likely that some multiple twist changes may be necessary in order to obtain a reasonable yarn strength.
10.1.3 Maintenance The rough-spun effect is achieved by allowing a certain amount of fibre to roll on the face of the card cylinder. Therefore, only cards with sharp, undamaged wire should be used, otherwise the cylinders will load excessively with fibre and may jam. Additionally, poorly maintained cards will lead to the production of variable roughness yarn.
10.1.4 Other Considerations • Production rates of the cards may be maintained at the same rate previously used to card the same raw material. • The rough-spun effect is not dependent on the type of wire or the make of the card used. • Sliver weight has no appreciable effect on the rough-spun effect. • Finer counts require longer fibre if yarn strength and ends down are to be maintained at reasonable levels. • Depending on circumstances and yarn quality requirements, a certain amount of waste may be introduced into the blend. However, this should be done only after the desired yarn roughness, strength and ends down levels have been achieved using standard raw cotton.
Textile Handbook 2-289 Table 10.1.4
Card Setting Of Rough-Spun Yarn Setting Points
Note:
Feed Roll To Plate Feed Plate To Licker-in Licker-in To Cylinder Back Plate Flats
Front Plate Doffer To Cylinder Take-Off Roll To Doffer Calendar Roll Screen
Trumpet Hole Diameter Arches To Cylinder (Not Shown)
Setting expressed in inches
Top Bottom Back Intermediate Intermediate Intermediate Front Top Bottom Top Bottom Front Middle Back Basket To Lickerin Nose To Lickerin Card Coiler
. 005 . 040 . 040 . 040 . 040 . 040 . 040 . 040 . 040 . 040 . 034 . 034 . 040 No Crushing Mill Standard Setting
Mill Standard Setting Mill Standard Setting
Spinning Processes and Types of Yarn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Rough Spun (ins)
2-290
Spinning Processes and Types of Yarn
10.2 Recommendation for Producing Linen-Look Yarn on Conventional Equipment (Source: Cotton Incorporated) Cotton Incorporated developed a totally new novelty yarn with a linen look which can be produced on conventional mill machinery without special attachments. It is called “linen look” because it simulates long stubs common to linen yarn but is made using 100% cotton. The slubs are formed by using small amounts of comber noils (short fibres) in the final drawing operation. One of the main targets for this yarn is women’s wear fabrics for blouses and skirts. In the current work, counts of Ne 18/1 were spun. The effective count range of this type yarn is projected to be from Ne 8/1 to Ne 28/1.
10.2.1 Operating Procedures • Process 100% upland comber noils into card sliver - a sliver weighing 30-55 grains per yarn (Ne 0.28-Ne 0.15) was produced. • Process carded upland cotton through the first drawing to produce a sliver weighing approximately 44 grains per yard (Ne 0.19). • Second Process Drawing - At the second drawing process blend one comber noil card sliver with six upland cotton slivers from the first drawing process. The comber noil sliver should be creeled in the middle of the six regular slivers. A 30-40 grains-per-yard sliver should be produced using a high front draft of at least 5. • Roving - Roving should be produced using the blended second process drawing sliver.The draft at roving should be as low as possible (2.5-4.0). It will be necessary to change the roving tension gear in order to build successfully a full package due to the heavy noil slubs in the roving. • Spinning - Adjust spindle speed, select traveller and adjust twist to achieve desirable yarn strength, and spinning efficiency.
Textile Handbook 2-291
10.2.2 Experiment Details a) Characteristics of fibre used in this project Type Grade Length (ins) Mic Strength (gr/tex) Comber Noil
-
US upland cotton SLM 1.12 3.8 - 4.6 24 and up any upland cotton noil
Opening Cleaning Cleaning Flock Feeder
- Fibre Controls Hoppers - Whitin Axi-Flo - Model A* - Centrif Air XL Step Cleaner* - Fibre Controls 310 Fine Opener
* Bypassed for noil processing c) Cards Card Chute Feed System - Fibre Controls - Snotlaker Saco Lowell Cards Rebuilt by Hollingsworth Production Rate (lb/hr) Sliver Weight (grains/yd) Sliver Count (Ne) Revolving Flats
Regular Cotton 40 57 0.146 yes
d) Drawing - First Process* Saco Lowell Production Rate (ft/m) Sliver Weight - 44 gr/yd Number of Slivers Fed
- Model DE8C - 600 - (0.19 Ne) -6
Draft Distribution Lifter roll to back roll Back roll to 4th roll 4th roll to 3rd roll 3rd roll to front roll Front roll to calender roll
0.99 1.18 1.25 5.07 1.01
Noils 15 55 0.151 yes
Spinning Processes and Types of Yarn
b) Opening and Cleaning
2-292
Spinning Processes and Types of Yarn
Roll Settings (center to centre - ins) 1
Back roll to 4th roll 4th roll to 3rd roll 3rd roll to front roll
1 2
22 32 5 8 17 32
*Card sliver made of noil is not introduced into the first process drawing. e) Drawing - Second Process Saco Lowell Production Rate (feet/minute) Sliver Weight - 30 grains/yard Number of Slivers Fed
- Model DE8C - 400 - (.27 Ne) -7 - 6 First process - 1 Noil card sliver
Draft Distribution Lifter roll to back roll Back roll to 4th roll 4th roll to 3rd roll 3rd roll to front roll Front roll to calender roll
0.99 1.18 1.25 7.3 1.01
Roll Settings (centre to centre - ins) Back roll to 4th roll
1
4th roll to 3rd roll
1
27 32 5 8
3rd roll to front roll
1
17 32
f ) Roving Saco Lowell Hank roving Twist multiple Tension gear (number of teeth)
- Rovematic (14x7) - 0.75 - 1.48 - 55*
Draft Distribution Back roll to middle roll Middle roll to front roll Total draft
1.34 2.01 2.70
Textile Handbook 2-293
Roll Settings (centre to centre - ins) Back roll to middle roll
1
Middle roll to front roll
2
23 32 1 4
*Note: Tension will have to be adjusted to build a proper package. g) Spinning - Zinser model 317 Spinomat - 2 14 -1 - 5000 Single
10.3 Slub Effect Yarn with Amsler GOE Device on OE Spinning Machine The system is based on a high dynamic servomotor which controls the basic as well as the overfeed rate of the OE-spinning machines input rollers. Variations in the feed rate are precisely controlled by an advanced microprocessor enabling all kinds of controlled yarn structure variations and slubs. The microprocessor also guarantees reliable reproduction of the desired effects.
10.3.1 Function The high speed slub servomotor with Amsler-differential gear controls the draft according effect patterninl. The slub device is fully integrated in the open-end frame headstock and operates synchronized with the production speed.
Spinning Processes and Types of Yarn
Spinning frame Ring size (ins) Flange # Spindle speed (RPM) Creeling
2-294
Spinning Processes and Types of Yarn Figure 10.3.1 (1) AMSLER-IRO fancy yarn attachment on AUTOCORO OEframe
Figure 10.3.1 (2)
Working principle Rotor slub GOE on Rieter-SSI RU 11/ RU 14
Textile Handbook 2-295
10.4 Amsler Cortex System 10.4.1 Features • Elastic CORE spun yarns with adjustable draft • Non-elastic CORE spun yarns with constant tensioning device • BI-Spun yarns with two roving’s per spindle covering the filament
• SPUN-BOUCLE yarn using the CORE device with overfeeding staplefibres and grooved Figure 10.4.1 (1) Principle sketch of AMSLER COR device, front and side view
1. FILAMENT SENSOR with GUIDING DEVICE on SWIVELLING ARM. 2. TRAVERSING DEVICE syst.AMSLER with new guiding supports. 3. CAN-BUS processor systems with full control of each individual spindle. 4.ELASTHAN DRIVE with MP-SERVO draft synchronisation, independent supervision 5.ALARM SYSTEMS, i.e. each spindle, -segment, central digital display. 6.CENTRAL CONTROLBOX for display, edit and network-communication 7.DELIVERY SYSTEM, 4-rollers, for filament with optional park position separators 8.OPTION - individual yarn stop motion syst.AMSLER 9. OPTION - additional synchron middle roller
Spinning Processes and Types of Yarn
• INJECTED color-slubs using the CORE device in combination with the AMSLER SLUB YARN device.
2-296
Spinning Processes and Types of Yarn Figure 10.4.1 (2) Option: variation for production of NON-ELASTIC coreyarn from bobbins
Figure 10.4.1 (3) Option: variation for production of INJECTED color-slubs with AMSLER SDE-slub device
Textile Handbook 2-297
10.5 Core Spun Yarn by Plyfil Spinning System PLYfiL machines are suitable for the production of both hard and soft core yarns. The core of hard core yarns is a continuous filament. Tensile strength and elongation of hard core yarns are mainly determined by the characteristics of the filament.
The sheath of hard and soft core yarns can be formed of natural as well as man-made fibres. These fibres are drafted in the PLYfiL drafting system. Compared to a conventional yarn, the total draft applied is increased by the percentage of the core. The core is fed to the sliver at the front roller pair of the drafting system by means of devices and guiding components specially designed for hard and soft core yarns. Both components then run through the assembly and spinning nozzles. Such devices and guiding components can be retrofitted to PLYfiL machines already installed.
10.5.1 Equipment for Hard Core Yarns A special creel is fitted on the PLYfiL machine for producing hard core yarns. As a rule, the filament is unwound overhead. A sensor in the feeding mechanism monitors the filament. The filament must be pretensioned before entering the drafting system. The pretension selected should not be so high as to permanently impair the elasticity of the filament. The filament must run exactly in the centre of the fibres to achieve good coverage. The yarn guiding element in front of the front top roller can be adjusted for this purpose. After leaving the drafting system, the filament and the fibres run through the assembly and spinning nozzles, receiving a false twist from the spinning nozzle. When this false twist is dissipated, the fibres wrap the filament to form a sheath capable of resisting slippage during the subsequent twisting procedure.
Spinning Processes and Types of Yarn
Soft core yarns incorporate an elastomeric core which provides the core yarn with high elasticity and the fabric with good recovery qualities.
2-298
Spinning Processes and Types of Yarn
The filament can be fed to one or two ends of the ply yarn. When it is fed to both ends, the operation of the machine is more complex. Finer filaments must be selected to maintain the given proportion of fibres and filament. Economic aspects must be considered, too, when finer filaments are required. The hard core yarns produced on the PLYfiL machine must finally be twisted and steamed.
Figure 10.5.1
Hard Core Yarns
10.5.2 Equipment for Soft Core Yarns The fibre sheath of soft core yarns is formed in the same way as for hard core yarns. The essential difference for the production of soft core yarns is that the elastomeric core must be pre-stretched. The necessary unwinding device for the bobbin carrying the elastomeric core material is fitted above the drafting system and incorporates two driven delivery shafts (see Figure 10.5.2 (1) & (2)).
Textile Handbook 2-299 Soft Core Yarns
Figure 10.5.2 (2)
Unwinding Device for Elastomeric Core
Spinning Processes and Types of Yarn
Figure 10.5.2 (1)
2-300
Spinning Processes and Types of Yarn
Usually, the degree of pre-stretching is between 3.5 and 4.5, which is achieved by an adjustable speed ratio between the unwinding device and the front roller pair of the drafting system. The elastomeric core is fed to the front roller pair over an adjustable guiding roll (see Figure 10.5.2 (3)). This guiding roll must feed the elastic filament into the centre of the drafted fibre sheath to ensure that it is completely embedded in the covering fibres. A sensor monitors the core. If it is missing, the corresponding winding position is stopped. The specific PLYfiL yarn structure makes it possible even in soft core yarns to feed the filament to only one yarn end. By combining the two yarn ends in the subsequent twisting operation, the wrapping fibres provide excellent coverage of the core. In principle, stretch filaments can be fed to both ends of the ply yarn. The soft core yarns produced on the PLYfiL machine must be subsequently twisted and steamed.
10.5.3 The advantages of PLYfiL • Compared with conventional ring spinning, three processing stages are omitted : - the roving frame or apron condenser frame - winding and clearing after spinning - separate assembly winding before twisting • The output of a PLYfiL spinning Position is 40 times higher than that of a ring spindle. • In twisting, only approximately 60 to 80% of the turns needed for the conventional process are necessary. The number of twisting positions therefore can be reduced.
Textile Handbook 2-301
The PLYfiL route thus offers the advantages of • • • •
reduced reduced reduced reduced
investment space requirements energy consumption labour requirements
Figure 10.5.2 (3) Adjustable Guiding Roll for Elastic Filament
Spinning Processes and Types of Yarn
10.6 Parallel Yarn by Parafil Spinning System 10.6.1 Structure of Parallel Yarn Parallel Yarn (PL yarn) consists of non-twisted parallel staple fibres held together by a filament wrapping them spirally. The filament provides the strength of the Parallel Yarn. It produces the necessary cohesion between the individual staple fibres by exercising radial pressure on them. This inter-fibre friction is increased when the PL yarn is subjected to tension. The number of filament wraps per unit length in a standard PL yarn is approximately the same as the amount of twist in a comparable ring-spun yarn of the same fineness.
2-302
Spinning Processes and Types of Yarn
10.6.2 Properties of Parallel Yarn a) Structure The cross-section of a Parallel Yarn is round. When not under tension, it shows a slightly undulating character. This is caused by the filament, which encircles the staple fibres spirally with a slight local compressive effect. Once embodied in a fabric, this feature of a PL yarn becomes unnoticeable. b) Volume During processing, PL yarn is relatively lean and smooth. That is the result of the constrictive effect of the wrapping filament which becomes effective under tension. This characteristic accounts for the ease with which PL yarns slip through thread guides, brakes, guide rods, needles, etc, On the other hand, when not under tension, PL yarns are considerably bulkier. This is because the staple fibres are without twist, which is very important, particularly after steaming, because the bulking capacity of the fibres is not inhibited by twist. c) Spinning Limits PLyarn can be produced with fewer fibres in the crosssection than is the case with conventional yarns. Yarn up to 15% finer in count can be spun, or alternatively coarser staple fibres can be used. d) Hairiness Compared with Ring and Open End yarns, PL yarn is less hairy. This results in a noticeable reduction of dust and fly during subsequent operations. The virtual lack of hairiness is the reason that PL yarn has less tendency towards pilling. e) Contraction through Twist Since PL yarn is not twisted, its fibre content is not shortened by twist as in the case of conventional yarn.
Textile Handbook 2-303 Figure 10.6.2 e
Parafil Spinning System
Spinning Processes and Types of Yarn
2-304
Spinning Processes and Types of Yarn
SECTION 11
WOOL SPINNING PROCESS
Two main systems are used to process wool from fibre into fabric. Worsted system uses fine long clean wool to produce high quality suit and fashion fabrics, while woollen system uses coarser, short wool to produce upholstery, bulky knitwear, blankets and tweeds.
11.1 Worsted System 11.1.1 The worsted spinning process flow is as follows Raw wool==>Scouring (opening & cleaning) ==>Drying (Scoured wool) ==>Oiling Carding==>Preparatory gilling==>Combing ==> Backwashing==> Finisher gilling (Wool top) ==> Drawing (Roving) ==> Spinning (worsted yarn)
11.1.2 Scouring This is another part of the opening, cleaning, and mixing process. Wool fleece contains grease, suint (sheep perspiration, or sweat), sand, dirt and vegetable matter, all of which have to be removed. Wool grease can be emulsified by an alkaline solution at a temperature above its melting point (55°C is the optimum). Suint contains potassium salts of various fatty acids and is soluble in water.Soft water is recommended, since hard water can precipitate the salt. Alternatively, in order to prevent the yellowing of wool in alkaline conditions, non-ionic detergents in a neutral solution at a higher temperature (60 to 70°C) can be used. The scouring machine contains a series of scouring bowls by a hopper feeder that feeds a uniform flow of wool at a rate that will provide uniform and adequate treatment. Felting (the excessive shrinkage of wool due to the interlocking of wool fibres) can occur when wool is agitated, and so careful control of the rate of agitation is essential. Fine wool contains more grease, and so requires more treatment.
11.1.3 Drying Wool is dried after scouring, in preparation for carding. It should not be dried excessively, since this may impair the wool’s elasticity and
Textile Handbook 2-305
formation of neps.
11.1.4 Oiling In order to minimize dust in the card room and to lubricate the fibre, about 0.5% by weight of oil is applied to it.
11.1.5 Carding
11.1.6 Backwashing This process is for cleaning and mixing. Large numbers of slivers are passed side by side through a wash bowl containing soap or detergent solution, then through a second one for rinsing. They are finally dried in a drier. In -a dry-combing process (explained in 11.1.7), backwashing straightens the fibre and removes the crimp from it. By doing this, individual fibres become wet and pliable, thereby helping the stretching process when dried under tension. In an oil-combing process, oil is added after drying so that the slivers are spread uniformly over the feed roller of the combing machine.
11.1.7 Combing This process is for opening, cleaning and mixing the fibres, to make them parallel and to assist in sliver formation. In the dry-combing system, a rectilinear comb (French comb) is used. Sheets of fibre are fed into the comber by an intermittent action. The fibre lap is advanced and gripped by a feed roller, leaving a fringe of fibres, which is combed by a half-toothed roller. The untoothed half of the roller carries the combed fringe to the draw-off rollers to join with the previously combed fringe to form a continuous strand. In the oil-combing system, a Noble comb is used. The machine consists of pins which are steam-heated and contain moisture. These enhance the sleek and silky appearance of the fibre arrangement. Eighteen balls of wool, each containing four slivers, are arranged around the circumference of the machine and the fibres are fed radially inwards. A pair of epicyclic comber wheels comb the fibre fringes to remove
Spinning Processes and Types of Yarn
This process is for further opening, cleaning and mixing and for sliver formation. The carding machine contains roller cards fitted with workers, strippers and fancy rollers. During carding, fibres are opened, and small traces of wool grease and dust residue from scouring are removed.
2-306
Spinning Processes and Types of Yarn
short fibres. The wool leaves the machine with the fibres well aligned and parallel.
11.1.8 Gilling This part of the process takes place both before and after combing. Before combing, the purpose of gilling is to reduce fibre entanglement. The pins of the gill boxes control the movement of short fibres, minimize the development of unevenness in the slivers and also straighten the fibres. After combing, the purpose of gilling is to improve the evenness of the combed sliver; to produce what is known as a top with an acceptable moisture content and linear density; to blend the output of a number of combs; and to package the top sliver in a suitable form for storage, handling and transport.
11.1.9 Drawing The drafting zone of this system is longer than for other yarns because of the longer fibre length required for worsted yarn. Fibre control is assisted by: (i) In an oil-combed system, two or three sets of carriers and tumblers set between the drafting rollers, consisting of driven steel bottom rollers, which control the fibre movement. (ii) In a dry-combed system, strands which are rubbed between reciprocating rubbing leathers to produce a twistless roving. A porcupine (a rotating roller covered with pins) is used to exercise some fibre control. It is placed just behind the front drafting rollers so that the fibres are drawn through its pins.
11.1.10 Spinning Finally, the roving is spun into worsted yarn. The system consists of a drafting zone with two pairs of rollers, the delivery rollers and the drafting rollers. In between, there are two pairs of additional rollers, the carrier rollers and the tension rollers, together with a flume (a narrow funnel-shaped guide). The top carrier roller enables twistless rovings to be drafted and is removed when twisted rovings are processed.
11.2 Woollen System 11.2.1 Woollen spinning process flow:Raw wool==> Scouring==> Carbonizing==> Dyeing (Optional) ==>
Textile Handbook 2-307
Blending and Oiling==>Carding==>Condensing (Slubbing) ==>Spinning (Woollen yarn)
11.2.2 Scouring and drying This is the same as for the worsted process.
11.2.3 Carbonizing
11.2.4 Dyeing The dried wool is dyed in lots or batches, to a number of shades. The different coloured wools are combined with fibres from other sources.
11.2.5 Blending The material is blended in large circular bins in which it is distributed by a rotating spreader. It is then passed through an opening machine and the whole operation may be repeated to improve the blending.
11.2.6 Oiling At the end of the blending process, oil is applied to make cleaning easier and to prevent dirt from entering the card.
11.2.7 Carding The carding machine straightens and attenuates the wool fibres. The carding process is very important, since the uniformity of the yarn depends upon it. There are two sections, called the breaker and the finisher. The blend is fed into the machine by a weighing hopper, whose function is to feed equal weights of material to the card at equal intervals of time to ensure uniformity in linear density. The condenser at the delivery end divides the carded web into strips which are rubbed by leather to form slubbings or rovings. Each slubbing is wound onto a separate package called a spool.
11.2.8 Spinning Finally, the slubbing is spun into woollen yarn. The spinning system, similar to the ring frame of cotton spinning, consists of feed rollers and delivery rollers. A false twister is located close to the delivery roller, and twists in the opposite direction to the spinning, mainly to
Spinning Processes and Types of Yarn
Carbonizing uses acid to turn buffs and grass seed into carbon for removal.
2-308
Spinning Processes and Types of Yarn
SECTION 12
TEXTURING
12.1 Purpose of Texturing The purpose of texturing is to introduce permanent waviness (crimp), loops, coils, and wrinkles and thereby to modify the geometry of the constituent filaments. Textured yarns may be classified into three major groups: stretch yarns, modified stretch yarns or set yarns and bulk yarns. Stretch yarns are characterized by their high extensibility and good recovery, but possess moderate bulk in comparison with the other two classes of textured yarns. They are produced mainly by the false-twist and by the edge-crimping processes. Modified stretch yarns may be defined as those with characteristics intermediate between stretch and bulk yarns. Overfeeding may modify stretch yarns. They may be first soft wound in packages and then heat set or stabilized either in an autoclave in steam or during the dyeing process. These yarns are generally used in knitted fabrics. Bulk yarns are characterized by their high bulk with moderate stretch and generally possess adequate recovery characteristics. They are mostly used in carpets, upholstery, and garments requiring warmth and comfort characteristics. Bulked yarns are produced by air texturing, stuffer box, knit-de-knit, gear crimping, twist texturing, and various other types of crimp texturing processes.
12.2 False Twist Method This is the most versatile and most widely used method of producing stretch-type textured yarns. The false-twist method combines all three stages, namely, twisting, heat setting, and untwisting in one continuous operation. The general principle of the false-twist texturing process is illustrated in figure 12.2. The yarn is drawn from the supply package, fed at controlled tension over the heater and through the false-twist spindle, and finally wound on a package. The twist in the yarn is set when it is between the input feed roll and the false-twist spindle, by heating and cooling before it leaves the false-twist spindle.
Textile Handbook 2-309
Draw texturing is a process in which an undrawn (fully or partially) flat yarn is drawn to the desired size and then textured in a continuous manner. The most important system of texturing combined with drawing is the false-twist process. The two-zone method produces yarn with characteristics similar to conventionally textured yarns.
Spinning Processes and Types of Yarn
Figure 12.2 Line diagram showing the path of a yarn through a false-twist texturing machine
2-310
Spinning Processes and Types of Yarn
12.3 Edge-Crimped Yarns Stretch and modified stretch yarns can also be produced by a process known as “edge crimping”. Thermoplastic yarns are edge crimped by a continuous process in which a yarn is tensioned, stretched, heated, bent, and drawn around an edge, followed by shrinking and cooling steps. The basic principle of edge crimping is illustrated in figure 12.3. The part of the filament touching the knife-edge is under compression, whereas that on the outside experiences extension. To develop crimp in the filament, the strains thus induced are relaxed by subsequently relaxing and heating the yarn under controlled conditions. Relaxation is carried out either in steam or in dry heat. Modified yarn with lower stretch and high bulk can be produced on the same machine by adding a bulk development section. Fabrics made from these yarns have a soft, full hand, good surface texture, very good dye uniformity, moderate stretch, and excellent recovery from stretch.
Figure 12.3
Principle of edge crimping
Textile Handbook 2-311
12.4 Stuffer-Box Crimping
Figure 12.4 Stuffer-box principle used for producing Textured yarns.
Spinning Processes and Types of Yarn
The process of texturing by the stuffer-box is based on the principle of heat setting filaments being held in a confined space in a compressed state, and then withdrawn in their crimped form. The chamber in which the filaments are stuffed is known as the “stuffer-box”. The thermoplastic feed yarn is positively fed by two feed rollers into the heated tubestuffer-box to be. On the output side, the yarn is passed through a weighted hollow tube or slug that impedes the progress of the crimped yarn travelling up the tube, thereby causing the yarn to back up inside the stuffer-box tube. At the same time the feed rolls keep delivering fresh yarn against the backed-up aggregate in the tube. The aggregate in the tube moves up, and is heat set at a required temperature in the stuffer-box, which is jacketed by the heater. The yarn is oiled as it emerges from the weighted tube, and then coned. The hot stuffer-box yarns generally have a wiry appearance, a soft feel, and high cover and bulk characteristics. These yarns also have good moisture absorption properties because of the minute spaces created between the filaments that can hold moisture.
2-312
Spinning Processes and Types of Yarn
12.5 Air-Textured Yarns The yarns used in air texturing generally have some initial twist. Bulk in continuous filament yarns can be produced by blowing a stream of air into a twisted yarn while it is being delivered at a higher rate than is being taken up by the winding process. The air stream creates a turbulence that causes the formation of random loops in overfed individual filaments. In this process, the yarn contracts in length, and as it emerges, the loops are locked in place to impart bulk to the yarn. The yarn thus produced has an appearance like a staple yarn but possesses higher bulk, greater covering power, reduced opacity and a warmer hand compared to flat continuous-filament yarn.
Figure 12.5 Cross section showing air-jet assembly used for producing Taslantype yarns.
Textile Handbook 2-313
Air-textured yarns generally exhibit lower tenacity and elongation-tobreak than that of the parent continuous-filament yarn before texturing. Processing conditions such as twist, overfeed, and air pressure significantly modify the tensile behaviour of air-textured yarns. Airtextured yarns are used in a number of end-use applications, such as apparel, furnishings, and some industrial fabrics.
12.6 Knit-De-Knit Method
12.7 Gear Crimping Bulk can also be produced in a continuous filament yarn when it is passed through closely meshed gears. The gear head is heated so that the crinkle produced in the yarn is permanent. These yarns are used in a variety of end-use applications, such as ladies’ and children’s knitted outerwear, sweaters, and ladies blouses.
12.8 Twist-Textured Yarns If two ends of yarn are twisted together around a common axis, rather than each yarn being twisted around its own axis, and the configuration is then heat set in the twisted state and finally untwisted, the yarn thus produced possesses excellent bulk. This is a very simple concept of introducing texture into thermoplastic continuous filament yarns. The yarns textured by this method have excellent dyeing uniformity, high
Spinning Processes and Types of Yarn
In this method, the flat yarn is first knitted, then heat set and unraveled to produce a crinkle structure, the crimp frequency and shape can be varied by varying the needle gauge on the machine and the fabric structure (plain jersey, rib, double jersey, interlock, etc.). The fabrics produced from knit-de-knit crinkle yarns have a pronounced sparkling boucle texture, excellent stretch and recovery from stretch, and full hand. These yarns are torque free and therefore do not require any subsequent heat setting.
2-314
Spinning Processes and Types of Yarn
cover, and extremely soft, smooth hand. Twisted textured yarns find uses in tricot fabrics, hosiery, and all types of knitted outerwear structures.
Figure 12.8
Principle of twist texturing
Chapter 3 Weaving and Woven Fabrics ..............3-2 Section 1 - Warp Preparation Process ................... 3-2 1.1
Warping Process ............................................................... 3-2 1.1.1 1.1.2 1.1.3
Direct Beaming ........................................................... 3-2 Section Warping .......................................................... 3-2 Ball Warping ................................................................ 3-3
1.2
Warping Data .................................................................... 3-3
1.3
Examples of Machine Settings for Warping ................... 3-5
1.4
Recent Development in Sectional Warping Machine .... 3-5
1.5
Defects and Possible Causes in Direct Beaming ............. 3-6
1.6
Warp Preparation for Rope Dyeing ................................ 3-9 1.6.1 1.6.2 1.6.3 1.6.4 1.6.5
1.7
A
Ball Warper Specification .......................................... 3-9 Ball Warping Process Parameters ................................ 3-9 Rope Dyeing ................................................................ 3-10 Typical Recipe Of Master Solution For Rope Dyeing 3-11 Technical Features Of Rope Dyeing Range ................ 3-12
Slasher Dyeing ................................................................... 3-13 1.6.6 1.7.1 1.7.2
Processing Parameters For Re-Beaming Of Rope Dyeing ......................................................................... 3-13 Warping Requirements ................................................ 3-14 Typical Recipes of Master Solution for Slasher Dyeing ......................................................................... 3-15
1.8 ROPE DYEING VERSUS SLASHER DYEING ................ 3-16 1.8.1 1.7.3 1.8.2
Characteristics of Rope Dyeing .................................. 3-16 Slasher Dyeing Processing Parameters ....................... 3-16 Disadvantages of Rope Dyeing ................................... 3-17
Section 2 - Warp Sizing ........................................... 3-19 2.1
Purpose of Warp Sizing .................................................... 3-19
A
2.2
Warp Size Types and Properties ...................................... 3-19 2.2.1 2.2.2
Warp Size Types And Properties ................................. 3-19 Size Auxiliary Chemicals ............................................ 3-23
2.3
Sizing Agents and Applications ........................................ 3-25
2.4
Examples of Recipes of Sizing Solution .......................... 3-25 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5
Protein sizes ................................................................ 3-25 Starch Sizes ................................................................. 3-25 Cellulose ether sizes .................................................... 3-26 Polyvinyl alcohol sizes ................................................ 3-26 Acrylate copolymer sizes ............................................ 3-27
2.5
Comparison of the Properties of Four Types of Sizing Agent .................................................................................. 3-27
2.7
Manufacturers and Brand of Commonly Used Liquid Wax ..................................................................................... 3-28
2.6
Emulsified Oil, Liquid Wax and Solid Wax ................... 3-28
2.8
Size Defects and Possible Causes ..................................... 3-29
2.9
Sizing Process Defects and Possible Causes ................... 3-30
2.10 Example of Warp Tension for Cotton Yarn during Sizing .................................................................................. 3-34 2.11 Guidelines for the Sizing of Denim .................................. 3-35 2.11.1 Size requirements ........................................................ 3-35 2.11.2 Causes of faults in sizing and its solutions .................. 3-35
2.12 Recent Development in Sizing ......................................... 3-37 2.12.1 2.12.2 3.1.1 3.1.2
3.2
WETSIZE Box SC (Sucker-Mueller-Hacoba) ............ 3-37 BEN-ECOSIZE (Benninger) ....................................... 3-37 Leasing ........................................................................ 3-38 Drawing-in .................................................................. 3-38
Specifications of Heald Wires .......................................... 3-38
Section 3 - Weaving Preparation ............................. 3-38 3.1
Introduction ....................................................................... 3-38
A
3.3
Specifications of Drop Wire ............................................. 3-40
3.4
Reed .................................................................................... 3-43
3.5
Tying-in .............................................................................. 3-44
3.6
Recent Development in Weaving Preparation ............... 3-44 3.6.1 3.6.2
Quick Style Change in Weaving ................................. 3-44 The process flow of a QSC system ............................. 3-44
Back to Table of Content
Chapter 3
WEAVING AND WOVEN FABRICS
3-2
Weaving and Woven Fabrics
CHAPTER 3.........
.......WEAVING AND WOVEN FABRICS SECTION 1 WARP PREPARATION PROCESS 1.1 Warping Process The purpose of warping is to arrange threads in long length parallel to one another preparatory to further processing. The primary operation of warp making in which ends withdrawn from a warping creel, evenly spaced in sheet form, are wound onto a beam to substantial length. There are three warping methods; the first is direct beaming, the second is section warping and the third is ball warping.
1.1.1 Direct Beaming Direct beaming is the winding of the total number of warp ends in full width in a single operation from a creeled bobbin, either onto a weaver’s beam or onto a sectional beam.
1.1.2 Section Warping Section warping is a two-stage-machine method of preparing a warp on a beam, consisting of firstly winding a warp in sections on to a reel, and then beaming-off the complete warp from the reel onto a weaver’s beam. Figure 1.1.2
Sectional Warping Machine
Textile Handbook 3-3
1.1.3 Ball Warping Ball warping is the winding of a number of warp ends from creeled bobbins into rope form and then winding it onto a ball warper. These ball warps are then sent for rope dyeing process.
1.2 Warping Data To ensure a perfect warp quality, it is necessary to input all warping data such as warp length, warping speed and warp density before warping. The following table is an example of data required for warping process designed by Benninger. Figure 1.2
Example of a Warping Data Sheet (Front side)
Weaving and Woven Fabrics
3-4
Weaving and Woven Fabrics Figure 1.2
Example of a Warping Data Sheet (Back side)
Textile Handbook 3-5
1.3 Examples of Machine Settings for Warping Table 1.3 Item
Product Specification
Unit
1
2
Product Number 4 5 6
3
7
8
cm 152.4 114.3 152.4
114.3
152.4
114.3
152.4
114.3
ends 4200 3510
3510
4680
3510
4680
3510
4680
tex (Ne)
84 (7)
58 (10)
48 (12)
36 (16)
g/m2
457.7
256.0
271.2
203.4
m/min piece m
600 to 1200 350 262/263 390 292/293 390
292/293 390 292/293
9000 11000 11500 15000 14000 18500 18500 24500
Beam flange mm 710 diameter No. of beams no. of 12 per batch beams g Tension 30-35 35-40 45-50 The creel can be divided into 3-5 zones for tension adjustment; yarn Remark tension at the rear part of the creel should be lower than the front part because the weight of the released yarn should be considered.
1.4 Recent Development in Sectional Warping Machine The sectional warping process is gaining importance due to decreasing order lengths. New models of the sectional warping machine usually equipped with roller units for a wider range of yarn tensions. These rollers are positioned between creel and sectional warping machine, enabling precise control of the breaking force. For example, the warping table of the T-2000 Sectional Warper (SuckerMueller-Hacoba) equipped with a sensor control roller automatically determines the right traverse, a deflecting roller for optimum guidance of the section of warped threads, and an articulated roller for correct measuring of the actual number of metres. This measuring system ensures equal lengths of all ends and uniform wound-on tension of the warping process. The operating principle is that once the article-specific
Weaving and Woven Fabrics
Fabric width Total ends Warp yarn count Fabric weight Warping speed Total number of cones Warp length
Examples of Machine Settings for Warping
3-6
Weaving and Woven Fabrics
pressure has been defined, the sensor control roller automatically determines the right traverse from the first revolution of the warping drum. The measuring accuracy of the sensor control roller ensures a traverse with a tolerance of less than 0.001 mm. The system continuously controls the measured traverse in the first section and compensates for error if necessary. The copying phase follows right after the measuring phase of the first section. All traverse values determined in the first section are then used to achieve exactly the same winding structure in the subsequent sections. The system will also automatically check the yarn counts warped in the subsequent sections and reacts accordingly.
1.5 Defects and Possible Causes in Direct Beaming Table 1.5 Defects and Possible Causes in Direct Beaming Defect Crossed end
Description
Possible causes
Broken end entangled with 1) Operator’s fault adjacent ends in the warp sheet 2) Malfunction or slow reaction of the auto-stop device 3) Improper function of drum brake, machine stops slowly causing free end wrap in warp sheet
Loose end Yarn tension of individual end (uneven tension) or group of ends is loosely wound on the warp
1) Insufficient tension applied or accumulation of waste or flies in the tensioner 2) Mis-threading of yarn through tensioner or yarn guide 3) Incorrect position or direction of tensioning device 4) Warp end coming out from the tension disc 5) Uneven density of the adjustable reed 6) Scratched surface of the guide roller behind the adjustable reed
Textile Handbook 3-7 Few ends on one or both edges 1) Wide gap between press roll and of the warp sheet are slack beam flange 2) Pressure of press roll is too high 3) Width of adjustable reed is either too wide or not centered so that edge yarns are pressed towards the flange 4) Deformed beam flange 5) Incorrect tension of edge yarn tensioners 6) Malfunction of traverse motion device of the reed holder
Convex edge
One or both edges formed a 1) Width of adjustable reed is either convex shape causing tight too narrow or not centered and the tension on edge yarns during gap between the edge yarn and flange unwinding is too wide causing the density of edge yarns to be relatively low 2) Deformed beam flange 3) Incorrect tension of edge yarn tensioners 4) Rear part of the creel humidity is too high
Broken end on Frequent end breaks on one or edge both edges during un-winding
1) Beam flange is deformed or rough 2) Convex edge
Missing end
Machine continues to run with end break
1) Malfunction of machine stop device 2) Improper function of drum brake 3) Stop motion sensor blocked with waste
Double end on An extra end entangle to an fabric face adjacent warp is woven into the fabric
1) A lengthy broken end was not properly pieced and adhered to adjacent warp that created a double end
Weaving and Woven Fabrics
Wave edge
3-8
Weaving and Woven Fabrics Waste accumulation
Waste yarn wrap into warp sheet
1) Operator’s fault 2) Waste yarn ends are not properly trimmed 3) Waste trapped in cones
Wrong yarn
Wrong yarn being wound into the beam
1) Wrong yarn wound to the cone during winding 2) Change of the wrong cone
Incorrect warp length
Warp length different from requirement
1) Malfunction of yardage meter 2) Malfunction of drum brake device 3) Incorrect setting of yardage meter 4) Malfunction of length control device
Wavy ends
Slack tension in group of a few or tenths of warp ends during un-winding
1) Beam shaft worn out or eccentric 2) The centre line of the warp beam and the press roll is not parallel 3) Big difference in humidity between both sides of the creel
Incorrect Variation in actual and nominal number of ends number of warp ends
1) Operator does not check the number of cones required
Stain
Stain on surface of the warp sheet
1) Soiled cones 2) Lubricant stains on roller or press roll during cleaning
Flies
Flies trapped in warp sheet during warping
1) Insufficient cleaning 2) Flies accumulated on cones 3) Tension disc does not rotate 4) Cleaning fan inefficient or inactive
Too many knots In a perfect warps, knots on single yarn shall not exceed 20 per 1,000 metre of warp. For high speed shuttless loom, knots on single yarn shall not exceed 10 per 1,000 metre of warp
1) Poor yarn quality 2) Improper cone winding 3) Cone holder on creel is not properly set 4) Tension too high 5) Rotten yarn or high moisture content 6) Knots on yarn too loose 7) Tensioner improperly set or worn out 8) Humidity too high
Textile Handbook 3-9
1.6 Warp Preparation for Rope Dyeing 1.6.1 Ball Warper Specification (Source: West Point Foundry And Machine Company)
Ball Capacity- Ball diameter up to 1200 mm (48") Ball Width - 1067 mm (42"), 1220 mm (48") Accessories- Leasing equipment, Digital Counter In-Line Creel: Package size up to 356 mm (14") diameter
Tension System- Post/Disc ROTATENSE® Fig 1.6.1
A Ball Warper
1.6.2 Ball Warping Process Parameters Parameters
Unit
Specifications
Yarn count
tex (Ne)
84 (7)
58 (10), 48 (12)
36 (16)
Number of cones
pcs
340~420
390~480
390~480
Warp length
m
10000~15000
15000~20000
24000~32000
Warping speed
m/min
250~300
250~300
250~300
Ball weight
kg
300~450
300~450
300~450
Warp density
g/cm
0.55~0.60
0.55~0.60
0.55~0.60
Lease interval
m
300~500
300~500
300~500
Yarn tension
g
45-50
35-40
30-35
Relative humidity
%
65-70
65-70
65-70
Weaving and Woven Fabrics
Stop Motion- Faller wire or drop wire, Motion sensitive (ELECTROSENSE®)
3-10
Weaving and Woven Fabrics
1.6.3 Rope Dyeing A group of undyed yarns (360 yarns) are twisted together and dyed as a single unit (rope like). This system allows all the yarns to be treated identically. The rope runs through a long machine where the yarn is dipped into indigo, taken out and allowed to oxidize and redipped again into the bath. Most rope dye machines allow 6 or 8 dips. Figure 1.6.3
Rope Dyeing Range
Textile Handbook 3-11
1.6.4 Typical Recipe Of Master Solution For Rope Dyeing Dyeing processing: 8 dips of oxidization, dyeing temperature 20 - 30oC, dye bath surface area 1.2m2 per vat Figure 1.6.4(1)
Tex (Ne)
Typical Recipe of Master Solution For Rope Dyeing
Master solution Ratio (by content of concentration (g/l by Total Dyeing D e p t h 100%) content of 100%) mass of no. of ends (g/min) s h a d e Indigo Sodium Caustic Indigo Sodium Caustic h y d ro - soda h y d ro - soda (%) sulphite sulphite
83.3 (7s)
4282
8223
106 (5.5s) 58.3 (10s) 36.4 (16s) 18.2 x 2 (32s/2) 9.7 x 2 (60s/2)
3630
8866
4640
6233
4760
3992
6496
5448
7140
3197
1.0 1.5 1.8 2.0 2.2 2.5 2.7 3.0 4.0 2.3 2.5 2.3 2.5 2.5 2.7 2.5 2.7 2.7 2.9
36 54 65 72 80 90 97 108 120 85 90 90 90 90 97 90 97 97 105
57 71 79.5 85.5 92.6 100 105.5 115 123.5 95 100 91 102 105.5 111 107.5 114 116 123
38.7 50.8 58 63 68.7 75.5 80.2 88 95.7 71.6 75.5 72.5 76.5 78.3 83 79 84.3 85.3 90.8
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1.58 1.32 1.22 1.19 1.16 1.11 1.09 1.06 1.03 1.12 1.11 1.14 1.13 1.17 1.14 1.19 1.18 1.20 1.17
1.08 0.94 0.89 0.88 0.86 0.84 0.83 0.82 0.80 0.84 0.84 0.85 0.85 0.87 0.86 0.88 0.87 0.88 0.86
Weaving and Woven Fabrics
Table 1.6.4(2)
Dye Bath of a Rope Dyeing Range
3-12
Weaving and Woven Fabrics
Remarks: This recipe may be suitable for the machine without a separate chemical feed-in device. For machines with a chemical feed-in, the ratio of Indigo : Sodium hydrosulphite : Caustic soda can be 1:0.8 ~ 0.9 : 0.8 ~ 0.9. The machine speed can be adjusted as long as there is no overflow or drop in level of the dyeing solution.
1.6.5 Technical Features Of Rope Dyeing Range The capacity of rope dyeing is determined by the number of ropes in each vessel. The number of ropes can be 10, 12, 18, 24, 36, etc., and the specification is listed in the table 1.6.5. Table 1.6.5 Technical Features Of Rope Dyeing Range Komatsu -bara Iron Works Co Ltd
Items
No. of ropes Cylinder width Machine length Machine height Power Water consumption Steam consumption Compressed air consumption No. of ends per rope Dyeing speed (max.) Dipping length per passage Oxidizing length per passage Dye vat surface area Dyeing passage No. of guide rolls per dye vat Annual production capacity
Morrison Textile Machinery Co
12 1220 56 8.6 72 3.5 1800 16
pcs mm m m Kwatt m3/h kg/h m3/h
10 1500 58 5.6 55 3.0 1600 16
ends
400-500 350-400 350-400 350-400 350-400 350-400 350-400
m/min <25
<36
m
8.0
m
18 1829 60 8.6 72 5.0 2500 16
<36
24 2134 75 8.6 72 7.8 3400 16
Greenville Machinery Corporation (KTM)
12 1220 60 8.6 74 3.1 1700 16
24 2290 76 8.6 74 7.5 3200 16
36 3200 93 8.6 126 11.3 4800 16
<36
<35
<35
<35
8.8 5.5 8.8
8.8
8.0
8.0
8.0
22.5
39
39
39
39
39
m2
2.13
1.16 0.89 1.66
1.95
1.2
2.0
3.0
No. pcs
8 7
8 5
8 5
8 5
8 5
8 5
8 5
Km
5500
8200
12000
16000 8200
16000
24000
39 39
8 3
Textile Handbook 3-13
1.6.6 Processing Parameters For Re-Beaming Of Rope Dyeing Table 1.6.6
Processing Parameters for Re-Beaming of Rope Dyeing
Items
Unit
Warp yarn count No. of ends Warp length Re-beaming speed Yarn tension Warp density Elongation Moisture regain of warp beam
tex (Ne) ends m m/min m/min g g/cm3 % %
Technological specification 84 (7) 350-400 10000-15000 15 150-300
36 (16) 380-480 24000-32000 15 150-250 0.55-0.60 0.5-0.7 8-9
1.7 Slasher Dyeing Slasher Dyeing is a special dyeing technique which is mainly used in the production of indigo dyed warp ends for denim fabric. It is a continuous process which combines dyeing and sizing in a single operation. Dyeing is done by continuously passing warp yarns in beam form through several (at least 5) troughs of indigo dye liquor for short intervals. The dyeing time is deliberately short to allow poor dye penetration and build-up. This results in interior washing and rubbing fastness of the dyed yarns, which accounts for the fashionable effect of denim after subsequent washes. The dyed yarns are then sized and wound onto a warp beam to be ready for use in the weaving process. A schematic diagram of a slasher dyeing range is below.
Figure 1.7
Beam creel of a Slasher Dyeing Range
Weaving and Woven Fabrics
0.50-0.55 0.5-0.7 8-9
58 (10) 380-480 24000-32000 15 150-250 150-200 or above 0.55-0.60 0.5-0.7 8-9
3-14
Weaving and Woven Fabrics
1.7.1 Warping Requirements a) Warping tension During the dyeing process, the warp ends of denim will cross, float and overlap on each other if the tension of the yarn sheet (or yarn rope) is not under control. This is because most of the time the ends are under wet condition, the processing is long, passing through many guide rollers and the yarn tensioning control is bad. While these floating and overlapping warps pass through each guide roller, the wrapping tension difference occurs repeatedly and alternatively which causes unexpected elongation and serious tension unevenness and therefore, significantly increased floating and crossing of warps, thus stopping the dyeing processing. For these reasons, the warping process should apply higher single yarn tension by using a multiple curvature tension device, and single yarn tension should around 4% of the original yarn strength. b) Yarn tension control during warping There are many methods of adjusting even warping tension, such as adjusting the setting between the cones and the creel guiding eyes, properly adjusting the washer weight by segment and by row, proper threading of the reed and suitably enlarging the distance between the bobbin creel and warping head. c) Warping speed In order to minimize the number of end breakages, and to increase the beam quality, the speed of warping of denim should not be too high. (i) If warping speed is too high, it is difficult to control the braking distance within the effective range, and the broken ends will easily run into the beam (warping machine) or ball (ball warping machine). This will cause breakage or crossed ends in the dyeing and sizing processes, consequently, increasing the unevenness of the yarn tension or lapping, and eventually affecting the dyeing evenness. (ii) The diameter of the unwinding balloon is large while the warping speed is high, especially for coarse yarn,
Textile Handbook 3-15
because of the setting limitation of the creel. If the balloon is too large, it hits the spindle and increases the end breakage rate. (iii) For coarse count, high density, if the warping speed is too high, the yarns easily cross and twist when braked, so when the machine starts again, the uneven tension will increase the end breakage rate.
1.7.2 Typical Recipes of Master Solution for Slasher Dyeing Dyeing processing: 6 dips; dyeing speed 18.5m/min; dyeing temperature 25 - 30oC; dye bath surface area 1.6m2 per vat.
Yarn Count tex (Ne)
83.3 (7S)
106 (5.5S) 58.3 (10S) 36.4 (16S) 18.2x2 (32S/2) 9.7x2 (60S/2)
Total no. of ends (pcs)
Dyeing Depth of mass (g/min) shade (%)
4284
6085
3630
6561
4640
4612
4760
2954
6496
4032
7140
2366
1.0 1.5 1.8 2.0 2.2 2.5 2.7 3.0 4.0 2.3 2.5 2.3 2.5 2.5 2.7 2.5 2.7 2.7 2.9
Master solution concentration (g/l by content 100%)
Ratio (by content 100%)
Sodium Caustic Sodium Indigo hydro- Caustic Indigo hydro- soda soda sulphite sulphite
32 48 60 65 72 80 85 90 110 75 80 75 80 80 85 80 85 85 90
78 89.5 101 103.5 109.5 115.5 118.5 120 132.5 112 115.5 119.5 122.5 128 131.5 127.5 131 139 141.5
47 57 66 69 73.5 79 82 84 96.5 76 79 79.5 82.3 85 88 84.7 87.5 91.3 94.2
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2.44 1.86 1.68 1.59 1.52 1.44 1.89 1.33 1.20 1.49 1.44 1.59 1.53 1.61 1.55 1.59 1.54 1.63 1.57
1.47 1.19 1.10 1.06 1.02 0.99 0.96 0.93 0.88 1.01 0.99 1.06 1.03 1.06 1.04 1.06 103 1.07 1.05
Weaving and Woven Fabrics
Figure 1.7.2 Typical Recipes of Master Solution for Slasher Dyeing
3-16
Weaving and Woven Fabrics
1.7.3 Slasher Dyeing Processing Parameters Dyeing process: 6 dips process Figure 1.7.3 Slasher Dyeing Processing Parameters Items
Unit
Technological specification
Dyeing temperature
o
C
20-30
Dipping duration
Sec
15-20
Oxidizing duration
Min
Each passage 1-1.5
Pick up
%
20-25%
Padder pressure
Ton
5-10
Depth of shade
%
2.5
1.8 ROPE DYEING VERSUS SLASHER DYEING 1.8.1 Characteristics of Rope Dyeing a) High Processing Speed and High Production Rate The speed sometimes can reach as high as 36 metres/minute, 50% higher than the conventional slasher dyeing. (The speed of slasher dyeing seldom exceeds 25 metres/minute) In a rope dyeing machine of 24 or 36 bundles (ball warp), the production rate is 2-3 times the rate of slasher dyeing. b) Rope Dyeing gives a Higher Quality Yarn It seldom has the problem of unlevelness and side-to-side variations as in slasher dyeing. In addition it has better penetration, higher degree of levelness and fastness. During the padding of the dye liquor, the rope formed of hundreds of yarns together will interact with one another to equalize the pick-up rate even there is a distortion of the pad-roll. (See Figure 1.8.1). With the slasher dyeing, it easily reveals an uneven pick-up along its width with the distortion of the pad-roll. The interacting pressure of individual yarn in rope padding will result in a better penetration and levelness. After dyeing, the rope beams have to be rebeamed. Dozen of warp beams are mixed together randomly, and sized to form the final warp beam. In this mixing process, small dyeing faults and minor variations in dyeing will be obscured.
Textile Handbook 3-17 Figure 1.8.1
The difference in rope and warp sheet padding
c) Better Warp Quality gives Higher Weaving Efficiency
1.8.2 Disadvantages of Rope Dyeing a) More Manpower Because of the many separate processes, more manpower is required than in slasher dyeing. b) Larger Capital Investment Because more machines are needed, a large land space is required. The machines for rope dyeing come in greater dimensions and thus require a different factory layout; generally a shop floor of L60xW10xH10 metres with adequate ventilation, good exhaustion, a well-planned drainage system and designed for safe operation. With the higher requirements of the factory, the investment cost of machine and factory together will be 8 to 10 times that of the slasher dyeing.
Weaving and Woven Fabrics
In rope dyeing, the dyeing process and sizing process are separated. There is a re-beaming process after dyeing. When strict quality control is used in the re-beaming process, the quality of the beam is assured and thus better efficiency in weaving. The sizing of the warp is conducted in a separate machine after dyeing, without being affected by the dyeing conditions and its limitations. There is ample time for loading and unloading of the warp beams, for reed setting and for handling of missing ends. With a shorter running distance of the warp sheet, it has the advantages of better penetration of the size and better control of the elongation of the yarn. These precise control of warp quality will result in a better warp beam for weaving, and a much better quality than the warp produced by dyeing and sizing in one process.
3-18
Weaving and Woven Fabrics
c) Precise operation control - Rope dye can be operated at a higher speed by dyeing several batches simultaneously. This requires precise control of the elongation of each warp beam. When a small variation of colour depth occurs in a certain section, the different elongation of different beams will cause dislocation of the section with the same colour during the warp sizing and combining processes. The result is a fabric with a few dozens or hundreds of metres in length of uneven stripy surface. In summarizing, though the rope dyeing requires more manpower, higher capital investment and precise operation control, it gives better quality fabric in respect of dyeing and weaving. It also has a higher production rate. The quality has better acceptance and competitiveness in the market, and it is more suitable for the production of heavy weight denim. In recent years, because of the keen competition, many conventional slasher dyers have replaced some of their machines with rope dyeing machines.
Textile Handbook 3-19
SECTION 2
WARP SIZING
2.1 Purpose of Warp Sizing
A
The main purpose of warp sizing is to give suitable weavability to warp threads to make good quality fabrics at low cost. However, due to the large number of different yarns that are produced at present, it is necessary to understand their own particular properties thoroughly, to prepare appropriate sizing agents, machines, and methods for their treatment.
The spun yarn is made of short fibres, e.g. staple fibres. The aims of spun yarn sizing are to give strength to the yarns by increasing the bonded force between those structural fibres, and to make a smooth surface of yarn, thus preventing yarn breakage caused by the entanglement of fluffs. In the case of filament yarn which consists of a number of single filaments, the cause of yarn breakage or fluff is due to the entanglement of a separated single filament. Hence, the purpose of filament yarn sizing is to prevent this single filament breakage by bonding those filaments together. The warp sizing is also useful to twist set of hard twist yarns. Other purposes of warp sizing are to adjust a suitable hand feel and weight of grey fabrics for shipping.
2.2 Warp Size Types and Properties 2.2.1 Warp Size Types And Properties Size is a mixture of primary and auxiliary chemicals. The subsections below describe the chemical makeup of typical size mixtures. a) Primary Component of Size The type of size used depends on the yarn type, weaving process (e.g., loom type, speed) and historical tradition
Weaving and Woven Fabrics
The spun yarns coarser than 40 count of two-ply yarns (40s/2), and the filament yarns more twisted than a medium hard twisted yarn (75 den, 800 tpm) are, generally, possible to weave without sizing. Except for those special yarns, almost all other kinds of yarns must be sized for weaving.
3-20
Weaving and Woven Fabrics
and experience in the textile facility. Three main types of size are currently used: •
Natural products (starch): Starch is the most common natural size and the most common size overall. It can be derived from a variety of substances, but corn and potatoes are preferred, Starch is used mainly for cotton products and other natural fibres.
•
Fully synthetic products: Synthetic sizes include polyvinyl alcohol (PVOH or PVA), polyvinyl acetate (PVAc), polyacrylic acid (PAA), and polyester (WD).
•
Semi-synthetic products (blends): Semi-synthetic sizes or blends include modified starches, starch ethers, starch esters, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), and carboxymethyl starch (CMS).
Table 2.2.1a (1)
Fibre Type Nylon Glass
Acetate Viscose rayon
Polyester
Sizing Materials Used for Filament Yarns
Basic Size Polyacrylic acid PVA PVA Dextrins Amylose derivatives Blends Stymer (styrene-maleic anhydride copolymer) Gelatin PVA Amylose derivatives CMC Blends Acrylic copolymers Alkali-soluble polyvinyl acetate Linear polyester
Textile Handbook 3-21 Table 2.2.1a (2)
Categorization of Spun Yarn Sizing Materials
Weaving and Woven Fabrics
Starches: Corn, Potato, Tapioca Unmodified-pearl Acid-modified, 20-60 fluidity Oxidized, several fluidities Dextrinized (British gum) Derivatized Acetate Hydroxyethyl ether Acrylate Styrene Cross-linked Cationic High amylose Low amylose (waxy) PVA Fully hydrolyzed Partially hydrolyzed Other CMC Blends Other polymers Table 2.2.1a (3) Environmental Advantages and Disadvantages of Alternative Synthetic Sizes Size CMC PVA
PAA
WD
Advantages Can reuse solutions Washes off with cool water Good adhesion Tough films Can mix with starch Washes off easily with hot water Washes off with alkali Good adhesion to nylon and synthetics Can control stiffness by copolymerization Good adhesion to polyester Washes off with very hot water
Disadvantages Supports mildew Cost Cost
Cost
Cost Can precipitate and cause spots
3-22
Weaving and Woven Fabrics
b) Starch Starch is the most common primary size component. Starch offers good performance on natural fibres and is often used in a blend with synthetic sizes for coating natural and synthetic yarns. A major problem with starch size is the inability to reuse or recycle the size because of degradation of the starch to various sugars during the desizing process. c) Polyvinyl Alcohol (PVA) PVA offers excellent mill performance when processing polyester/cotton goods and pure cotton fabrics and washes out completely to facilitate uniform dyeing. The strength, adhesion, viscosity, and other properties of PVA are affected by the degree of hydrolysis (the percentage of acetate groups replaced by hydroxyl groups). PVA can be used as size in either 100-percent pure form, or in blends with natural sizes such as starch. A typical blend formulation contains 50 to 95 percent PVA, depending on the type of fabric used and other processing parameters. For spun yarn, highviscosity PVA is used to bind the surface fibres and coat the yarn with a continuous film to suppress neps. In this application, a fully hydrolyzed PVA/starch mixture is usually employed. For filament fibres, low-viscosity partially hydrolyzed PVA is used to penetrate the yarn to prevent fibre splitting and breaking. d) Sodium Carboxymethyl cellulose CMC is an anionic polyelectrolyte that is soluble in either cold or hot water. CMC size is used primarily for polyester/ cotton and polyester/rayon blended yarns. For sizing pure synthetic fibres such as polyester, competing sizes provide better adhesion, stronger film, less shedding, and less sensitivity to moisture than CMC size. CMC and acrylics might compete with PVA, but these sizes do not provide the necessary strength for all applications. Also, at high humidities, CMC sizes do not perform as well as other alternatives.
Textile Handbook 3-23
e) Hydroxyethylcellulose (HEC) HEC size is available in water-soluble or alkali-soluble grades, with a range of properties including wide-ranging solution viscosity. Alkali-soluble HEC is used in textile sizing, although in negligible quantities.
2.2.2 Size Auxiliary Chemicals Sizes generally consist of mixtures of the primary chemicals (2.2.1a - e) plus additional auxiliary chemicals added to improve weaving performance, enhance the stability of the size or sized yarn, distinguish between sizes and for many other purposes. Auxiliaries used in sizing mixtures include: Adhesives and binders: To assist in binding the size to the yarn. Examples include natural gums (locust bean gum, tragasol, but not starch), gelatin, soya protein, casein, acrylates, PVA and CMC.
•
Antistatic agents: To suppress static in high speed weaving.
•
Antisticking agents: To reduce fouling of dry cans and guide rollers. Examples include waxes, oils, sulfated tallow, pine oil, kerosene and Stoddard solvent.
•
Biocides (preservatives): To improve the shelf life of woven goods. Example includes orthophenyl phenol (OPP).
•
Defoamers: To suppress foam in locations where process water is very soft. Examples include zinc and calcium chloride, light mineral oil, isooctyl alcohol but not silicones.
•
Deliquescents: To protect against overdrying. Examples include zinc and calcium chloride, polyalcohols (PEG), glycerine, propylene glycol, diethylene glycol (DEG) and urea.
•
Emulsifiers, dispersants and surfactants: To stabilize size mixtures during application and assist in desizing operations. Examples are nonionic ethylene oxide compounds.
•
Humectants: To protect against drying.
Weaving and Woven Fabrics
•
3-24
Weaving and Woven Fabrics
•
Lubricants and softeners: To improve the bending and frictional characteristics of the yarns. Examples include fats, waxes, oils, tallow, sulfated tallow, butyl stearate, glycerine and mineral oil.
•
Penetrants: To assist in penetration of size on filament yarns but not spun yarns.
•
Release agents: To facilitate removal of size during desizing.
•
Thinning agents: To increase penetration (similar to penetrants). Examples include enzymes, oxidizers, perborates, persulfates, peroxides and chloramides.
•
Tints: To identify warps.
•
Weighters: To increase the density of woven yarn. Example: clay.
Lubricants are grouped in two general classes: saponifiables and unsaponifiables. The unsaponifiable lubricants are considered the best friction reducers and include crude-scale paraffin wax and refined paraffin wax. Removal of these during desizing, however, requires added surfactants, which have high aquatic toxicity. Saponifiables include fats and fatty components such as fancy tallow, hydrogenated tallow glycerides, and fatty esters, These compounds can also be used as emulsifiers for the unsaponifiables. Any of these additives that are present in the size mixture will later be removed in wet processing (preparation, desizing, and scouring), and thus all of these materials will appear in waste streams from desizing operations, Undesirable materials (e.g., zinc salts, OPP) are generally not used on domestic (U.S.A) goods but regularly appear in imported fabrics. This is an important point in the process at which to perform quality control for raw material screening in textile operations.
Textile Handbook 3-25
2.3 Sizing Agents and Applications Table 2.3
Sizes and applications
Polarity Hydroxyl group
Sizes Starch, PVA, CMC
Suitable fibres Cotton, Rayon Acetate
Ester group
Acrylic esters series, Maleic acid series
Polyester, Acetate
Amide group
Acryl-amide series (PAM)
Nylon, Silk, Wool
Hydrogen bond
Starch, PVA, CMC, PAM Synthetic/natural powder blended
Cotton, Rayon, Acetate, Nylon Man-made spun and filament, man-made/natural fibre blends, cotton yarn
2.4.1 Protein sizes •
Warp: Cotton 17 tex (Nm 60/1), 50 ends/cm,(35s) 2% Protein size 10% Potato starch 0.2% Wax
•
Warp: Viscose staple rayon 25 tex (Nm 40/1), 50 ends/cm, (24s) 1% Protein size 5% Potato starch 0.2% Wax
•
Warp: Acetate filament 2.8dtex f70 (2.5 den 70), 90 ends/cm 7% Protein size
•
Warp: Viscose filament 133dtex (120 den 24), 50 ends/cm 2.5-3% Protein size
2.4.2 Starch Sizes •
Warp: Cotton 20 tex (Nm 50/1), Satin stripe, (30s) 6.5% Potato starch 2.5% Modified starch 0.2% Size fat
•
Warp: Rayon staple 30 tex (Nm 34/1), 2680 ends, (20s) 2% Potato or maize starch 2% Modified starch 0.2% Size fat
Weaving and Woven Fabrics
2.4 Examples of Recipes of Sizing Solution
3-26
Weaving and Woven Fabrics
•
Warp: Worsted 32-25 tex (Nm 32-40/1) 7% Potato or maize starch 2.5% Modified starch 0.2% Size fat
•
Warp: Polyester/cotton 14 tex (Nm 70/1),(42s) 11% Starch ether 3% Polyvinyl alcohol 0.5% Size fat
2.4.3 Cellulose ether sizes •
Warp: Cotton 25 tex (Nm 40/1), (24s) 5% Cellulose ether
•
Warp: Cotton 30 tex (Nm 34/1), (20s) 2-3% Cellulose ether 4-6% Starch ether
•
Warp: Polyester 10 tex (Nm 100/1), (60s) 6% Cellulose ether 4% Polyvinyl alcohol
•
Warp: Wool yarn (woollen spun) 3% Cellulose ether 6% Maize starch
2.4.4 Polyvinyl alcohol sizes •
Warp: Acetate 2.8dtex f70 (2.5 den 70), 80-90 ends/cm 6% Polyvinyl alcohol
•
Warp: Polyamide filament, 7% Polyvinyl alcohol
•
Warp: Polyamide staple fibre yarn 12.8 tex (Nm 79/1), (46s) 10% Polyvinyl alcohol
•
Warp: Polyester filament 10% Polyvinyl alcohol
•
Warp: Polyacrylonitrile staple fibre yarn 17tex (Nm 60/1), (35s) 5% Polyvinyl alcohol 5% Cellulose ether 0.2% Size fat
Textile Handbook 3-27
2.4.5 Acrylate copolymer sizes •
Warp: Polyester filament 12% Acrylate size
•
Warp: Acetate 2.8dtex f70 (2.5 den 70), 90ends/cm
•
Warp: Polyamide staple fibre yarn 12.8 tex (Nm 79/1),(46s) 5-10% Acrylate size
2.5 Comparison of the Properties of Four Types of Sizing Agent Properties of Four types of sizing agent
Sizing properties
Starch
Carboxymethy Polyvinyl Acrylate starch alcohol
Film forming Adhesion Elasticity Evenness Easy to operate No foaming Stable viscosity No tendency of precipitation Not sensitive to weather change Solubility in water Reaction to alkaline Heat resistance Chemical oxygen demand Biodegradability
0 0 + + +
+ 0 + + + + 0 0
+ 0 + + + + 0
+ + + + 0 + + +
Size 3256 (Acrylate type) + + + + 0 0 + +
0
+
+
-
+
+
0 +
0 -
+ +
+ +
+
+
0 -
+ 0
0 -
+
-
-
-
+
Remark: (+) is good, (0) is normal, (-) is poor.
Weaving and Woven Fabrics
Table 2.5
3-28
Weaving and Woven Fabrics
2.6 Emulsified Oil, Liquid Wax and Solid Wax Table 2.6
Comparison of emulsified oil, liquid wax and solid wax
Properties Decomposition Rinsability Coverage Temperature of oil box or wax box
Emulsified oil Not easy Low temperature No Always warm
Liquid wax Possible Low temperature Partial Always warm
Solid wax Possible High temperature Yes Should be heated
Recommended usage of liquid wax (% of warping weight) as follows: Worsted yarn Woollen yarn Polyester wool Polyester staple yarn Polyester filament
1-2 3-4 2-3 1-2 0.5 - 1
Acrylic staple yarn Polyester linen Viscose rayon filament Cotton yarn Jute yarn
2 3 1 1 3
-
3 4 2 2 4
2.7 Manufacturers and Brand of Commonly Used Liquid Wax Table 2.7 Manufacturers and Type of Commonly Used Liquid Wax Maker
Rotta, German
Type
Colour
Kettwachs 900
Pale yellow transparent liquid Same as above
Rapid schlichte 933 G100-A
Fibrofix, Swiss G46 L504 Melior, France
L550 L501
Structure Viscosity (mPa.s)
Remark
Non-ionic 90
Same as above
195
Concentrated liquid wax
Pale yellow viscosity liquid
Same as above
42
Same as above Pale yellow transparent liquid Same as above Same as above
Same as above Same as above
28 -
For yarn and thread
Same as above Same as above
-
For filament
-
Concentrated liquid wax
Textile Handbook 3-29
2.8 Size Defects and Possible Causes Table 2.8 Problem Too much foam
Precipitation of size
Low viscosity
Coagulation of size
Floating of oils
Possible causes Too much protein in starch. The temperature of size in the size box is too high. P.V.A. foams easily. Missing surfactant in the oil, or the quantity of oil is not enough. 5. Stirring speed of the size storage box is too fast. 6. No defoaming agent or penetrating agent. 7. No starch splitter agent. 1. Size has been kept too long. 2. Sizing liquor viscosity is too low; the size contains talcum powder. 3. The stirrer of the size storage box stopped. 4. pH value is too low. 5. Too much defoaming agent. 6. Too much starch splitter agent. 7. Affinity of size is not good. 1. The concentration is too high or there is insufficient water. 2. The boiling time is not long enough and the boiling temperature is not high enough. 3. No starch splitter agent. 4. The viscosity of sizing agents are too high. 5. Size temperature too low. 6. Water hardness is too high. 7. pH value is too high. 1. The concentration is too low. 2. Boiling temperature is too high. 3. Boiling time is too long. 4. Size has been kept too long. 5. Water leaking because the valve has not been tightly shut. 6. Water content of steam is too high. 7. Too much starch splitter. 8. Water hardness is too high. 9. pH value is too low. 1. The stirrer was not in motion while pouring the sizing agent. 2. Pouring speed is too fast. 3. Hydrosoluble sizing agents had coagulated. 4. The pouring sequence is wrong. 5. Water temperature is too high while pouring. 1. Emulsibility of oil is poor, or it has not been emulsified. 2. Emulsification of emulsifier has been taken by other sizing agent. 1. 2. 3. 4.
Weaving and Woven Fabrics
High viscosity
Size Defects and Possible Causes
3-30
Weaving and Woven Fabrics
2.9 Sizing Process Defects and Possible Causes Sizing Defects and Possible Causes Defects Cross end
Selvedge cross end
Problem due to traverse cause concave and convex edges
Missing end
Light size
Possible causes (1) Yarn separation in wrong sequence or not thorough (2) Insufficient number of yarn separations (3) Relocation of warp yarns in adjustable reed during warping (4) Frequent ends break and cutting of broken yarn wrapped on roller or incorrect handling of yarns accumulated at the reed. (5) Yarn sheet is densely set at adjustable reed (6) Slack tension in leasing zone (7) Warp ends are unevenly threaded on the adjustable reed (8) Heavy sizing, (9) Slack tension in leasing zone during slow speed processing (10) No leasing after clearing of ends cumulating at reed or size stain (1) Slack tension of edge yarns during warping cause wave edge during un-winding (2) Insufficient padding on edge yarns (3) Deviation in position on both edges of the warp beam (4) Long tuck-in of the free end of the leasing thread which causes edge yarns overlap (1) Side positions of warp beam are not correct (2) Wave edge (3) Deformed warp beam or flange (4) Inaccurate positioning of adjustable reed (5) Edge yarns are either loosely or densely set at the adjustable reed (6) Uneven tension on both sides during warping (1) Frequent cutting end and yarn cumulating on reed (2) Accidentally damage the adjacent yarn during cutting (3) Yarn sheet is densely set at adjustable reed (4) Ends twisted together due excess steam in the size box, ends break during leasing (5) Ends break due to high leasing force required by heavy sizing (1) Mismatch of size recipe and material (2) Improper cooking of size (3) Sizing solution viscosity too low (4) Low strength of size (5) Too much wax content in sizing solution, yarn too soft (6) High moisture absorption of sizing solution, yarn too soft after moisture regain (7) Sizing solution temperature too low causing poor penetration (8) Sizing solution viscosity too high causing poor penetration (9) Sizing solution has been stored for too long causing over degradation (10) Low pick up or no waxing
Textile Handbook 3-31
Over size
Size Stain
Yarns over stretch Edge yarns damage Uneven winding of weaver’s beam Cutting
Snarling
Weaving and Woven Fabrics
Size film formed on drying cylinder
(11) Too much condensed water in steam pipe (12) Improper supply of sizing solution to size box (13) Sizing solution temperature too low at start (14) Squeeze roller pressure too high or Squeeze roller surface damaged (15) Insufficient length of impregnation (16) Squeeze roller pressure is not properly reduced at slow sizing speed (17) Insufficient drying (1) Sizing solution concentration too high (2) Squeeze roller pressure too low (3) Size has not been fully cooked during cold sizing (1) Sizing solution overflow from size box (2) Size deposit are padded on the yarn sheet (3) Sizing solution spilt on yarns due to over heating (4) Sizing solution spilt on yarns due to rinsing of pipe (5) Steam pipe is not properly installed so that size deposit between the immersion rollers are pressed on yarns (6) Machine stop for long time or temperature inside size box dropped caused size film form on sizing solution surface (7) Machine stop for handling defects or changing beam is too long (8) Squeeze roller pressure drop or damaged (9) Back yarn separation roll stop rotation (10) Dirty size box containing size film or deposit (1) Low wax content in sizing solution (2) Yarn tension in size box is too low or variation in tension between two warp sheets (3) Drying cylinder temperature is too low (4) Teflon coating on cylinder surface damaged (1) Warp beam pressure too high causing rotation problem (2) Yarn tension too high due to malfunction of tensioning system, (1) Edge yarns being cut by rough edge of the yarn press roll (2) Rough or deformed beam flange (1) Yarns are not evenly set in adjustable reed (2) Dent distance is not evenly set (3) Too many cutting and uneven transfer of yarns (1) Loose twist yarn (2) Too many ends break in warp beam (3) Cross end happened in warp beam (4) Tensioning device is not properly set or malfunction (1) Machine stops rapidly (2) Warp beam braking device malfunction (3) Yarn twist is too high or tension too low; snarling occurred in warp beam
3-32
Weaving and Woven Fabrics Piece mark missing
Incorrect length
Difference moisture from both selvedges
Excessive moisture regain
Insufficient moisture regain
Uneven dryness
Oil stain Dirts
Mould
(1) Malfunction of length measuring device (2) Length marker malfunction (3) Measuring device incorrectly set (1) Malfunction of length measuring device (2) Yarn tension too high and yarn over stretched (3) Tension deviation between warp sheets (4) Tension is incorrectly set (1) Failure of water regulator of the drying cylinder (2) Harness on both edges of the squeeze roller is different or squeeze roller deformed (3) Pressure setting on both edges of the squeeze roller is inconsistent (4) Roller bearing damaged on one side (5) Yarns wound on immersion roller or squeeze roller (6) Temperature difference in two sides of the size box (1) Temperature control failure in drying cylinder (2) Machine speed too high, steam pressure too low or water regulator failure (3) Sudden drop of squeezing pressure (4) Malfunction of the moisture content control meter (5) Insufficient pre-heating of drying cylinder during machine running cold (6) Residue cooling water inside drying cylinder (7) Surface of drying cylinder cumulated with size deposit and waste so that the surface heat conductivity is affected (1) Machine speed too slow or drying cylinder over heated (2) Temperature control of the drying cylinder failure (3) Malfunction of moisture detector or the setting of moisture content is too low (4) Machine stop too long (1) Unstable steam pressure (2) Immersion roller or squeeze roller bent (3) Incorrect setting of moisture detector (1) Improper oiling (2) Contamination (1) Rusted or improper cleaning of feeding pipe, pump, size pan and size box (2) Dirty air extraction hood contains cotton waste and water drops (3) Lubricant drop into size box, stain on yarn press roll or drying cylinder (4) Yarn passage guides damaged or rusted (5) excess precipitate in size box are not cleaned (6) Steam piping rusted (1) High moisture regain of sizing, sized beam storage too long (2) Water drop on warp sheet (3) Insufficient preservative added
Textile Handbook 3-33 Water mark
Weaving and Woven Fabrics
(1) Poor exhaustion of baking chamber or drying cylinder, steam condensed to water and drop on warp sheet (2) Air extraction hood lack of cleaning cause accumulation of dirty water Flies (1) Too many flies in Workshop and around the air extraction hood (2) Flies accumulated on warp beam creel are not removed Loose ends in group (1) Incorrect setting of adjustable reed during weaving (2) Warp beam flange loosen or deformed (3) Low winding tension of weaver’s beam (4) No or low pressure applied on press roll of the weaver ’s beam End breaks due to (1) Excessive size pick up yarn knots (2) High viscosity of sizing solution and poor penetration (3) Low strength of size film (4) Low wax content in size recipe (5) No or insufficient waxing Yarn breaks due to (1) Low moisture content due to over drying over drying (2) Sizing tension too high so that yarn extensibility decreased (3) Excessive tension of beaming machine or pressure of press roll that reduce the yarn extensibility Difficulty in yarn (1) Excessive size pick up separation at the (2) Low wax content in size recipe back rest of a loom (3) Insufficient drying (4) Size film absorbs too much moisture (5) Wet leasing at size box missing Fabric fluffy surface (1) Low pressure on squeeze roller (2) High size pick up (3) Low wax content in size recipe, yarn too stiff
2.10 Example of Warp Tension for Cotton Yarn during Sizing
3-34
Weaving and Woven Fabrics
Textile Handbook 3-35
2.11 Guidelines for the Sizing of Denim 2.11.1 Size requirements a) The essential size and size ratio: the essential size is high concentration low viscosity modified starch and polyacrylate size together. For soft handle, polyvinyl alcohol (PVA) size is rarely used and preferably not at all. The ratio of starch to polyacrylate is 9 : 1 to 7 : 3 for a solid content of polyacrylate size at 25%. A higher percentage of polyacrylate size is used with finer yarn.
c) High concentration and low viscosity size, but ensure good wetting and adequate pick-up. d) High speed and high pressure promote high efficiency and quality.
2.11.2 Causes of faults in sizing and its solutions There are two main kinds of fault. One is caused by the process operation and the other by the sizing recipe. a) The following are caused by the process operation: (i) Inadequate warping and disorderly beaming will make the sizing process difficult to carry out smoothly. (ii) An unskillful sizing operation with a high amount of knots and cross-ends will cause weaving faults. Without taking preventive measures to avoid unnecessary stoppages, frequent stoppages will cause stop marks on the fabric.
Weaving and Woven Fabrics
b) Auxiliary size: sizing Solution using modified starch, softening agent is added to the sizing solution but no wetting agent or other auxiliary. The softening agent used should have minimum influence on the viscosity of the sizing solution, this is important and has to be controlled for good quality sizing. If the softening agent has the same effect as polyacrylate, it may cause a great change to the viscosity of the sizing solution.
3-36
Weaving and Woven Fabrics
(iii) Uneven padding pressure along the pad-roll will cause shade variation. To prevent this, regular checking of the padding pressure along the pad-roll is required. This is checked with two sheets of white paper of the same length as the rolls and sandwiched between them with a sheet of carbon paper. The pad-rolls are kept closed with the usual working pressure for a few seconds. Take out the paper after the release of pressure and check if there is a change of width of the carbon mark on the paper along the roll length. The change of the carbon mark width from one end towards the other end or towards both ends shows a pressure difference exists. The usual fault is higher pressure at the sides than the middle. This is caused by high pressure applied on both ends resulting in a distortion of the pad-roll. To solve this, the rubber pad-roll is cut oval shaped with thicker diameter in the middle. There is such a kind of pad-roll on the market. This design is to compensate the distortion of the pad-roll when pressure is applied on it. The swimming rolls manufactured by Kuester (a German company) give the best solution to this problem. b) Faults caused by inappropriate sizing process and recipe: (i) It is advisable to use good quality sizing agent to ensure purity and to keep out any undesirable foreign matter. These impurities will get onto the warp yarn causing sizing marks. (ii) Clarity of sizing agent is also important. It ensures that the true colour is not obscured and minimizes colour variation on the surface. (iii) If the viscosity is too high, a thick film of size will form on the yarn surface. In the subsequent processes of yarn separation and weaving, the abrasion between yarns will cause abrasion marks and these marks will carry to the fabric. (iv) If the sizing temperature is too high near to its boiling point, small specks of size will splash on the web causing size marks. If the temperature is too low, a skin will form. When this thicker and harder size gets onto the web, it will also cause size marks.
Textile Handbook 3-37
Judging from the causes of faults, it is necessary to have better production control, more operational training and enhance production upgrading.
2.12 Recent Development in Sizing 2.12.1 WETSIZE Box SC (Sucker-Mueller-Hacoba)
2.12.2 BEN-ECOSIZE (Benninger) The Ben-Ecosize adopted the padding method for the application of a low-temperature sizing agent with high adhesive powers, which are also water-soluble, recyclable or biodegradable. The major economic benefit of the Ben-Ecosize is based on low size liquid pick-up (low energy requirement for drying) and lower dry substance add-on. Application control ensures an even and programmable product pickup. Figure 2.12.2
Ben-Ecosize
Weaving and Woven Fabrics
The Wetsize box SC combines pre-wetting and sizing in one unit. The first size box is filled with hot water (80-90oC) only, while the complete warp is sized in the second size box. The wetting and washing of the yarns with hot water before sizing improves the adhesive power of the sizing agent on the yarn, increases abrasion resistance and reduces hairiness. The pre-wetting process for warp yarns leads to a reduction in the quantity of sizing agents of 30 to 40%.
3-38
Weaving and Woven Fabrics
SECTION 3
WEAVING PREPARATION
3.1 Introduction During sizing, the exact number of warp yarns required in fabric is wound onto the loom beam. The warp ends, which may be leased, are then passed through the drop wires of the warp stop motion the heald wire of the heald frames and the dents at the reed. This can be achieved by drawing -in or tying-in, the choice depending upon whether or not the new warp is different from the warp already on the loom. Warp Preparation after Sizing Sizing machine
Leasing
Drawing-in
Loom
Warp tying
3.1.1 Leasing Leasing is the selection of warp so as to maintain the ends of the warp in an orderly arrangement during warping, preparation processes and weaving.
3.1.2 Drawing-in This process of drawing every warp end through its drop wire, heald wire thread eye and reed dent can be performed manually or by means of automatic machines. In both cases, a length of warp yarn, just long enough to reach to the other side of the frame, is unwound. Leasing at this stage simplifies the separation of the yarns. Then they are threaded through drop-wires, heald wire thread eyes and reed dents. The automatic drawing machine can handle the leasing and drawing-in processes in one single operation.
3.2 Specifications of Heald Wires Healds were originally made of twisted cord; however twisted-wire or flat steel healds which are free to move sideways on bars mounted just inside the framework of the heald frame are now more popular.
Textile Handbook 3-39
Examples of heald specification (Source: Grob) Table 3.2 (1)
Healds With C-Shaped End Loops
Table 3.2 (2)
Healds With J-Shaped End Loops
Weaving and Woven Fabrics
Table 3.2 (3) Healds With O-Shaped End Loops
Note: Note:
1) GROBmicro PLUS surface is only available with OPTIFIL thread eye
5.5 x 1.2 mm in GROBINOX stainless steel. - The dimensions of Grob healds correspond with ISO Standards 11677-1 and 11677-2 - GROBETXTEX, GROBIMTEX, GROBIMEXTEX, GROBAMEXTEX, SOLOPR, SOLOMIX, INTERMIX, DUOMIX, OPTIFIL, GROBmcro Plus, and GROBINOX are registered trade marks of Grob Horgen AG. - Optifil® is a patented design thread eye with increased airspace available for warp yarns as they run through the harness, which leads to less friction between warp yarns and neighbouring healds and causes less warp breakages.
3-40
Weaving and Woven Fabrics
3.3 Specifications of Drop Wire Drop wire or dropper is part of the warp stop motion. It is a thin strip of metal to be supported on each warp so that when the warp breaks the drop wire will fall and operate the warp stop mechanism. The drop wire may vary in design depending on different circumstances; for example designs for electrical warp stop-motion and automatic drawing-in. Examples of drop wire (Source: Grob) Table 3.3 (1) Drop Wires (Non-standardised) for electrical warp stop motions
Textile Handbook 3-41 Table 3.3 (2)
Drop wires ISO 441 for electrical warp stop motions
Weaving and Woven Fabrics
Table 3.3 (3) Drop wires ISO 1150 for electrical warp stop motions, designed for automatic drawing-in
3-42
Weaving and Woven Fabrics Table 3.3 (4) Determination of drop wire weights Tex System
Metric. count Nm
Denier Td
below 9 9 - 14 14 - 20 20 - 25 25 - 32 32 - 58 58 - 96 96 - 136 136 - 176 above 176
above 111 111 - 71 71 - 50 50 - 40 40 - 31 31 - 17 17 - 10 10 - 7 7-6 below 6
below 80 80 - 125 125 -180 180 - 225 225 - 290 290 - 520 520 - 860 above 860
English count Ne below 66 66 - 42 42 - 30 30 - 24 24 - 18 18 - 10 10 - 6 6-4 4-3 below 3
Weight g below 1 1 - l.5 1.5 - 2 2 - 2.5 2.5 - 3 3-4 4-6 6 - 10 10 - 14 14 - 17.5
• Guidelines for weights and densities have been developed through extensive application experience. However, they can be influenced by warp yarn types, required densities, or pattern parameters. • Manufacturers of high-speed weaving machines recommend drop wires which may weigh up to 30% more.
Table 3.3 (5) Maximum Drop Wires Densities Thickness
Number per row
S = mm
cm
inch
0.2
20
50
0.3
14
36
0.4
10
26
0.5
7
18
0.6
5
13
0.65
4
10
0.8
3
8
1.0
2
5
Textile Handbook 3-43
3.4 Reed The reed is a closed comb of flat metal strips, which are uniformly spaced at intervals corresponding to the required spacing of the warp ends. The spaces between the metal strips through which the ends pass are known as dents. Figure 3.4(1) Reed
Dent
Reed
Number Number
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54
Thickness
mm
1.270 1.154 1.058 0.976 0.907 0.847 0.794 0.747 0.705 0.668 0.635 0.604 0.577 0.552 0.529 0.508 0.488 0.470 0.453 0.438
Dent
Reed
mils Number Number 50.0 30 56 45.5 31 58 41.0 32 60 38.5 33 62 35.7 34 64 33.3 35 66 31.2 36 68 29.4 37 70 27.8 38 72 26.3 39 74 25.0 40 76 23.8 41 78 22.7 42 80 21.7 43 82 20.8 44 84 20.0 45 86 19.2 46 88 18.5 47 90 17.9 48 92 17.2 49 94
Note: 1mils=1/1000in
Thickness
mm
0.423 0.410 0.397 0.380 0.373 0.363 0.352 0.343 0.334 0.326 0.318 0.310 0.301 0.295 0.289 0.282 0.276 0.270 0.264 0.259
Dent
Reed
mils Number Number 16.7 50 96 16.2 51 98 15.6 52 100 15.2 53 102 14.7 54 104 14.3 55 106 13.9 56 108 13.5 57 110 13.2 58 112 12.8 59 114 12.5 60 116 12.2 61 118 11.9 62 120 11.6 63 122 11.4 64 124 11.1 65 126 10.9 66 128 10.6 67 130 10.4 10.2
Thickness
mm
0.254 0.249 0.244 0.240 0.235 0.231 0.227 0.223 0.219 0.215 0.212 0.208 0.205 0.201 0.198 0.195 0.192 0.189
mils 10.0 9.8 9.6 9.4 9.3 9.1 8.9 8.8 8.6 8.5 8.3 8.2 8.1 7.9 7.8 7.7 7.6 7.5
Weaving and Woven Fabrics
Table 3.4 (2) Relationship Between Dent Number and Reed Number for Cotton Fabric
3-44
Weaving and Woven Fabrics
3.5 Tying-in Usually tying-in is used when a fabric of a particular type is being mass produced. The new warp beams will be identical with the exhausted beams on the looms. Therefore, if every end on the new beam is tied to its corresponding end on the old beam, the drawing-in process can be omitted. Tying-in may be done by means of a small portable machine on the loom or as a separate operation away from the loom. Figure 3.5
Tying Machine (Staeubli)
3.6 Recent Development in Weaving Preparation 3.6.1 Quick Style Change in Weaving The preparation of the loom warps is an expensive and time-consuming factor in the process of weaving. The greatly increased weaving speeds of recent times, together with a progressive demand for small lots of a wide range articles, call for improvements in preparatory procedures. The makers of weaving machines and ancillaries have come up with a concept of “Quick Style Change” (QSC) which is regarded as the standard for greater flexibility, and shorter processing times in weaving preparation. The QSC enables appreciable time savings to be made in changes of the warp and style being woven. The modules of the weaving machine are held by clamping device and moved by transporter to the warp preparation site for drawing-in or tying in.
3.6.2 The process flow of a QSC system is as follows: a) Signal appears on a weaving machine when it needs an article changed and the machine stops.
Textile Handbook 3-45
b) Woven-out warp, together with droppers, healds and reed, is taken out of the weaving machine and transferred using a transporter module to the warp preparation department. c) If for warp change only, the woven-out warp together with droppers, healds and reed will be clamped by a transportable ancillary device and the tying machine will join the wovenout warp to a full warp beam. d) Automatic drawing-in of the warp through the droppers, healds and reed takes place with the aid of the driven clamp roll. e) If a style change is required, a full warp beam will be prepared by the automatic drawing-in machine. Weaving and Woven Fabrics
f) A film is fused to the warp yarns of the full warp beam by a warp welding device, and the new warp is ready for direct mounting in the weaving machine.
Figure 3.6
Quick Style Change Warp Preparation System (Staeubli)
3-46
Weaving and Woven Fabrics
Section 4 - Weaving
3-47
4.1
Introduction ....................................................................... 3-47
4.2
Basic Motions of A Weaving Machine ............................. 3-47 4.2.1 4.2.2 4.1.3
Shuttle Loom ............................................................... 3-47 Shuttleless Looms ....................................................... 3-48 Useful Calculation Formulae for Weaving .................. 3-54
Section 5 - Woven Fabric Features
3-56
5.1
Introduction ....................................................................... 3-56
5.2
Warp and Weft Yarns ....................................................... 3-56
5.3
Selvedges ............................................................................ 3-57 5.3.1 Selvedge Structure for Conventional Loom ................... 3-58 5.3.2 Selvedge Problem ........................................................... 3-62
5.4
Yarns Per Unit Length ...................................................... 3-62
5.5
Face and Back ................................................................... 3-63
5.6
Top and Bottom ................................................................. 3-63
Section 6 - Woven Structure
3-64
6.1
Introduction ....................................................................... 3-64
6.2
Plain Weave ....................................................................... 3-64 6.2.1 6.2.2 6.2.3
6.3
Twill Weave ....................................................................... 3-67 6.3.1 6.3.2
6.4
Characteristics ............................................................. 3-64 Ribbed Plain Fabrics ................................................... 3-65 Plain Weave Derivative ............................................... 3-66
Characteristics ............................................................. 3-69 Broken Twill Weave .................................................... 3-70
Satin Weave ....................................................................... 3-70 6.4.1 6.4.2 6.4.3
Satin-Weave Fabric ..................................................... 3-71 Sateen Fabric ............................................................... 3-71 Characteristics ............................................................. 3-72
A
A
6.5
Comparison of Basic Weave Properties .......................... 3-72
6.6
Special Weave Sturctures ................................................. 3-72 6.6.1 6.6.2 6.6.3 6.6.4 6.6.5
6.7
Woven Pattern Design ...................................................... 3-77 6.7.1 6.7.2 6.7.3
6.8
Pile Weaves ................................................................. 3-72 Double-cloth Weave .................................................... 3-75 Crepe Weave ................................................................ 3-75 Leno Weave ................................................................. 3-76 Swivel Weave .............................................................. 3-76
Introduction ................................................................. 3-77 Dobby Pattern .............................................................. 3-77 Jacquard Pattern .......................................................... 3-78
A Summary of Special Weaves and their Characteristics .. 3-79
Section 7 - Woven Fabric Analysis ........................... 3-81 7.1
Introduction ....................................................................... 3-81
7.2
Identification of the Construction of a Fabric ............... 3-81
7.3
Determining Yarn Counts of a Fabric ............................. 3-82
7.4
Fabric Weight .................................................................... 3-82 7.4.1 7.4.2
Expression of Fabric Weight ....................................... 3-82 Fabric Weight Calculation ........................................... 3-82
7.5
Converting Fabric Weight from one System to Another 3-83
7.6
Weight of Silk Fabric ........................................................ 3-84
7.7
Woven Fabric Design ........................................................ 3-84 7.7.1 7.7.2 7.7.3
7.8
Cloth Setting Theories ................................................. 3-84 Similarly Built Cloths ................................................. 3-89 Other Expression of Setting ........................................ 3-91
Fabric Cover ...................................................................... 3-92 7.8.1 7.8.2
Cover and Cover Factor (F.T. Peirce) ......................... 3-92 Cloth Cover Factor ...................................................... 3-94
Back to Table of Content
Textile Handbook 3-47
SECTION 4 WEAVING 4.1 Introduction
A
This is the process of interlacing two or more yarns at right angles to each other to produce woven fabric. The yarns which run lengthwise are called warp (end), while the cross yarns running at right angles to the warp are called filling or weft (pick).
4.2 Basic Motions of A Weaving Machine
Shedding
- raising and lowering of the warp yarns by the harnesses to make an opening for the weft yarn to pass through.
Picking
- the passage of the shuttle or other device across the loom to put a weft yarn in the shed.
Beating-up - the pushing of each loose weft yarn into the cloth by the reed, after the shuttle has been moved through the reed. Warp let-off - this motion delivers warp to the weaving area at the required rate and at a suitable constant tension by unwinding it from a warp beam Cloth take-up- this motion withdraws fabric from the weaving area at the constant rate that will give the required pick-spacing and then winds it onto a roller.
4.2.1 Shuttle Loom This conventional loom utilizes a shuttle that contains a pirn of weft yarn, which emerges through a hole inside. As the shuttle is batted across the loom it leaves a trail of the weft yarn across the shed of the warp yarns. It has certain disadvantages such as pirn-winding, and a slow and noisy operation due to the dynamic problems created by picking and checking mechanisms. In addition the shuttle sometimes causes abrasion on the warp yarns as it passes over them and may
Weaving and Woven Fabrics
The machine used for weaving is called a loom. The basic operations of a loom include shedding, picking, beating-up, warp let-off and cloth take-up motions. The functions of these operations are:
3-48
Weaving and Woven Fabrics Figure 4.2.1 Shuttle Loom (Cross-Section)
4.2.2 Shuttleless Looms To overcome the disadvantages of the shuttle loom, several different kinds of shuttleless looms have been developed. Each type uses a different method of picking, which provides specific characteristics and applications. a) Rapier Loom A rapier loom uses a rapier to pull the weft yarn across the loom. It can be in the form of a single rapier or a double rapier. For a single rapier, a long rapier device is required to extend across the full width of the warp. For a double rapier loom, two rapiers may enter the shed from opposite sides of the loom and transfer the weft from one rapier head to the other at a point near the centre of the loom. In this case the rapiers may be either rigid or flexible. It is generally an advantage to use a two-rapier system because only 50% of the rapier movement is utilized in weft insertion for the single rapier loom.
Textile Handbook 3-49 Figure 4.2.2a
Double Rapier System
b) Gripper or Projectile Loom
A
Figure 4.2.2b
Projectile Loom
Weaving and Woven Fabrics
The picking action is accomplished by a small bullet-like gripper which grips the weft yarn and carries it through the shed. This is a more positive way of inserting the filling without resorting to the heavy shuttle. Because the mass of the gripper is low, the forces needed to accelerate it are less and the picking mechanism can be lighter. In addition, the running speed of the looms can be increased significantly compared with a conventional shuttle loom. In the most widely used system, a torsion bar is used to store strain energy prior to picking, and this energy is released during the acceleration of the gripper by a toggle action. The whole system is very compact and effective. After a gripper has completed its task of carrying the filling, it then is collected and is transported back to its initial position, ready for another pick. The first commercial projectile loom was made in early 1950s by Sulzer.
3-50
Weaving and Woven Fabrics
c) Jet Looms
A
Jet looms take the weft yarn across the loom by using a high-speed jet of either air or water. The force of the air or water carries the yarn from one side to the other. For an air-jet loom, a blast of air would seem to be an effective way of inserting the filling, but to get enough traction on the filling yarn it is necessary to use very high air velocities. When an air jet is allowed to expand freely, the moving air is contained within an imaginary cone whose axis is coincident with that of the air jet. The air just emerging from the nozzle is highly energetic and, as it moves away from the nozzle, it entrains some of the surrounding air which tends to slow the mass down. Thus as the moving mass of air moves away, it grows larger and becomes slower. The air velocity component parallel to the jet axis declines sharply with both axial distance and radius. A series of orifice plates is used to restrain the jet from breaking up into turbulence and these improve the performance. These looms are noisy and consume considerable amounts of energy. A water-jet is more coherent than an air jet. It is effective in terms of energy requirements and is quiet. When the jet does break up, it goes into droplets which create very little turbulence to disturb the weft yarn. Two main reasons for the efficiency of the water-jet loom are that there are no varying lateral forces to cause the filling to contort, and the moving element is more massive because it is wet. Thus there is less chance of fault due to contact with the warp. Figure 4.2.2c(1) Air-jet Loom
Textile Handbook 3-51 Figure 4.2.2c(2) Water-jet Loom (Toyoda)
A
The M8300 of Sulzer Textil inserts four weft yarns simultaneously. To open a number of sheds one after another in the warp direction, the warp is led over a continuously rotating drum - the weaving rotor. The latter is provided with combs consisting of numerous individual elements. These combs form the shed as well as the guide channel for the insertion of the weft as soon as the shed is opened. Before the comb grips into the warp yarn plane, the warp positioners displace the warp ends in the weft direction in such way that they are located over the shoulders of the shed-forming elements or the spaces in between. The rotating movement of the weaving rotor lifts the threads off the shoulders and lays them over the weft channel, while the remaining threads come to rest below the weft channel. With every immersion of a comb in the warp yarn plane, the warp positioners determine the threads that are to be raised. In view of the extremely low mass of the warp positioners and the movements of only a few millimetres, the frequency with which the positioners are moved can be very high. Once a shed is formed completely, low-pressure air carries the weft yarn through the weft insertion channel. During this insertion, further weft yarns start to enter the combs that follow. As soon as a weft yarn has been inserted completely, it is clamped and cut on the feed side. After this, the weft yarn is beaten up by the special reed that follows each shed-forming comb.
Weaving and Woven Fabrics
d) Multi Phase Weaving Machine
3-52
Weaving and Woven Fabrics
The free end of the weft yarn is led to the next free insertion position. This is effected by the weft yarn controller, which consists of two disks with their respective multi-channel system, arranged concentrically to the rotor. The threads introduced into the controller are then moved continuously over a measuring drum with the assistance of air, and in such a way that they line up exactly with the shed-forming combs. The weft yarn controller also serves as the main nozzle. If a weft yarn is not inserted completely, the machine stops to facilitate the removal of the residual weft yarn. Additional necessary interventions to repair mispicks are signalled to the weaver via a terminal, whereby the movements necessary on the machine side are effected automatically. If thread breakages occur in the area between the packages and weft feeder, the machine repairs them automatically. A few characteristic features of the M8300 Weft insertion rate Weft insertion Weaving width Warp density Weft density Yarn count range Selvedge Warp change duration Figure 4.2.2 d (i)
potentially more than 5000 m/min with low pressure air 190 cm up to 32 ends/cm adapted to warp density 15 to 60 tex standard leno 15 to 20 minutes
Shed-forming Elements
(1) Shed-forming element; (2) Beat-up comb; (3) Weft channel; (4) Warp positioners; (5) Upper shed; (6) Lower shed
Textile Handbook 3-53 Figure 4.2.2 d (2)
Weft Insertion Elements
Figure 4.2.2 d (3) Weft Beating-up
(1) Fabric support; (2) Beat-up comb
Weaving and Woven Fabrics
(1) Supply bobbins; (2) Weft measuring rollers; (3) Weft controller; (4) Weaving rotor
3-54
Weaving and Woven Fabrics Figure 4.2.2d (4)
Comparison of Weft Speed
M8300
Air-jet loom
weft insertion cycle
weft insertion cycle weft insertion rate weft speed
4.1.3 Useful Calculation Formulae for Weaving a) Technical Calculation And Production Formulae
(i) Total warp ends = fabric width(inches) x warp density + added selvedge ends
=
( reed width x reed number x no. of warps / reed eye ) + added selvedge ends 2 warp yarn length - fabric length
(ii) Warp contraction =
warp yarn length
sizing length - fabric length =
weft yarn length - fabric width (iii) Weft contraction=
(iv) Sizing length
=
weft yarn length
fabric length 1-warp contraction
=
sizing length
reed width - fabric width reed width
Textile Handbook 3-55
(v) Reed width
fabric width
=
=
1 - weft contraction
=
total ends - added selvedge ends number of ends per reed eye
(total ends - added selvedge ends) x 2 reed number x number of ends per reed eye
warp density (1 - weft contraction) x 2 = warp ends per reed eye
(vi) Reed number =
total ends - added selvedge ends reed width x warp ends per reed eye
b) Production And Efficiency Calculation operation hours x 60 x number of picks per minute weft density x 36
= yards
actual production yardage (ii) Production efficiency per machine =
(iii) Defect ratio =
calculated production yardage
x 100% = efficiency %
total number of fabric rolls produced - number of fabric rolls of Grade A
= defect %
total number of fabric rolls produced
(iv) Number of weaving machines in production =
total number of fabrics in delivery x fabric length per roll total working days x production rate per machine x efficiency x (1 - defect ratio)
= total number of weaving machines in production per month
Weaving and Woven Fabrics
(i) Production rate per machine =
3-56
Weaving and Woven Fabrics
SECTION 5
WOVEN FABRIC FEATURES
5.1 Introduction Warp and weft yarns, threads per unit length, selvedges, face and back, and top and bottom are features commonly found in all woven fabrics. By knowing these fabric characteristics, one can understand the fabric structure and suitability for particular uses.
5.2 Warp and Weft Yarns Generally, fabrics are cut with the warp yarns running the length of the garment, so the designer needs to know the drapability of the fabric in warp of the direction, and must make sure that this property meets the garment requirements. Fabric technician also needs to be able to distinguish the warp and weft so that he can analyse the information such as fibre content, yarn count and twist. Warp yarns can be distinguished from weft yarns in the following ways: Selvedge:
the yarns parallel to the selvedge are in the warp direction.
Yarn Count:
warp yarns are usually thinner so as to reduce abrasion when passing through the loom, and rubbing against the various parts (e.g., heald wire and reed). If a fabric contains both filament yarns and spun yarns, the filament yarns will usually be the warp set.
Twist :
generally spun warp yarns have more twist than spun weft yarns. This is due to the fact that they are thinner and needs more twist to have sufficient strength to withstand the tensions exerted on the yarns in weaving and finishing.
Yarns per Inch:usually the number of yarns per inch in warp set is higher than that in weft set. This makes the fabric stronger in the lengthwise direction to withstand most of the tensions created during the finishing processes. However, some fabric constructions consist of same, number of ends and picks per inch, and occasionally the picks density is even higher.
Textile Handbook 3-57
plied yarn will be stronger than the same sized single yarn, so the warp yarns are occasionally plied to give added strength while the weft yarns remain single. Plied weft yarn will usually be used to give a special ribbed effect across the fabric.
Stiffness:
in all spun-yarn fabrics, the warp yarns are generally stiffer than the weft yarns because they usually have more twist. In pure filament yarn fabrics, the weft yarns are usually stiffer because they generally are thicker. A stiffer set of yarns will usually result in less fabric drapability in that direction.
Stripes:
most woven stripes appear in the lengthwise direction, because of cheaper production cost.
5.3 Selvedges The selvedge prevents the fabric from ravelling and the edges from tearing when the fabric is under the stresses and strains of processing. Normally, the selvedge area is made stronger than the body by using: heavier warp yarns; more warp yarns per inch; plied warp yarns; greater twist for spun yarns; and different weave. There are different types of selvedge produced by different sorts of looms. Plain (True) Selvedge:
created with shuttle loom from same warp yarns and weave as the fabric body, but with higher number of warp yarns per inch.
Fringed Type Selvedge :
created from cut filling yarns on a shuttleless loom, leaving a fringe on the fabric edges. To prevent unravelling, sometimes either a leno weave section is made at the edge (leno selvedge) or the fringe ends are tucked back into the fabric (tucked-in selvedge).
Fused Selvedge :
can only be used when the fabric has a high percent of thermoplastic fibre. The edges of the fabric are heated, causing the fibres to melt and fuse together. Fused selvedge is harsh and stiff.
Weaving and Woven Fabrics
Ply Yarns:
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Weaving and Woven Fabrics Figure 5.3
Various types of selvedge
a. selvedge as produced by the shuttle loom. b. Selvedge made on a shuttleless loom such as fringe. c. leno d. tucked-in selvedge.
5.3.1 Selvedge Structure for Conventional Loom Woven structure, warp density and warp contraction should be taken into consideration while deciding the selvedge structure. Usually warps for selvedge are sharing the heald shafts of the fabric. An additional device is only applied for a 3/1 structure and a sateen of 5 warps. a) In order to minimize yarn breakage on selvedge during production of coarse, medium and fine plain weave fabrics, a 2/2 weft rib weave is used as for the selvedge structure. Due to small weft shrinkage of poplin fabric, plain weave is used for the selvedge structure. b) For 2/1 twill, the ground structure and the selvedge structure are the same. For 2/2 twill, there can be three different types of selvedge structure: the arrow in the figures show the weft in section direction. i. For serge, whose warp density is not high, the ground weave structure and selvedge weave structure are the same.
Textile Handbook 3-59 Figure 5.3.1.b (1)
Left weave
Same Weave for the Ground and the Selvedge structures for 2/2 Twill Type Serge
Ground weave
Right weave
(ii) For gabardine and even-sided drill, which have high warp density, their selvedge structure is usually a countertwill or rib plain weave.
Figure 5.3.1.b (2) Counter Twill Weave Selvedge Structure for 2/2 Twill Type Gaberdine or Even-sided Drill
Left weave
Ground weave
(counter twill selvedge weave)
Right weave
Weaving and Woven Fabrics
(ground weave and selvedge weave are the same)
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Weaving and Woven Fabrics Figure 5.3.1.b (3) Rib Plain Weave Selvedge Structure for 2/2 Twill Type Gaberdine or Even-sided Drill
Left weave
Ground weave
Right weave
(rib selvedge weave)
c) For 3/1 warp-faced drill, because the front and the back has different structure, if the selvedge weave is countertwill, the fabric will curl on both sides during dyeing and printing processing (selvedges curl towards the back). It is therefore better to use rib weave. However, if there are curling selvedges in dyeing and printing processing for rib selvedge weave, increase the number of warps per reed from 4 per reed to 6 per reed for selvedge warps. d) In order to have a neat selvedge and consider that the warp contraction of selvedge weave and ground weave is similar, The selvedge weave for 5 warps Steep Twill can be 2/2 basket weave or double weft 3/3 fancy weft rib. However, because Reclining Twill is too thin, basket selvedge weave cause selvedge curls during dyeing and printing. It is better to use double weft fancy filling rib as selvedge weave. e) For 5/3 warp satin, selvedge weave can be 2/2 regular basket weave.
Textile Handbook 3-61 Figure 5.3.1.e
Left weave
Basket Selvedge Weave for 5/3 Warp-Faced Satin
Ground weave
Right weave
Left weave
Ground weave
Right weave
Figure 5.3.1.f
Triple Warps and Double Weft Fancy Weft Rib Selvedge for 5/2 Weft-Faced Satin
Left weave
Left weave
Ground weave
Ground weave
Right weave
Right weave
Weaving and Woven Fabrics
f ) For 5/2 weft sateen, selvedge weave can be triple warps and double weft fancy weft rib structure.
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Weaving and Woven Fabrics
5.3.2 Selvedge Problem If the selvedge warp yarns have greater shrinkage during the finishing process, a tight selvedge occurs, resulting in the puckering of an area near the fabric edge. This will be a problem when the material is spread on the cutting table where the cloth does not lie flat. Cutting off the selvedge to eliminate the stress on the fabric can eliminate the tight selvedge problem. The loose edge can either be fused, if the fabric is thermoplastic, or glued by adhesive to prevent unravelling. If the tight selvedge problem is only noticed when the fabric has been laid on the cutting table, the puckering can be eliminated by cutting into the selvedge every six inches to twelve inches, allowing the cloth to relax, although of course, this will generate higher cutting wastage.
5.4 Yarns Per Unit Length This is the number of warp or weft yarns in a specified length and is denoted by two numbers with an “X” between them. For example, 108 X 58 means 108 yarns per inch in the warp and 58 yarns per inch in the weft. The first number is for warp yarns per inch and the second is for weft yarn per inch. For fabrics with the same number of yarns in both warp and weft, the indication for yarns per inch is referred to as square. For example a 60-square plain cloth has 60 ends and 60 picks per inch. With some finished goods, such as sheeting, the number of yarns is given as a single number indicating the total number of yarns per square inch. For example, if sheeting has 70 warps and 70 wefts per inch, the type number (thread count) is 140. Yarns per inch is also a measure of fabric quality; a higher number of yarns per inch gives the fabric the following quality: • Higher Strength- the breaking force for breaking 20 yarns is higher than that for breaking 10 yarns. • More Weight - the weight of fabric depends on the weight of yarns. • Better Hand - more yarns grouped together produces an even surface which gives a smooth hand feel. • Yarn Distortion- the chance for yarns to slide or shift by rubbing action or force is greatly reduced. • Better Abrasion Resistance - more yarns grouped together make them more compact, stronger, heavier and durable against abrasion.
Textile Handbook 3-63
5.5 Face and Back Fabrics have a technical face side and a technical back side. The face side has the better appearance and usually forms the outside of the garment. Fabrics are packed so that the face is protected during handling and storage, therefore the back usually forms the outer surface of the fabric roll. The face and back of some fabrics can also be distinguished by their weaves or finishes. For examples the face side of a satin fabric is shinier and smoother than the back side, and coating finish is usually applied to the face side only.
5.6 Top and Bottom Some fabrics have a top and a bottom on the face side owing to the weave or the finish. Fleece and corduroy are having an obvious top and a bottom to the face. The colour of these fabrics might vary from dark to light as the fabric is turned 180o on a flat surface because of the difference in the angle of light reflection. With fabrics having an obvious top and bottom, the garment must be made with all its parts in the same top down or bottom down direction.
Weaving and Woven Fabrics
It is important to distinguish the face and back of a fabric because if a garment is made with some parts showing one side of the fabric and the other parts showing the other side, it will often show a slight difference in lustre or colour when the garment is assembled and worn.
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Weaving and Woven Fabrics
SECTION 6
WOVEN STRUCTURE
6.1 Introduction The manner in which groups of warp yarns are raised by the harnesses to permit the insertion of the weft yarn determines the pattern of the weave. Weave patterns affect the durability and appearance of the fabric. There are three basic weaves commonly used for the majority of fabrics. Other weaves are a variation or a combination of these weaves. Some important constructions or woven designs are also obtained from various special weaves such as pile, double cloth, leno (gauze), swivel, dobby and jacquard.
6.2 Plain Weave Plain weave is the simplest and the most used weave. It is found in a wide range of fabrics such as gauze, gingham, voile flannel, taffeta, poplin and canvas. Plain weave fabrics require only two harnesses because the weave repeats every two ends. Fabric with a plain weave is reversible, unless one side is chosen as the face by finishing or printing.
6.2.1 Characteristics Plain weave fabric normally has firm constructions. It wears well and ravels less than comparable fabrics of other weaves. It provides a good background for printed and embossed designs because of the plain surface. Plain weave tends to wrinkle more than fabrics of other weaves do. Frequent interlacing does not allow the yarns to move in the fabric to relieve stress from the bent fibres/yarns, and it also results in less bias stretch. Plain weave fabric has lower tear strength than comparable fabrics of other weaves. This is because when tearing a plain weave fabric, the yarns break one at a time.
Textile Handbook 3-65 Figure 6.2.1 (1)
Plain Weave
Figure 6.2.1 (2)
Plain Weave on graph paper
6.2.2 Ribbed Plain Fabrics
A weft ribbed effect has the potential problem that the weft yarns that form the ribs may have been made bulky by having little twist and/or short staple fibres. If the heavy weft yarns are not covered and well protected by the set of thinner warp yarns, the heavy yarns will abrade quickly.
Figure 6.2.2 (1) Drawing of a ribbed or corded effect running in the direction of the warp
Weaving and Woven Fabrics
The ribbed or corded effect is caused by the variations of the plain weave. The rib may be produced in the warp or in the weft by alternating fine yarns with coarse yarns or single yarns with doubled yarns. Warpribbed fabrics are usually referred to as having a corded effect. A weft ribbed effect is produced when the weft yarns are thicker than the warp yarns. Bengaline or ottoman fabric has a pronounced rib effect. The rib effect is also easily visible in a faille or poplin fabric, but it is less visible in broadcloth or taffeta.
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Weaving and Woven Fabrics Figure 6.2.2 (2)
Drawing of a ribbed effect running in the direction of the filling
6.2.3 Plain Weave Derivative Basket weave, a major derivative of plain weave, is made by using groups of two or more warp yarns interlacing as one yarn with groups of two or more weft yarns that also interlace as one yarn. It is a decorative weave and most of them are made with relatively low yarns per inch and with low twist yarns to increase the weave effect. This type of fabrics tends not to be durable and will easily shrink in washing. Two well-known basket weave structures are monk’s cloth and hopsack. Oxford may be considered as a basket weave (2x1) or a rib weave.
Figure 6.2.3 (1)
Basket Weave
Textile Handbook 3-67 Figure 6.2.3 (2)
Oxford Cloth
6.3 Twill Weave
Twill weaves are named according to the number of harnesses required to make the design. The simplest twill weave is either a 1/2 or a 2/1 twill which repeats on a three ends and three picks. This category is frequently referred to as three-leaf twills. A 3/1 twill and a 1/3 twill are always called four-leaf twills. Twill weaves are also classified as balanced or unbalanced according to the number of warp and weft yarns that are visible on the face of the fabric. The balanced twill, for example, shows an equal number of warp and weft yarns in the recurring design, such as two over and two under. Most twills are either warp-face or unbalanced, which produces a more obvious twill line and also a more abrasion-resistant surface. Increased ornamentation may be obtained by varying the slant of the diagonal line of the twill fabric. In a twill weave the succeeding warp yarn to the right has the corresponding interlacing one weft yarn higher, and the weave is a 45 degree right-hand twill. The step can also be more than one. If the corresponding interlacing on the succeeding warp yarn is two weft yarns higher or lower, a 63 degree twill weave is produced.
Weaving and Woven Fabrics
A distinct design in the form of diagonals is characteristic of the twill weave. In a right-hand twill, the diagonals run upward to the right. In a left-hand twill, the lines run upward to the left. Although there is no advantage of one over the other, the direction of the diagonal can aid in the recognition of the face of the fabric. Denim, gabardine and chino are some well-known twill weave fabrics.
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Weaving and Woven Fabrics
A fabric with a 45 degree twill weave has 45 degree diagonal lines only when the yarns per inch in the warp and the yarns per inch in the weft are the same. Usually, there are more yarns per inch in the warp, so that most 45 degree twill weaves have diagonals of more than 45 degree. The steepness of the diagonal can indicate strength and durability in the fabric. Figure 6.3 (1)
Twill Direction
Right hand twill
Figure 6.3 (2)
Balanced 2/2 Twill Weave
Figure 6.3 (3)
Warp Face 2/1 Twill Weave
Left hand twill
Textile Handbook 3-69 Figure 6.3 (4)
Weft Face 1/2 Twill Weave
Figure 6.3.(5)
Degree of twill angle
The values of the twill weave include its strength and drapability. The diagonally arranged interlacings of the warp and weft provide greater pliability and resilience than the plain weave. Also twill fabrics are frequently more tightly woven and will not get dirty as quickly as the plain weave, though twills are more difficult to clean when they do get soiled. The yarns are usually closely beaten, making especially durable fabric. Twill weaves are therefore commonly used in men’s suits and coats. The twill lines can be made more prominent by using: plied yarns; high-twist yarns; twill weaves with longer floats; high number of yarns per inch; and yarn twist opposite to the twill-line direction. Fabric with these prominent lines may become flattened by wear and pressure, and thus become shiny.
Weaving and Woven Fabrics
6.3.1 Characteristics
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Weaving and Woven Fabrics
6.3.2 Broken Twill Weave Many combinations and variations of twill constructions are possible. These produce interesting pattern effects. The most well known variations of twill weave are herringbone (broken twill), gabardine, and corkscrew twill. Figure 6.3.2 Broken Twills Weaves
(a) and
(b) Herringbone (c) Gabardine (d) Corkscrew
6.4 Satin Weave Satin weave is similar to the twill weave, but the diagonal line of the satin weave is not visible. It is purposely interrupted in order to contribute to the flat, smooth, lustrous surface desired. There is no visible design on the face of the fabric because the yarns that are to be thrown to the surface are greater in number and finer in count than the yarns that form the reverse of the fabric. In a true satin weave each warp yarn and each weft yarn only interlace once in each repeat of the weave. Also no two interlacing points ever touch or are adjacent. Thus, the satin weave fabrics have relatively long floats. In a warp-face-satin, the face is predominantly warp yarn, while for a weft-face satin, the weft yarns are predominant on the face. Satin weaves are numerous; they may be designated by the number of harnesses they require in weaving, such as a five-harness satin. Five is the lowest possible number of harnesses usable for a regular satin weave. Satins can be made from five, from seven or from any number beyond seven, up to the harness capacity of the loom. No regular satin weave can be made with six harnesses. Most satins are made on five harnesses, but seven and eight harness satins are also commonly produced.
Textile Handbook 3-71
The number of interlacings is the same as the number of harnesses used. A five-harness satin has only five interlacings in one repeat of the weave. The length of the floats in a satin is one less than the number of harnesses used. The number of harnesses used is also the size of the repeat in the warp end in the filling directions. Figure 6.4
Satin Weave
c. 5 shaft weft face satin d. 5 shaft weft face satin on graph paper
6.4.1 Satin-Weave Fabric Satin is also the name of a fabric with that weave. Satin fabric is made from filament yarns, with the warp yarns predominant on the face. Satin fabrics are smooth and lustrous because lustrous filament yarns are used; there are few interlacing points, that gives long floats; and the face yarns are very fine and closely packed. Since the greatest lustre is in the length-wise fabric direction (the direction of the floats), garments using this fabric are made in this direction is vertical in the garment, thereby maximizing the lustre.
6.4.2 Sateen Fabric Sateen fabric is a durable cotton fabric, usually with a weft-face satin weave. It is not as lustrous as satin fabric as spun yarns are used. Since it is also heavier, with thicker yarns, it is not as drapable as satin fabric.
Weaving and Woven Fabrics
a. 5 shaft warp face satin b. 5 shaft warp face satin on graph paper
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Weaving and Woven Fabrics
6.4.3 Characteristics Satin-weave fabric drapes well because the weave is heavier than the twill weave. The compactness of the weave gives the fabric more body as well as less porosity, which makes the fabric warmer. The quality of drapability also makes satin fabrics preferable for evening wear and the warmth contributes to its value as lining material. Although the long floats of the yarns provide lustre to the satin weave fabrics, they are also responsible for the poor wearing quality of many of these fabrics. Under certain conditions however, good abrasion resistance and strength can occur in satin-weave fabrics due to the fact that long floats allow more yarns per inch. Fabric made from very high yarns-per-inch implies the fibre density will be high, and if spun yarns are used, snagging is no longer a serious problem.
6.5 Comparison of Basic Weave Properties Table 6.5
Comparison of Basic Weave Properties
Weave
Surface Effect
Lustre
Tearing Strength
Snag Wrinkle Resistance Resistance
Plain Twill Satin
Flat Twill lines Smooth
Poor Fair Good
Low Medium High
Good Poor Good Fair Poor if Good long floats
6.6 Special Weave Sturctures 6.6.1 Pile Weaves This is a special weave structure with a raised hair-like or fur-like surface. The surface is produced with an extra set of yarns (warp or weft) known as pile yarns. The other warp and weft yarns forming the foundation are called the ground yarns. Two well-known fabrics with such a surface are velvet and terry cloth. There are two basic types of pile-weave fabrics; the warp-pile fabrics, which have an extra set of warp yarns, and the weft-pile fabrics, which have an extra set of weft yarns. When the pile yarns are cut, the fabric is called cut-pile weave fabric. If the pile yarns are not cut, an uncut pile weave fabric is produced.
Textile Handbook 3-73 Figure 6.6.1 Pile Weave Fabric
Fabric (a) (b) (c)
Warp Pile Fabric
Weft Pile Fabric
Warp ground yarn Weft yarn Warp pile yarn
Weft ground yarn Warp yarn Weft pile yarn
a) Cut Pile Fabrics Velvet is an example of a cut-warp pile-weave fabric, while terry cloth is an example of an uncut-warp pile weave fabric. Weft-pile weave fabrics, such as corduroy or velveteen, are always cut. Two methods are used for making cut-warp pile fabrics. In the first method a double cloth is woven with pile yarns interlacing between and connecting the two fabrics. The completed fabric is cut into two by cutting the interlacing warp yarns. These cut yarns form the pile for each of the resulting fabrics. In the second method, after a number of picks have been inserted, a special rod with a blade at one end is interlaced instead of a weft yarn. The harnesses operate so that only pile warp yarns pass over the rod. The cut yarns stand up to form the pile. The insertion and removal of the rod is continuous after a few picks. Weft cut-pile fabrics are cut on the face after the fabric is completely woven. There is no raising of yarns by wires. The pile-weft yarns are woven to float over a group of warp yarns and are then cut at the centre of the float. The floats in corduroy fabric are placed in length-wise rows, while the floats in velveteen are randomly spaced. When
Weaving and Woven Fabrics
Yarn
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Weaving and Woven Fabrics
corduroy fabric is cut, the characteristic wale or hill-andvalley effect is produced. When velveteen fabric is cut, and an overall cut-pile surface is produced, cutting floats can selectively create decorative patterns and effects. Cut-pile weave fabrics are made with different heights of pile. Velvet has a low pile height, velour has a higher pile, and plush has still higher pile. A garment made with the cut pile fabric facing downward will offer a smoother surface to the light and so appear more lustrous. The pile construction affects the fabric wearability. The short lengths of cut-pile yarn may have a V shape. The W-shape pile is more firmly held in place because it interlaces with three yarns, while the V-shape interlaces with only one yarn. Thus, the W-shape pile yarn will be held more securely, preventing a bald spot from developing. The W-shape pile, however, is not as dense as the V-shape because the latter has two pile ends for each interlacing, while the V-shape, pile has two pile ends for every three interlacings. A denser pile can better resist crushing, gives better cover and stands more erect, but it is more costly. Usually the ground structure of corduroy and velveteen fabrics is made with a plain or a twill weave. b) Uncut Pile Fabrics The fabric consists of ground warp and weft yarns, plus an extra set of warp yarns for the pile in the form of loops on the surface of the cloth. One of the method to form loops is by having the extra warp yarns raised by a wire inserted across the loom. The wire is then removed until the next set of loops are to be formed. Two warp beams are used for weaving terry. A pile warp yarn may be almost four times longer than a ground warp yarn from the same cloth. Similar to cut-pile weave, strong ground fabric and a dense pile makes a durable material. High loops and thick, lowtwist pile yarns makes a more absorbent, but less durable, fabric. Sometimes the pile loops are cut in a terry cloth for decorative effect.
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6.6.2 Double-cloth Weave In the double-cloth weave, two fabrics are woven one on top of the other at the same time. The fabric may have different structure on both sides. Each of the fabrics requires separate sets of warp and weft yarns. They are combined by interlacing some of the warp or weft yarns or by means of a complete fifth set of stitching yarns. Double-cloth weave fabric is normally warm due to the bulk and thickness. Double-cloth fabrics may be made of spun yarns or of spun and filament yarns, and depending on their composition and construction, they can be used for robes, blankets, coat materials, and a variety of upholstery fabrics. Figure 6.6.2 Double-cloth Weave
Weaving and Woven Fabrics
6.6.3 Crepe Weave Plain weave fabric made from hard-twist and textured yarns or embossing finishes are used to produce rough, pebbly surfaces which called “crepe effect”. Similar effects can be obtained by variations in the plain and satin weaves with the use of a dobby attachment on the loom. The result is a somewhat rough-textured material. The characteristics of crepe-weave fabrics depend largely upon the kind of yarn used. Combinations of yarns and weave construction can produce fabrics of interesting appearance and texture that have good drapability, resilience, stretch, and serviceability.
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Weaving and Woven Fabrics Figure 6.6.3 Crepe Weave Structure
Crepe woven fabrics have a random distribution of floats so as to produce an ‘all-over’ effect in the fabric to disguise the repeat.
6.6.4 Leno Weave The Leno weave is made on a leno loom. The doup attachment, on the leno loom, is a hairpin-like device at the heald which alternately pulls the second warp yarn up or down to the right or left with each pick passage. This causes the pair of warps to be twisted around each weft yarn. Fabrics made with the leno weave are very sheer. Typical materials are Grenadine and Marquisette, which are used for curtains, shirtings and blouses. Figure 6.6.4 Leno Weave
each pair of warp yarns twists to hold the filling yarns.
6.6.5 Swivel Weave The swivel weave is the method by which decorative effects, such as dots, circles, or other figures, are interwoven on the surface of a fabric while it is being constructed on the loom. Extra weft yarn, additional insertion devices and a separate shed are required for weaving the figures into the fabric surface. The decoration produced by the swivel weave is not considered durable, because the swivel yarns are cut
Textile Handbook 3-77
when the fabric is completed and cannot be securely fastened. The swivel weave is employed with sheer light-weights, such as Dotted Swiss and Grenadine, and medium-weights, such as Madras. Figure 6.6.5 Swivel Fabric
6.7 Woven Pattern Design 6.7.1 Introduction Woven design was actually created by selective long and short floats as well as the placement of interlacing. These designs are generally called dobby patterns, and jacquard patterns.
6.7.2 Dobby Pattern This pattern is a design which contains simple geometric forms or motifs. It is produced on a loom with a harness control mechanism called a dobby head. The dobby mechanism can control as many as thirty two harnesses. Figure 6.7.2
Dobby fabric is a fabric with a small woven-in design
Weaving and Woven Fabrics
Those surface-figure in which a figure is achieved by the introduction of additional filling yarns into a base fabric to produce spot effects.
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Weaving and Woven Fabrics
6.7.3 Jacquard Pattern This pattern is a design which contains very detailed motifs. It exceeds the capacity of the harness looms, as a special loom is usually used which has no harnesses, and the ends are controlled by a jacquard head located at the top of the loom. Traditional jacquard head uses a set of punched cards laced together to control the warp yarns. Hooks and needles are used to raise and lower the warp yarns by controlling the cord attached to each heddle. Since there are no harnesses, any combination of yarns can be raised or lowered to produce the design. Figure 6.7.3 Jacquard fabric
Textile Handbook 3-79
6.8 A Summary of Special Weaves and their Characteristics Table 6.8
Special Weaves and Their Characteristics
Weave
Structure
Crepe
Combination of Irregular, indistinct Interesting hand; could plain and satin or pattern with pebbly, have good strength, sateen weave. textured surface. resilience, drapability, and serviceability depending upon fiber, yarn twist, compactness, structure.
Granite; moss crepe; sand crepe; wool crepe,
Pile
Extra set of warps or fillings woven over ground yarns of plain or twill weave to form loops.
Three-dimensional Soft, warm, resilient, effect formed by absorbent; interesting y a r n s e n t e r i n g surface effects. perpendicularly into the ground weave.
Cut and uncut pile fabrics ranging from toweling to rugs.
S o f t , b r u s h l i k e As above. surface; may have rows of cut pile.
Corduroy; velvet; velveteen.
Uncut Pile
Pile loops intact.
Soft, though rougher than cut pile; loops apparent and close together, covering ground weave; loops may be on both sides. Tw o f a b r i c s o f Two different independent weaves surfaces, sometimes woven together with reversible; thick; extra set of yarns. heavy.
Properties
Typical fabrics
As above. Softness and Frieze; terry. absorbency depend upon Compactness of loops and twist of pile yarn.
Strong; warm; may be Blanket bulky. cloth; coatings; upholstery. G a u z e P a i r s o f w a r p s Open-mesh with Sheer but durable for its Grenadine; (Leno) twisted over each yarns securely held; weight. marquisette. other with each variations produce passing of filling. corded effects. Double -Cloth
Swivel
Small designs interwoven on surface of fabric with extra filling yarn insertion mechanism.
Decorative designs, Attractive; design yarns D o t t e d tend to roughen on back swiss; sometimes multicolored; extra and may pull out. madras. yarns forming design are cut on reverse side.
Weaving and Woven Fabrics
Cut pile Pile loops cut.
Appearance
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Weaving and Woven Fabrics Dobby
Small, geometric designs composed of short floats created by dobby loom attachment. Jacquard Any combination of weaves and patterns possible, since each warp is individually controlled with each pick passage.
Decorative designs, Attractive; generally often with corded good body. effect which may give textured surface. Unlimited range of Attractive; drapes well; intricate designs on serviceable but durability dependent all types of upon weave and yarn. backgrounds; multicolor effects.
Huckaback; granite cloth; pique. Brocade; brocatelle; damask; matelasse; tapestry.
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SECTION 7
WOVEN FABRIC ANALYSIS
7.1 Introduction The objective of fabric analysis is to identify the construction of a fabric, the count of the yarn being used, and fabric weight. It helps to reproduce a proposed fabric and to evaluate the fabric’s properties.
7.2 Identification of the Construction of a Fabric
a) Warp and Weft Densities (Fabric Count) This is the number of ends or picks per unit length (usually in inch or cm) for woven fabrics. Counting warp and weft densities is made easier by the use of a device known as a pick glass. In different parts of the same fabric, the yarns per inch often vary, therefore the warp or weft densities should be taken at several places along the length and width of the fabric. Fabric count usually is an average of tests in the length and width directions and is expressed in whole numbers. If the fabric is not of uniform construction, the following formula can be used: Ends(Picks) per repeat = Average ends (Picks) per repeat Inches per repeat b) Weave Observation Owing to the densely packed nature of the yarns, the warp yarn needs to be pulled from the fabric in order to observe the weave. The weave pattern is then drawn on a point paper (graph paper) using the method whereby an “x” represents when the warp crosses over the weft, and a blank represents when the weft crosses over the warp. A complete pattern is when the weave starts to repeat in both warp and weft directions.
Weaving and Woven Fabrics
The first step in analysing the construction of a fabric is to define the face and back, and warp and weft direction of the fabric. For details of this step please refer to Chapter 3 Section VI, Woven Structure. The next step is to find out the warp and weft densities and the weave structure of the fabric.
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7.3 Determining Yarn Counts of a Fabric In calculating the yarn count, two parameters - the length and weight - must be known. Owing to interlacing, the yarns in the fabric are crimped. The true length can be calculated by adding the crimp percentage which can be obtained using the following formula:Crimp Percentage =
straightened length - crimp length x 100% crimp length
After finding the length of the yarns, their weight can be obtained by means of a balance. By knowing the length and weight of the yarns in the fabric, the yarn count can be calculated by the appropriate formula according to the types of fibres.
7.4 Fabric Weight 7.4.1 Expression of Fabric Weight • Ounces per square yard or grams per square metre. This is the weight of a piece of fabric measured as 36 inches by 36 inches or 100 cm by 100 cm in length and width respectively. • Ounces per linear yard or grams per linear metre. This is the weight of a piece of fabric measured as 36 inches long and as wide as the entire fabric or 100 cm in length by the entire width of the fabric respectively. • Linear yards per pound or linear metres per kilogram. This is the number of yards or metres of the cloth equal to 1 pound or 1 kilogram in a specified width respectively.
7.4.2
Fabric Weight Calculation
There are two ways to find the fabric weight. The first method is to directly weigh a sample of fabric on a balance and then convert the weight into the required expression. For example, the fabric in grams per square metre can be calculates using the following formula:
Textile Handbook 3-83
Fabric Weight =
Weight of sample(g) x 10000 g/m2 area of sample(cm2)
The second method is that if the yarn count in the warp and weft is already known, the fabric weight can be found by using the following formulae : Fabric Weight in lb/yd2 100+warp(weft)crimp % 100 warp(weft) count (cotton) x 840
No.of ends/inch x36 x Fabric of Warp(Weft) =
7.5 Converting Fabric Weight from one System to Another Quite often fabrics are specified in one manner, but must be compared to a fabric whose weight is designated differently. For example, to determinate which fabric is heavier if one is expressed in ounces per square yard and the other in grams per square metre, it is necessary to convert from one system to another. The following formulae can be used for conversion: • Ounces per square yard to ounces per linear yard: fabric width x oz./sq.yd Ounces / Linear Yard = 36 • Ounces per square yard to linear yards per pound: 36 x 16 Linear Yards / Pound= width x oz./ sq.yd. • Ounces per linear yard to linear yards per pound: 16 Linear Yards / Pound= oz./ linear yd.
Weaving and Woven Fabrics
Weight of Fabric = Weight of Warp + Weight of Weft
3-84
Weaving and Woven Fabrics
• Ounces per square yard to gram per square metre: oz / yd2 =
28.35 0.9144 x 0.9144
= 33.906 g/m2
7.6 Weight of Silk Fabric The weight of silk fabric is usually expressed in terms of momme (MM). A silk fabric of 6 MM is very light in weight while a silk fabric of 22 MM is very heavy. A silk fabric is defined as 1 momme when its size is 1.04 square yard and weighs 3.75 gram. The Conversion of Momme to Ounce per Square yard is : MM ÷ 7.86 = ozyd2
7.7 Woven Fabric Design By means of fabric analysis, one can re-produce a fabric from an existing sample. However, if a new type of fabric is to be developed, and in order to produce the proposed fabric smoothly and accurately, some calculations and theories of fabric geometry should be considered.
7.7.1 Cloth Setting Theories Sett is a term used to indicate the spacing of ends or picks or both in a woven cloth; this should be expressed as threads per unit length. The state of the cloth at the time should be described as loom, grey or finished state. a) Ashenhurst’s Diameter-intersection Theory (1884). When the counts of warp and weft are the same, it is assumed that an intersection takes up as much space as a thread. Let D = diameters per inch of the yarn. w = threads in one repeat of weave. i = intersections in one repeat of the weave. T = threads per inch. Then T = D
w (w+i)
Textile Handbook 3-85
For the more common weaves, the factors “w” and “(w + i)” are given along with the average floats of weaves. and e.g., estimated settings using 2/36s worsted for warp and weft. w
Plain 2/1 twill 2/2 twill 2/3 twill 3/3 twill 3/4 twill 4/4 twill
2 3 4 5 6 7 8
(w+i) 4 5 6 7 8 9 10
Average Float 1 1.5 2 2.5 3 3.5 4
D for 2/36s worsted = 90 90 x 2/4 = 45 threads per inch 90 x 3/5 = 54 threads per inch 90 x 4/6 = 60 threads per inch 90 x 5/7 = 64 threads per inch 90 x 6/8 = 67 or 68 threads per inch 90 x 7/9 = 70 threads per inch 90 x 8/10 = 72 threads per inch
b) Armitage’s Maximum Setting Theory (1907) According to Armitage’s theory, cloths which are similarly built are equally firm. For regular twill weaves, Armitage devised the following formula: • Let
T = threads per inch. c = counts of worsted yarn. F = average float of weave.
Then T = 6 x c x(F+4) e.g. Estimate the maximum settings for 2/2, 3/3, and 4/4 twills made with 2/48s worsted yarn. 2/2 twill
T == 6 x 24 x (2+4) =72
threads per inch.
3/3 twill
T == 6 x 24 x (3+4) =84
threads per inch.
4/4 twill
T ==
6 x 24 x (4+4) =96
threads per inch.
Weaving and Woven Fabrics
Weave
3-86
Weaving and Woven Fabrics
• For other weaves, Armitage gave the following “setting ratios” in place of (F + 4). Table 7.7.1b Setting Ratios (Armitage) Plain weave 2/2 hopsack 3/3 “ 4/4 “ Mayo or Campbell
4.75 6.25 7.5 8.5 6.5
Twilled hopsack 4-end satin 5-end 6-end 8-end
6.5 6.5 7.5 7-7.5 9
All regular twill weave (P+i) c) Law’s Maximum Setting Theory (1922) • According to Law, the diameters per inch of yarns can be calculated by the following data: Worsted D= 500 x counts Woollen (Yorkshire Skein) D=
230 x counts
Cotton
800 x counts
D=
• From the diameters per inch of the yarn, calculated as above, and the average float at the weave, the setting can be determined by the following formulae. Let T = threads per inch. D = diameters per inch of yarn. F = average float.
then T =
DxF + various percentages (F + 1)
• For common weaves, the settings can be obtained as follows:-
Plain weave T =
DxF (F + 1)
Textile Handbook 3-87
Twill weaves T =
DxF + 5% for each float exceeding 2. (F + 1)
DxF + 4.5% for 2-float (F + 1) or 9.5% for each float exceeding 2. DxF Satin weaves T = (F + 1) + 5.5% for each float. Hopsack weaves T =
• Example : Estimate the settings for 3/3 twill, 3/3 hopsack and 6-end satin made with 2/40s worsted.
3/3 twill 3/3 hopsack 6-end satin
Table 7.7.1c
500 x 20
Weaving and Woven Fabrics
D for 2/40s worsted =
=100
100 x 3 x 1.05 = 79 4 100 x 3 x 1.095 = 82 4 100 x 3 x 1.165 = 87 4
Weave Values or Setting Ratios as calculated by Law.
Float
Plain
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
0.5
Twill 0.6 0.66 0.73 0.79 0.84 0.88 0.92 0.95 0.99 1.02
Mat
0.7 0.82 0.95 1.06 1.17
Satin
0.74 0.82 0.87 0.93 0.93 1.02 1.06 1.10 1.14
The weave values given above can be used to replace F + percentage F+1
4-end satin. 5-end satin. 6-end satin. 7-end satin. 8-end satin. 9-end satin. 10-end satin. 11-end satin. 12-end satin.
3-88
Weaving and Woven Fabrics
d) Brierley’s Maximum Setting Theory (1931) • According to Brierley’s theory, square settings vary according to the following formula: m KC x F
T= where
T = threads per inch. K = constant varying according to kind of yarn and system of numbering. C=
average counts of yarn.
F=
average float.
m=
constant varying according to type of weave.
“K” for worsted yarns
= 134
“K” cotton yarns
= 200
“K” for Yorkshire skein
= 60
There are few woollen cloths made to this standard of firmness. “m” for twill weaves
=0.39
“m” satin weaves
=0.42
“m” plain weaves
=0.45
“m” hopsack weaves
=0.45
Table 7.7.1d Fm values for twill, satin and hopsack weaves (Brierley) Average Float
Twill
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
1.17 1.3 1.43 1.54 1.63 1.72 1.8 1.87 1.94 2
Weaves Satin Plain and Hopsack 1 1.34 1.47 1.59 1.69 1.79 1.88 1.96 2.04 2.12
1.37 1.64 1.87 2.06 2.25
Textile Handbook 3-89
• e.g. Estimate the maximum square setting for 2/2 twill, 4-end satin, and 2/2 hopsack made with 2/24S worsted. 2/2 twill
T=
(134 x 12) x 20.39 =40 x 1.3=52 ends and picks.
4-end satin T=
(134 x 12) x 20.42 =40 x 1.34= 53/4 ends and picks.
2/2 hopsack T=
(134 x 12) x 20.45 =40 x 1.37= 54/5 ends and picks.
7.7.2 Similarly Built Cloths a) Changing Settings and Counts of Cloths using the same weave.
Setting of given cloth
2 x
Counts of required cloth
=
2
Setting of required cloth
x
Counts of given cloth
• e.g. A cloth is made with 72 ends and 72 picks per inch of 2/48S worsted. Using the same weave and 2/24S 722 x 12 = x2 x 24 x=
722 x 12 = 51 ends and picks 24
worsted, estimate the ends and picks per inch. b) Changing Settings, Counts and Weights of cloths using same weave. To obtain similarly built cloths, when the weights of the cloths are altered, the settings and counts must also be changed in a particular way to retain the same balance of structure. The following formulae are applicable: I.
II.
Setting of given cloth Counts of given cloth
x
Weight of given cloth
x
Weight of given cloth
=
2 =
Setting of required cloth Counts of required cloth
x
Weight of required cloth
x
Weight of required cloth
2
Weaving and Woven Fabrics
When the same weave is employed, settings vary as counts for yarns of similar type and quality to give similarly built cloths.
Weaving and Woven Fabrics
3-90
• e.g. A 2/2 twill cloth is made of 2/48S worsted with 72 ends and picks per inch and it weighs 12 oz. per yard. A similarly built cloth is required weighing 24 ounces. Give setting and counts of yarn required. I.
72 x 12 = x x 24 x=
II.
72 x 12 24
= 36 ends and picks
72 x 122 = x x 242 x=
24 x 12 x 12 = 6 or 2/12s worsted 24 x 24
c) Changing Setting, Counts, Weights and Weaves of Cloths. To obtain similarly built cloths, the data should be altered according to the following formulae: I.
Setting of given
II.
x
cloth
Counts of
Weight of
cloth
x
x
given
cloth
given
Setting ratio
Weight of
given cloth
2
2
Setting of
=
of required
required
cloth
2
Setting ratio
x
of required
2 =
x
cloth
Counts of
Weight of
cloth
x
Setting ratio
x
required
cloth
required
cloth
Weight of
required
of given cloth
2
2 Setting ratio
x
cloth
of given cloth
w for Ashenhurst’s theory. (w + i) (f + 4) for Armitage’s theory.
N.B. - In place of setting ratio, use -
Weave values for Law’s theory. Fm for Brierley’s theory.
Textile Handbook 3-91
• e.g. A 12 oz. cloth is made with 2/2 twill, 72/72 sett of 2/15S worsted. Give setting and counts for 14-ounce cloth made with 3/3 twill. (Use Armitage’s setting ratios). I.
72 x 12 x 72 = x x 14 x 62 x=
II.
72 x 12 x 7 x 7 = 84 ends and picks 14 x 6 x 6
24 x 122 x 72 = x x 142 x 62 x=
24 x 12 x 12 x 7 x 7 = 24 or 2/48s worsted 14 x 14 x 6 x 6
“Setting.” - This term is used to designate the proximity of the warp and weft in any given cloth, and is expressed in the linen trade chiefly as follows: (i) The setting of the warp is based on the total number of splits or dents in a standard width of 40 in. Normally there are two threads of warp through each split, but sometimes, for finer sorts, three or more threads are passed through each dent, in which case the “set” is increased prorata, e.g. 1.
600 splits 2 ends in a split on 40 in. = 600 set.
2.
600 splits 3 ends in a split on 40 in. = 900 set.
(ii) Drills are often calculated on the number of “beers” of 40 ends each in a standard width of 30 in; thus, a 60 beer drill is equivalent to: 60 beers x 40 ends per beer = 80 ends per in. 30 in.standard width
Weaving and Woven Fabrics
7.7.3 Other Expression of Setting
3-92
Weaving and Woven Fabrics
7.8 Fabric Cover In fabrics constructed from yarns, cover may be considered as the fraction of the total fabric area that is “covered” by the component yarns. The yarn has a circular cross-section of diameter d, and adjacent yarns are displaced by a distance s. The fractional cover is then d/s, or as a percentage, 100d/s. In this model, s will be equal to 1/n, where n is the number of threads per unit length. The fractional cover could be expressed in terms of d and fractional cover = d x n. Figure 7.8
Simplified Version of the Cross-section of a Woven Fabric
7.8.1 Cover and Cover Factor (F.T. Peirce) In previous studies of fabric geometry, a formula for yarn diameter in inches was derived: 1 d(in) = 28 N where N is the yarn count expressed in the English cotton count system. If s is the thread-spacing in inches, then the fractional cover is: 1
d s
=
28 N
x 1 s
Furthermore, since 1/s=n, the number of threads/in., d s
n =
28 N
By multiplying by 28, the cover factor (k)is produced : 1 k= 28 N
Textile Handbook 3-93
i.e. the threads per inch divided by the square root of the English cotton count. If all yarns just touched, the cover factor will be 28 according to the formula above. However, since space between the yarns must be left to allow the transverse yarns to interlace, a cover factor of 28 is theoretically impossible. This theory assumes, however, that the yarns remain circular in cross-section, but in practice as yarns can be compressed and distorted, cover factors even in excess of 28 can be achieved. The maximum cover factor, i.e. the weaving limit, is increased according to the number of heald frames. This is due to the decrease in the number of interlacing points of yarns, e.g. the maximum cover factor of satin weave is the highest amongst three basic weaves.
Table 7.8.1 (1) Fibre Viscose Acetate Nylon Vinylon Saran Polyester Teviron Silk Cotton Staple fibres (1.5den x1.5in)
Yarn diameter based on specific gravity
Specific gravity 1.52 1.32 1.14 1.30 1.70 1.38 1.39 1.36 0.92 (apparent) 0.91 (apparent)
Yarn diameter (in) den /2139 den /1993 den /1852 den /1977 den /2529 den /2038 den /2048 den /2023
1/(26.8 N ) 1/(26.37 N )
Yarn diameter (mm) 0.01189 den 0.01274 den 0.01371 den 0.01285 den 0.01004 den 0.01246 den 0.01242 den 0.01256 den 1/(1.055 N ) 1/(1.038 N )
Weaving and Woven Fabrics
In practice, a soft hand fabric is obtained when a cover factor is around 9 to 13. However a fabric of cover factor less than 8 is too rough for clothing. Apparent yarn diameter is different with its specific gravity. Table 7.8.1 shows the yarn diameter formulae according to various kinds of textile fibres. Table 7.8.1 (2) lists the maximum cover factors of several kinds of spun and filament yarns.
3-94
Weaving and Woven Fabrics Table 7.8.1 (2)
Maximum cover factors (Kmax )
Constant weight system
Constant length system
Cover factor = Yarns per in/ N Fibre
Kmax
Cover factor = Yarns per in. den
Conversion ratio to cotton
28.00
1.000
Woollen
17.10
Worsted
22.00
Fibre
Kmax
Conversion ratio to cotton
Silk
2310
0.0121
1.637
Nylon
2100
0.0133
1.227
Polyester
2400
0.0117
Polyester 26.30
1.070
Rayon
2500
0.0112
Glass
1.832
Acetate
2330
0.0120
Cotton
15.28
7.8.2 Cloth Cover Factor If K1 represents the cover factor of the warp yarns in a fabric and K2 represents the cover factor of the weft yarns apparently the cloth cover factor may be equal to the sum of K1 and K2. However, this is not strictly accurate because there are interlacing points on a woven fabric. Therefore, the cloth cover factor is the sum of K1 and K2 minus the overlapping areas. Hence, the Cloth Cover Factor (Kc) should be : KC = K1 + K2 - kK1K2 where k is a constant. Figure 7.8.2 represents a simplified version of one unit cell of a plain weave. The unit cell is the rectangle ABCD. The shaded area is the part of the total area covered by both yarns. Figure 7.8.2
The Unit Cell of a Plain Weave
Chapter 4 ......................................................... Knitting and Knitted Fabrics .............4-2 Section 1 - Knitting .................................................... 4-2 1.1
Knitting Process ................................................................ 4-2
1.2
Weft-Knitting .................................................................... 4-2
1.3
Weft Knitting Machines ................................................... 4-3 1.3.1 1.3.2
1.4
Two Types of Knitting Machines Using Beard Needles . 4-3 Two Types of Knitting Machines Using Latch Needles .. 4-4
Key Components for Weft Knitted Fabric Formation .. 4-5 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5 1.4.6
Knitting Needles .......................................................... 4-5 Needle Bed .................................................................. 4-6 Cam Box ...................................................................... 4-7 Yarn Feeding ............................................................... 4-7 Sinker .......................................................................... 4-8 Key Terms of Knitted Fabric ....................................... 4-9
1.5
Stitch (loop) Formation Sequence on a Latch Needle ... 4-10
1.6
Types of Knitting Stitches ................................................ 4-11 1.6.1 1.6.2 1.6.3
1.7
A
Plain Stitch .................................................................. 4-11 Miss Stitch (Welt or float) ........................................... 4-11 Tuck Stitch .................................................................. 4-11
Recent Developments in Weft Knitting ........................... 4-12 1.7.1 1.7.2
Examples of Recent Developments in Flat Knitting ... Machines ..................................................................... 4-13 Examples of Recent Developments in Circular .......... Knitting machines ....................................................... 4-14
Section 2 - Typical Weft-Knit Structure .................. 4-17 2.1
Methods Used to Represent Weft-Knitted Structures ... 4-17 2.1.1
Three kinds of methods used to represent Weft ......... Knitted Structure ......................................................... 4-17
2.2
Single Knit Structures ...................................................... 4-18 2.2.1 2.2.2
2.3
Double Knit Structures .................................................... 4-20 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7
2.4
Plain Knit. ................................................................... 4-18 Lacoste ........................................................................ 4-19
Rib ............................................................................... 4-20 Half Milano ................................................................. 4-20 Full Milano .................................................................. 4-21 Full Cardigan ............................................................... 4-21 Half Cardigan .............................................................. 4-22 Purl Structure .............................................................. 4-22 Interlock Fabrics .......................................................... 4-24
Structures and Techniques Commonly Applied to Sweaters ............................................................................. 4-24 2.4.1 2.4.2
Intarsia ......................................................................... 4-24 Designs Through Loop Transfer ................................. 4-25
Back to Table of Content
Chapter 4
KNITTING AND KNITTED FABRICS
4-2
Knitting and Knitted Fabrics
CHAPTER 4......... .........KNITTING AND KNITTED FABRICS SECTION 1
KNITTING
1.1 Knitting Process Knitting is a fabric manufacturing process in which yarn loops are intermeshed to form a fabric. The conversion of yarn into loops can be done either in a horizontal direction or in a vertical direction. Therefore, two types of knitting trades have been developed,. The fabric built up in horizontal direction is called weft-knitting, while the fabric built up in vertical direction is called warp-knitting. Knitting
Weft-Knitting
V-bed Machine, Circular Machine (Latch needle)
Warp-Knitting
Straight Bar Machine, Loop Wheel Machine (Beard needle)
Tricot Machine (Beard/Compound needle), Raschel Machine (Latch/ Compound needle)
1.2 Weft-Knitting This is a flat or circular knitting process that places one yarn at a time to form loops running across the fabric. In a weft-knitted structure, the intermeshed loops touch each other only in a few places, and the fabric can be stretched along the width or the length under a low stress.
Textile Handbook 4-3 Figure 1.2
Plain Knit Structure
1.3 Weft Knitting Machines
1.3.1 Two Types of Knitting Machines Using Beard Needles a) The straight bar type, in which the beard needles are arranged in a straight line. An example of this type of machine is the fully-fashioned straight bar machine. A fully-fashioned straight bar machine is usually programmed to knit the parts of a knitted garment in the shape required, that is the front panel, back panel, sleeve, etc. Figure 1.3.1 a Fully-Fashioned Straight Bar Machine (Monk Cotton International Ltd)
Knitting and Knitted Fabrics
Machines for plain knitting can be generally divided into two groups based on types of needles being used: the beard needle group of machines and the latch needle group of machines.
4-4
Knitting and Knitted Fabrics
b) The circular bar type, in which the beard needles are arranged in a circle on a cylinder. A typical example of this type of machine is a loop wheel machine. On this machine, the fabric is drawn vertically above the cylinder so that the last course of loops is held in tension at the needle heads. The loop wheel machine can be used for producing plain, fleecy and terry fabrics. However, this machine is now rarely used.
1.3.2 Two Types of Knitting Machines Using Latch Needles a) The flat bed type, in which the latch needles are arranged in a straight line. A V-bed flat machine is a typical example of this type. As its name implies, the V-bed machine has two needle beds arranged in an inverted v-shape. This machine can be hand-operated or controlled by computer. The flat bed machine is widely used in the sweater industry. Figure 1.3.2 a
Hand Flat Knitting Machine
b) The circular type, in which one set of latch needles is arranged on the circumference of a vertical cylinder, and another set of needles may be arranged perpendicular to the first set and mounted on a horizontal dial. Typical examples of this type of machine are the open top sinker machine, and the cylinder and dial machine. Most of the circular knitting machine are used for the piece-goods trade.
Textile Handbook 4-5 Figure 1.3.2b
Circular Knitting Machine (Mayer & Cie)
1.4.1 Knitting Needles Knitting needles have been the heart of the weft-knitting process. There are three main types of needles in industrial knitting; latch, spring beard and compound. Beard Needle: the beard needle is the oldest type. To open and close the hook during loop production, the beard needle needs an auxiliary attachment, a presser. The attachment restricts the production speed and limits the use of this needle type in modern knitting machine. Latch Needle: this is the most popular needle used in knitting. The latch of the needle is pivoted and can swivel to open and close the hook. Compound Needle: this is commonly used in warp knitting and is seldom found in weft-knitting. The hook of the compound needle is opened and closed by a closing element sliding within a grove in the main part of the needle.
Knitting and Knitted Fabrics
1.4 Key Components for Weft Knitted Fabric Formation
4-6
Knitting and Knitted Fabrics Figure 1.4.1 Knitting Needles
1.4.2 Needle Bed The needle bed of a flat knitting machine is a metal plate in which precisely measured slot (tricks) are milled. Needles are inserted in these tricks and are forced to slide backwards and forwards to form the knitting sequence. For a plain circular knitting machine, the needles are housed vertically in the tricks of a cylinder. For a double jersey knitting machine, there is another set of needles mounted on a dial, which is perpendicular to the cylinder needles.
Figure 1.4.2 Needle Bed
Textile Handbook 4-7
1.4.3 Cam Box To facilitate the knitting action of a flat bed machine, a carriage assembly is moved back and forth along the needle bed. During the traverse of the carriage, the needle butts are guided by the cam track to slide up and down in the tricks. This carriage is connected to a cam system which consists of several individual cams which form together the cam track. Figure 1.4.3
Cam Box of a V-bed Knitting Machine
On the flat bed machine, yarn coming off from cone(s) and through the tensioning device is then threaded through a yarn carrier. The carrier is set on a profiled rail, along which it can slide the length of the needle bed to provide the descending knitting needles with yarn. On a modern circular knitting machine, the yarn supply equipment consists of a cone carrier device, a yarn guiding and monitoring device, a yarn tensioner and a yarn metering and storage device. Figure 1.4.4 (1)
Yarn Feeding of a V-bed Machine
Knitting and Knitted Fabrics
1.4.4 Yarn Feeding
4-8
Knitting and Knitted Fabrics Figure 1.4.4 (2)
Yarn Feeding of a Circular Machine
2
1
1. Yarn package 2. Stop motion 3. Positive feed 4. Yarn break detector 5. Yarn feeder
3 4
5
1.4.5 Sinker In the production of plain knitted fabric on a circular type singlejersey knitting machine or straight-bar type flat knitting machine, sinkers are used to hold the fabric in position while the needle rises. This means that the fabric is tighter and the appearance and knitting speed can be improved. For Circular machine, the sinker is made of metal, housed in the radial grooves of a sinker ring placed on the top part of the needle cylinder. The movement of the sinkers is controlled by the sinker cam segment which is fixed to a stationary sinker cam ring.
Figure 1.4.5 Sinker
(1) Throat, (2) Nib, (3) Platform
Textile Handbook 4-9
1.4.6 Key Terms of Knitted Fabric a) Wales and Courses: Vertical columns of stitches in a knitted fabric are called wales. Wales run lengthwise through the entire fabric, and in that sense are similar to the warp in a woven fabric. Horizontal rows of stitches are called courses. Courses run widthwise from side to side of the cloth, and in that sense are similar to the weft in a woven fabric.
Figure 1.4.6a
Courses and Wales
1 inch
1 inch
Course
Wale b) Cut and Gauge : These are the expressions of fineness and coarseness of stitches in knitted materials. A five-cut fabric has five wales per inch. In a weft knitting machine, the number of slots per inch is called the cut of the machine. The term “cut” is used in weft knits only. Gauge is a term used in both weft and warp knitted fabrics. In fully-fashioned straight-bar type knits, gauge refers to the number of needles in 1.5 inches of the knitting machine. In a circular knitting machine, this refers to the number of needles in 1 inch. In warp knitted tricot, the term also refers to 1 inch, but in warp-knitted raschel, the gauge is the number of needles in 2 inches.
Knitting and Knitted Fabrics
The number of wales-per-unit width of fabric depends on the closeness of the needles and their thickness. The number of courses-per-unit length of fabric depends upon the distance the needle pulls the yarn when the loop is made, or the amount of yarn fed and wrapped around the needle.
4-10
Knitting and Knitted Fabrics
One should be careful of the fact that the terms “cut” and “gauge” refer to measurements. The number of wales per inch in a fabric may not exactly correspond to the cut or gauge designation.
1.5 Stitch (loop) Formation Sequence on a Latch Needle One working cycle of a latch needle produces a single knitted loop. The sequence of loop formation is illustrated in Figure 1.5. Figure 1.5
Stitch Formation by Latch Needle
Yarn feeder
Previous loops
New yarn Needle bed
1
2
3
4
5
Stitch formation sequence: 1,2 and 3 The needle rises and, as it does, the previous loop opens the latch and slides down onto the needle shank. 4 As the needle begins to descend, a new yarn is fed onto the needle hook. As the needle continues to descent, the previous loop slides onto it and causes the latch to close. 5 The needle continues downward and the old loop slides off the needle compleltly (called the knock-over action). In doing so, it becomes interlooped with a new loop which has just been formed in the needle hook, thus creating the knitted fabric structure.
Textile Handbook 4-11
1.6 Types of Knitting Stitches There are three fundamental stitches utilised in knit fabrics. They are plain stitch, miss-stitch and tuck stitch. These three stitches form the basis of all knitted fabrics.
1.6.1 Plain Stitch The plain stitch is the basic knitting stitch. It has two different faces according to the relative positioning of the producing needle and the fabric. When the fabric is viewed from the side where the loop exhibits the arms of the curved formation, this is called a plain stitch. If the loop, viewed on the same side of the fabric, exhibits the arc of the top and the root of the structure, this loop is called a purl stitch.
A miss stitch is created when one or more knitting needles are deactivated and do not move into position to accept a yarn. The yarn merely passes by and no stitch is formed. The idled needle has retained its loop longer than the rest of the needle. The miss stitch is used to create colour and figure designs in knitted fabric.
1.6.3 Tuck Stitch A tuck stitch is formed when a knitting needle holds its old loop and then receives a new yarn, two loops will then be collected in the needle hook. The action may be repeated several more times, but the yarns eventually are cast off the needle and knitted. The different appearance of the tuck stitch can be used for patterning, increasing fabric weight, thickness and fabric width, etc.
Knitting and Knitted Fabrics
1.6.2 Miss Stitch (Welt or float)
4-12
Knitting and Knitted Fabrics Figure 1.6
Formation of the three basic knitting stitches
Figure 1.6 shows the height of movement of needles to form the various stitches. Needles 6 to 10 represents the completion of a cycle to form a plain stitch. To produce a miss stitch, needles 11 to 14 should not ascend the slope of the raising cam and should instead be unaffected throughout the sequence. In order not to activate the needle, the raising cam should be withdrawn from contact with the needle butt. For tuck stitch, needles 1 to 5 should ascend the slope of the raising cam into a tucking height but not all the way to the clearing position. To achieve this, the raising cam is divided into two individually controlled parts, of which the upper raising cam should be inactive.
1.7 Recent Developments in Weft Knitting The focus of development is placed on expansion of processing methods for new products, the effectiveness and flexibility related to quick machine conversion for pattern and material changes. In the area of expansion of processing methods for new products, knitting machine makers are endeavouring to improve the processing of spandex yarns on flat and circular machines. In additional, efforts have been made to produce complete three-dimensional products directly on knitting machine which opens up new possibility of “seamless” fashioning applicable for elegant women’s clothing and technical textiles. In terms of flexibility, some flat knitting machines are using multi-
Textile Handbook 4-13
gauge techniques to provide a wide spectrum for fashion design, while the manufacturers of circular machine provides easy cam changeover system and quick change of cylinder size or cylinder gauge without the need to change cams.
1.7.1. Examples of Recent Developments in Flat Knitting Machines a) The Shima Seiki SWG-X Whole Garment Knitting Machine
b) The Stoll CMS 330 TC4 Knit and Wear This is another flat knitting machine to produce complete garments. It can apply the Stoll-multi-gauge feature. This feature allows a wide variety of gauge combinations to be produced without gauge conversion or needle exchange. The knitting system is controlled by step motor, so that cam functions and stitch tensions are collectively controlled. Flexible stitch can be freely programmable. Stitches of differing tensions can be knitted in one and the same course Figure 1.7.1.b
Step Motor for Knitting System Control (Stoll)
Knitting and Knitted Fabrics
The SWG-X is capable of producing shaped, fine gauge, whole garment products. By using their slide needle and pull down device which adjust take down tension independently for front and back bodies, three-dimensional shaping can be performed. Slide needle is a compound needle with a divided slider for stitch transfer. Stitch transfer operations necessary for fashioning is carried out with the slide needle, transfer jack and holding down sinker holders. The SWG-X is configured with 4 needle beds and an additional loop presser bed.
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Knitting and Knitted Fabrics
c) Shima Seiki SES 122 RT Rib Transfer Flat Knitting Machine This is a four needle bed knitting machine consists of two additional beds to the conventional V-bed design. This arrangement combines conventional transfer between the lower front and back beds, and together with transfer with and between the additional upper beds. This multiple transfer capability enhances shaping and integral knitting through the use of inside narrowing of rib stitches, tubular stitches, Milano and Cardigan stitches. Figure 1.7.1.c
Four Needle Bed Transfer System (Shima Seiki)
1.7.2 Examples of Recent Developments in Circular Knitting machines a) Piezo Individual Needle Selector In this individual needle selection system, it consists of a piezoceramic bending transducer module composed of two ceramic plate stacked together. When one of the plates is bent by the effect of current and voltage it makes the levers in the selector move up or down to execute needle selection.
Textile Handbook 4-15
b) Quick Cam Change System The introduction of the drop cam system by Terrot allows the cams of either cylinder or dial to be changed from the outside of the cam box which eliminates the time spent in taking out the cam box block for changeover. There is another system developed by Fukuhara called Rotary Drop Cam system having similar objective. The Rotary Drop Cam System required no yarn re-threading when changing fabric construction. All cam changes are done externally without the need to remove needles or cam section. It allows more than one technician to work on the machine simultaneously. These quick cam change systems bring about simpler operation and more flexible in design changes.
The MCTmatic is a monitoring system for setting and altering the yarn infeed and tensioning. It is able to set motors for feed wheel, central stitch adjustment and fabric takedown. All the above settings can be set by one command.
Figure 1.7.2.c(1)
Setting of Motors for Feed Wheel (Mayer & Cie)
Knitting and Knitted Fabrics
c) Mayer & Cie MCTmatic Quality Monitoring System
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Knitting and Knitted Fabrics
MCTmatic also makes a substantial contribution to quality assurance. In the event of non-conformance within a userselected tolerance, the machine will be stopped and the fault indicated in the display of the system.
Figure 1.7.2.c(2)
MCTmatic Display Panel
Textile Handbook 4-17
SECTION 2
TYPICAL WEFT-KNIT STRUCTURE
All common weft-knitted fabric structures are classified into three basic groups according to the arrangement of loops in their courses and wales. These basic structures are the plain (jersey), the rib and the purl.
2.1 Methods Used to Represent Weft-Knitted Structures
a) Loop Diagram: the actual loop of the fabric is drawn. One can see the fabric structure clearly. This is suitable for simple structure. Figure 2.1.1a
Loop Diagram
b) Notation: special symbols are used to represent a particular stitch. A cross is used to represent a plain stitch and a circle represents a reverse plain stitch (back side of a plain stitch). A blank space is used to represent a miss stitch and a dot represents a tuck stitch. It is quite difficult to use this methods to indicate an interlock fabric which is knitted with two sets of needles lying directly opposite each other.
Knitting and Knitted Fabrics
2.1.1 Three kinds of methods used to represent Weft Knitted Structure
4-18
Knitting and Knitted Fabrics Figure 2.1.1b
Notation
Plain stitch
Purl stitch
Tuck stitch
Float stitch (Blank)
c) Yarn-path diagram: this is the best way to represent any weft knitted structure. A straight line perpendicular to the yarn path is used to represent a needle. For a single jersey, one set of straight lines is used to represent one set of needles. For double jersey structure, two sets of straight lines are used to represent two sets of needles. A stitch is represented by a loop drawn around the needle. A tuck stitch is represented by the yarn touching the tip of the needle and the miss stitch is represented by the yarn drawn across the needle without touching it. Figure 2.1.1c
Yarn Path Diagram
Knit stitch
Tuck stitch
Miss stitch
2.2 Single Knit Structures 2.2.1 Plain Knit. Plain knit is also known as single knit or “Jersey” in the trade. This is the simplest and most basic structure. Fabrics of this type have all loops drawn to one side of the fabric (all plain stitches) and are easily recognized by the fact that the smooth side is the face, while the back has a textured and mottled appearance. Plain knitted fabric is stretchable, and usually it can be stretched more along the curling width than along the length. The fabric is unbalanced, and has a tendency to curl at the edges because the loops are being pulled in one direction. This condition can be corrected in fabric finishing.
Textile Handbook 4-19
One disadvantage of jersey fabric is that if one yarn breaks, it causes an unravelling of adjoining stitches, called a “run”. A wide variety of knitted fabrics are made with jersey knit, ranging from lightweight hosiery to thick, bulky sweaters. Figure 2.2.1 Plain Knit Structure
This is a four courses repeat single knit structure, while knitting the four courses, tuck stitches are included in every alternate course and on alternate needles. It has a honeycomb appearance, will not ladder easily. This structure is generally knitted on a fine gauge machine for summer T-shirts. Figure 2.2.2 Lacoste
Knitting and Knitted Fabrics
2.2.2 Lacoste
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Knitting and Knitted Fabrics
2.3 Double Knit Structures 2.3.1 Rib This structure is produced by the needles of both beds with alternate wales of plain stitches and purl stitches on both sides of the fabric. When all the needles in the machine participate in the knitting procedure, a 1x1 rib is formed. If two wales of plain stitches and two wales of purl stitches appear alternately on both sides of the fabric, this is called a 2x2 rib. A 3x1 rib has three wales of plain stitches and one wale of purl stitches on one side. Rib-knit fabric, usually being symmetrical on both sides, is not subjected to unbalanced stresses. It does not curl at the edges. Also, rib knits have greater elasticity in their width than their length. Rib structures are bulkier and heavier than plain structure provided the yarn used and machine gauge are similar. Rib structure cannot be unravelled from the edge knitted first, that is from the bottom. Similar to plain structure, a dropped stitch can start a chain reaction and produce a “ladder” in the structure.
Figure 2.3.1 Ribs
1x1 Rib
2x2 Rib
2.3.2 Half Milano This is a rib based, two courses repeat structure. The first course is 1x1 rib, the second course knit on the front needle and welt (miss) on the back needle. The fabric is harsher and tighter than ordinary rib, and this method is mainly used for sweater production.
Textile Handbook 4-21 Figure 2.3.2 Half Milano
Face
Back
2.3.3 Full Milano
Figure 2.3.3 Full Milano
2.3.4 Full Cardigan This is a rib based two courses repeat structure, the first course knit knit on the front needle and tuck on rear needle. the second course is the reverse of the first course. It has same appearance on both side, but it is shorter and wider than ordinary rib structure. Because of the large number of tuck stitches, full cardigan are very bulky. They are used for heavy outerwear when knitted in coarse gauge. It also can be used as T-shirt collar.
Knitting and Knitted Fabrics
This is a rib based, three courses repeat structure. The first course is simply 1x1 rib. The second course is knitted on the back needle but missed on the front needle. The third course is knitted on the front needle but missed on the back needle. Full milano has the same appearance on both faces of the fabric. As the structure contains miss stitches, the widthwise stretchability of the fabric is tighter than 1x1 rib fabric.
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Knitting and Knitted Fabrics Figure 2.3.4 Full Cardigan
2.3.5 Half Cardigan This structure is a special effect produced when one half of the cardigan repeat is substituted for a regular 1x1 rib structure. One side of the fabric looks like a “Cardigan” structure, while the loops of the other side acquires a very rounded and attractive shape which is usually used as the face side.
Figure 2.3.5 Half Cardigan
2.3.6 Purl Structure Purl knits require the participation of both needle beds for the production of the loops. In purl-knit fabrics, each wale contains both plain stitches and purl stitches. Simple purl fabric looks the same on both sides of the fabric, and they both appear somewhat like the back of jersey. A purl-knit fabric, where one course has all plain stitches and the next course has all purl stitches, and the cycle repeats on the third course, is known as a 1x1 purl.
Textile Handbook 4-23
Originally, purl-knit production required special equipment using double ended latch needles. The needle beds of this machine are set on the same plane instead of being in an inverted “V” formation. It is called a links/links machine, thus, the fabric produced is sometimes called links/links fabric. Nowadays, purl structure can be produced on a sophisticated “V” bed flat knitting machine with loop transfer mechanism. Purl-knit fabrics tend to lie flat and do not curl as jersey knits do. Basic purl knit structures, such as 1x1 or 2x1, contract in the length direction. They have greater elasticity in the length direction. It is probably this property that makes purl knits so widely used in infant’s and children’s wear. Also purl knits are thicker and thus better insulators than jersey knits of the same yarns and densities.
Sinker
Needle bed
Figure 2.3.6(2)
Purl Knitted Structure
1x1 Purl
Fancy Purl
Knitting and Knitted Fabrics
Figure 2.3.6(1) Knitting Procedure of a Links/Links Machine
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Knitting and Knitted Fabrics
2.3.7 Interlock Fabrics This is a variation of rib knits made on the interlock gating circular machine. On interlock knits, columns of wales are directly behind each other, thus the back of any given plain stitch on the interlock fabric will reveal another plain stitch directly behind it. Interlock knits, when compared to similar 1x1 rib knits, are smoother, more stable and better insulators. Their dimensional stability plus the fact that they do not tend to easily stretch out of shape contributes to their popular usage for outerwear and underwear.
Figure 2.3.7 Interlock
2.4 Structures and Techniques Commonly Applied to Sweaters 2.4.1 Intarsia This is a weft-knitted plain or purl fabric containing designs in two or more colours. Each area of colour is knitted from a separate yarn, which is contained entirely within that area. Figure 2.4.1 Intarsia
Textile Handbook 4-25
2.4.2 Designs Through Loop Transfer These include open-work design such as pointelle, cable design and fully-fashioned knits. a) Pointelle: this is an open-work design, where the aperture is created by transferring loops from needles to their adjacent needles. The empty needles can later resume the knitting operation and produce the desired apertures.
Figure 2.4.2a Pointelle
Figure 2.4.2b
Cable
c) Fully-fashioned knits: fashioning is a method of shaping (narrowing and widening) a knitted fabric during the knitting process. It is popular in sweater manufacture where the shape and contour of the shoulder and bust can actually be knitted to body contour shape. Full fashioning is done on flat bed full-fashioned knitting machines. The knitting machine adds or drops stitches at the end of the fabric to
Knitting and Knitted Fabrics
b) Cable design: when two groups of needles transfer their loops from one to another and then continue to knit through them, their wales cross at the transfer points and produce the cable design.
2.5
Special Knit Fabrics Produced by Circular Knitting ... 4-26 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7
High-Pile Knits ............................................................ 4-26 Knitted Terry ............................................................... 4-27 Knitted Velour ............................................................. 4-28 Fleecy Fabric ............................................................... 4-28 Coloured Stripe Fabrics ............................................... 4-29 Jacquard Fabric ........................................................... 4-30 Polar Fleece ................................................................. 4-31
Section 3 - Yarn Count and Machine Gauge ........... 4-32 3.1
Yarn Count and Machine Gauge for Circular Knit ...... 4-32
3.2
Yarn Count and Machine Gauge for Wool Knitwear .... 4-34
Section 4 - Quality and Production of Circular Knitting .................................................... 4-36 4.1
Pre-requisites of a Circular Knitting Machine ............... 4-36
4.2
Production Conditions for Knitting ................................ 4-37 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5
4.3
Production Calculations ................................................... 4-38 4.3.1
4.4
Selection of Proper Yarn Count ................................... 4-37 Setting of the Knitting Machine. ................................. 4-37 Yarn Storage ................................................................ 4-38 Air Conditioning of the Knitting Plant ........................ 4-38 Cleaning of Knitting Machines ................................... 4-38
Introduction ................................................................. 4-38
Quality Characteristics of Ring-spun 100% Combed Cotton Yarn for Circular Weft Knitting ......................... 4-40
Section 5 - Fabrics analysis ........................................ 4-45 5.1
The Geometry of Plain Weft-knitted Fabric .................. 4-45
5.2
ßStitch Density (Fabric count) ......................................... 4-46
5.3
Cover Factor ...................................................................... 4-46
5.4
Prediction of Knitted Performance by Mathematical Model ................................................................................. 4-47 5.4.1 5.4.2 5.4.3 5.4.4
5.5
Engineering the Fabric ................................................ 4-47 Checking the Specification ......................................... 4-47 Calculations Based on K values .................................. 4-48 Limitations of K values ............................................... 4-50
STARFISH - Engineered Knitted Program for Cotton Circular Knits ................................................................... 4-51
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Knitting and Knitted Fabrics
widen or narrow the cloth desired. Fully-fashioned articles can be recognized by fashioning marks which appear as distorted stitches in the area of the shaped portion.
Figure 2.4.2c
Shaping of a Knitted Panel
2.5 Special Knit Fabrics Produced by Circular Knitting Many unique and versatile fabrics can be created in weft-knitting. Fabrics which look like terry cloth towelling, a smooth velour, or even a simulated fur are examples of this group of specialized knit fabrics.
2.5.1 High-Pile Knits Imitation furs are usually made from a special type of jersey knit which involves feeding staple fibre in the form of sliver into the knit material while the yarns are passing through the knitting needles as the fabric is being made. Acrylic is the most popular fibre used for the pile portion. After knitting, a variety of finishing treatments are given to produce the desired fur-like effect. In addition to their popular use in imitated fur coats, high-pile knits are widely used as coat lining, car and airline blankets, lining for footwear and hat.
Textile Handbook 4-27 Figure 2.5.1(1)
High-pile Circular Knitting Machine
SK-18 II (Mayer Industries Inc.)
Figure 2.5.1(2)
High-pile Knitted Falnic
Back
2.5.2 Knitted Terry These fabrics are jersey-knit materials which are knitted with two yarns feeding simultaneously into the same knitting needles. When completed, one yarn appears on the face, the other on the back. One of the yarns is called a loop yarn, the other a ground yarn. The loop yarns are pulled out by special devices and become the loop pile of the knitted terry fabric. Figure 2.5.2(1)
Terry Structure
Ground yarn Loop yarn
Knitting and Knitted Fabrics
Face
4-28
Knitting and Knitted Fabrics Figure 2.5.2(2) Special Sinker for Pile Loop Formation
Figure 2.5.2(3)
Knitted Terry Fabric
Technical Back
Technical Face
2.5.3 Knitted Velour These fabrics are made in the same way as knitted terry. The loop pile is cut by a process called shearing, and then brushed. Knitted velours have a soft, downy, suede-like texture, resembling velveteen. They are softer and more flexible than velveteen. Figure 2.5.3 Knitted Velour
2.5.4 Fleecy Fabric Two-thread fleecy and three-thread fleecy fabrics are mainly produced on plain circular knitting machines. On the technical back side (the side that V-shaped loops cannot be seen) of these fabrics yarn floats along the rows and is inlay tucked at intervals into the fabric base. Such yarns are called backing or fleecy yarns.
Textile Handbook 4-29
The most common form of the interlacing points for inlay tucking are at each second needle (1:1 fleecy) or at each fourth needle (3:1 fleecy) of a row. Fig 2.5.4 shows the technical back of a staggered 3:1 fleecy. In row 8, the fleecy yarn 7 is inlay tucked at the wales 3, 7, 11, etc., and in row 10 the fleecy yarn 9 is inlay tucked at the wales 1, 5, 9,. etc. It is common that the technical back of the fleecy fabric will be raised to produce a soft hairy surface. In the three-thread fleecy fabric structure, the fleecy yarn is invisible on the technical front even when using yarns with differing thickness. The structure is composed of fleecy yarn, binding yarn and face yarn. It is produced on a special plain circular knitting machine. The specially constructed holding-down/knocking-over sinker has two throats. Simple Staggered Fleecy 3:1 Structure
1,2,3,4,5 = wales 6,7,8,10,12 = ground yarn 7,9,11 = fleecy yarn
Figure 2.5.4(2)
Fleecy Fabric
Back
Face
2.5.5 Coloured Stripe Fabrics Horizontal colour stripes in weft-knit fabrics is the simplest designer technique by colour arrangement of yarns. In circular knitting, it requires only the proper arrangement of colour yarn cones in sequence on the yarn creel. No mechanical adjustments or alteration of stitch types is necessary. Using this method, a wide variety of colour combinations is possible. However, the size of the repeat pattern of the horizontal colour stripe produced by colour yarn cones arrangement is limited. If uneven colour stripe width and larger pattern repeats are required, it is neceesary to apply the yarn changer device-stripers. The striping
Knitting and Knitted Fabrics
Figure 2.5.4(1)
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Knitting and Knitted Fabrics
pattern is achieved by selecting the colour finger on each feeder. The number of fingers on each feerder is ranged from 4 to 6. The selection of the colour finger is either controlled by a series of pin on a mechanical chain (engineering stripe) or controlled by a microprocessor where the pattern data is stored (computerised auto stripe). Figure 2.5.5
Yarn Change Device (Terrot)
2.5.6 Jacquard Fabric In jacquard knits, each needle can be individually controlled for each course and therefore patterns can be created. Jacquard structure can be produced on either single or double jersey fabrics. Single jersey colour jacquard is usually composed of two or more yarns of differing colour to give a construction that consists essentially of knit and float loops. If the float is too long, tuck loop is incorporated. The surface pattern is derived from the chosen arrangement of the colour yarns and of the knit and float loops. For rib colour jacquard produced on a circular machine, the pattern-based needle selection is undertaken on the cylinder needles, while the reverse side of the jacquard fabric is produced on the dial needle. In order to control the fabric weight and the course density on the back side of the jacquard fabric, different knitting patterns (backing) can be used for the dial needles. Figure 2.5.6
Jacquard Fabric
Textile Handbook 4-31
2.5.7 Polar Fleece
Figure 2.5.7 Polar Fleece Fabric
Face
Back
Knitting and Knitted Fabrics
This is a knitted fabric either with very high specific volume or very bulky. The bulkiness of polar fleece is obtained by brushing both sides of the knitted fabric. Regular polar fleece fabric weighs 240 g/ m2, 280 g/m2 and 320 g/m2 and has a width of 60 to 62 inches. Singlesided loop pile knitted fabric, commonly known as French Terry, is used as the ground fabric structure. After dyeing, the fabric is brushed. Brushing is the process to convert the plush fabric into polar fleece. The whole process consists of several stages of brushing. To give a finishing touch to the face side of the polar fleece, a raising process is carried out by passing the fabric over a flexible card wire machine. The raising process has the effect of paralleling the fibres on the fabric surface and also increasing the bulk. Shearing takes place right after raising to give an even surface. The transformation of a plush fabric into a polar fleece fabric can be considered as completed. However, most polar fleece fabrics are subjected to a further process called antipilling for improving the pilling resistance. The entire process is carried out using a tumble dryer. Mechanical agitation and heat causes the fibres on the fabric surface to tend to bunch up and form regular beads on the surface. Bunched up fibres reduce the freedom of fibre movement and the pilling resistance can be improved. Finally, the fabric goes through a stenter to heat set the dimension and adjust the required fabric weight.
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Knitting and Knitted Fabrics
SECTION 3
YARN COUNT AND MACHINE GAUGE
3.1 Yarn Count and Machine Gauge for Circular Knit The following tables contain practical values of the average count of yarn to be used depending on the machine gauge and several fabric types. The values in Ne refer to staple fibre yarns and those in dtex are related to filament yarns. Filament yarns are always finer as compared to staple fibre yarns due to the differences in the running behavious.
Machine gauge Needles/inch 14 15 16 18 20 22 24 26 28 30 32
Table 3.1(1) Machine gauge Needles/inch 12 14 15 16 18 20 22 24 26 28 30 32
Yarn count Ne 8.5/1 - 14.0/1 10.5/1 - 16.5/1 12.0/1 - 19.0/1 14.0/1 - 23.5/1 18.0/1 - 26.0/1 21.5/1 - 29.5/1 23.5/1 - 35.5/1 426.01 - 41.5/1 29.5/1 - 47.5/1 35.5/1 - 59.0/1 41.5/1 - 71.0/1
dtex 200 x 2 - 235 x 1 150 x 2 - 200 x 1 250 x 1 - 167 x 1 200 x 1 - 150 x 1 167 x 1 - 122 x 1 150 x 1 - 110 x 1 140 x 1 - 100 x 1 122 x 1 - 84 x 1 110 x 1 - 76 x 1 100 x 1 - 67 x 1 84 x 1 - 55 x 1
Yarn Count and Machine Gauge for Single Jersey Fabric Yarn count Ne 2.5/1 - 9.5/1 3.5/1 - 12.0/1 4.7/1 - 14.0/1 6.0/1 - 16.5/1 7.0/1 - 18.0/1 8.5/1 - 20.0/1 10.5/1 - 23.5/1 14.0/1 - 26.0/1 16.5/1 - 29.5/1 19.0/1 - 35.5/1 21.5/1 - 41.5/1 23.5/1 - 47.5/1
dtex 720 x 2 - 622 x 1 620 x 2 - 500 x 1 500 x 2 - 420 x 1 833 x 1 - 360 x 1 660 z 1 - 300 x 1 500 x 1 - 280 x 1 360 x 1 - 200 x 1 300 x 1 - 167 x 1 250 x 1 - 150 x 1 200 x 1 - 122 x 1 150 x 1 - 110 x 1 122 x 1 - 84 x 1
Textile Handbook 4-33 Table 3.1(2) Yarn Count and Machine Gauge for Fleecy Fabric Machine gauge Needles/inch 14 15 16 18 20 22 24
Yarn count Ne 16.5/1 - 23.5/1 20.0/1 - 29.5/1 23.5/1 - 35.5/1 29.5/1 - 47.5/1 41.5/1 - 53.0/1 47.5/1 - 59.0/1 53.0/1 - 71.0/1
dtex 235 x 1 - 150 x 1 200 x 1 - 122 x 1 167 x 1 - 100 x 1 150 x 1 - 90 x 1 122 x 1 - 76 x 1 100 x 1 - 67 x 1 84 x 1 - 55 x 1
Table 3.1(4) Yarn Count and Machine Gauge for Interlock Fabric
Table 3.1(5)
Yarn count Ne 12.0/1 - 16.5/1 14.0/1 - 19.2/1 16.5/1 - 21.5/1 21.5/1 - 23.5/1 23.5/1 - 29.5/1 28.5/1 - 35.5/1 33.0/1 - 41.5/1 35.5/1 - 47.5/1 41.5/1 - 53.0/1 47.5/1 - 59.0/1 53.0/1 - 71.0/1
dtex 235 x 1 - 167 x 1 220 x 1 - 150 x 1 200 x 1 - 133 x 1 167 x 1 - 110 x 1 150 x 1 - 100 x 1 133 x 1 - 100 x 1 122 x 1 - 90 x 1 110 x 1 - 84 x 1 10 x 1 - 76 x 1 90 x 1 - 67 x 1 76 x 1 - 50 x 1
Yarn Count and MachineGauge for Jacquard Fabric
Machine gauge Needles/inch 14 15 16 18 20 22 24 26 28 30
Yarn count Ne 13.0/1 - 18.0/1 14.0/1 - 19.0/1 16.5/1 - 21.5/1 18.0/1 - 23.5/1 21.5/1 - 26.0/1 23.5/1 - 28.5/1 26.0/1 - 33.0/1
dtex 235 x 1 - 200 x 1 220 x 1 - 167 x 1 200 x 1 - 150 x 1 167 x 1 - 122 x 1 150 x 1 - 110 x 1 122 x 1 - 100 x 1 100 x 1 - 84 x 1 84 x 1 - 78 x 1 78 x 1 - 67 x 1 67 x 1 - 50 x 1
Knitting and Knitted Fabrics
Machine gauge Needles/inch 14 15 16 18 20 22 24 26 28 30 32
4-34
Knitting and Knitted Fabrics Table 3.1(3) Yarn Count and Machine Gauge for Fine Rib Fabric
Fibre Wool Cotton Polyester filament Polyamide filament Acylic yarn
Machine gauge (needles/inch) 10 12 14 640 500 420 300 280 235 190
15 300 280 140
16 30 235 140
18 250 220 140
20 250 194 122
22-24 28-32 40-42 200 150 125 63 95 50
400 350 250 150 150
125
125
100
300 235 200 200 200
167
150
76
33
Table 3.1(6) Mean Yarn Counts (in dtex) for some Fibre Materials in relation to the Machine Gauge
3.2 Yarn Count and Machine Gauge for Wool Knitwear Table 3.2 on yarn count conversion and machine gauge has been compiled for guidance only. It should be stress that this information is only intended as a rough guide and knitting trials should always be carried
Textile Handbook 4-35
out when introducing a new yarn to a machine. Machine Type
Machine Gauge
Metric Count
Tex
Needles per Table 3.2 Relationship between Machine Gauge and Yarn for Wool Knitwear Straight Bar Fully Fashioned
Double Jersey
Single Jersey
8/2 - 11/2 11/2 - 18/2 13/2 - 20/2 20/2 - 28/2 22/2 - 32/2 28/2 - 36/2 32/2 - 40/2
250/22 - 176/2 176/2 - 110/2 147/2 - 98/2 98/2 - 74/2 88/2 - 64/2 74/2 - 55/2 64/2 - 50/2
Needles per Inch 2 1/2 3 1/2 5 7 8 10 12 14
2/2 - 4/2 3/2 - 7/2 7/2 - 16/2 13/2 - 18/2 16/2 - 25/2 25/2 - 36/2 30/2 - 47/2 36/2 - 60/2
885/2 - 442/2 590/2 - 295/2 295/2 - 126/2 147/2 - 110/2 126/2 - 80/2 80/2 - 55/2 68/2 - 42/2 55/2 - 34/2
Needles per Inch 12 14 16 18 22
18/1 - 26/1 22/1 - 32/1 28/1 - 36/1 32/1 - 40/1 36/1 - 45/1
55/1- 40/1 44/1 - 32/1 37/1 - 28/1 32/1 - 25/1 28/1 - 22/1
Needles per Inch 5 7&8 10 12 14 16 18 20 22 24 26 28
11/2 - 27/2 18/2 - 32/2 22/2 - 36/2 27/2 - 40/2 32/2 - 45/2 36/2 - 50/2 40/2 - 30/1 45/2 - 32/1 28/1 - 34/1 32/1 - 39/1 36/1 - 45/1 40/1 - 50/1
176/2 - 74/2 110/2 - 63/2 88/2 - 552 74/2 - 50/2 63/2 - 44/2 55/2 - 40/2 50/2 - 34/1 44/2 - 32/1 37/1 - 30/1 32/1 - 26/1 28/1 - 22/1 25/1 - 20/1
Knitting and Knitted Fabrics
Flat ‘V’ Bed and Circular
1.5 inches 9 12 15 18 21 24 27
4-36
Knitting and Knitted Fabrics
SECTION 4
QUALITY AND PRODUCTION OF CIRCULAR KNITTING
4.1 Pre-requisites of a Circular Knitting Machine • The machines must be installed on a horizontal floor and, as far as possible without vibration. • The bobbin carriers must be mounted in such a way that the yarn does not rub against the sides of the package when it is withdrawn. • Yarn should be guided from the package up to the knitting area without unnecessary deviations in order to avoid additional increases in tension. • If basic knitted structures are used to a large extent, the machines should be equipped with yarn feeding units which generate a constant and low yarn tension (running-in tension) and deliver a uniform yarn length. • Yarn guide devices must be flawless; eyelets made of porcelain or sintered ceramic must have a smooth surface without any furrows. • The needles must also be flawless. If synthetic yarns are processed to a large extent in a 3-shift operation, they might have to be renewed after just 6 months. • The shape of the needle, and especially of the needle hooks, must be adapted to the machine gauge and the yarn count. • The needle beds must be exactly centered towards one another. • Needle beds are subject to a high strain while producing tight fabrics from synthetic yarns. If wear and tear occurs here, it can cause problems in subsequent processing (roughening, cracks) • The fabric take-down and wind-on tensions must be capable of being set individually and in such a way that tension peaks, reverting back to the knitting zone, do not arise.
Textile Handbook 4-37
4.2 Production Conditions for Knitting 4.2.1 Selection of Proper Yarn Count The selection of yarn count is primarily determined by the gauge of the knitting machine. For example, for a worsted type 100% wool yarn: Machine pitch x 2 = correct yarn count (Ne or Nm), except for plain and purl machines Machine pitch x (1.0 to 1.5) = correct yarn count (Ne or Nm) for plain and purl machines.
• different machine types and difference in basic construction of the same type of machine; • knitted structure related to number of feeders involved; and • types of yarn such as processing a blended yarn when in practice a finer yarn should be used;
Figure 4.2.1 Relation Between Knitted Structures and Processing Problems The degree of difficulty in processing varies with the different knitted structures. Degree of Difficulty in Processing
Structures
Low
Interlock, 2-colour jacquard, 3-colour jacquard, 2:2 cross tubular, Ponti di Roma
Medium
Double pique, 4-colour jacquard
High
Rib, Half milano, Relief and combined patterns of muticolour jacquard
4.2.2 Setting of the Knitting Machine. Optimum setting is difficult because several factors must be balanced against one another in a proper relationship. This balanced relationship should be found between : • yarn tension before and after the yarn feeder (minimum yarn tension prior to the yarn feeder)
Knitting and Knitted Fabrics
Deviations from this formula may be due to factors including
4-38
Knitting and Knitted Fabrics
• drawing-in of yarn at the cylinder and the dial (it is easier to obtain a loose fabric by having a larger distance between dial and cylinder than by having a longer drawing-in range for the needles) • height of dial (with the tightest setting a minimum distance between dial and cylinder is necessary) • fabric take-up tension (it should be as low as possible)
4.2.3 Yarn Storage Dried yarn has limited extension, so it should be stored in rooms with at least 65% relative humidity (at 200C). Storage under extreme temperatures must be avoided because in high temperatures there might be a danger of wax migration, while at low temperatures water condensations build up.
4.2.4 Air Conditioning of the Knitting Plant It is recommended a relative humidity of 55% ± 10% at a temperature of 25oC ± 3oC.
4.2.5 Cleaning of Knitting Machines Fluff removal should take place at least at the end of each shift, fly accumulated in the cam area should be removed as it becomes visible, and residual wax on tension discs and yarn guide elements should be removed occasionally
4.3 Production Calculations 4.3.1 Introduction The performance of the circular knitting machine is affected by the elements such as frame, drive, yarn feeder, cam set-up, fabric takeup, yarn delivery device and monitoring and servicing devices. To calculate the production it is necessary to have several characteristic values of the corresponding knitting machine and the product being produced.
Textile Handbook 4-39
a) Elements Knitting Machine Parameters - machine diameter “D” (inch) - gauge “E” - no. of feeders “S” - no. of machine revolutions/min “n” - efficiency “ η“
Product Parameters - structure - type and count of yarn - course density “MR./cm” - wale density “MS/cm” - fabric weight “FG” (g/m 2)
The efficiency (“η ”) is the ratio of the practically obtained performance to the theoretical performance and is always smaller than 1. b) Formulae : Machine performance “L” in metre per hour (m/h): S x n x 60 xη feeders / course x MR / cm x 100
Fabric width “B” in metres: B (m) =
D x 3.14 x E MS / cm x 100
Machine performance “G” in kg per hour (kg/h) G (kg / h) =
L x B x FG 1000
c) Example : - Machine diameter 30 inch - gauge E 28 - no. of feeders 96 - machine speed 35 rpm - efficiency η 0.85
- structure : plain (single jersey) - yarn : cotton Ne29.6/1 - course density 18 MR/cm - wale density 13 MS/cm - fabric weight 125 g/m2
Machine performance L (m/h) 96 x 35 x 60 x 0.85 =95.2m / h L= 1 x 18 x 100 Fabric width B (m) 30 x 3.14 x 28 =2.03m B= 13 x 1000 Machine performance G (kg/h) G=
95.2 x 2.03 x 125 =24.2kg / h 1000
Knitting and Knitted Fabrics
L (m / h) =
4-40
Knitting and Knitted Fabrics
4.4 Quality Characteristics of Ring-spun 100% Combed Cotton Yarn for Circular Weft Knitting (Source: Zellweger Uster) A knitting yarn (100% combed cotton) for high-production circular weft knitting and good quality knitwear should exhibit the following quality characteristics Table 4.4 (1)
Quality Requirement of a Cotton Yarn for Knitwear
Count variation CVt, cut length 100 m** Count variation CVt, cut length 10m** Breaking tenacity* [Fmax/tex] Variation of breaking force [CVF max] Elongation at breaking force [Efmax] Variation of elongation at break Yarn twist ( ∝ m value) Paraffin waxing/surface friction value Yarn irregularity ** Thin places/Thick places/Neps Hairiness H*** Between-bobbin hairiness variation H**** CVb Seldom-occurring thin and thick places faults (CLASSIMAT values) Remaining yarn faults (CLASSIMAT values)
<1.8% <2.5% <10 cN/tex <10% <5.0% <10% Ring-spun yarn 94-110 ideal around 0.15µ <25% value of the USTER® STATISTICS <25% value of the USTER® STATISTICS [e.g.>50% value of the USTER® STATISTICS] <7% A3/B3C2/D2 OR D1 or more sensitive (clearing limit) A3 + B3 + C2 + D2 = <5/100,000m
*
A low breaking force value must be compensated by a higher elongation at breaking force value
**
Highest requirements with single jersey
*** Higher, but constant hairiness as a result of the cloth appearance and handle. The minimum hairiness value must be set based on agreements between the partners **** Variation between packages. Higher values can lead to rings with singlecoloured fabrics.
Textile Handbook 4-41
From Table 4.4 (1), it can be seen that it is not one single peak value which determines the quality of the end product, but a compromise between the various quality characteristics. In contrast to weaving yarns, the yarn strength of knitwear yarns, for example, is secondary, as the loading placed on the yarn during knitting is lower than that with a high-production weaving machine. The yarn must, however, exhibit enough elongation and elasticity. There must be no weak places or thick places which can result in stops, holes in the knitted material or even broken needles. Particularly important is the ability of the yarn to be guided easily through the various elements of the machine (low friction value). The moisture content of the yarn should be evenly distributed. Conditioned yarns provide better running properties and better appearance of the finished fabric.
Particularly important is the yarn evenness and count variation. Both the short and medium-term, as well as the long-term count variations lead to cloudy or stripy fabrics as soon as a certain mass variation level is over stepped. Also neps and vegetable matter, as well as a high dust content, refer to the types of foreign matter which are particularly disturbing. These lead to wear of the needles, holes in the knitted material and even to dyeing problems. All these yarn characteristics can be responsible for downgrading the knitted fabric, and can have some influence on the ‘knitability’, ‘spirality’, ‘dyeability’ or ‘contamination’ problems associated with circular weftknit fabrics. A large European Knitwear manufacturer has set out the yarn specifications for certain types of knitted structure. Table 4.4.(2) shows the yarn quality specifications corresponding to the yarn count and recommended raw material.
Knitting and Knitted Fabrics
In most cases, an even and high hairiness value with a low twist is required in order to achieve a soft material handle. This hairiness value must, however, remain constant and be without periodic variations.
4-42
Knitting and Knitted Fabrics Table 4.4 (2) Yarn specifications demanded by a European knitwear manufacturer Evenness Thin Neps Knitwear Thick (cvm%) places places per km type * per km per km * (-50%)
Nm (Tex) Cotton Combed
Twist factor /(inch)
Break tenacity (cN/ tex)
CV (Fmax %)
34 (29.5) Am
3.3
12.5
9.0
13.0
4
50
60
Single jersey
40 (25) Am
3.3
13.0
9.0
13.0
6
50
70
Single jersey
50 (20) Maco
3.3
3.3
9.0
14.0
8
35
80
Double rib
50 (20) Peru
3.5
12.0
9.0
14.5
10
70
80
Double rib
50 (20) Am
3.5
13.0
9.0
14.5
10
70
90
Fine rib
55 (18.2) Am
3.5
13.5
9.0
15.0
12
90
110
60 (16.6) Maco 60 (16.6) Am
3.4
16.0
9.0
14.5
12
50
90
Fine rib + Single jersey Double jersey
3.5
13.5
9.0
15.0
15
100
150
Double jersey
70 (14.4) Am
3.6
13.5
10.0
15.5
20
100
120
Tricot + Fine rib
70 (14.4) Maco
3.3
16.0
9.0
14.5
15
50
90
Fine rib
85 (11.8) Maco
3.5
16.0
9.0
15.0
20
60
100
2/85 Tricot 2:2
100 (10) Maco
3.5
16.0
10.0
15.5
25
70
100
Fine rib
120 (8.4) Maco
3.6
16.5
11.0
16.5
40
90
120
Fine rib
• Settings of sensitivity at the USTER® TESTER 3
Textile Handbook 4-43
There is another set of yarn specifications for knitted fabric recommended by a well-known European retailer of knitted goods. It refers to five yarn counts of 100% combed cotton yarns used for various structures in weft circular knitted fabrics. Table 4.4 (3) Yarn specifications demanded by a European retailer of knitted goods Ne 24 25 tex
Ne 30 20 tex
Ne 34 17.5 tex
Ne 38 15.5 tex
Evenness CVm%
max.*
max.*
A% CVt100% Twist/m
±* ≤* 568±38
±* ≤* 675±85
max. 12.3 ±1.5 ≤1.8 755±38
max. 13.0 ±1.5 ≤1.8 826±38
max. 13.5 ±1.5 ≤1.8 910±38
THIN/km (-50%)** THICK/km ** NEPS/km ** Tenacity Fmax/tex CVFmax%
max.*
max.*
max.5
max.5
max.8
max.*
max.*
max.20
max.25
max.35
max.*
max.*
max.40
max.60
max.80
min.13CN
min.13CN
min.13CN
min.13CN
min.13CN
≤10.0
≤10.0
≤10.0
≤10.0
≤10.0
Elongation at Break Efmax%
min.6.2
min.6.0
min.5.8
min.5.6
min.5.5
A1/B1/ C1/D1*** /100km (remain) A3/B3/ C2/D2*** /100km (remain)
mean 75 max.150
mean 85 max.170
mean 100 max.200
mean 125 max.250
mean 150 max.300
mean 3 max.5
mean 3 max.5
mean 3 max.5
mean 4 max.7
mean 5 max.8
E/100km*** (remain)
max.1
max.1
max.1
max.1
max.1
H2/I2 100km*** (remain)
max.3.5
max. 3.5
max. 3.5
max. 3.5
max. 3.5
* ** ***
According to agreements with the yarn processor Settings of sensitivity at the USTER®TESTER 3 Sensitivity levels of the USTER®CLASSIMAT
Knitting and Knitted Fabrics
Ne 18 27 tex
4-44
Knitting and Knitted Fabrics
If it is to be expected that the setting out of yarn specifications as the basis for agreements between the yarn manufacturer and the yarn processor will become a standard procedure in the same way that a yarn can be “engineered”, based on the fibre properties, a knitted fabric can also be “engineered” based on the yarn quality characteristics. This will necessitate a closer collaboration between the spinner and the knitter, and the need for the knitter to become better acquainted with the yarn quality characteristics and the values which can be expected.
Textile Handbook 4-45
SECTION 5
FABRIC ANALYSIS
5.1 The Geometry of Plain Weft-knitted Fabric The dimension and construction properties of fabrics are important for the control of quality as well as for end-use determination. The theory of fabric geometry for a plain weft knitted fabric can be defined as follows: S = the number of stitches per square unit c = the number of courses per unit length
l = the stitch or loop length. Wales/cm = w Courses/cm = c Stitch length = AB = l mm Stitches/cm2 = S
Figure 5.1 A
Plain Weft Knitted Structure
Apart from the dominant factor, that is, the length of yarn in the knitted loop (stitch length), there are three dimensionally stable (relaxed) states possible for a knitted structure must be considered when applying the theory of the fabric geometry.
Knitting and Knitted Fabrics
w = the number of wales per unit width; and
4-46
Knitting and Knitted Fabrics
The three relaxed states of a knitted fabric are: • Dry-relaxed state: the fabric has been taken off the knitting machine and in course of time attains a dimensionally stable condition called the dry-relaxed state. • Wet-relaxed state: if the fabric is soaked in water and allowed to dry flat, the wet-relaxed state is attained, again a dimensionally stable condition. • Finished relaxed state: in order to reach this stable condition, the fabric is subjected to agitation in water or steam, and a denser fabric results.
5.2 Stitch Density (Fabric count) The stitch density of a weft-knitted fabric can be expressed as the number of wales per unit length times the number of courses per unit length.
5.3 Cover Factor Covering power refers to the ability of an item to occupy space or to cover an area. A fabric with better cover will be warmer, look and feel more substantial, and be more durable. Cover Factor can be defined as a number that indicates the extent to which the area of a knitted fabric is covered by the yarn. It is also an indication of the relative looseness or tightness of the knitting. The Cover Factor (C.F.) can be determined by the following formula: CF=
tex stitch length (mm) or
CF=
1 stitch length (inch) x worsted count
Textile Handbook 4-47
5.4 Prediction of Knitted Performance by Mathematical Model 5.4.1 Engineering the Fabric Fabric engineering in the modern sense implies that equations have to be available which can be used to calculate the fabric properties of interest, starting from the known manufacturing and processing conditions. The known manufacturing and processing conditions comprise: • The yarn (or selection of yarns) available for knitting.
• The knitting specification (essentially, the length of yarn fed for each revolution of the machine). • The wet processing and finishing machinery characteristics.
5.4.2 Checking the Specification Normally the dyer and finisher does not participate in the fabric design and specification exercise. He has to accept whatever fabric is supplied, and he will usually be required to deliver the dyed and finished fabric at a certain weight and width and with certain maximum levels of shrinkage. If the fabric has not been appropriately engineered, then there is no way that the dyer and finisher will be able to meet all of these requirements. Therefore, it is absolutely essential that the dyer and finisher should be able to check whether the fabric is correctly engineered before he puts it into work. If the dyer and finisher has access to the equations which are used for fabric engineering, then he is able to make such checks.
Knitting and Knitted Fabrics
• The knitting machinery characteristics (essentially, the number of needles).
4-48
Knitting and Knitted Fabrics
5.4.3 Calculations Based on K values The K values were derived from observations made by research workers more than two decades ago that there is a strong relationship between the number of courses and wales per cm in a relaxed cotton knitted fabric and the reciprocal of the loop length used in knitting (see Figure 5.4.3). “Relaxed” means after the fabric has been subject to an appropriate wetting and drying procedure (e.g. a shrinkage test). Loop length is the average length of yarn in each knitted loop. It is given by the length of yarn fed to the knitting machine per revolution (or per pattern repeat) divided by the number of needles which are knitting.
The two basic equations are: Course per cm = Kc/loop length in cm Wales per cm = Kw/loop length in cm Kc and Kw are constants for a given fabric construction and fibre type, and these K values can be used to calculate the course and wale densities in any fabric, provided only that the knitted loop length is known. Once the course and wale densities have been found for the relaxed fabric, then these can be used together with yarn count, the knitted loop length, and the number of needles in the knitting machine to calculate the relaxed fabric weight and width. Wt = tex x loop length x course x wales x F1 Width = number of needles/wales x F2 Where F1 and F2 are scaling factors, depending on the units of measurement. Courses and wales, weight and width in the unrelaxed fabric (i.e. as delivered to the customer) can then be derived by proportional scaling, according to the appropriate level of shrinkage. Length Shrinkage = (Cr - Cd) / Cr Width Shrinkage = (Wr - Wd) / Wr Where Cr and Wr and the relaxed courses and wales, Cd and Wd are the as-delivered values.
Textile Handbook 4-49
If the calculated as-delivered weight and width values do not coincide with what the customer has specified, then the fabric has not been correctly engineered, and this is a matter for serious discussion between the dyer and finisher and the customer. If the calculated weight and width do coincide with the customer’s requirements, then the calculated values for as-delivered courses and wales provide the dyer and finisher with his primary finishing targets. If he can hit these values in the delivered fabric, then the calculated weight and width, and the shrinkage values used in the calculation are guaranteed.
Since the yarn count and loop length should be known from the knitting specification, it would seem to be a simple task for the dyer and finisher to check that a given grey fabric has been correctly engineered so that the weight, width and shrinkages required by the customer can actually be delivered. Kc and Kw values can easily be picked up from the literature, or can be determined on the grey fabric already to hand. Figure 5.4.3
Effect of Loop Length on Grey Courses and Wales per cm
Knitting and Knitted Fabrics
The finishing targets can be used as the basis for setting and operating control systems on stenter and compactors, which will aid the finisher in achieving his targets, and thus the required fabric performance. In practice the width will be used in preference to the number of wales per cm for control purposes, but there is no satisfactory substitute for courses per cm as the primary length control parameter.
4-50
Knitting and Knitted Fabrics
5.4.4 Limitations of K values Unfortunately, it is now know that Kc and Kw are actually not constants. They are affected quite significantly by several factors including especially certain aspects of the yarn specification, and any wet processing which may have been carried out on the fabric. For example, K values for plain jersey fabrics, which have appeared in the literature over the last two decades, range from 5.1 to 5.8 for Kc and 4.1 to 4.95 for Kw. This range of variation is not some kind of experimental error. It is a reflection of real differences in K values, due to differences in the experimental conditions used by the various workers. It also represents approximately the range of K values which are found in experimental work. Some of these effects are illustrated by Figure 5.4.4 (1) and Figure 5. 4.4 (2) which show the influence of knitted Tightness Factor and wet processing on the values of Kc and Kw for a wide range of plain jersey fabrics, knitted from seven different yarns. Tightness Factor is given by the square root of the yarn count in tex divided by the Loop Length in cm. There are relatively large differences between the K values for grey fabric and those for the two sets of finished fabrics, and the wide scatter in the data, within a given wet process, is a reflection of the influence of the yarn properties upon the K values. In this context, it should be noted that a difference of only a unit in Kc represents difference in length shrinkage of about two percentage points; a similar difference in Kw represents two and a half percentage points of width shrinkage. Figure 5.4.4(1)
Effect of Tightness Factor on Kc
Textile Handbook 4-51 Figure 5.4.4(2)
Effect of Tightness Factor on Kw
5.5 STARFISH - Engineered Knitted Program for Cotton Circular Knits (Source: Cotton Technology International) STARFISH is short for “START as you mean to FINISH. The STARFISH computer program is a simulator. It models the key elements of production and processing of cotton circular knitted fabrics and it calculates their expected performance. The STARFISH computer program is founded on a database which comprises test data on more than 5,000 separate fabric qualities, and is still growing year by year. Almost all of the data come from fabrics which have been manufactured and processed at full scale. These data are mainly of two types. Firstly, there are the systematic series of fabric qualities to perform the basic mathematical analysis to develop the underlying equations. Secondly, there are the results from sets of serial samplings of individual qualities, taken over a period of weeks or months in dyeing and finishing plants. These serve to validate the
Knitting and Knitted Fabrics
Therefore, a dyer and finisher who wants to make use of simple K values to check for correct fabric design, or to develop finishing targets, should take care to use the appropriate values. Because the K values are affected by the wet process, he would be well advised to carry out determinations of courses and wales on his own finished fabrics. It is definitely not the case that he can determine K values on the grey fabrics and use these for making calculations. Indeed, the only value for the dyer and finisher in making measurements on grey fabrics is to ensure that the yarn count and loop length are exactly as specified.
4-52
Knitting and Knitted Fabrics
predictions of the current program and also to establish the normal variation which can be seen in commercial production. Using these data, it is possible to model (amongst others) the average influence of different types of yarns and different wet processing regimes, so that these average effects are already built into the model. Thus, using the STARFISH computer program, the average values for courses and wales, and the weight and width of an extremely wide range of dyed and finished fabrics can be estimated very rapidly and pretty accurately without the need for any physical knitting or finishing trials. The program will also calculate finishing targets for any desired level of shrinkage or any requested weight and width. It will also show whether a given set of customer demands can actually be met in principle, using the yarns, knitting machines, and wet processing machinery which are actually available. It should be emphasised that the equations used by STARFISH are not dependent in any way on K values. They include additional terms which allow for the yarn type, the yarn count, the wet process, and the depth of shade. To get started with a basic simulation model, the user can select from a list of four standand yarn types, ten standard processes and eight depths of shade. Up to nine different yarn count values can be specified, as well as nine different knitting machines (to simulate a body-width range).
Section 6 - Typical Fabric Imperfections on Circular Knitting .................................... 4-53 6.1
Fabric Skew ........................................................................ 4-53 6.1.1 6.1.2 6.1.3 6.1.4
6.2
Definition .................................................................... 4-53 Causes ......................................................................... 4-53 Evaluation of the Effect of Yarn, Knitting and ............ Finishing Parameters on Skew .................................... 4-54 Summary ..................................................................... 4-58
Barre .................................................................................. 4-58 6.2.1 6.2.2
Definition of Barre ...................................................... 4-58 Causes of Barre ........................................................... 4-58
Section 7 - Warp Knitting and Warp Knitted Fabrics ..................................................... 4-61 7.1
Warp Knitting ................................................................... 4-61
7.2
Warp Knitting Machine Classification ........................... 4-61 7.2.1 7.2.2
7.3
Knitting Elements of Warp Knitting Machine ............... 4-63 7.3.1 7.3.2 7.3.3 7.3.4
7.4
Tricot Machines ........................................................... 4-62 Raschel Machines ........................................................ 4-62
Needle ......................................................................... 4-63 The Sinker ................................................................... 4-64 Guides and Guide Bars ................................................ 4-64 Driving Mechanisms of Knitting Elements ................. 4-65
Key Terms of Warp Knits ................................................ 4-66 7.4.1 7.4.2 7.4.3 7.4.4 7.4.5 7.4.6 7.4.7
Course and Wales ........................................................ 4-66 Stitch Density .............................................................. 4-66 Loop Parts ................................................................... 4-66 Open and Closed Laps ................................................ 4-67 Technical Back ............................................................ 4-67 Technical Face ............................................................. 4-67 Run-in .......................................................................... 4-68
7.5
Common Warp Knit Fabric Structures and their Characteristics .................................................................. 4-68 7.5.1 7.5.2
Tricot Fabrics .............................................................. 4-68 Raschel Fabrics ........................................................... 4-72
Textile Handbook 4-53
SECTION 6
TYPICAL FABRIC IMPERFECTIONS ON CIRCULAR KNITTING
6.1 Fabric Skew (Source: Cotton Incorpocated) 6.1.1 Definition
Figure 6.1.1 Examples of Skew
6.1.2 Causes When discussing tubular knit goods, the skew deviation is usually composed of distortion caused by the yarn, the number of feeders on the machine, and the manner in which the yarn is knitted. Skew caused by the yarn is realized as a spiraling of the wales at a steep angle around the knitted tube. This type of skew causes the tube to torque. If a single wale is followed up the length of this tube, it can easily be seen that the wale will spiral around the tube. The courses will generally not be deflected from the horizontal. Distortion of the wale loops is usually seen in goods that are processed in tubular form in a preparation or dyeing process. In fact wale skew is readily seen when the fabrics are unloaded from the preparation or dyeing vessel
Knitting and Knitted Fabrics
Skew can be defined as a fabric condition resulting when the knitted wales and courses are angularly displaced from the ideal perpendicular angle. Other terms such as torque, spirality, bias and shear distortion are often used to refer to the same phenomena. Regardless of the term used, this displacement of the courses and wales can be expressed as a percentage or as an angle measurement in degrees. Examples of skew can be seen in Figure 6.11.
4-54
Knitting and Knitted Fabrics
prior to de-twisting and extraction. If the fabric is then finished in a tubular manner and the wales are not straightened, then the distortion of the wales will be obvious. The level of course skew will include both yarn and machine influence. Also, it is important to realize that if the fabrics are slit in the grey on the same wale line and are undergo from wet processing to dry processing, then the wales will be straight and the courses may be skewed. Machines with a large number of feeders will make a fabric that has substantial ‘course skew’ as the fabric comes off the knitting elements. However, the course skew will be eliminated when the fabric is slit into open-width form. Yarn parameters that affect skew include twist level (twist multiple or turns per inch of twist), twist direction (S or Z), twist liveliness, and the spinning system. It is important to realize that skew from the yarn and the skew from the number of feeders on the machine can combine together to create more skew, or they may partially offset each other and result in less skew. This addition or subtraction of skew depends primarily on the yarn twist direction and the direction of rotation of the cylinder on the knitting machine.
6.1.3 Evaluation of the Effect of Yarn, Knitting and Finishing Parameters on Skew a) Test Method: the sample fabrics are measured for skew using a proposed test method being developed by AATCC. The samples are marked with a square before washing and tumble drying. If the fabric skews after five washes and dry cycles, the square can be measured for percent skew. The method uses a mathematical formula for shear distortion (skew) and is shown below:
2(AC-BD) x 100
% Skew = AC + BD
Textile Handbook 4-55 Figure 6.1.3.a Proposed Test Method for Shear Distortion (Skew) of Knitted Fabric
Where AC and BD are the diagonals of the square,
b) Effect of Twist Multiple, Twist Direction and Yarn Spinning System on Skew The sample fabrics are knitted into 18 gauge single jersey with 18/1 Ne carded 100% cotton yarn. The Twist Multiples (TM) used for the Ring and O-E spinning systems are 3, 3.5 and 4. However, only one TM is used for the Air Jet spinning system. Table 6.1.3.b
Effect of Twist Multiple, Twist Direction and Yarn Spinning System on Skew
Grey Goods Ring Spun Z twist 3.0 3.5 4.0 Ring Spun S twist 3.0 3.5 4.0 Open-End Z twist 3.0 3.5 4.0 Murata Air Jet Z S
% Skew (5 HLTD’s)*
Skew Direction
10.5 12.6 18.5
Right Right Right
15.8 17.6 20.3
Left Left Left
3.5 5.2 8.7
Right Right Right
12.3 17.6
Right Left
Note: * 5 washes and dry cycles
Knitting and Knitted Fabrics
DA’B’ > 90o
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Knitting and Knitted Fabrics
c) Effect of Twist Multiple, Twist Direction and On Machine Cylinder Rotation Direction on Skew Sample fabrics were made on two 28 gauge single jersey machine. 30/1 Ne Combed cotton ring spun yarns were knit at a tight stitch. The difference between the machines was the direction of cylinder rotation. Knitting evaluations included three yarn feeder setups. Comparisons included fabrics made with all feeds of S twist, all feeds of Z twist and alternating feeds of S and Z twist. Grey goods were tested for skew using the proposed AATCC method for shear distortion (skew)-the results are shown in Table 6.1.3c Table 6.1.3.c Effect of Twist Multiple, Twist Direction and on Machine Cylinder Rotation Direction on Skew Grey Goods
% Skew (5 HLTD’s)
Clockwise Rotation Z 15.3 S&Z 1.4 S 11.0 Counterclockwise Rotation Z 5.7 S&Z 2.6 S 7.5
Skew Direction
Right Right Left Right Right Left
d) Effect of Tightness of Stitch on Skew Sample fabrics were knitted with four different stitch tightness on a 28 gauge single jersey machine. The yarn used is a 30/1 ring spun 100% cotton and both grey goods and dyed goods were compared for skew. Table 6.1.3.d Effect of Stitch Tightness on Skew Course Length (ins) 245 260 270 280
Skew (5 HLTD’s) * Grey 8.6 12.3 15.1 16.8
Note: * All samples had right hand skew.
Dyed Corrected for Skew 8.1 9.5 15.2 17.2
Textile Handbook 4-57
e) Effect of Skew Using Plied and Parallel Yarn The used of balanced, plied yarns has been practiced for years to give torque free fabrics. Table 6.1.3.e shows the skew test data for “S” and “Z” yarns spun side-by-side on a Air-jet spinning system and wound parallel onto the same package, and two strand of “Z” twist wound onto the same package and then plied on an uptwister at different twist.
Table 6.1.3.e
Effect of Parallel and Plied Yarns on Skew Using the Murata Air Jet Spinning System
S & Z - 0 TPI 1.2 Z & Z - 0 TPI 21.0 Z & Z - 2.5 TPI Z & Z - 6.5 TPI Z & Z - 12.5 TPI Z & Z -14.5 TPI
% Skew 5 HLTD’s
Direction
Right Right 17.0 11.3 0.0 3.5
Right Right None Left
Note : * Each individual strand was a 40/1 Ne Air Jet Yarn.
f) Effect of Finishing Techniques on Skew Sample fabrics, knitted on a 28 gauge single jersey machine with a 30/1 Ne combed ring spun yarn, were pre-treated and dyed on a jet machine, dried and finished by either compaction or resin treatment. One group of the finished fabrics has included skew correction. The skew test result are shown in table 6.13f Table 6.1.3.f Effect of Finishing Techniques of Skew
Sample Grey Dyed & Compacted Dyed & Resin Finished
% Skew, 5 HLTD’s With Correction — 8.1 6.0
Without Correction 8.6 3.5 2.0
Knitting and Knitted Fabrics
18 Cut, 100% Cotton*
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Knitting and Knitted Fabrics
6.1.4 Summary Skew on 100% cotton single jersey is related to the level of yarn twist, the spinning system used, the strand configuration, the tightness of the knitted stitch, the number of feeders on the knitting machine, the rotational direction of the knitting cylinder and the finishing technique used. Any process that could be developed to reduce the twist liveliness of yarns could help reduce the total level of skew. Also, development of finishing techniques that could relax the yarns without inducing torque would be of interest. Today, the best answer for skew reduction is either the use of plied yarns or alternating feeds of opposite twist. If single yarns must be used, then resin finishing offers reasonable control of skew.
6.2 Barre 6.2.1 Definition of Barre The noun “BARRE” is defined by ASTM as an unintentional, repetitive visual pattern of continuous bars and stripes usually parallel to the courses of circular knit fabric. In a warp knit, barre normally runs in the length direction, following the direction of yarn flow.
6.2.2 Causes of Barre a) Factors which may cause or contribute to barre are listed as follows: (i) Raw Material - Fibre • Failure to control fibre diameter (micronaire or denier) from laydown to laydown. • Too high a C.V. of micronaire in the laydown for a given mill’s opening line blending efficiency. • Failure to control the fibre colour in the mix (greyness Rd, yellowness +b). Most, if not all, fibre barre can be controlled by the above three items; however, under certain unusual circumstances it may be beneficial to select mixes using ultraviolet reflectance information for each bale of cotton.
Textile Handbook 4-59
(ii) Yarn Formation/Supply • Variations in carding; i.e., different amounts of nonlint content removal from card to card. • Poor blending of fibre in opening through finisher drawing. • Running different types of spindle tapes on ring spinning frame. • All cots running on a given set of ring frames producing yarn for the same end use should be exactly the same. • Mixing yarns of different counts.
• Mixing yarns with different blend levels. • Mixing yarns from different suppliers. • Mixing yarns with different twist level/twist direction. • Mixing yarns with different degrees of hairiness. • Mixing yarns with different amounts of wax. • Mercerization differences. • Excessive backwinding or abrasion during this process. • If yarns are conditioned, then each lot must be uniformly conditioned. (iii) Fabric Formation • Improper stitch length at a feed. • Improper tension at a feed. • Variation in fabric take-up from loose to tight. • Excessive lint build-up. • Variation in oil content. • Worn needles, which generally produce length direction streaks. • Uneven cylinder height needles (wavy barre). • Double feed end.
Knitting and Knitted Fabrics
• Mixing yarns of different spinning systems.
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Knitting and Knitted Fabrics
b) Prevention of Barre Barre is caused by inconsistencies in materials, equipment, or processing. To prevent barre from occurring, consistency must be maintained through all phases of textile production. Stock yarns should be properly and carefully labelled to avoid mixups. Fugitive tints can be useful for accurate yarn segregation. Inventory should be controlled on a First In/First Out basis. All equipment should be properly maintained and periodically checked. Before beginning full scale production, sample dyeings can be done to check for barre. Salvaging a fabric lot with a barre problem may be possible through careful dye selection. Colour differences can be masked by using shades with very low light reflectance (navy blue, black), or high light reflectance (light yellow, orange, or finished white). Dye suppliers should be able to offer assistance in this area. Also, if the cause of the barre is an uneven distribution of oil or wax, a more thorough preparation of the fabric prior to dyeing may result in more uniform dye coverage. With close cooperation between production and quality control personnel, barre problems can be successfully analyzed and solved.
Textile Handbook 4-61
SECTION 7
WARP KNITTING AND WARP KNITTED FABRICS
7.1 Warp Knitting Warp knitting is defined as a loop-forming process in which the yarn is fed into the knitting zone, parallel to the fabric selvedge. The source of yarn on a warp knitting machine is a warp beam similar to a warp beam on a loom. The yarns form a vertical loop in one course and then move diagonally (shogging) to another wale to make a loop in the following course. The yarns zigzag from side to side along the length and connect the loops into a fabric.
Figure 7.1
Warp Knitting Mechanism
Warp Knitting Mechanism
7.2 Warp Knitting Machine Classification There are two types of warp knitting machines: Tricot and Raschel. The distinction between Tricot and Raschel machines can be made by the type of sinkers with which the machine is equipped, and the role they play in loop formation.
Knitting and Knitted Fabrics
Warp knitting machines are usually flat machines, and each warp yarn is knitted by one needle. All the needles of the machine are mounted on a long needle bar equal to the width of the machine. When the needle bar is activated, all the needles act in unison. Each yarn is threaded through a yarn guide, and all the yarn guides are mounted on a yarn guide bar. Movement of the guide bar moves all the yarns mounted on it. The yarn guide bar moves laterally from left to right for several wales, and then back again. It guides the yarn to a new needle and wraps the yarn around it for its next stitch.
4-62
Knitting and Knitted Fabrics Figure 7.2
Tricot Machine (Karl Mayer)
7.2.1 Tricot Machines The sinkers used for tricot machines control the fabric throughout the knitting cycle. The fabric is held in the throats of the sinkers while the needles rise to clear and the new loops are knocked over in between them. Modern tricot machines are constructed with compound needles, while in the past tricot machines were equipped with beard needles. Tricot machines are commonly equipped with from two to four yarn guide bars and require the same number of warps to be used.
7.2.2 Raschel Machines In Raschel knitting, the sinkers are only used to ensure that the fabric stays down when the needles rise. The fabric is controlled by a high take-up tension, for this reason, the fabric produced on a raschel machine is pulled tightly downwards from the knitting zone, at an angle of about 160o to the backs of the needles. In the past, a raschel machine could be distinguished from a tricot machine by its use of latch needles; however modern raschel machines use compound needles. Raschel machines are usually equipped with a larger number of guide bars than the tricot machines. The number ranges from 4 to 70 allow the greater patterning capability of these machines. Two types of guide bars are used in Raschel knitting. The first type is fully threaded and used for the construction of the ground fabric. In most cases 1 to 3 such guide bars are used. The second type of guide bars are use to apply the pattern onto the fabric. These bars usually require only 1 thread for each patterning repeat, so that only a few yarns are threaded across the whole width of such a bar.
Textile Handbook 4-63
7.3 Knitting Elements of Warp Knitting Machine 7.3.1 Needle Beard and latch needles are cast in units of 1 inch long. Compound needles are set in tricks cut in the needle bed of the machine, while the closing elements, being cast in units half an inch long, are set in a separate bar.
Figure 7.3.1(1)
Beard Needle Unit
Figure 7.3.1(2) Latch Needle Unit
Knitting and Knitted Fabrics
Figure 7.3.1(3)
Compound Needle and Closing Element
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Knitting and Knitted Fabrics
7.3.2 The Sinker The sinker is a thin plate of metal which is placed between each needle. The sinkers are usually cast in units 1 inch long, which in turn are screwed into the sinker bar. The neb of the sinker and throat are used to hold down the fabric, while the belly of the sinker is used as a knocking-over platform. Figure 7.3.2
A Sinker Unit (Tricot Machine)
7.3.3 Guides and Guide Bars The individual guides of a tricot machine are usually cast in 1 inch units which in turn are fitted on the guide bars. The guides swing between and around the needles in order to wrap the yarn around them to form a new loop. They also shog sideways to join the wales into a fabric. In a raschel machine, the bars are designed to be narrow and light-weight strips of metal with individual guide fingers attached so that a greater number of bars can be assembled. The guide bars can be set in groups in the same displacement line called “nesting”. Each nest can be considered as one guide bar for the swing movement. Tube guide fingers can be used for bulky and fancy yarns. Figure 7.3.3 (1) Jacquard Displacement Bar (Raschel Machine)
Textile Handbook 4-65 Figure 7.3.3 (2)
A Guide Unit
7.3.4 Driving Mechanisms of Knitting Elements
The guide bar needs a combination of a swing movement and a shogging lateral movement to wrap the yarn around the needle and to displace the yarn guides from one needle to another. The swing movement is generated by a mechanism very similar to that which produces the vertical movement of the needle. It is transmitted by the push rod and converted by the lever into the swing movement of the guide bars. The lateral movement of the guide bars is generated by the patterning mechanism which consists of a pattern drum and pattern chain (see Figure 7.3.4 (2)). A chain made of links of different heights is placed on the pattern drum. While rotating, the different chain links move the roller and slide so that the push rod moves the guide bar and displaces it laterally. Since raschel machines are equipped with more pattern guide bars, a pattern mechanism which operates the guide bars through shogging levers are used. In addition, an electronically controlled patterning mechanism is used to replace the traditional chain link mechanism. Figure 7.3.4 (1)
Main Shaft with Cranked Drive for Knitting Elements (Tricot Machine)
Knitting and Knitted Fabrics
The needle bar and the sinkers are driven up and down or horizontally by means of cams or eccentrics. In order to achieve a movement containing the dwelling of the needle bar at the clearing position, the eccentrics are connected to the needle bar by a crank assembly (see Figure 7.3.4 (1)).
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Knitting and Knitted Fabrics Figure 7.3.4(2)
Pattern Drum and Pattern Chain
7.4 Key Terms of Warp Knits 7.4.1 Course and Wales Similar to weft knit, a horizontal row of loops is called a course while a vertical column of loops form by a single needle is called a wale. Figure 7.4.1
Two-guide Bar Loop Structure
7.4.2 Stitch Density The stitch density in the fabric is defined as the total number of loops in an unit area. The stitch density is the number of wales times the number of courses in that area.
7.4.3 Loop Parts The warp knitted loop structure is made of two parts. The first one is the loop which is formed by the yarn being wrapped around the needle and drawn through the previous loop. This part of the structure is called an overlap. The second part is the length of yarn connecting the loops, which is called an underlap. It is formed by the shogging movements of the ends across the needles. The length of the underlap is defined by needle spaces according to the shogging movement. The longer the underlap, the more stable in widthwise direction, but a shorter underlap will increase lengthwise stability.
Textile Handbook 4-67
In order to control the dimensional stability and the appearance of the fabric, a second set of ends are knitted in an opposite shogging movement to the first.
7.4.4 Open and Closed Laps Two different lap forms are used in warp knitting, depending on the way the yarns are wrapped around the needles to produce an overlap. When the overlap and the next underlap are made in the same direction, an open lap is formed. If the overlap and the following underlap are in opposition to one another, a closed lap is formed. Figure 7.4.4 Open and Closed Lap Configurations
Knitting and Knitted Fabrics
a = Open loop; b = Closed loop
7.4.5 Technical Back The structure can be recognized by the underlaps floating on the surface and is called the “technical back”. This side is facing the knitter while working on the machine.
7.4.6 Technical Face The loop structure shows on the “technical face” of the fabric. When the fabric is formed by more than one set of yarn ends, all the yarns which overlap the needle will appear in the loop.
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Knitting and Knitted Fabrics
7.4.7 Run-in All yarn ends threaded through the guides of one guide bar knit the same construction and are fed equally. The yarn consumption of each guide bar is called “run-in” and is measured as the length of each yarn knitted into the fabric during 480 knitting cycles. A cycle of 480 knitted courses is called a “rack”. By feeding different amounts of yarn into the knitting zone, the size of the loops is changed. A longer run-in produces a looser fabric while a shorter run-in produces small and tight loops. When a new fabric is produced, the run-in should always be recorded. This information will be very useful to reproduce the fabric again at a later stage. When knitting with more than one guide bar, the relative amount of yarn fed from each warp is very important; this relation is called the “run-in ratio”.
7.5 Common Warp Knit Fabric Structures and their Characteristics 7.5.1 Tricot Fabrics Tricot fabrics are used for a wide variety of fabric weights and designs. Typical uses for tricot fabrics are lingerie, sleepwear, blouses, shirts, dresses, slacks, uniform for nurses, bonded fabric material, outerwear, and automobile upholstery. Most lingerie tricot is two-bar fabric. Dress wear tricot and men’s wear tricot are often three-bar or four-bar fabrics. a) Plain tricot or tricot jersey: this is the basic fabric using two-bar constructions. The most widely produced warp knitted fabric is probably locknit. Locknit structure is produced when the back guide bar shogs a 1- and -1 lapping movement, and the front guide bar shogs two needle spaces. The lapping movement of the two guide bars is illustrated in Figure 7.5.1 a. Locknit gives a pleasant touch and a considerable elasticity make the fabric most suitable for ladies’ lingerie. Locknit construction tends to contract on leaving the knitting zone. The final width may only be two-thirds of the needle bar width. Locknit fabric is normally produced on 28, 32 and 40 gauge machines.
Textile Handbook 4-69 Figure 7.5.1 a Locknit Loop Structure
FGB
BGB
FGB= Front Guide Bar BGB= Back Guide Bar
Figure 7.5.1 b Three-needle Satin Loop Structure
FGB
BGB
c) Sharkskin : the sharkskin fabric is constructed as a reverse version of satin. The structure shows the longer underlaps of the back guide bar locked under the short underlaps of the front guide bar. These trapped underlaps restrict the shrinking potential of the fabric which is therefore more rigid and more stable than locknit and satin tricot.
Knitting and Knitted Fabrics
b) Satin tricot : is a variation of the locknit structure with an increased lapping movement up to 6 wales on the front bar. While the technical face is similar in appearance to locknit, the technical back is smoother and shiner. It should be noticed that the longer the underlap floating on the surface of the technical back, the heavier the fabric and the greater the risk of snagging.
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Knitting and Knitted Fabrics Figure 7.5.1 c
Sharkskin Loop Structure
FGB
BGB
d) Queen’s Cord : the fabric is formed when the front guide bar moves in the shortest lapping so that the yarn is knitted continuously on the same needle while the back guide bar has a reciprocating 3- and-1 or 4- and -1 movement. The dimensions of queen’s cord fabric change only very slightly in width on leaving the knitting zone, and the final width is very similar to the knitted width. If the front guide bar is threaded with coloured yarns, a pin-stripe effect is produced. This makes queen’s cord very popular for the production of shirting fabric.
Figure 7.5.1 d
Queen’s Cord Loop Structure
FGB
BGB
Textile Handbook 4-71
e) Brushed Tricot (Pile Fabric) : Two-bar fabrics can be produced or finished as pile fabric in order to improve their appearance or their thermal properties. In brushed fabric, the lapping movements of both bars are carried out in the same direction. The fibres raised out of the long underlaps of the front guide bar can be easily pulled out during the finishing process. Brushed fabric is widely used for robes and sleepwear. Using of heavier yarns, fabrics for upholstery (automotive and furniture) can be made.
Figure 7.5.1 e Brushed Tricot
Knitting and Knitted Fabrics
f ) Mesh-Effect and Fancy Open-Effect Tricot Fabrics : By omitting some knitting needles and yarns at intermittent places, mesh or open effect can be produced. These fabrics are used for producing novelty lingerie or curtains.
Figure 7.5.1 f
Net Loop Structure (Tricot)
FGB
BGB
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Knitting and Knitted Fabrics
7.5.2 Raschel Fabrics The large number of guide bars in a raschel knitting machine provides the potential for wide diversification and great variation in raschel fabric from fine laces to heavy blankets and even carpets. For example, a widely used type of thermal underwear with a distinct waffle surface effect is a raschel knit structure. Power net fabrics used in foundation garments and swimwear are also raschel fabrics. a) Net Fabrics: Net fabrics can be considered as one of the major products manufactured by the raschel machine. Net structures can be classified into the following two types: (i) Structures with Vertical Pillars: The net in which the distance between the vertical pillars (wales) is determined by the distance between the knitting needles. Usually, the horizontal mesh bars are produced by another set of yarns which bridge the gap between each two wales. The shape of the opening is determined by the lapping movement and by the tension applied to the yarns. In most cases the pillars (vertical chain of loops) can keep straight. To produce this type of net structure, the guide bars are usually fully threaded and the net appearance is obtained by using fine yarns. A simple construction of this structures is illustrated in Figure 7.5.2.a.(1)
Figure 7.5.2 a (1)
A Pillar and Inlay Loop Structure
FGB
BGB
Textile Handbook 4-73
Figure 7.5.2 a (2)
Marquisette Loop Structure
FGB
BGB
Knitting and Knitted Fabrics
Sometimes, the horizontal mesh bars may not necessarily be produced during each knitted course. The Marquisette net structure is formed in this way. The loop structure of three-guide-bar Marquisette net is shown in Figure 7.5.2 a (2). The front guide bar is constantly chaining to produce the vertical pillars whilst the horizontal connections are produced by the inlay yarns which are threaded in the back guide bars. These two bars work in opposite direction during the tracing of the vertical pillars and during the horizontal crossings. It is usual to shog one of the back guide bars by one needle space and the other one by two needle spaces. In this way the fabric is sufficiently stable and is usually finished to the same width in which it has been knitted. Marquisette structures are very popular in the production of net curtains.
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Knitting and Knitted Fabrics
(ii) Structure with Interlacing Pillars: The side connections are formed by the inclination and distortion of the wale, no special yarns are necessary to connect the pillars. The typical openings of these nets are diamond shaped although other openings can be produced. The basic structure of this type of net is shown in Figure 7.5.2 a (3). To produce this structure, the guide bars are threaded in a sequence of 1 in, 1 out. Both guide bars are constantly chaining with each yarn to produce only one pillar on the same needle. After a number of courses, the guide bars are shogged in opposition to one needle space. During this course, each of the guide bars draws its new loops through the loops previously made by the adjacent yarns. When the connection is made, each guide bar is shogged to its original position and resumes the chaining lapping movement. The next connection is carried out in the opposite direction to the first and diamond shaped openings are formed. A typical product of this type of structure is fishing net.
Figure 7.5.2 a (3) The Loop Structure of a Net with Diamond Shaped Openings
FGB
BGB
Textile Handbook 4-75
b) Dress laces : Lace fabrics are produced by multi-guidebar raschel machine with 32, 42, 56 or 78 guide bars and usually with an electronically controlled patterning mechanism. The ground structures of dress laces can be classified into two major groups. One group is the tulle ground structure (interlacing pillars) as shown in Figure 7.5.2. b (1) & (2) and the other is made of a chaining bar with the pillars being pulled together and connected by the patterning yarns as shown in Figure 7.5.2 b (3) & (4).
Figure 7.5.2 b (1)
A Tulle Net Loop Structure
Figure 7.5.2 b (2)
BGB
A Lace Fabric with Tulle Ground Structure
Knitting and Knitted Fabrics
FGB
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Knitting and Knitted Fabrics Figure 7.5.2 b (3) A Lace Fabric with Ground Chains Connected by Patterning Yarn
Chapter 5 Textile Coloration and Finishing Treatment .............................................5-2 Section 1 - Textile Coloration and Finishing ........... 5-2 1.1
Introduction ....................................................................... 5-2
1.2
Preparation of Cotton Goods ........................................... 5-2 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7
Grey Inspection .......................................................... 5-3 Singeing ....................................................................... 5-3 Desizing ....................................................................... 5-3 Scouring ...................................................................... 5-3 Bleaching ..................................................................... 5-4 Mercerization .............................................................. 5-5 Summary ..................................................................... 5-5
1.3
Fluorescent Brightening ................................................... 5-5
1.4
Dyeing ................................................................................ 5-6 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5 1.4.6 1.4.7 1.4.8 1.4.9
1.5
Terminology Relating Dyeing ..................................... 5-6 Factors that Affect Dyeing .......................................... 5-7 Classification of Dyes ................................................. 5-8 Colour Formulation ..................................................... 5-10 Colour Fastness ........................................................... 5-10 Application of Pigments .............................................. 5-12 Methods of Dyeing ...................................................... 5-12 Special Dyeing Effects ................................................ 5-20 Computer Colour Matching ........................................ 5-20
Printing .............................................................................. 5-22 1.5.1 1.5.2
General Printing Procedures ....................................... 5-23 Methods of Printing ..................................................... 5-25
Back to Table of Content
Chapter 5
TEXTILE COLORATION AND FINISHING TREATMENTS
5-2
Textile Coloration and Finishing Treatments
CHAPTER 5.........
.......TEXTILE COLORATION AND FINISHING TREATMENTS SECTION 1 TEXTILE COLORATION AND FINISHING 1.1 Introduction After textile materials have been made, by being spun into yarn or woven into fabric, they still contain impurities which make them undesirable for immediate use. Such textiles are usually referred to as ‘grey goods’ - they are unattractive to consumers because of their appearance, handle, and lack of serviceability and durability. Textile wet processing is the collective term for the processes that are used to improve the textiles in terms of the above-mentioned properties. The most common way to examine textile wet processing is to split it into the following three stages: • Pre-treatment (preparation) • Coloration (Dyeing and Printing), and • Finishing
1.2 Preparation of Cotton Goods A typical continuous processing sequence for the preparation of cotton woven fabric is given as follows : Grey inspection Singeing Desizing Scouring Bleaching Mercerization
Textile Handbook 5-3
1.2.1 Grey Inspection
1.2.2 Singeing Singeing of cotton goods is necessary to remove the unwanted surface loose hair so as to give a uniform surface. The process is done by passing the fabric rapidly over a singeing machine with gas burners. The burners are specifically arranged such that both sides of the fabric are singed. The speed at which the fabric travels must be carefully adjusted so that it will not catch fire or be scorched. After singeing, cooling of the fabric, by either cooling cylinders or water bath, is needed to recover the handle.
1.2.3 Desizing This is to remove the sizes that have been applied to the warp yarns for reinforcement during the weaving process. Sizes are normally composed of starches or other synthetic chemical agents, like Polyvinyl Alcohol (PVA). Traditionally removal of sizes are done by some chemical treatments, such as acid steeping, alkali steeping and oxidative treatment, etc., which are quite time consuming and polluting. Nowadays, a more practical and faster method is to make use of biochemical enzyme which decomposes and digests the size, especially starch based ones. The enzyme, together with the decomposed size residues, are then removed by successive hot and cold water rinsing.
1.2.4 Scouring This is carried out to remove the natural impurities and dirts of grey textiles so as to produce a clean white ground and improved water absorbing property, which is suitable for later colour processing. The main types of impurities associated with the cellulosic cotton are seed fragments, waxes, oils, dirts and natural colouring matters. The most common method used for scouring is the treatment using strong alkali (caustic soda) with detergent at a temperature near the boiling point
Textile Coloration and Finishing Treatments
This is to identify any fabric faults that exist in the grey state. The inspection is carried out visually, either on a traditional long inspection table or by means of specially designed inspection machine. Faults are usually marked with coloured threads or other means of markings on the fabric selvedges for identification. If the number of faults exceed the inspection requirement and are unable to be mended, the goods will be rejected at this stage. After inspection, the goods will be madeup into a continuous form by sewing the short pieces together.
5-4
Textile Coloration and Finishing Treatments
for an optimum period of time. Excessive scouring will result in oxidation of cellulose which will weaken the fabric strength. Figure 1.2.4
Scouring and Bleaching range
1.2.5 Bleaching Bleaching enhances the whiteness of the scoured textiles to produce a brighter white ground suitable for fluorescent whitening effect as well as for coloration in brilliant shades. The three common kinds of bleaching agents used are Sodium Hypochlorite (NaClO), Sodium Chlorite (NaClO2) and Hydrogen Peroxide (H2O2). Their general applications and descriptions are summarised in Table 1.2.5. Table 1.2.5 Bleaching Descriptions 1. Operating temperature 2. pH 3. After-treatment 4. Damage due to over oxidation
20-30 C 10-11 anti-chlor
80-90 C 3-4 anti-chlor
80-90oC 10-11 not necessary
large
5. Handle
poor
small good
medium good
6. Whiteness 7. Yellowing after storage 8. Equipment requirement
dull
bright
bright
Easy simple
medium complicate
9. Production cost
low
high
not easy simple medium
NaC1O o
NaClO2 o
H 2O 2
Textile Handbook 5-5
From of the above comparison, it can be observed that each bleaching method has its own merits and drawbacks. Nowadays, the two chlorine based methods are becoming less important than the peroxide method. Due to the similar application conditions of scouring and peroxide bleaching, combined scouring and bleaching becomes possible to shorten the production lead time as well as to conserve energy.
Mercerization is the chemical treatment of the cotton fabric in a cold bath of concentrated caustic soda under controlled tension in a specialized mercerizing machine. The effect of the strong alkali causes the flat, twisted ribbon-like cotton fibre to swell into a straight and round shaped appearance, which results in a silk-like outlook with better lustre, dimensional stability, fabric strength and chemical reactivity. Double mercerization is a process whereby yarns are mercerized and knitted into a fabric, and the fabric is subsequently mercerized. Another chemical treatment called “Liquid Ammonia” process especially for yarn and knitted fabric. It can also produce the same effect as mercerization, However, it is not as popular as mercerization because of the complicated application (operation temperature at -30oC in a vacuum chamber).
1.2.7 Summary The above-mentioned is the general sequence of processing of cotton woven fabric. For yarn and knitted fabric, the operation is much simpler as they do not need to be singed and desized. Moreover, mercerization of yarn and knitted fabric is not as popular as in the case of woven fabric. Therefore, the general preparation of yarn and knitted fabric involves scouring and bleaching only. Being scoured and bleached, the goods are always left in the same machine and ready for the next coloration process.
1.3 Fluorescent Brightening Fluorescent brightening, also called fluorescent whitening or optical brightening/ whitening, is a process to further enhance the bleached textiles that are used for white goods. Due to its complex organic structure the Fluorescent Brightening Agent (FBA) possesses the ability to absorb light energy in the ultra-violet zone and re- emit the energy in the visible blue or violet light region. This results in a fluorescent whitening effect making the treated material look whiter. In some cases,
Textile Coloration and Finishing Treatments
1.2.6 Mercerization
5-6
Textile Coloration and Finishing Treatments
a blue or violet tint may be incorporated together with the FBA which results in a even whiter appearance. The classification and application of FBA is somewhat similar to that of dyeing. Different classes of FBAs are specifically applied on different types of fibres. The application of FBA is usually combined in the scouring and bleaching processes. The drawbacks of FBA include poor colour fastness to washing and to light. In addition, yellowing may occur when atmospheric nitrogen oxides as well as the anti-oxidant of some polyethylene bags contaminate the treated material.
1.4 Dyeing Textile dyeing together with printing are commonly called the textile coloration process. In both cases, either dyes and pigments are to be used as the colorants. Essentially dyeing involves the use of highly complex organic synthetic (but occasionally natural) dyestuffs, which under proper conditions such as presence of salts, acids/alkalis, temperature and pressure, actually combine with the textile fibre molecules. Coloration by pigments, however, differs from dyeing in the sense that pigments do not combine with the textile fibre molecules as dyes do. They are only physically held and glued onto the fibre surface by means of resin binders. To differentiate between dyes and pigments in terms of their application method, their general properties are compared follows: Dyes - smaller particle size
Pigments - larger particle size
- soluble in its application medium
- insoluble in its application medium - without affinity to fibres
- with affinity to fibres
1.4.1 Terminology relating to dyeing a) Affinity, also called substantivity, is the physical attraction between the dye or chemical particle and the fibre molecule. b) Liquor ratio is the ratio by weight of the material to dye/ chemical liquid. For example, 1:10 means 1 gram of material to 10 gram of dye/chemical liquid. c) Recipe is the formulation of the quantity of dyes and chemicals, temperature and treatment time that are used for processing.
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d) The depth of shade is the quantity of dye exhausted by the material expressed as a percentage by weight of the material. It is normally used to describe the darkness or lightness of dyeing. e) Stripping is the removal or destroying of colour (dye molecules) from the dyed material by chemical treatments.
g) Continuous process is the process in which materials are handled in sequence through a series of stages, resulting a continuous output of processed materials. Its production rate is far more higher than batchwise process. Due to the intensive tension exerted throughout the processing, it is not recommended for knitted fabric production. h) Semi-continuous process is the process combining the batchwise and continuous processes to maximise production. The typical example is the pad-batch process. i) Padding is the operation of impregnating dye or chemical liquid into the fibre of the material by means of pad mangles. It is the basic installation used in the continuous process range.
1.4.2 Factors that Affect Dyeing Briefly speaking, the dyeing process is a very complex chemical reaction. It involves the use of dyes as well as other assisting chemicals, known as auxiliaries, and is processed under the optimum condition. Different classes of dye applying on different types of fibre require a careful selection of such dyeing auxiliaries and conditions. The major factors that affect dyeing are listed as follows : • Quantities of dyeing auxiliaries, such as salts, levelling agent, etc. • pH, to be adjusted by acids and alkalis • Liquid ratio
Textile Coloration and Finishing Treatments
f ) Batch process is the process in which materials are handled as lots or batches. The size of each lot or batch is subject to the size of the machine. The batchwise dyeing process is also called exhaustion dyeing.
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• Temperature and rate of heating • Treatment time • Agitation • Any after treatment to be given, such as dye fixation, oxidation, etc.
1.4.3 Classification of Dyes There is no class of dye that is capable of dyeing all textile fibres. A specific class of dye can only be applied to a given type of textile fibre. The classification of dyes and their general description are summarized in Table 1.4.3. Table 1.4.3 Dye Class
Classification of dyes General description
Main application
Simple application; cheap; complete colour range; moderate colour fastness but can be improved by after-treatment with copper salts and cationic fixing agents.
Mainly used for cellulosic fibres; can also be applied on rayon, silk and wool.
Complicated application; limited colour range Azoic (Naphthol) (red, orange, navy among the best); bright shade at moderate cost; generally good wet fastness but moderate to poor dry cleaning and rubbing fastness; also called naphthol dye due to the use of naphthol, or ice colour because of the usage of ice during application.
Mainly applied on cellulosic fibres, especially on brilliant red shade.
Vat
Difficult to apply (requires reduction treatment to make soluble in water and oxidation to resume insoluble state after dyeing); most expensive; incomplete colour range (strong in blue and green but weak in brilliant red); good all round fastness except indigo and sulphurised vat species; tending to decrease in popularity due to increasing use of reactive dyes.
Commonly used for high quality cotton goods, e.g. towel; specially used in the dyeing of denim fabric.
Sulphur
Difficult to apply (application similar to vat dyes); cheap particularly for dark shade; incomplete colour range (strong in black, navy, khaki and brown but no bright shade); poor washing and rubbing fastness and sensitive to chlorine; may cause fabric rendering of cellulose upon storage (aging).
Mostly used for heavy cellulosic goods in dark shades.
Direct
Textile Handbook 5-9 Dye Class
General description
Main application
Easy application; moderate price; complete colour range; good fastness due to direct reaction with fibres.
Commonly used for all cellulosic goods especially in knitted fabric batchwise dyeing; selective dyes can also be applied on wool, silk and rayon; increasingly used in printing due to good fastness.
Acid
Easy application; complete colour range with very good bright shades; fastness properties may vary among individual dyes.
Commonly used for wool, silk and nylon.
Metalcomplex
Relatively difficult to apply; expensive; complete colour range but duller shade than acid dyes; good fastness due to high molecular size and metal complex structure.
Mainly used for wool and nylon.
Chrome Mordant
Complicated application; expensive; complete colour range but very dull shade; good all round fastness.
Mainly used for wool products especially for the end use of carpet.
Disperse
Require skill in application (either by carrier or under high temperature); moderate price; complete colour range; limited solubility in water (normally dispersed in water for application); good fastness after reduction clearing treatment; sublimation property.
Mostly used for polyester and acetate; can also be applied on nylon and acrylic.
Basic (Cationic)
Careful application required to prevent unlevel dyeing and adverse effect in hand-feel; complete colour range with very good brilliant shades.
Mainly used for acrylic.
Textile Coloration and Finishing Treatments
Reactive
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1.4.4 Colour Formulation The choice of a specific colour for a particular material is the responsibility of the textile designer or colourist who perceives the colour to be in conformity with the fashion requirement. It is the job of the textile dyer to match the designer’s colour with the proper dyes or pigments as well as to meet the colour fastness requirements for the specific end-use of the material. In brief, the designer’s role is part of the world of artistry and creativity, while the dyer’s role is in the world of science and technology. Matching of colour shades by the dyer requires the skilful blending and formulation of different dyes and pigments, as well as an understanding of the nature of fibres and the numerous chemicals needed to carry the dyeing process. Colour match recipes are first developed on a small laboratory basis. Once the dyer has formulated a colour match and achieved a satisfactory sampling (often known as the labdip), this becomes the standard which all future dye lots or batches must follow. In actual production, however, each dye lot is more or less different in shade from all other lots. This lot-to-lot shade variation is caused by several factors such as differences in dyes/auxiliaries concentration, fabric lots and different dyeing machine settings, etc.
1.4.5 Colour Fastness A good dye must possess an acceptable degree of retention by the textile fibre so as to withstand the subsequent treatment (e.g. laundering, dry cleaning, etc.) or environmental wearing (e.g. rubbing, light exposure, etc.). The degree to which a dyed material can withstand such treatments and wearing is called colour fastness. No dye or pigment used for textiles is absolutely fast to all colour fastness conditions. Only a careful selection and formulation of dyes and auxiliaries can result in a desirable dyeing, and conform with the colour fastness requirements. The most common colour fastness items for textile material are laundering (washing), light exposure, dry cleaning, perspiration and rubbing (crocking). The common fastness properties of different dye classes are summarized in Table 1.4.5.
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Table 1.4.5
Common colour fastness properties of different dye classes Colour fastness to
Dye Class
Direct
Light
Dry cleaning
Perspiration
Rubbing
Moderate (can be improved after proper a f t e r treatment)
Good
Good
Good
Good
Moderate
Good
Moderate
Excellent
Good
Excellent
Good
Azoic Good Vat (except Excellent indigo) Sulphur
M o d e r a t e Good (sensitive to chlorine)
Good
Good
Moderate (poor on d a r k shades)
Reactive
Good
Good
Excellent
Excellent
Good
Acid
Moderate to poor
Good
Good
Moderate
Good
Metalcomplex
Good
Excellent
Good
Good
Good
Chrome Mordant
Excellent
Excellent
Good
Good
Good
Disperse
Good
Good
Good
Good
Good
B a s i c (Cationic)
Good
Moderate to poor
Good
Good
Good
Textile Coloration and Finishing Treatments
Washing Moderate (can be improved after proper a f t e r treatment)
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1.4.6 Application of Pigments Pigments are very popular in textile coloration especially in printing. The advantages of using pigments are given as follows : • easy to apply with good shade matching from lot to lot; • full colour range; and • can be applied on all textile fibres and their blends. The application of pigments involves the use of adhesives (commonly known as binders) to bond the pigments to the surface of textile fibres. Pigment dyed materials generally have inferior washing, dry cleaning and rubbing fastness properties. The handle of the pigmented dyed materials are also adversely affected due to the binder film being formed on the surface of the fibre surface. Nowadays, a fashion trend of “garment wash” or “pigment wash” has become increasingly popular. The basic principle is to make use of the properties of the poor washing and rubbing fastness of pigments to deliberately produce a colour fading effect after a severe machine washing.
1.4.7 Methods of Dyeing Dyeing can be done during any stage from fibre right through to the finished garment. The following are the four stages at which dyeing can be carried out: • Fibre dyeing (also called Stock dyeing) • Yarn dyeing • Fabric dyeing (also Piece dyeing) • Garment dyeing The considerations that govern the choice of the dyeing stage are mainly technical and economical. Dyeing at the fibre stage is much more expensive than at other stages, but it will normally give the best fastness result, as well as enabling production of a fancy colour effect such as mottle, heather, etc after a fibre blending process. Yarn dyeing is mainly used to produce a checks or stripe effect with different coloured yarns. Threads for sewing and embroidery are also dyed in yarn form. Fabric dyeing is commonly used for economic large batch production of solid
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colour. Garment dyeing has increasingly been used to produce solid coloured garments with minimized shading problem among garment parts. The above considerations have only mentioned the general outline. Details of which will be discussed in turn as follows : a) Fibre Dyeing:
Fibre dyeing usually results even dyeing and excellent penetration of dyes into the fibres, and hence good fastness properties. However, it is the most costly method for dyeing because the production rate is relatively low and there is 10-15% waste due to loss of fibres during the process. A similar process for worsted wool that takes place nearer to the finished yarn stage than fibre dyeing is known as Top dyeing (top means sliver of worsted yarn). The process is classified as fibre dyeing because the dyeing is done using the same dyeing machine with similar applications, dyeing properties and limitations. Figure 1.4.7 a Loose-stock Dyeing Machine
Dye Circulation
Loose fiber
Textile Coloration and Finishing Treatments
Fibre dyeing is carried out on loose-stock before the fibre is spun into yarn. It is done by putting packed loose fibres into the container of the Loose-stock dyeing machine (as shown in Fig. 1.4.7a) in which the dyeing will take place. The process is mostly used in the production of woollen materials especially when mottled and heather-like colour effects are desired.
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Textile Coloration and Finishing Treatments
b) Yarn Dyeing Yarn dyeing is the process of dyeing carried out after fibre has been spun into yarn. The process is mainly used to produce various effects of stripes, checks, plaids or other multi-colour designs with different coloured yarns in the weaving and knitting process. Moreover, threads for sewing and embroidery purposes are all dyed at the yarn stage. Yarns may be dyed in different forms : • Hank dyeing • Package dyeing (Cone dyeing) • Slasher dyeing • Rope dyeing (i) Hank dyeing (also called skein dyeing) is especially suitable for dyeing of soft, lofty yarns such as wool and acrylic knitting yarns, to retain a good hand-feel after processing. Yarns are prepared in loosely wound hanks which are then hung and submerged into a refrigerator-like container called the Hank dyeing machine. The door of the machine will be kept closed during processing to ensure complete immersion of the materials in the dye liquid. The major advantage of this dyeing method is that good even dyeing can be achieved due to good circulation of the dye liquid. However, the dyeing cost is much higher because of the high liquor ratio which means a larger consumption of dyes and auxiliaries. (ii) Package dyeing is commonly used for dyeing yarns made from cotton and synthetic fibres. Yarns are wound onto perforated spools to form cones which will be stacked on perforated rods in a rack. The filled rack is then loaded into a tank with dye liquid for dyeing. Dye liquid is forced through the cones under pressure alternately inside-out and outside-in to enable a better penetration of dyes into yarns with high twist. The dyeing machine is called the Package dyeing machine (Figure 1.4.7b). The Package dyeing machine can be pressurized to be capable to process materials made of synthetic fibres above boiling point, for example 130oC
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for polyester. Package dyeing is more productive over hank dyeing, but the dyed yarns do not retain the softness and loftiness that hank dyed yarns do. In addition, uneven dyeing may occur between the inner and outer portions of the cone of yarns. Figure 1.4.7 b Package dyeing machine
(iv) Rope Dyeing : Please refer to Chapter 3, section 1.6
c) Fabric Dyeing Fabric dyeing, also called piece dyeing, is the most popular production method for solid colour, as it gives the greatest flexibility to the manufacturer in terms of inventory as well as production capacity. Large orders of woven fabric can be dyed in a continuous process, i.e. Pad dyeing, while the batchwise Jig dyeing is suitable for small batch production. For tension sensitive materials, such as knitted fabrics or some thin woven fabrics, the batchwise process of Winch dyeing and Jet dyeing are the most appropriate dyeing methods. The description of each dyeing method is discussed in the following paragraphs. (i) Pad dyeing, as already mentioned, is a continuous process used to dye mainly woven fabric in open width form. The fabric is passed through a trough of dye liquid and then squeezed evenly by a pair of pad mangles to impregnate dye deep into the fibres. After padding, a series of operations like intermediate drying, chemical
Textile Coloration and Finishing Treatments
(iii) Slasher Dyeing : Please refer to Chapter 3, section 1.7
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fixing of the dye, steaming, successive washing-off and final drying will be followed. Such arrangement can be adjusted in any logical sequence depending on the application techniques of dyes and properties of fabric materials. The combination of the operations is commonly called Continuous dyeing range. A typical example of such dyeing range is shown in Figure 1.4.7c(i). Figure 1.4.7 c (i)
A typical example of continuous dyeing range
Pad dyeing, using continuous dyeing range, is undoubtedly the most productive method for solid colour. However, enormous machine investment, factory space consumption and energy consumption are the main drawbacks. For an economical approach, a Pad-batch process is developed for some specific occasions, such as cold pad-batch dyeing of cotton with reactive dye. The process includes the padding of dyes and auxiliaries simultaneously, and then leaving the padded material in a wet state under specific conditions for a period of time (mostly overnight) for reaction. Afterwards, the material is washed-off and dried to complete the process. (ii) Jig dyeing is commonly used in the production of tightly woven fabric of medium to heavy weight, e.g. corduroy, canvas, etc. In the Jig dyeing machine (also called Jigger, shown in Figure 1.4.7c (ii), the fabric is held on rollers in open width form and is transferred repeatedly from one roller to another through a trough of dye liquor. Since great tension is exerted in the lengthwise direction during fabric movement and takeup by rollers, it is not recommended for those tension
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sensitive materials, such as knitted fabric, and stretchable or light weight woven fabric. Furthermore, jig dyed fabrics often exhibit shade variation from centre to selvedge and from end to end of a fabric piece.
Figure 1.4.7 c (ii)
Jig dyeing machine (Jigger)
Textile Coloration and Finishing Treatments
(iii)Winch dyeing is the traditional dyeing method in the production of knitted fabrics. Pieces of fabric (to make up appropriate weight) sewn in rope form are loaded into the Winch (Figure 1.4.7c(iii)) which essentially consists of a dye vessel fitted with a motor-driven wheel (also named winch). During operation, the winch will rotate and initiate an endless fabric movement with minimised tension through the dye liquid. The operation of winch dyeing is among the simplest, and the dyed materials retain much of the original fullness and softness. However, this method is becoming less popular because of the relatively lower production capacity and manpower consumption as well as possible formation of creases and rope marks. It is also incapable of satisfactorily dyeing synthetic fibres above 100°C under pressurized conditions.
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Textile Coloration and Finishing Treatments Figure 1.4.7 c (iii)
Winch dyeing
(iv)Jet dyeing is somewhat similar to winch dyeing in the sense that fabric in rope form is circulated through a dye liquid bath. In a Jet dyeing machine (Figure 1.4.7c(iv)), fabric movement is generated by a jet flow of dye solution instead of mechanical pull as in winch dyeing. As such, the dyed fabrics are almost free from creases and rope marks. Moreover, the rapid circulation of the dye liquid results in better even than winch dyeing. Pressurized dyeing up to 130°C is also possible for synthetic fibres . Recent development in jet dyeing machines is moving towards process automation and cost reduction. Today all jet dyeing machines are equipped with a microprocessor to control the dyeing parameters, such as machine speed, rate of heating, dyes and auxiliaries dispensing and successive washing-off. The invention of a very short liquid ratio (as low as 1:5) in dyeing tends to conserve dyes, chemicals, water and energy.
Textile Handbook 5-19 Figure 1.4.7 c (iv)
Jet dyeing machine
Garment dyeing is the dyeing of completed garments. It is primarily an economical method used for non-tailored garments such as sweaters, hosiery and pantyhose, etc. Nowadays fashion trends also require some cotton jeans and shirts to be dyed in completed garment form. During processing, an appropriate number of garments are loaded into the specific dyeing machine, either paddle type, or rotating drum type which is more or less similar to that of a domestic washing machine, and are kept agitated in the dye bath for colour build-up. The most important advantage of garment dyeing is that it is done shortly before the actual sale of the merchandise, thus minimising the risk of rapid change in fashion trends. However, the drawbacks of this method include garment distortion, seam puckering, poor penetration of colour and comparatively poor fastness properties. It is also important that the initial size of the garments be adjusted during design and manufacture to account for the shrinkage which may occur during the process.
Textile Coloration and Finishing Treatments
d) Garment Dyeing
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1.4.8 Special Dyeing Effects Piece dyeing, as described above, primarily produces a solid colour throughout the goods being dyed. It is possible, however, to create effects such as multicolours or multishades by any yarn dye or piecedye method. Each of these is described in the following section. a) Cross Dyeing - This is a special type of dyeing in which a yarn, a fabric, or even a garment made with two or more generic fibre types having different dyeing qualities is dyed in a single bath containing two different classes of dyes. Each kind of dye colours only one type of fibre. Two different colours can be dyed in one dye bath or either type of fibre may be dyed, leaving the other white. b) Union Dyeing - Union dyeing is the same as cross dyeing except that instead of multicolour effects, one solid colour is produced. The dyer accomplishes this by using two or more classes of dye, each of the same colour. c) Tone-on-Tone Effects - They are light and dark shades of the same colour on a fabric containing only one generic fibre. This effect can be produced by combining two different types of polyester in the same fabric. Both types are capable of combining with the same dye class, but one fibre has a stronger affinity than the other. The fibre with the stronger affinity combines with a greater quantity of dye, becoming deeper in shade, while the second fibre remains a lighter shade of the same colour.
1.4.9 Computer Colour Matching Traditionally colour matching and formulation is the art of skilful blending of colorants on a trial and error basis. The process may be time consuming depending on the experience of the dyer, and metameric match may sometimes result. In addition, the colour comparison between the sample and the standard are all based on visual assessment which is quite subjective. Following the introduction of the CIE Colorimetry, it becomes possible to predict a coloration recipe using colour measuring instruments as well as computer technology. The commercial application of computer colour prediction of recipe is increasingly popular with the following benefits:
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• quicker in developing the shade • closer matching of the shade • providing a number of alternative combinations of dyes • choosing recipes of minimum cost or minimum metamerism • capable of quick recipe correction and adjustment
The principle of computer colour matching is largely built upon the theory postulated by the Kubelka-Munk Function which involves quite a long and complex formula. The adoption of the computer colour matching in recent years has been demonstrated its success and usefulness. However, there are several considerations which should be carefully taken into account when employing such a system: a) Data bank - To facilitate the effectiveness of the computer prediction, it is necessary to establish a data bank containing the spectral reflectance properties of all colorants at different concentrations when applied on various fabric substrate. The preparation of such a data bank is very time consuming and the data bank is required to be updated from time to time to ensure its proper function. b) Investment - Relatively high investment in colour measuring instruments and computer hardware is required. In addition, regular maintenance and calibration of the equipment are necessary to ensure accuracy and consistency. c) Colorant - The selection of dyestuffs should be careful to ensure good repeatability and reproducibility between lotto-lot dyeing, as well as laboratory-to-bulk production. Moreover, fluorescent brightening agents and fluorescent dyes cannot be applied when using this technology. d) Fibre substrate - The present technology is mainly concerned with pure fibre substrate and is less reliable when applied to fibre blends. Moreover, the prediction will be less accurate if the standard and the sample are of different substrate. Vast research works are still undergoing to develop a powerful system to tackle such problem.
Textile Coloration and Finishing Treatments
• better quality control in strength of incoming dyes
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Textile Coloration and Finishing Treatments Figure 1.4.9 Spectrophotomer (Macbeth)
1.5 Printing Textile printing has often been described as a localized dyeing process to produce single or multi-coloured patterns on fabrics. It utilizes the same dyes or pigments of similar principles of application and colour fastness properties as that of textile dyeing. Among all the colorants available in dyeing, the most used is the pigment. The advantages of using pigment are summarised as follows: • Economical in terms of lower machine investment, good reproductivity, less difficulty in washing-off, quick sampling and high production rate. • Can be applied on all fibres and their blends. • Complete colour range. • Especially suitable for colour resist and discharge printing due to inert chemical nature. However, the disadvantages of pigment print are inferior washing, rubbing and dry cleaning fastness properties as well as inevitable harsh (hardened) hand-feel. Therefore, other dye classes may sometimes be used to overcome the weakness of pigment. Not all dye classes can be
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used in printing because of such reasons as solubility difficulty, low colour yield and poor print paste stability. The appropriate dye classes applied on different fibre types are listed as follows : Suitable for
Reactive
Cotton and other cellulosic fibres, Rayon, Wool and other animal fibres, Silk. Wool and other animal fibres, Silk Polyester, Acetate Acrylic
Acid Disperse Basic (Cationic)
1.5.1 General Printing Procedures In spite of the various methods and styles of printing, the typical textile printing procedures include the following steps : • Preparation of ground colour of the fabric; • Preparation of print paste; • Printing; • Drying; • Fixation; • Washing-off a) Preparation of ground colour - The printing process can be either done on a bleached white ground or over-printed on a coloured ground. In the former, the preparation of fabric involves a series of wet processing such as desizing, scouring and bleaching of the grey fabric, the details of which will be discussed later on. In the latter, the coloured ground may be produced by either a dyeing or printing process. b) Preparation of print paste - Before a printing process can take place, print paste of the required colour must be prepared. The basic components of print paste are dye or pigment, water, thickening agent (thickener) and suitable chemicals. Water is used to dissolve or disperse the dye, pigments and chemicals. It also serves to regulate the overall viscosity of the print paste. The thickening agent is used
Textile Coloration and Finishing Treatments
Class of dye
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to give the print paste the desired viscosity so that the printed patterns are of good sharpness and definition. The most common thickening agents are starch and gum products which, however, tend to form a hard gel after drying and should be removed afterwards to avoid stiff handle. Emulsion thickener, a cream-like product produced from a high speed stirring of mixture of water and petroleum oil, may be used as a substitute, or to mix with starch and gum, to give a softer handle. Other types of thickening agents that may sometimes be used in particular occasions are starch derivatives, cellulose derivatives, alginates and synthetic-polymer thickeners. The functions of adding chemicals are to assist dye solubility or pigment dispersion, dye fixation and print paste stability, etc. c) Printing - The methods of printing can mainly be classified as roller printing, rotary screen printing and flat bed screen printing. Among each method of production, various techniques or types of prints can be applied. The common examples are direct print, resist print, discharge print and burn-out print. These various methods and types of prints will be discussed in 1.5.2. d) Drying - After printing, the fabric may be required to dry to prevent smudging (marking-off) of the wet print. Drying may not be necessary if a dry-heat (hot air baking) fixation is just after printing. e) Fixation - Fixation is normally done by means of either dry-heat (over 100°C) or steaming. It is an important step to enable the absorbed dye or pigment molecules to penetrate and fix to the fibres. f ) Washing-off - A washing-off process, with soaping and sufficient numbers of cold and hot water rinsing, is used to remove the unfixed dye, thickening agent and residue chemicals. Particular care, such as control of washing temperature and addition of special detergent, will be taken during the process to prevent the staining of the unprinted areas by the unfixed dye in the wash liquid.
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1.5.2 Methods of Printing Roller printing, flat screen printing and rotary screen printing, are widely used in commercial production. However, transfer printing and digital printing are entering the market. Details of each method will be discussed in the following paragraphs. a) Roller Printing
The size of the print repeat is governed by the printing machine and the size of the roller. Most machines accommodate rollers with a maximum 16-inch circumference which means the size of the print repeat cannot be larger than 16 inches. The roller width varies from 30 to 80 inches and is normally wider than the fabric to be printed. The numbers of colours within a print repeat are limited by the numbers of rollers that the machine can accommodate. An example of a roller printing machine is shown in Figure 1.5.2a and its operation sequences are as follows. (i) The engraved copper rollers (A) in rotation make contact with the colour furnishers (B) which are immersed in the colour boxes (E) to pick up print paste. The entire surface of the rollers (A) become covered with print paste. (ii)The print paste on the surface of the engraved rollers are scraped off by the sharp steel blades, called the doctor blades (C), such that only the engraved portions are filled with print paste.
Textile Coloration and Finishing Treatments
Roller printing is a continuous automatic production in which the process is carried out with the aid of engraved copper rollers. A separate engraved roller is used for each colour. In the past, the design was engraved by hand, but this was found to be unreliable and time consuming. Nowadays, the photographic engraving method, together with the chemical (mainly strong acids) etching technique, is the widely used approach.
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Textile Coloration and Finishing Treatments Figure 1.5.2a
Roller printing machine
(iii) The fabric to be printed is guided between the cylinder roller and the engraved rollers. The pressure created at the points of contact causes the print paste to be transferred from the engravings to the fabric. (iv) Another steel blade, called the lint doctor (D), will come in contact with each engraved roller to remove any lint picked up from the fabric being printed. This prevents contamination of the colour boxes. (v) The back grey is a fabric that moves along at the back of the fabric to be printed. Its function is to absorb the excess print paste which may strike through and stain the cylinder roller cover. A printing blanket may sometimes be used with the back grey to serve as cushioning to protect the cylinder roller against the constant pressure. The back grey and the blanket will be washed successively for repeated uses. (vi)The printed fabric will be guided to leave the machine for drying, fixation and washing-off by appropriate means.
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b) Flat Screen Printing
In this method the design is transferred to the screen, either by manual manipulation or by photochemical means. The unprinted areas are blocked, whereas the areas to be printed are left open. The screen is then mounted onto a wooden or metal frame. One screen is needed for each colour in the design. During printing, the fabric to be printed is spread smoothly onto a table whose surface has been coated with a light semi-permanent adhesive, such that fabric is guaranteed not to move during printing. The mounted screen is positioned accurately and the print paste is then poured onto the screen. The print paste is forced through the open areas of the screen with a flexible, synthetic rubber blade (known as the squeegee). The squeegee is drawn steadily across the screen at a constant angle and pressure to ensure a sharp and uniform printing quality. The steps are repeated when multi-colour is required in the design. The printed fabric is then taken away from the table for successively drying, fixation and washing-off. The quality of flat screen printing is normally governed by several variables, such as mesh size of the screen, the fraction of the open area (i.e. the style of the design), the squeegee angle and pressure, and the number and speed of squeegee strokes. To control and standardise such variables, the commercial practice is shifting from hand screen printing towards semi-automated or even fully automatic production. Screen printing was originally done by hand. All operations, such as precise positioning of the screen frame, operating the squeegee and handling of the fabric, etc., are manipulated by workers. Although the method is of less commercial
Textile Coloration and Finishing Treatments
This printing is so called because the process makes use of meshed screen for transferring the print paste to the fabric. In the past, the screen was made of silk and thus the process was also called silk-screen printing. Nowadays, due to high cost of silk fabric as well as the inferior durability, the strong synthetic fibres such as nylon and polyester are commonly used as the screen material.
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interest in the sense of long production runs, it is used for small sized production of garment parts or very large design which cannot be achieved by other means. In semi-automated production, some manual works, such as raising and lowering of the screen, filling of print paste and activating of the squeegee, are replaced by automatic means. It requires less labour than hand screen printing, but the productivity is still not high when compared with fully automatic production. In fully automatic production, the fabric to be printed is gummed onto an endless conveyor belt type blanket which moves and stops at intermittent fashion, one screen repeat distance at a time. All the screens equipped with automatically operated squeegees are positioned precisely over the blanket. Printing is done simultaneously among all screens while the fabric is stationary. After one operation step, the screens are lifted up and the blanket moves to carry the fabric to a next stop for printing. A schematic diagram of fully automatic flat screen printing machine is shown in Figure 1.5.2b. Figure 1.5.2 b
Fully automatic flat screen printing machine
c) Rotary Screen Printing This printing method, which utilizes seamless cylindrical screens made of nickel foil, combines the advantages of the high production roller printing and flexible flat screen printing. It has proved very successful, especially in terms of large production at relative lower cost than roller printing. The basic operation of rotary screen printing is very similar to that of the fully automatic flat screen machine. The fabric is gummed onto an endless conveyor belt blanket which moves continuously in contrast to the intermittent
Textile Handbook 5-29
action of the automatic flat screen machine. The rotary screens, which are equipped with special types of print paste feeding device and squeegee inside the screens (as shown in Fig. 1.5.2c), are continuously rotating at a relatively high speed to force the print paste through the screens to the fabric. The printed fabric successively undergoes drying, fixation and washing-off.
d) Transfer Printing By a simple heat process, a design printed on a piece of paper is transferred to the fabric. The dyes used are capable of vaporizing under the heat conditions of the process and therefore have a high affinity for the fibres of the fabric. Transfer printing has long been used on polyester and polyamide. Starting from the late 80’s, attempts have been made in developing a method for indirect reactive printing
Textile Coloration and Finishing Treatments
Figure 1.5.2 c Rotary screen printing machine
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Textile Coloration and Finishing Treatments
on natural fibres. The first cotton process from Dansk Transfertryk A/S (Denmark) came on to the market in 1992. The “Cotton Art Process” allows transfer printing on cellulosic, silk and wool fibres. Figure 1.5.2 d Transfer Printing Machine (Kuester)
e) Digital Printing This is a process of creating prints generated and designed on a computer and then printing the design on textile substrates using ink jet technology. The use of digital technology means that a digital file can be communicated worldwide, and fabrics of identical colour patterns, and quality produced anywhere in the world. It reduces traditional order-to-delivery lead times. Ink jet printing also makes it possible for firms to print images which cannot normally be produced by rotary screen or flat bed screen printing. For instance, very fine lines and photographic imagery can be printed by ink jet, as well as an infinite number of colours and sizes. There are two main types of ink jet technology. The first is continuous ink jet, in which a stream of ink droplets generated through nozzle drops are circulated and selectively printed . Excess ink is then re-circulated into the ink supply. The second is drop on demand, in which drops are produced and printed only when required. When the ink in the print cartridge’s firing chamber is heated, a vapour bubble forms, expands and forces the ink out through a nozzle. When the heat is turned off, the bubble collapses and the print head is ready for another cycle.
Textile Handbook 5-31
Currently, digital printing technology applies to printing sample garments, swatches or novelty applications such as T-shirts in the apparel industry Figure 1.5.2 e
Digital Printing (Stork)
Textile Coloration and Finishing Treatments
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Textile Coloration and Finishing Treatments Table 1.5.2 f Printing Methods
Comparison of Printing Methods Advantages
Disadvantages
Roller
- best for long production runs - best for fine lines and small patterns, e.g. paisley - half-tone and fall-on effects possible
- limited size of repeat, normally 16 inches maximum - not economical for short yardage due to long machine set up time and high engraving costs - limited number of colours according to machine type - dull colour due to very high pressure exerted during printing - wet-on-dry printing impossible (not suitable to knitted fabric) - requires skilled workers
Hand screen
- best method for low yardage, small items (e.g. towel) and garment parts (front panel) - large repeat size possible - wet-on-dry effect possible - no limitation on number of colours - good colour brightness with good definition - rapid preparation of screen, and thus rapid style change possible - can be applied on all fabric types
- half-tone effect impossible - not recommended for lengthwise stripes, fine lines and small patterns - very low productivity
F u l l y automatic flat screen
- better productivity than hand screen method - large repeat size possible - good colour brightness with good definition - rapid preparation of screen and thus rapid style change possible - can be applied on all fabric types
- larger machine investment than hand screen - half-tone effect impossible not recommended for lengthwise stripes, fine lines and small patterns - wet-on-dry printing impossible - higher cost in screen preparation than flat screen method and thus
Rotary screen
- the highest production capacity among all printing methods - larger repeat size possible compared with roller printing, but smaller than flat screen printing methods - good colour brightness with good definition - rapid changeover of designs possible - can be applied on all fabric types
- higher cost in screen preparation than flat screen method and thus not economical for short yardage - not recommended for fine lines and small patterns - half-tone effect not as good as roller printing - wet-on-dry printing impossible
Transfer Printing
- no further aftertreatment required - simple process - print defects are low because print paper can be inspected prior to printing - no environmetally pollution - execellent sharpness and clarity of design
- special transfer paper and dyestuff to be used - special dye fixation treatment required for natural fibres - safety margin for ordering transfer paper to avoid short shippment - minimum order for transfer paper, otherwise additional charge required
Digital Printing
- print pattern can be produced directly from design - design requirement can be transfer electronically - order-to-delivery lead time much shortened - high resolution approcahing photographic quality
- high capital investment in CAD system and ink jet printer - production rate is lower than other methods - use special dyes for the ink
1.5.3 1.5.4 1.5.5
1.6
Printing Effects ............................................................ 5-33 Types of Prints ............................................................. 5-33 CAD/CAM System for Textile Printing ...................... 5-35
Finishing ............................................................................ 5-36 1.6.1 1.6.2 1.6.3
Preparation .................................................................. 5-36 Finishing ...................................................................... 5-37 Classification of Finishing .......................................... 5-37
Section 2 - Common Finishing Treatments for Cotton Fabrics ......................................... 5-44 2.1
Wrinkle-free Treatment of Cotton Fabrics and Garments ........................................................................... 5-44 2.1.1 2.1.2
2.2
General Considerations for Wrinkle-free Treatment ... 5-44 Treatment Processes .................................................... 5-45
Flame Retardant Treatment on Cotton Fabric by Precondensate/NH3 Process ............................................. 5-50 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7
Fabric Preparation ....................................................... 5-50 Precondensate Formulation ......................................... 5-50 Application .................................................................. 5-51 Ammoniation ............................................................... 5-51 Oxidation and Process Washing .................................. 5-53 Fabric After-Treatments .............................................. 5-54 Treatment of cotton blended fabrics ............................ 5-54
2.3 Hints for Wet Processing of Cotton/Spandex Fabric .......... 5-55 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7 2.3.8 2.3.9 2.3.10
Spandex in Knitted Fabric ........................................... 5-55 Relaxation ................................................................... 5-55 Heat-Setting ................................................................. 5-56 Dyeing ......................................................................... 5-57 Drying ......................................................................... 5-58 Cotton/Spandex Woven Fabric .................................... 5-58 Relaxation ................................................................... 5-58 Heat-Setting ................................................................. 5-58 Dyeing ......................................................................... 5-59 Finishing ...................................................................... 5-59
Back to Table of Content
Textile Handbook 5-33
1.5.3 Printing Effects a) Wet-on-wet and Wet-on-dry Effects
In other methods of printing, since the time lapse between each colour is relatively short, the first colour is still wet when a second colour is applied which results in the colours mixing to produce a third colour. This is called the weton-wet effect. In this case, the registration of each colour must be very precise so as to minimise out-of- register defect. However, sometimes designs are purposely made wet-on- wet to produce such overlapping of colours and this is called a fall-on effect. b) Half-tone Effect The coloured area of a printing design is presented by a gradation of tones to give a finer and a more three dimensional appearance.
1.5.4 Types of Prints In addition to the various methods of printing, numerous types of prints can be attained by employing different production skills and techniques. The three common types of prints are the direct, discharge and resist. Other miscellaneous types of prints, for example burn-out print, may also be used for some special effect. The various types of prints are to be discussed in turn in the following texts. a) Direct print is simply the printing of patterns with dyes or pigments directly onto the fabric, either on white background or on fabric previously coloured by dyeing/printing. The latter case is called an overprint, and it is the most popular printing style as the operation is straightforward.
Textile Coloration and Finishing Treatments
Wet-on-dry effect is obtained when a second colour is printed over a first printed colour which has been dried. The second colour will cover the first one and only the distinct second colour appears. It has an advantage that if the second colour is slightly out-of-register, it may not become a defect as the second will cover the first and make the first invisible. Only the hand screen printing method is able to produce such an effect because of the long time lapse between the application of each colour.
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Textile Coloration and Finishing Treatments
b) Discharge print is done on fabric which has already been dyed or directly printed to produce a ground colour. During the process, a specially prepared print paste containing an appropriately selected discharging agent is applied to destroy the ground colour at the pattern areas. It is called a “white discharge” if the ground colour is completely destroyed to leave a white colour. In some cases, a “colour discharge” is produced either by incomplete destruction of the ground colour, or by incorporating a chemically inert colorant into the discharge print paste. Not all coloured fabric can be discharge printed because of the difficulty in destroying the ground colour. The common ground colours, which are suitable for discharge print, include direct dyes, reactive dyes, acid dyes, disperse dyes and basic dyes. Because it is chemically inert, pigment cannot be used as the ground colour for discharge print, but it is the most suitable colorant to be added to the print paste to produce colour discharge. This printing style is commonly used when very fine and light coloured lines or patterns are to be printed on a dark coloured background. c) Resist print produces a similar effect to that of discharge print. The design is first printed onto the fabric with a specially prepared print paste containing chemicals or waxlike substances which will resist subsequent coloration. The printed fabric is then overdyed or overprinted to finish the process. Like discharge print, both white or colourresistant prints can be produced. Resist print is not a popular printing style to be used in the industry when compared with discharge print. It is used when the background colour is difficult to be discharged. A common resist print application is the well-known Batik cloth which is widely used as handicraft in some countries of South East Asia and Africa. d) Other miscellaneous styles of print may sometimes be employed to produce special effects. (i) Flock print is a type of printing in which tiny particles of fibres are made to adhere to a pattern design of a fabric. The process consists of first printing a paste of adhesive rather than dye or pigment, and then exposing the fibre flock to the printed area to finish the process. To produce colour flock print, the fibre flock will be dyed prior to printing.
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1.5.5 CAD/CAM System for Textile Printing a) CAD System (i) Digitization. With the help of a scanner, digital camera or digitising pad, print design on paper, film or cloth is first digitised to a digital file and imported into computer. This replaces the work of a skilled artisan in tracing the outline or re-drawing the sample supplied by the customer. (ii) Image Processing. The functions of the computer software can in general be divided into four phases: • Colour reduction: the number of colours is automatically reduced to help the operator determine the economic number of colours. • Setting the repeat: enlargement, reduction, rotation, mirroring, displacement and copying are extended functions for design repetition. • Touch up: edition of outline/smoothing of outline and filtering out impurities. • Colour separation: making of the colour separation and the rastering of half tones. These functions are equivalent to the stenciling and colour matching processes in the traditional processing. However, the efficiency depends very much on: • The capability of the software; • The speed and memory of the hardware; • The complexity of the design; and • The skill of the operator
Textile Coloration and Finishing Treatments
(ii) Another miscellaneous print style is the born-out print. As the name implies, the principle simply uses a print paste containing a chemical which is capable of dissolving or destroying the fabric in the printed area to produce an eyelet effect. This print style is often applied to blended fabric in which one fibre type is removed to leave the other undamaged. Again, colour effects can be achieved by adding colorants to the print paste.
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Textile Coloration and Finishing Treatments
b) CAM System • Film Plotters: the plotting of the film is carried out at high speed which can be two to three times faster than when using the step and repeat machine. • Laser Engravers: a laser beam controlled by computer memory engraves the design directly on the lacquer coating which is insensitive to light. • Ink Jet Printers: the sample or mini strike-off can be produced without the process of making from and engraving screen. • Automatic Colour Kitchen: its functions include colour prediction, estimation of print paste and automatic dispensing. c) Integration The use of CAD system provides a means for the linking up of the design studio with production or other CAD systems through data communication. The CAD system can be interfaced with the CAM systems for textile printing, thus affording a greater flexibility and shortening of throughput time for pre-print processing. A complete system also provides a fast prediction of the final printing result as early as possible.
1.6 Finishing Broadly speaking, textile finishing refers to those textile processes and treatments starting from the grey state to finished state, excluding the coloration (i.e. dyeing and printing) stage. Finishing includes the following two different categories of processing: • Preparation (before coloration); and • Finishing (after coloration).
1.6.1 Preparation Preparation consists of a series of processes and treatments which are applied to textiles in the grey state. Grey textiles cannot be dyed or printed for numerous unfavorable reasons, such as natural impurities,
Textile Handbook 5-37
additives used in knitting and weaving processes, harsh handle, inherent yellowness and poor water absorbency. The preparation processes are required to improve the grey textiles to make them water absorbent and dyeable in the successive processing (see 1.2 for the Pre- treatment).
1.6.2 Finishing
1.6.3 Classification of Finishing There are several kinds of classification of textile finishes, such as temporary, permanent, mechanical, chemical, textural and functional. It is most commonly and convenient to classify finishes according to textural effects or functional effects in the following manner: • Finishes that impart textural effect Shrinkage control Calendering Raising Softening • Finishes that impart functional effect Resin (crease resistant) Water repellent and waterproof Flame retardant Moth-proof and mildew-proof a) Shrinkage Control (i) Shrinkage control means the dimensional stabilising of textile fabrics against their progressive shrinkage that may occur during subsequent washes. Although fabrics are under high tensions in the numerous processing steps, they will tend to revert to their original dimensions and shapes once they are relaxed. A good shrinkage control finishing will help to pre-shrink the fabric to a desirable extent such that the residual shrinkage in the fabric is within the customer’s expectation. The shrinkage control finishes applied to
Textile Coloration and Finishing Treatments
Finishing is the final processing carried out after coloration and before the materials are made up into garments. Its purposes are to furnish the textile materials suitable for their end uses (e.g. water repellent) as well as to meet certain customers’ expectation (e.g. shrinkage control).
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knitted fabric can be achieved through a resin treatment followed by a stenter curing. For woven fabric, the shrinkage control is done through a compressive shrinkage (also known as pre-shrunk finish or sanforized finish) before the resin and stenter treatments are applied. (ii) In compressive shrinkage, the fabric is lead through a rubber belt under controlled tension in contact with a pressure roller, such that the length of the fabric will be shortened due to compression of the spacing of weft yarns to achieve the pre-shrunk effect. Figure 1.6.3a shows the rubber blandet action. From A to B, the outer surface of the fabric is extended by the rubber blanket. Afterwards the pressure of the heated pressure roller forced the fabric to compress to follow the shape of the rubber blanket at C to D, the fabric is thus compressed or shortened. The amount of stabilisation is determined mainly by the thickness of the rubber blanket. The process was originally invented and patented as “Sanforized” finish which declared a fabric shrinkage of no more than one percent on repeated laundering. (iii) A careful stenter setting can also control shrinkage especially in the case of knitted fabric. The lengthwise shrinkage can be reduced by means of over-feeding, i. e. a faster speed of feeding of fabric than the chain of the machine, while the widthwise shrinkage is controlled through the adjusting of the distance of the pin-chains of the stenter machine.
Textile Handbook 5-39 Figure 1.6.3a
Principle of compressive shrinkage
(i) Calendering is essentially an ironing process which gives sheen to a fabric. A calendar is a mechanical device consisting of two or more large rotating cylindrical rollers stacked on top of each other. The cylindrical rollers are usually heated and in contact with each other under pressure. Fabric being calendered passes around and between these cylinders. The specific type of calendering finished fabric varies with the nature of the cylinder surface, the speed of the cylinders and the nature of the fabric being finished. Calendering finish is only a temporary finish which will be substantially diminished in home laundering or drycleaning. Incorporation of resin treatment will enhance the finish to become durable. Some examples of calendering finishes are described as follows : Glazing calendering makes use of friction calender which is made of highly polished steel. High pressure of the
Textile Coloration and Finishing Treatments
b) Calendering
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Textile Coloration and Finishing Treatments
cylinders tends to flatten the yarns from their normal round configuration which results in a highly glazed, lustrous, polished effect on one side of the fabric surface. Chintz is the typical example of this kind of finish. Embossing produces a three-dimensional design on the fabric. This is done on a special embossing calender in which the roller cylinder is engraved with the embossing design. The pattern is pushed or shaped into the fabric when it passes between the rollers. Schreiner calendering produces a low and soft lustre on the fabric surface as distinct from the high glaze of the glazing calendering. To produce such effect, one of the steel cylinders of the calender is embossed with fine diagonal lines, about 250 lines per inch. c) Raising (i) Raising, also called napping, is a mechanical finish to provide a softer hand and better insulation than the same unraised material. The fabric to be raised is passed against rotating, bristled wire-covered brushes (as shown in Figure 1.6.3 c) which results in fibres being raised from the fabric surface. The degree of hairiness on the fabric surface can be adjusted by the number of processes as well as machine setting. Raised fabric suffers from problems of pilling and burning rapidly especially on cotton and its blends. Figure 1.6.3 c
Diagrams of raising machine
Textile Handbook 5-41
Raised fabric may sometimes undergo a shearing process to give a more attractive and smoother surface. The process is done by a shearing machine with revolving blades which cut off any raised fibres that are longer than the setting. In some cases, shearing can also be used to produce some patterns, e.g. high and low surface levels, by special arrangements of the blades.
d) Softening (i) Softening: finish enhances the hand feel of fabric and some physical properties of fabric, such as tearing strength and abrasion resistance. Fabric softeners are commonly emulsified thermoplastic resin and silicon based polymer. Softening finish is a temporary finish whose effect will be diminished after only one or two home laundering. Therefore, it is always the last processing step in the whole textile finishing sequence. e) Resin Finish (i) Resin treatment is a permanent, chemical finish primarily applied on cotton and its blended fabric. It is essentially used to improve dimensional stability as well as shape retention in the case of calendering. In addition, by varying the application techniques, the effects of crease resistance (i.e. wash and wear) and permanent press can be achieved. (ii) Resins are monomers. They tend to cross-link to the cellulosic when subject to a high temperature treatment (usually by means of stenter), called curing, at 160°C to 210°C. The most commonly available resins are based on urea formaldehyde type and melamine formaldehyde type. The drawbacks of resin finish include loss of fabric strength, stiff handle, soiling problem and release of free formaldehyde which is hazardous to human health.
Textile Coloration and Finishing Treatments
(ii) Sueding also called emerizing or sanding, can be used to produce a soft and chamois-like surface. It is different from that of raising in the sense that its degree of hairiness is shorter and lesser. The process involves the abrading of a fabric against a series of emery-covered rollers. It is commonly applied on high quality worsted fabrics and is now widely used on in the production of silk items.
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Textile Coloration and Finishing Treatments
f ) Water Repellent and Waterproof (i) Water repellent and waterproof are chemical finishes which resist the penetration of water into or through the fabric. They are differentiated because the former permits the passage of moisture or air whereas the latter does not. The ability of allowing the passage of moisture and air enables the fabric to breath and hence makes it comfortable to wear. (ii) Water repellent finish is usually a thin film of coating, either visible or invisible, on the surface of fabric. The chemicals used are normally emulsified polymers of polyvinyl chloride (PVC) and polyurethane (PU). Nowadays, some water repellent finishes based on fluorocarbon compounds are manufactured to accommodate not only water repellent properties but also other related properties like oil repellent and soil release. (iii) Waterproof finish is produced by laminating a film or impregnating the fabric with natural or synthetic rubber or synthetic polymer. The interstices between yarns will be completely blocked to achieve the waterproof effect. The finish is generally applied on those items designated for raincoats as well as camping tents. (iv) Although both type of finishes are chemical types, their durability to subsequent home laundering or drycleaning may range from good to poor depending on which type of chemical agents are used. To guarantee the performance, it is a common practice for the finisher to test the finished fabrics for water repellence or resistance before they are proceed to the next processing stage.
Textile Handbook 5-43
g) Flame Retardant (i) In the past flame retardant finish has been regarded misleadingly as flameproof finish, which means nonflammable. Except for those mineral fibres like asbestos, no textile fibre can be made flameproof.
h) Moth-proof and Mildew-proof Moth-proof and mildew-proof finishes are applied to fabrics, especially wool and silk materials, to make them less susceptible to attacks by moth and mildew (fungus). A moth-proof finish can be attained by incorporation of nontoxic pesticide, such as dieldrin- based compounds, into the textile material which makes the fibre poisonous to moths, while a mildew-proof finish can be achieved by treating the textile material with non-toxic germicide, such as metallic salts, halogenated phenols and organic mercury compounds.
Textile Coloration and Finishing Treatments
Flame retardant is a chemical finish that is applied to prevent propagation, or slow down the rate of burning of a fabric. The chemicals used are mainly based on insoluble inorganic salts, phosphorus-containing compounds, organic halogenated compounds and synthetic resins, The flame retardant treated fabric is usually suffering from the shortcomings of loss of fabric drapeability, loss in strength and lack of durability to repeated home laundering. To date, there is no completely satisfactory flame retardant product or technique. The industry is still continuing a vast research effort towards this goal.
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SECTION 2 COMMON FINISHING TREATMENTS FOR COTTON FABRICS 2.1 Wrinkle-free Treatment of Cotton Fabrics and Garments Garments made from cotton have many advantages, such as the ability to absorb moisture, durability, easy to clean and comfort. However, 100% cotton garments do have problems include wrinkle and considerable shrinkage after washing. During the 1980’s, the back-to-nature lifestyle became firmly entrenched in the U.S.A. Cotton garments were in great demand and this trend continued into the 1990’s. The consumer’s lifestyle demands that the product be carefree. With the improvement of the strength of cotton and the advancement of resin finishing technology, the trend for wrinklefree cotton garments became very popular.
2.1.1 General Considerations for Wrinkle-free Treatment It is particularly important to select an appropriate resin and finish formulation. If excessive crosslinking is achieved, the strength and abrasion resistance may be reduced. If too little crosslinking is obtained, there may be inadequate shrinkage control, smoothness and crease retention, and undesirable surface appearance. Treatment of sulphur dyed fabrics may present a special problem. The resin finish may deteriorate due to the generation of acid from the sulphur dye, in particular sulphur blacks. To reduce the problem, the sulphur dyes should be thoroughly oxidised, and the resin-impregnated fabric must be cooled on the tenter frame before rolling. Sewing thread with minimum shrinkage is important. The stitch length and tension should be appropriate to lessen the distortion. Doubleneedle flat-felled seams, for example, will frequently cause more puckering than single-needle seams. When processing on garments, garment accessories and trimmings should be selected that will not be adversely affected by the chemicals or heat. A sample garment should be treated with the finish solution before committing to a large run, and the influence of the finish on durable press, strength, abrasion resistance, shade, and hand must be ascertained.
Textile Handbook 5-45
2.1.2 Treatment Processes There are various processes to make wrinkle-free cotton garments. Diagram 2.1.2
Treatment Processes
Textile Coloration and Finishing Treatments
a) Pre-cure Process This is the simplest and easiest method to achieve wrinkle resistance. The crosslinking resin is applied and cured in the textile finishing mill. Table 2.1.2 (a)
Suggested Formula for Precure
Fabric: 100% Cotton Oxford Shirting Non-ionic Wetter Buffered DMDHEU (45%) Magnesium Chloride Hexahydrate (64%) Polyurethane (40%) High Density Polyethylene (25%)
% on weight of Bath 0.1 10.0 2.5 4.0 2.0
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Textile Coloration and Finishing Treatments
• % wet Pickup: 82 • Dried for 5 minutes at 93°C • Cured for 3 minutes at 150°C. (In production, curing is normally done on a tenter frame; however, a loop cure oven may also be used when curing at low temperatures for a longer period of time, e.g. whites.) • Advantages: the fabric is smooth, stable and cheaper to produce. • Disadvantages:the puckering at the seams and creases cannot be set. b) Post-cure Process The finish, including a crosslinking resin and catalyst, is impregnated by the finishing plant and dried with little or no curing. After the garment is made, and pleats or creases are imparted by pressing, the garment is passed through a curing oven to let the resin achieve the crosslinking effect. During processing, the pH of the fabric before finishing should be 5.0-7.0 with the total alkalinity not greater than 0.05% NaOH. In order to minimise any curing of the impregnated fabric, it should come off the tenter frame with about 10% moisture measured by a moisture meter. Table 2.1.2 (b) Suggested Formulae For Post-Cure Fabric; 100% Cotton Twill, 8.0 oz/yd2
Non-ionic wetter Buffered DMDHEU (45%) MgCl2 Hexahydrate (64%) High Density Polyethylene (25%) Amino-functional Silicone (20%) Polyurethane (Water Soluble) (40%) Cationic High Density Polyethylene (25%)
% on weight of Bath 1 2 3 0.1 0.1 0.1 12.5 12.5 12.5 3.1 3.1 3.1 3.0 — — — — 2.0 — 5.0 5.0 — 3.0 3.0
Textile Handbook 5-47
• % wet Pickup: 60 • Dried for 5 minutes at 95°C • Cured for 3 minutes at 155°C • Advantages: the seams are better set with improved seam smoothness as compared with the pre-cure process.
c) Garment Dip Process In this process, all of the finishing is conducted in garment form. After the garments are constructed from ordinary fabric, they are impregnated with a finish quite similar to the conventional post-cure process, extracted, dried, pressed, and cured. In the first step, dry garments are impregnated or dipped into the finishing solution, and they should be thoroughly saturated with the finish. After impregnation or dipping, the garments are extracted to about 50 to 70% wet pickup. The wet pickup level will depend on the fabric construction. Tumble drying the impregnated garments is a critical step. Curing may take place at the creased area if it becomes too dry and hot. Moisture in the area to be creased should not fall below 8 to 10%. This can be easily determined by a moisture meter. After tumble drying, the conditions for pressing should permit a sharp crease to be formed. The final step is curing in an oven. The oven should allow continuous operation for about 15 minutes and at a temperature of 145°C-150°C. Lower temperatures may be required for whites to prevent yellowing.
Textile Coloration and Finishing Treatments
• Disadvantages: the shelf life of fabric with the resin is unsure as it cures slowly even at room temperature. The resin may start setting during garment making, resulting in permanent wrinkles. These make higher demand on the garment maker in terms of sewing, good pressing, and control of and investment in the oven.
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Textile Coloration and Finishing Treatments
Advantages: - creases can be set. - There is improved seam performance. - The quality of the finishing is as good as the pressing. - Very soft hand feel and washing effects can be produced on the garments and better shelf appeal. - It provides better inventory control. Disadvantages: - Demands higher technical standards in the garment factory and investments in equipment and oven.
Table 2.1.2 (c) (1)
Garment Dip Process
Influence of Resin Selection Fabric 100% Cotton Slacks, 8 oz//yd 2
Wetting Agent DMDHEU (Buffered) (45%) DMDHEU (Not Buffered) (45%) DMUG (45%) Appropriate Catalyst for DMUG MgCl2•6H2O (64%) Polyethylene (25%) Amino-functional Silicone (20%) Perfume
% of Product as Received Based on Bath Weight 1 2 3 4 5 0.1 0.1 0.1 0.1 Untreated 12.5 5.0 10.0 20.0 15.0 10.0 5.0 5.0 5.0 3.1 3.0 3.0 3.0 3.0 0.5 0.5 0.5 0.5 0.1 0.1 0.1 0.1
% Wet Pickup: 45. (In commercial practice, 50-70% wet pickup is typical, and formulate should be adjusted accordingly.) Cured 15 minutes at 155°C.
Table 2.1.2 (c) (2)
Test Results
Durable Press (AATCC124) % Shrinkage, Warp (AATCC135) % Shrinkage, Fill (AATCC135) Crease Retention (AATCC88C) Tensile, fill (ASTM D5034) Tear, Fill(ASTM D1424) Stoll Flex Abrasion, Warp (ASTM D3885)
1 4.2 0.2 0.2 4.3 4 202
2 4.0 0.2 0.4 2.0 72 3.2
3 3.2 0.0 0.2 2.3 70 3.0
4 3.8 0.2 0.6 2.7 62 2.
5 2.3 1.8 1.6 1.0 101 2.8
219
1348
175
860
1101
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d) Dip Spray Process
Advantages : - The spray method creates no waste, - no effluent, no contamination of the finish bath, - no depletion of individual components; - allows the use of premixed finish solutions, - and has the ability to perform wet-on-wet processing. e) Vapour Phase This is a post-finishing in which the garments are made with fabric without or with some resin and softeners. After pressing the garments, they are put into a special chamber in which steam, sulphur dioxide and formaldehyde gas are injected. The crosslinking is formed in situ. Afterwash is required to remove any vapour acquired during treatment. Advantages: Creases can be set as in post-cure finishing. The quality of the finishing is as good as the pressing. Disadvantages :This process is not environmentally friendly and requires expensive equipment. The process demands good control and safety measures and high running costs. Shade change may occur with some dyes.
Textile Coloration and Finishing Treatments
This process is similar to the garment dipping process, except that finish solution is applied to the garments by a spraying system. The spray system is a metered addition process which applies only the necessary amount of finish solution needed to achieve the final predetermined wet pickup. After the spray application is completed, the garments continue to rotate to allow for the migration of the finish from high to low concentrated areas. Then the garments are processed by the normal sequence of tumble drying, pressing and oven curing.
5-50
Textile Coloration and Finishing Treatments
2.2 Flame Retardant Treatment on Cotton Fabric by Precondensate//NH3 Process (Source: Cotton Incorporated) The precondensate/NH3 process is designed to impart durable flame retardance to 100% cotton fabrics when applied under proper application procedures. This process provides fabrics with good fabric handle and strength retention.
2.2.1 Fabric Preparation Fabrics should be scoured, bleached and dyed before application of the flame retardant. The fabric should be neutral or slightly acidic, free of alkali and other extraneous matter, and absorbent.
2.2.2 Precondensate Formulation Precondensate is the designation for a tetrakis-hydroxymethyl phosphonium salt pre-reacted with urea or another nitrogenous material. The products are proprietary complex oligomers of chemical suppliers. A generalized precondensate formulation, applicable to a range of fabric weights and constructions, is the following:
Table 2.2.2
% By Weight of Precondensate % By Weight
Precondensate Sodium acetate (anhydrous) Nonionic sufactant Water
20.0 to 50.0 0.8 to 2.0 0.2 to 0.2 79 to 47.8
The amount of anhydrous sodium acetate is 4% of the amount of precondensate used. Some precondensates are available with the sodium acetate already combined. The wetting agent diluted with water is added last to the mix. The pH of the pad bath should be approximately 5.0. Pad baths of precondensates usually are stable for at least eight hours.
Textile Handbook 5-51
2.2.3 Application The amount of flame retardant required depends primarily on the fabric type, application conditions, and test criteria to be met. Application of different phosphorus levels should be made by changing the pad bath formulation rather than adjusting pad roll pressure.
A critical factor in the successful application of precondensate/NH3 flame retardant is control of fabric moisture before ammoniation. Generally, moisture levels between 10% and 20% give successful treatment. The following methods of moisture determination has been used: %M=
Wm-Wd x 100 Wm
M = Moisture in fabric Wm = Weight of moist fabric Wd = Weight of dried fabric (including solids add-on)
2.2.4 Ammoniation a) Chemical curing is accomplished by exposing the moist, precondensate-padded fabric to anhydrous, gaseous ammonia. For commercial application, a continuous ammonia delivery and exposure unit is used. Generally, the best results are obtained when the delivery system forces ammonia through the fabric. The objective is to ensure adequate and thorough ammoniation to form an insoluble polymer with the cotton fibres. b) The amount of ammonia required for a given treatment is calculated readily considering the following factors: • Weight of fabric (lbs./lin.yd.) • Desired running rate (yd./min.)
Textile Coloration and Finishing Treatments
For optimum performance, it is essential that the bath be distributed homogeneously within the fibres. Experience shows that padding with multiple dips and nips, followed by 30 to 60 seconds dwell, is good for this purpose.
5-52
Textile Coloration and Finishing Treatments
• Percent of phosphorus applied to fabric • Desired excess Thus, for an 8 oz./lin.yd. fabric, at 50 yds./min., containing 5% P (on the weight of the fabric): 8 x (1/16) x (50) x (0.05) x (1/31) x 17 = 0.69 lbs. NH3/min. where 1/16 = conversion from oz. to lbs. 1/31 = conversion to mole of phosphorus 17 = molecular weight of NH3 c) The rate of ammonia delivery should be controlled by a flow meter. The amount of ammonia delivered at a given flow rate can be determined from the ammonia supplier’s flow conversion tables or determined by measuring the rate of neutralization of hydrochloric acid solution, as below: Determination of Ammonia Flow by HCl Titration Equipment Ammonia delivery system (tank, tubing, flow-meter) Balance Magnetic stirrer 250ml. Erlenmeyer flask Rubber Tubing Pipette Graduated cylinder (100 ml) Stop watch Reagents Hydrochloric acid Methyl orange indicator Anhydrous ammonia
Textile Handbook 5-53
d) Procedures (i) Make up a stock solution of 1 normal HCl (100 gram 37% HCl in one litre) (ii) Add an aliquot of 100 ml of stock solution to 100ml of water in a 250 ml Erlenmeyer flask. (iii)Add a few drops of methyl orange to the solution.
(v) Repeat steps 2-4 at different flow meter settings. Because 0.1 mol of HCl is used in all cases, the ammonia time/ flow relationship can be converted directly to the time required to deliver 0.1mol of NH3. Example :
It takes 5 seconds to neutralize 0.1 mol of HCl. Since 0.1 mol of NH3 is required to neutralize 0.1 mol of HCl, 5 seconds are required to deliver 0.1 mol of NH3, or 50 seconds to deliver one mol. The reciprocal of 50 is the mole per second of ammonia delivered; therefore, 0.02 mols of NH3 are delivered in one second. 0.1 mol NH3 5 seconds
= 0.02 mol NH3
second
2.2.5 Oxidation and Process Washing The final steps in achieving a high quality precondensate/NH3 finish are oxidation of the phosphorus polymer, process washing of the fabric to remove unreacted chemicals, and adjustment of the fabric pH. Oxidation can be accomplished by either a batch or a continuous process, employing commercial hydrogen peroxide.
Textile Coloration and Finishing Treatments
(iv)Pass anhydrous ammonia into the rapidly stirred solution, using the delivery system at a specific setting on the flow meter. Record the time required for neutralization (colour change)
5-54
Textile Coloration and Finishing Treatments
For the batch process, 10% H2O2 (50% concentration based on the weight of the treated fabric) is added to sufficient water at 50oC to 60oC to provide a 20:1 liquor-to-fabric ratio. Oxidation for 10 minutes in a rope washer is normally sufficient to complete conversion of the phosphorus to the pentavalent, or durable state and to remove traces of odour. Rinsing with warm water or a dilute, (2% to 5%) Na2CO3 solution finishes the process wash. Fabric pH should be 5 to 8 following the wash. For open-width, continuous oxidation, 10% H2O2 (50% concentration) is padded at room temperature onto the fabric from a bath containing the appropriate amounts of H2O2. Sufficient time to allow 30 to 60 seconds exposure of fabric to this solution is required before rinsing and pH adjustment. If the wet pick-up of the treated fabric is significantly below 100%, the peroxide bath should be adjusted to an appropriate higher concentration. Continuous washing requirements after oxidation are dependent upon fabric weight and construction and on the amount of unfixed polymer to be removed. After oxidation, the fabric is normally acidic and may require chemical neutralization in addition to water washing to neutralize the acidity. After washing, the fabric is framed to width and dried.
2.2.6 Fabric After-Treatments Ammonia cure flame retardant fabrics can apply further chemical treatments, such as top softening, durable press, and water repellency treatments. Normal procedures for these applications should be followed.
2.2.7 Treatment of cotton blended fabrics Blends of cotton with other fibres, when cotton is the predominant fibre in the blend, can sometimes be successfully treated with the Precondensate/NH3 finish. Often, higher chemical add-ons are required to impart adequate fire retardance to such blends than would be required for 100% cotton fabrics of similar construction.
Textile Handbook 5-55
2.3 Hints for Wet Processing of Cotton/Spandex Fabric 2.3.1 Spandex in Knitted Fabric
2.3.2 Relaxation Knitted fabric should be relaxed before dyeing to reduce residual stresses caused by tensioning of the elastic yarns during knitting. This will result in improved dimensional stability. By relaxing the fabric to its full relaxed state, the maximum weight and minimum width can be determined. The full relaxed state can be determined by “boil-off” of a full width sample of two yards length. The bath used in the boil-off should contain textile detergent or scouring agents to be used in processing. After boil-off, the samples can be dried in a sample oven, and the fabric width can be measured. This width will be the absolute minimum width to which the fabric will shrink. This information will prevent the finisher from trying to finish at a width that is less than the relaxed width. a) Relaxation Methods for Open-width Fabrics: • Passing the fabric over a steam box off-line of the tenter frame after slitting. • Steaming the fabric after slitting while it is held by the pins on a tenter frame. • Prescouring in a soft flow jet before slitting. • Padding through a 120-140oF (50-60oC) bath with a wetting agent after slitting. b) Relaxation Methods for Tubular Knit Fabric: • Sending the fabric through a tensionless steam calendar. • Steaming in an autoclave in a batched roll.
Textile Coloration and Finishing Treatments
Cotton/spandex knitted fabrics may contain spandex in every course or in alternating courses. The spandex may appear as plaited bare spandex, core spun or covered by cotton fibres. Spandex yarn deniers between 40 and 70 are the most commonly used in circular knits. Typical stretch levels for cotton knit fabrics with spandex are in the 50-100% range.
5-56
Textile Coloration and Finishing Treatments
2.3.3 Heat-Setting If heat-setting is performed on grey goods, spinning oils, waxes, and knitting oils may cause discoloration or yellowing that cannot be removed in subsequent scouring and bleaching processes. Therefore products for spinning and knitting lubricants should be carefully chosen for potential discoloration in grey heat-setting. In this case, the yellowing of grey fabric during heat-setting can be removed with normal cotton bleaching procedures. If heat-setting is performed following the dye process, there is little that can be done about the discoloration. Also, heat-setting after dyeing may leave fabrics with poor stretch uniformity, variations in width, stitch distortion, or pattern distortion. When heat-setting is performed after proper fabric relaxation, it also helps to prevent crease, rope and crack marks from developing in subsequent wet processing operations. However, if the fabric is relaxed in rope form, care should be taken not to generate creases that could permanently remain in the fabric. Heat-setting temperatures range from 182-196oC. A fabric heat-setting temperature of 182oC is used if the desired effect is to maintain the fabric while retaining good stretch and growth properties. However, a fabric temperature of 196oC is recommended when a sheer look with reduced stretch is desired. Temperatures above 196oC will cause the fabric to lose “power” due to the denier reduction of the spandex. The ability of a fabric to stretch and then recover from that stretch is referred to as power. For knit constructions that have a tendency to curl, such as jersey and tricots, a low heat-setting history may demonstrate a higher curl potential. Since there is residual shrinkage in spandex and shrinkage in cotton fibre, the heat-setting width should be 5-15% wider than the desired width to allow additional shrinkage that may occur in subsequent wet processing. In case of open-width knitted goods, the fabric may need to be extended wider than 15% in order to remove the centre line. A fabric that is wet from a previous process (e.g. prescour or relaxation) should be rewet and padded at the entrance to the tenter to ensure
Textile Handbook 5-57
uniform moisture content throughout the fabric. If the fabric is not rewet and brought to a uniform moisture content, the drier areas will get hot faster and have a different heat history. This will result in uneven heat-setting and thus uneven dyeing, shrinkage, stretch, and recovery. Therefore, a uniform moisture content in the fabric is essential for uniform drying and heat setting.
2.3.4 Dyeing It is usually recommended that open-width fabrics be processed on a pad-batch or beam system to keep the fabrics flat and reduce the amount of tension applied. It may be necessary to gum the edges of the fabric to eliminate curl when the fabric is processed open-width on padbatch or beam equipment. Both tubular and open-width fabrics can be processed in either jets or paddle machines. If the fabric is processed in a jet, then the use of a soft flow or overflow version with a tensionless lift and a plaiter to preserve fabric stretch and recovery properties should be investigated. Low profile jets are also recommended and paddle dyeing is advocated for lightweight goods. Cotton/spandex blends may be dyed according to the usual procedures for dyeing cotton. It is recommended that a lubricant be used when processing the fabrics in jets. Centrifugal extraction is preferred over padding or vacuum to remove excess water after dyeing.
Textile Coloration and Finishing Treatments
Cycles of high pressure steam under vacuum in an autoclave is commonly used for heat-setting tubular knits. Since knitted tube is rolled in a flattened configuration, the edges of the tubular goods might be permanently set during this process. It is recommended that entire dye lots be autoclaved together to avoid any dyeing anomalies that may result from non-uniform autoclave conditions. After any heatsetting process, the fabric should be cooled before going to any preparation, dyeing, or finishing process. This is especially true if it is going to be pad-batch dyed or printed directly after heat-setting, as residual heat in the fabric could affect the resulting shade. However, the heat-setting stage can be omitted if the fabric is designed to optimize contraction and power.
5-58
Textile Coloration and Finishing Treatments
2.3.5 Drying Open-width fabric may be dried on a pin tenter frame with over feed. It is not recommended to apply more than the minimum amount of heat required so the fabric does not become yellow during the drying stage. The recommended temperature range for drying is 121-135oC. Open-width fabric, as well as tubular fabric, may also be dried on a relaxation dryer. A continuous tumbler is another option for drying a tubular fabric. If the goods are heat-set after preparation and before dyeing on a continuous or pad system, they must be cooled to a uniform temperature to prevent shading during dyeing.
2.3.6 Cotton/Spandex Woven Fabric Typically, the spandex used in woven goods will be found in a corespun yarn. Lightweight woven goods, weighing up to 5.5 oz/yd2 (186 g/ m2), typically incorporate spandex yarns ranging from 40 to 70 denier. Heavier goods, those weighing more than 7.5 oz/yd2 (254 g/m2), may contain yarn that is as heavy as 140 denier. The choice of denier depends on the aesthetic properties that are desired. Stretch levels are typically 15 to 50% for woven structures.
2.3.7 Relaxation Cotton/spandex woven fabrics need to be boiled-off to determined the fully relaxed state as knitted fabric. However, the chemical used should be the same as for desizing. During the pre-treatment process, the temperature of either the quench box or wet-out bath should be at least 71oC to allow for the fastest and most controlled width relaxation. Higher bath temperatures will result in greater width losses and it is recommended that the linear speed of the range be slowed to allow for full width relaxation.
2.3.8 Heat-Setting Following the relaxation stage, the “filling stretch” fabric has contracted to become less than the desired width. Heat-setting is most effectively used at this point to re-stretch and stabilize the fabric close to the desired width. If desired, heat-setting can also be conducted following
Textile Handbook 5-59
preparation or dyeing. The fabric should be heat-set on a pin tenter with much care given to width control and heat distribution. The amount of overfeed and the framing width will depend on the desired fabric weight, width, and stretch level. During the heat-setting stage, the spandex is held under tension, and this results in a denier reduction that corresponds to a reduction in a power and reduction in width retraction.
Heat-setting temperatures for wovens range from 182-196oC on the fabric, and are chosen according to the desired performance properties of the fabric. The set width for “filling stretch” fabrics should be 515 percent higher than the desired width to account for any additional shrinkage that may occur in dyeing. The amount of stretch set into “warp stretch” fabric can be determined by the overfeed or pull on the tenter. The stretch of a fabric should be evaluated after it has been relaxed but before heat-setting. Also, after heat-setting the goods must be cooled before subsequent dyeing or printing processes where dyes will be directly applied to the dry fabric. Differences in dye shade will result from the areas of different temperature.
2.3.9 Dyeing Jig, pad-batch or continuous open-width equipment is recommended for dyeing cotton/spandex woven fabric. For filling-stretch fabric, the width must be carefully controlled. If heat-setting is conducted between pre-treatment and dyeing, the fabric must be uniformly cooled if it is to be dyed, either continuously or by the pad-batch system.
2.3.10 Finishing Silicone elastomers combined with resin crosslinkers will yield the best control of finished width and/or growth resulting from stretch during wear. Heat-setting and crosslinking may be done at the same
Textile Coloration and Finishing Treatments
In the case of “warp stretch” fabric, desizing should be done in a manner that will allow bulking to occur in the warp direction. If a “warp stretch” fabric is to be processed on equipment that will impart tension in the warp direction, such as a continuous range or a jig, the fabric should be allowed to relax prior to heat-setting. Heat-setting fabric in its relaxed state will enable the fabric to retain its maximum retractile power.
5-60
Textile Coloration and Finishing Treatments
time; however, temperatures above 182oC may result in problems with shade change and strength loss. An anti-curl finish can also be applied to stabilize the fabric for later cut and sew operations. Fabrics containing spandex can withstand many of the same mechanical finishes as cotton fabrics. However care should be taken not to apply tension to hot fabric to avoid denier reduction of the spandex fibre.
Chapter 6 Textiles Testing and Quality Control..6-2 Section 1 - Cotton Fibre Testing ............................... 6-2 1.1
Terms Relating to the Conditioning and Testing of Textiles ............................................................................... 6-2
1.2
Recommendations for a Physical Testing Laboratory for Fibre and Yarn ............................................................ 6-3
1.3
Fibre Testing Condition .................................................... 6-4 1.3.1
1.4
Fibre Moisture ................................................................... 6-4 1.4.1 1.4.2 1.4.3
1.5
1.6
1.5.1 1.5.2 1.5.3
Staple Diagram Method - Shirley Comb Sorter .......... 6-9 Fibrograph ................................................................... 6-11 Comparison and Evaluation of Staple Diagram and Fibrogram ............................................................. 6-13
1.5.4
Staple Length Conversion ........................................... 6-17
Fibre Fineness Testing ..................................................... 6-17 Micronaire Testing Procedure ..................................... 6-18 Calculation of Average Fibre Fineness ........................ 6-19
Fibre Maturity Testing ..................................................... 6-20 1.7.1 1.7.2 1.7.3
1.8
Measurement of Moisture Regain ............................... 6-4 Commercial Moisture Regain Values .......................... 6-5 Relationship of Temperature and Relative Humidity on Moisture Regain of Cotton ..................................... 6-7
Fibre Length Testing Principle ........................................ 6-8
1.6.1 1.6.2
1.7
Ambient Laboratory Conditions for Fibre Testing ...... 6-4
Microscopic Array Method ......................................... 6-20 Differential Dyeing ..................................................... 6-21 Caustic Method ........................................................... 6-21
Fibre Strength Testing ...................................................... 6-22 1.8.1 1.8.2 1.8.3
Pressley Fibre Strength Tester ..................................... 6-22 Stelometer ................................................................... 6-24 Pressley Index and Fibre Strength (lb/in2) .................. Conversion Table ......................................................... 6-25
1.9
Fibre Dust and Trash ........................................................ 6-26 1.9.1 1.9.2
Definition of Dust and Trash ....................................... 6-26 Trash And Dust Measurement By Using Shirley ......... Analyzer ...................................................................... 6-27
1.10 Fibre Identification ........................................................... 6-29
Back to Table of Content
Chapter 6
TEXTILES TESTING AND QUALITY CONTROL
6-2
Textiles Testing and Quality Control
CHAPTER 6.........
.......TEXTILES TESTING AND QUALITY CONTROL SECTION 1
COTTON FIBRE TESTING
1.1 Terms Relating to the Conditioning and Testing of Textiles (Source : ASTM D1776-85 and ASTM D123) 1. Moisture Content - the amount of water in a material determined under prescribed conditions and expressed as a percentage of the mass of the moist material, that is the original mass comprising the dry substance plus any resent water. 2. Moisture Equilibrium - the condition reached by a sample when it no longer takes up moisture from, or gives up moisture, to the surrounding atmosphere. 3. Moisture Equilibrium for Preconditioning - the moisture condition reached by a sample or specimen after exposure to moving air in the standard atmosphere for pre-conditioning. 4. Moisture Equilibrium for Testing - the condition reached by a sample or specimen during free exposure to moving air controlled at specified conditions. 5. Moisture Regain - the amount of water in a material determined under prescribed conditions and expressed as a percentage of the mass of the water-free material. 6. Standard Atmosphere for Preconditioning Textiles - an atmosphere having a relative humidity (RH) of 10 to 25% and a temperature of not over 50°C (122°C). 7. Standard Atmosphere for Testing Textiles - air maintained at a RH of 65±2% and at a temperature of 21±1°C(70±2°F). (For ISO Standard, the standard atmosphere is at RH 65%± 2% and at a temperature of 20±2°C.) In tropical and subtropical countries, RH 65%±2% and temperature of 27±2°C may be regarded as standard condition.)
Textile Handbook 6-3
8. Relative Humidity - the ratio of the pressure of water vapour present to the pressure of saturated water vapour at the same temperature. The ratio is generally expressed as a percentage or as a decimal fraction. For normal testing conditions, the ratio of the actual absolute humidity to the maximum possible humidity at the same temperature does not differ appreciably from the ratio of the pressures used in this definition. The agreement holds for temperatures up to 200˚F (93˚C) and below saturation.
1.2 Recommendations for a Physical Testing Laboratory for Fibre and Yarn Equipment Recommended Evenness Tester Yarn Fault Classification Tester Winder (6 place) Single End Yarn Tester Skein Reel Roving Reel Yarn Counter Tester Yarn Numbering Processor, multi-scale w/RS232 output Yarn Appearance Winder, multi-board Twist Tester Precision Balance, 10 mg Digital Fibrograph Tensile Tester Fibronaire HVI (High Volume Instrument Testing)
Textiles Testing and Quality Control
9. Dew Point - the temperature below which condensation of water vapour begins to take place when the atmosphere is cooled. As air is cooled, the amount of water vapour which it can hold decreases. If air is cooled sufficiently, the saturation water vapour pressure becomes equal to the actual water-vapour pressure, and any further cooling beyond this point will normally result in the condensation of moisture.
6-4
Textiles Testing and Quality Control
1.3 Fibre Testing Condition 1.3.1 Ambient Laboratory Conditions for Fibre Testing Conditioning and testing of textile fibres must be carried out under constant standard atmospheric conditions. The standard temperate atmosphere for textile testing involves a temperature of 20 ± 2oC (68 ± 4oF) and 65 ± 2% relative humidity. To attain the moisture equilibrium, a conditioning time of at least 24 hours is required and 48 hours is preferred. During conditioning, samples should be arranged in single layers in perforated trays to allow conditioned air to circulate freely. Laboratory conditions should be monitored by appropriate devices that record both short-term fluctuation and long-term drift. References : ISO 139, EN 20 139 or DIN 53 802: Standard atmosphere for conditioning and testing
1.4 Fibre Moisture 1.4.1 Measurement of Moisture Regain The basic method of measuring regain must be to weight a sample of not less than 5 gm. in its original condition, to dry it, and then to weigh it again. The dry weight is obtained by drying at a temperature of 105 ± 3oC. In B.S. 1051 the drying conditions specified include a recommendation to use a ventilated drying oven with a positively induced air current. When successive weights obtained at intervals of 20 minutes differ by less than 0.05 percent, it may be assumed that a constant weight has been reached. (The standard of moisture regain for cotton is 8.5%) Calculations: W-W’ x100 W’ W-W’ x100 Moisture content % = W’ W : the original weight of the sample Moisture regain % =
W’ : the oven dry weight of the sample
Textile Handbook 6-5
Remarks: •
Since regain affects the weight, it is essential that the tests are carried out with the fibres in equilibrium with a standard testing atmosphere.
•
While pre-heating, the testing parameters, such as temperature, humidity and drying period of the oven should be carefully recorded.
•
The balances must be accurate, and checked or calibrated before use.
Commercial moisture regain is an arbitrary value formally adopted as the regain to be used with the oven-dry weight when calculating (1) the linear density, (2) the commercial or legal weight of a shipment or delivery of any specific textile material, or (3) the weight of a specific component in the analysis of fibre blends. Table 1.4.2 (1) Commercial Moisture Regain Values (Source : ASTM D1909) Fibre Acetate (secondary) Acrylic Aramid, for Plastic reinforcement Filtration fabrics and safety apparel Reinforcement of rubber goods Azlon Cotton Raw cotton* Natural cotton yarn Dyed cotton yarn Mercerized cotton yarn Flax (raw) Fluorocarbon Glass Hemp Jute Linen Metallic
Commercial Moisture Regain % 6.5 1.5 3.5 4.5 7.0 10.0
7.0** 8.0** 8.5** 12.0 0.0 0.0 12.0 13.75 8.75 0.0
Textiles Testing and Quality Control
1.4.2 Commercial Moisture Regain Values
6-6
Textiles Testing and Quality Control Modacrylic Class I Class II Class III Nylon (polyamide) Olefin Polyester Ramie Raw Scoured Rayon (regenerated cellulose) Rubber Saran Silk Spandex Triacetate (primary) Vinal Vinyon Wool (all Forms)
0.4 2.0 3.0 4.5 0.0 0.4 7.6 7.8 11.0 0.0 0.0 11.0 1.3 3.5 4.5 0.0 13.6
Note : * There is no commercial regain value for raw cotton in U.S. trade. The value specified in Rule 15 of the Egyptian sales contracts and in Rule 105 of the Liverpool sales contract for Egyptian and Syrian cotton is 8.5. The value 8.5 is also used customarily for the cotton component of blends containing cotton in the process of performing quantitative analysis. ** Commercial Standard CS11-63, which is issued by the National Bureau of Standards, recommends these values to be used for cotton yarns by dyers and finishers.
Textile Handbook 6-7 Table 1.4.2 (2) M.R. 5.25 6.23 7.53 8.70 9.89 11.11 13.36 13.64
M.C. 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0
M.R. 14.96 16.28 17.65 19.05 20.49 21.95 23.46 25.00
M.C. 4.76 5.66 6.54 6.98 7.41 7.83 8.26 9.09 9.91
M.R. 5.0 6.0 7.0 7.5 8.0 8.5 9.0 10.0 11.0
M.C. 11.11 11.52 12.28 13.04 13.79 14.53 15.25 15.43 15.97
M.R. 12.5 13.0 14.0 15.0 16.0 17.0 18.0 18.25 19.0
Note: M.R. = Moisture Regain; M.C. = Moisture Content M.R.+100 100 = 100-M.C. 100
1.4.3 Relationship of Temperature and Relative Humidity on Moisture Regain of Cotton Table 1.4.3 (1) Relationship of Temperature and Relative Humidity on Moisture Regain of Cotton (Hertshorn) Temp RH M.R.%
500F (100C)
600F (15.60C)
700F (21.10C)
800F (26.70C)
900F (32.20C)
1000F (37.80C)
40% 50 60 70 80 90 100
5.90 6.89 8.00 9.14 10.58 12.28 14.12
5.79 6.78 7.78 9.00 10.42 12.10 14.00
5.65 6.63 7.69 8.79 10.23 11.85 13.60
5.47 6.45 7.44 8.58 9.95 11.56 13.65
5.25 6.18 7.13 8.32 9.70 11.43 13.70
5.03 5.86 6.80 8.05 9.60 11.85 14.50
Textiles Testing and Quality Control
M.C. 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0
Moisture Regain and Moisture Content Conversion Table
6-8
Textiles Testing and Quality Control Table 1.4.3 (2)
R.H.%
5 10 15 20 25 30 35 40 45 50
Relationship of Relative Hunidity on Moisture Regain of Cotton
M.R.% at absorption state 2.0 2.5 3.0 3.5 4.0 4.2 4.5 4.7 5.0 5.5
M.R.% at desorption state 2.2 3 3.5 4 4.5 4.7 5 6 6.5 7
R.H.%
M.R.% at absorption state
55 60 65 70 75 80 85 90 95 100
6.0 7.0 7.5 8.0 9.0 10.0 11.5 13.0 17 25
M.R.% at desorption state 7.5 8 8.5 9.5 10.5 12 13 15 18.5 25
Muller’s Theory R = (a + bH) √100-tc
R= Moisture Regain % of Cotton tc= Temperature oC H= Relative Humidity (40-80%) a=0.8067
(cotton )
b=0.02912
(cotton)
1.5 Fibre Length Testing Principle In the evaluation of the raw materials, two important dimensions available to the spinner are fibre length and fineness. There is a relationship between these two quantities. Staple length is a quantity estimated by personal judgement by which a sample of fibrous raw material is characterized. Technically, fibre length is regarded as the most important dimension. The first determination of the length characteristics of the cotton is carried out by classers who use the hand stapling method. Effective length is defined as the length of the main bulk of the long fibres. The term effective is used because it is to this length value that many machinery settings are adjusted, in particular the distances between the nips of successive pairs of drafting rollers.
Textile Handbook 6-9
1.5.1 Staple Diagram Method - Shirley Comb Sorter The fibre sorter (see Figure. 1.5.1 (1)) is an instrument which enables the sample to be divided into length groups. Nine bottom combs and eight top combs are used, each set spaced 1/4 inch apart except the first two bottom combs which are 3/16 inch apart. Manipulation of the fibres is by a grip, an aluminium depressor and a blunt needle. Figure 1.5.1 (1)
Shirley Comb Sorter
•
Preparation of a tuft The weight of the sample is about 20mg. The sample is carefully drawn and doubled by hands several times until the fibres are straightened and parallelised.
•
Separation of fibres -
The prepared sample is slightly twisted and placed in the lower combs.
-
A tuft is pulled from the sample. This tuft is combed several times and transferred to the left-hand side of the sorter.
-
This process is repeated until all the samples of lint are transferred to the left-hand side of the sorter.
Textiles Testing and Quality Control
Basically, the operation involves four main steps:
6-10
Textiles Testing and Quality Control
•
•
Preparation of a sorter diagram by laying the fibres on a black velvet pad in decreasing order of length -
The sorter is turned round so that the longest hairs project towards him.
-
The fibres are pulled out in tufts of successively shorter lengths by means of the grip, the longest first. The fibres are combed, straightened, and laid down on the velvet pad with the straight edge against the marked line.
Analysis of the diagram
The diagram is traced onto paper for detailed analysis. Figure 1.5.1.(2)
Staple Diagram
OB = 16cm
OE = 1/4 OD’
OH = 1/4 OG’ = PG’
OATR = 1/2 OAB
ON = 1/8 OH
OC = 1/2 OA
EF = 1/2 EE’ OAB OB = TR(calculated from the area OAB)
Mean length =
OATR OR = SU(calculated from the area OATR)
Upper Half Mean Length =
Textile Handbook 6-11
Effective length = HH’ Maximum length = OA Percentage short fibre =
G’B OB
x100
Ratio of longest length to effective length =
NN’ HH’
(Value of 1.1 represents normal quality, if value exceed 1.15 represents poor quality) HH’- PP’ x100 HH’
1.5.2 Fibrograph a) Servo-Fibrograph Photoelectric cells are used for measuring the length characteristics of cotton. A fringe of cotton is prepared by taking about 1/2 oz of cotton and combing it by means of two hand combs. The prepared sample is in a straightened condition with the fibres divided between the two combs. The fibre fringes are placed on the measuring unit in such a way that they lie over a long narrow slot behind which are mounted the photoelectric cells. A light source illuminates the fringes and the amount of light penetrating through the fringes is measured electronically. The instrument automatically records the change in the amount of light reaching the cells as a special form of frequency distribution. Figure 1.5.2 a
Fibrogram
Relative number of fibre (%)
U.H.M.L. (Upper Half Mean Length) = OU M.L.(Mean Length) = OM OM Length uniformity ratio = OU
x100
Textiles Testing and Quality Control
Dispersion of effective fibres =
6-12
Textiles Testing and Quality Control
b) Digital Fibrograph The Digital Fibrograph method consists of placing representative specimens of cotton weighing approximately 30 centigrams at random on a pair of combs, making parallel the beards of cotton extending from one side of the combs, and scanning these beards photoelectrically on the instrument at 3 length intervals beginning at 0.15 inch from the teeth of the combs and ending near the outer fringe. The 2.5 percent span length and the 50/2.5 uniformity ratio values reported for each lot are based on five specimens tested by each of two techniques. The Digital Fibrograph 2.5 percent span length values reported indicate the length which will be spanned by 2.5 percent of the fibres when they are parallel and randomly distributed. It is also the length where the amount of fibres indicated by the instrument is 2.5 percent of the amount at the starting point of 0.15 inch. The Digital Fibrograph 2.5 percent span length values are closely related to staple length designations. The Digital Fibrograph 50/2.5 uniformity ratio values reported indicate the relative uniformity of fibre length in the samples. They represent the ratios between the 50 percentages. Larger values indicate more uniform fibre length distribution. Unusually low fibre length uniformity tends to increase manufacturing waste, to make processing more difficult, and to lower the quantity of the product. The following adjective descriptions will serve so classify cottons from the standpoint of 2.5 percent span length and fibre length uniformity:
Uniformity ratio % =
50% span length x100 2.5% span length
Floating fibre index (F.F.I.) =
2.5% span -1.0 x100 3(66.7 span-0.1)
Textile Handbook 6-13
1.5.3 Comparison and Evaluation of Staple Diagram and Fibrogram There are two main differences between the Staple Diagram and Fibrogram in measuring fibre length. Firstly is the information they present and secondly is the sampling techniques they employ. These differences can best be understood with the aid of graphics.
Figure 1.5.3 (1)
Staple Diagram
The Fibrogram uses a different technique to obtain a sample and it analyses that sample differently. Instead of measuring all fibres in a small tuft, the Fibrogram randomly selects fibres from a larger group, one that might equal several staple diagrams. For example, Fibre 1, 2 and 3 from separate staple diagrams could occur in a single Fibrogram as illustrated in Figure. 1.5.3 (2). The Fibrogram is thus made up of a collection of fibres randomly selected from a wider group. The Fibrosampler selects fibres for the Fibrogram by randomly catching fibres along their lengths, producing span lengths - the lengths that fibre extend from their catch points. These span lengths are then measured using Fibrograph. The span lengths are arranged in a fashion
Textiles Testing and Quality Control
In a staple diagram (Fig.1.5.3 (1)), the horizontal X-axis shows fibre length; each wavy line represents a fibre. The fibre ends are aligned, touching the Y-axis. The staple diagram, shows fibres arranged by length along the Y-axis, and gives information about end-to-end length. (In reality, staple diagrams are usually constructed with a Y-axis scale of weight percentage rather than showing each individual fibre. However, individual fibres are shown here for ease of explanation.) The staple diagram is constructed by taking a small sample from a large population. The small sample is used to approximate the bale’s fibre length distribution.
6-14
Textiles Testing and Quality Control
similar to the staple diagram, but this time the X-axis represents fibre segment length and the fibre catch points touch the Y-axis. (In practice, when the Fibrogram is plotted, the Y-axis gives the percentage f fibre whose span length is at least the corresponding value of the X-axis. Again, individual fibres are shown here of ease of explanation.) Figure 1.5.3 (2)
Staple Diagrams for Entire Bale Population
The significant difference between the methods is that, rather than having the total fibre lengths shown on the X-axis, as in the staple diagram, the Fibrogram shown span lengths. The fibre’s catch points are aligned at the X axis’s point of origin, 0, and one can imagine the remaining portions of the fibres extending to the left of the Y axis, as shown by the dotted lines. To the right of the Y-axis, only span lengths are to be seen. The end-to-end length information is there as well, but it must be derived. The full, end-to-end fibre length distribution can be easily determined by constructing tangents.
Textile Handbook 6-15
A point on the Fibrogram curve (Figure 1.5.3 (3)) is selected D distance from 0 along the X-axis. At this point, a tangent to the curve is drawn which intercepts the X and Y-axes. The Y axis intercept indicates the percentage of fibres that are at least D distance long but not necessarily all D distance in length. To get a better idea of their lengths, one must look at the X axis intercept, which tells the mean or average length of all fibres longer than the D distance. Figure 1.5.3 (3)
Point of Tangency
Figure 1.5.4 (4)
Long Fibre Content Curve
Textiles Testing and Quality Control
The overall fibre length distribution can be determined by developing a set of these tangents for different percentage levels on the Y-axis (Figure. 1.5.3 (4)). The intercepts thus created become co-ordinates for points that together make up a “long-fibre-content curve”. From this curve, the mean length of any percentage of the longer fibres can be determined.
6-16
Textiles Testing and Quality Control
To summarise, the X-axis of the Fibrogram gives the span lengths of the fibres; that is the distance fibres extend when caught at random along their lengths. The Y-Axis gives the percentage of fibres whose span length equals or exceeds a particular distance along the X-axis. Thus, for example, a 2.5% span length would be the minimum distance that 2.5% of the fibres extends when caught at random along their lengths. The 2.5 % span length is usually used in drafting and yarn spinning because it correlates with the classer’s call (Figure. 1.5.3(5)). However, the staple diagram represents only end-to-end fibre lengths which may not be very useful for actual processes of yarn spinning as the fibres do not lay out in an orderly array. It also need skilled hands and to perform and the sample may not be representative. Figure 1.5.3 (5)
2.5% Span Length
Textile Handbook 6-17
1.5.4 Staple Length Conversion Table 1.5.4 Category Short
Staple Length Conversion Chart 32nds 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
Decimals 0.81 0.84 0.88 0.91 0.94 0.97 1.00 1.03 1.06 1.09 1.13 1.16 1.19 1.22 1.25 1.28 1.31 1.34 1.38 1.41 1.44 1.47 1.50 1.53 1.56 1.59 1.63
mm 20.6 21.4 22.2 23.0 23.8 24.6 25.4 26.2 27.0 27.8 28.6 29.4 30.2 31.0 31.8 32.5 33.3 34.1 34.9 35.7 36.5 39.3 38.1 38.9 39.7 40.5 41.3
1.6 Fibre Fineness Testing Fibre fineness can be determined either by measuring the fibre linear density per unit length or by measuring the fibre’s shapes and diameters of the cross sections. Micronaire is expressed in terms of µg/inch while Arealometer is expressed as the ratio of surface area, of the fibre to its volume, mm2 /mm3 .
Textiles Testing and Quality Control
Inches 13/16 27/32 7/8 29/32 15/16 31/32 Medium 1 1 1/32 1 1/16 1 3/32 Medium to long 1 1/8 1 5/32 1 3/16 1 7/32 1 1/4 Long 1 9/32 1 5/16 1 11/32 1 3/8 1 13/32 Extra long 1 7/16 1 15/32 1 1/2 1 17/32 1 9/16 1 19/32 1 5/8
6-18
Textiles Testing and Quality Control
1.6.1 Micronaire Testing Procedure Place a sample of 50 grains into the fibre compression chamber of volume 16.4 cm3 (see Figure.1.6.1). The sample is then subjected to an air current at a known pressure (0.42 kg/cm2 ). The rate of air flow through this porous plug of fibres is measured, the specific surface area of the fibre can be determined and consequently the fibre diameter. Then, by using a value for the density of the material, the fibre weight per unit length can be derived. As micronaire is a combination of fineness and maturity, the coarse fibres generally have higher micronaire values. However, for immature cotton, a lower micronaire value is given. By measuring the weight of a known length of fibre, a quantity called the linear density is obtained. Linear Density is the mass per unit length of a fibre or filament expressed in millitex (milligrams per kilometre). In England, the linear density is called the hair weight per centimetre. The unit of weight is the milligram x 10-5. In USA, the weight unit is the microgram µg (gm x 10-6 ) and the length unit is the inch. In Egypt, the hair weight unit per centimetre is the 100 microgram (gm x 10-4 ), i.e. 100µg/cm. For man-made fibre, the hair weight unit is denier, g/9000m. The formula of converting µ/in into Tex or Denier is: F(µ/in)39.4(in/m)=F’µg/m or F’ milli tex Denier = W(µ/in)x0.3543
Figure 1.6.1 Cotton Fineness Meter
Textile Handbook 6-19
1.6.2 Calculation of Average Fibre Fineness F=
100 100 = P P2 P3 … Pn P1 ∑ n + + + fn f2 f3 fn f1
where F = average fibre fineness of a blend of n types of raw cotton; P = blend ratio or bale number
Table 1.6.2 P/f Value (P : no. of bale; f: micronaire value) P 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
f P/f
5.0 above (5.2) 0.192 0.385 0.577 0.769 0.962 1.154 1.036 1.538 1.731 1.923 2.115 2.308 2.500 2.692 2.885 3.077 3.269 3.462 3.654 3.846 4.038 4.231 4.423 4.615
4.5-4.9 (4.7) 0.213 0.426 0.638 0.851 1.064 1.277 1.489 1.02 1.915 2.218 2.340 2.533 2.766 2.979 3.191 3.404 3.617 3.830 4.42 4.255 4.468 4.681 4.894 5.106
4.0-4.4 (4.2) 0.238 0.476 0.714 0.952 1.190 1.429 1.667 1.905 2.143 2.381 2.619 2.857 3.095 3.333 3.571 3.810 4.048 4.286 4.524 4.762 5.000 5.238 5.476 5.714
3.5-3.9 (3.7) 0.270 0.540 0.811 1.081 1.351 1.622 1.892 2.162 2.432 2.703 2.973 3.243 3.514 3.784 4.054 4.324 4.595 4.865 5.135 5.405 5.676 5.946 6.216 6.486
3.0-3.4 (3.2) 0.312 0.625 0.938 1.250 1562 1.875 2.188 2.500 2.812 3.125 3.438 3.750 4.062 4.375 4.688 5.000 5.312 5.265 5.938 6.250 6.562 6.875 7.188 7.500
2.5-2.9 below 2.4 (2.2) (2.7) 0.370 0.740 1.111 1.482 1.852 2.222 2.593 2.963 3.333 3.704 4.074 4.444 4.815 5.185 5.556 5.926 6.296 6.667 7.037 7.407 7.778 8.148 8.518 8.889
0.454 0.909 1.364 1..818 2.273 2.727 3.182 3.636 4.091 4.545 5.000 5.455 5.909 6.364 6.818 7.273 7.727 8.182 9.636 9.091 9.545 10.000 10.454 10.909
Textiles Testing and Quality Control
f = fibre fineness of individual type of raw cotton
Textiles Testing and Quality Control
6-20
25 26 27 28 29 30 40 50
4.808 5.000 5.192 5.385 5.577 5.769 7.692 9.615
5.319 5.532 5.745 5.957 6.170 6.383 8.511 10.638
5.952 6.190 6.429 6.667 6.905 7.143 9.524 11.905
6.755 7.027 7.297 7.568 7.838 8.108 10.811 13.514
7.812 8.125 8.438 8.750 9.062 9.375 12.500 15.625
9.259 9.630 10.000 10.370 10.741 11.111 14.815 18.518
11.364 11.818 12.273 12.727 13.182 13.686 18.182 22.727
1.7 Fibre Maturity Testing 1.7.1 Microscopic Array Method A convenient method of measuring cotton maturity is by integrating the sodium hydroxide swelling method and the staple diagram array method together. A fibre tuft is taken from Fibrograph and placed under a high performance microscope with a magnifying power of 400. The fibres should be parallel but separated. The fibres are then irrigated with a small amount of 18% caustic soda solution which has the effect of swelling them. The presence or absence of convolutions is then observed. Mature fibres with a well-developed cell wall and pronounced convolutions in the raw state become rod-like after swelling. Dead fibres appear ribbon-like even after swelling. Generally, normal fibres have a wall thickness thicker than 1/2 of the diameter of a lumen. Immature fibres usually are darker in shade and lack luster. Figure 1.7.1 Maturity of Cotton
a1 and a2 b a1 +a 2 ≥ b a1 + a 2 < b
: : : :
wall thickness lumen mature cotton immature cotton A Percent maturity = x100 A+B where A:number of mature cotton fibre; B:number of immature cotton fibre
Textile Handbook 6-21
1.7.2 Differential Dyeing Steps are: • Two dyes are used in the same bath, a red and a green dye. They are Diphenyl fast red 5 BL Supra 1 (Geigy) (Color index C.I. Direct Red 81) 1.2%, Chlorantine fast green BLL (Ciba) (Color index direct green 26) 2.8%.
• The sample is then transferred to the boiling dye bath. After 10 minutes, the sample is temporarily removed to allow sodium chloride to be added to the bath. A second 15 minutes boiling is again followed by temporary removal to allow further sodium chloride to be added to the dye bath. • The sample is boiled in the dye bath for a final 15 minutes before rinsing and washing not less than 8 to 10 times in 40 - 50 warm water and dried. • Mature fibres are stained red and immature fibres green, the red color being developed in the cellulose of the secondary wall.
1.7.3 Caustic Method Testing a sample of cotton before and after swelling by a solution of caustic soda would offer a convenient method of estimating maturity. However, this method is not suitable for practical use because of its inaccuracy. Steps are: • Take 7 to 10 gm cotton fibres; processed half of it with the airflow method and read the micronaire value. The half is immersed in a 40 TW (18-20%) caustic soda bath with 1-1.5% wetting agent added. After swelling, the sample is rinsed, dried and the micronaire value is read again.
Textiles Testing and Quality Control
• A 3 gm sample of cotton is stitched loosely into a piece of gauze to form a thin flat pad. This is thoroughly wetted in boiling distilled water for 30 minutes. The boiling distilled water should weight of 50 times the sample weight.
6-22
Textiles Testing and Quality Control
• Calculation: Maturity Index=
Micronaire value before caustic treatment x 100 Micronaire value after caustic treatment
Fineness (µg/in) = 1.185+0.0075(T2)-0.020 (M.I.) where T: micronaire value of specimen after treatment; M.I. is maturity index
Table 1.7.3 Results of M.I. & fineness due to different NaOH concentration % and treatment time NaOH Fineness Concentration Maturity index % (TW) A B C A B 34 83 86 72 5.4 4.4 40 80 86 70 5.5 4.6 46 82 86 72 5.5 4.5 50 82 86 71 5.4 4.5 Average 86 81.8 71.2 5.45 4.5
C 3.3 3.1 3.0 3.0 3.0
Time of treatment 5 10
Maturity Fineness index 84 5.2 84 5.4
15
83
20
84
5.2
25
84
5.2
5.3
1.8 Fibre Strength Testing 1.8.1 Pressley Fibre Strength Tester The normal specimen length for the Pressley is from zero(one end of the fibre) to 1/8 inch. From the bulk of the cotton several small tufts are selected at random and manipulated into a parallel ribbon about 36 mm wide. The ribbon is placed across the two black clamps which are held in the vice. Fibres protrude from each side of the clamps are trimmed off. A heavy rolling weight is released and rolls down which breaks the ribbon of fibres. The breaking force is read on the graduated beam and the two halves of the broken specimen are collected, and then accurately weighed on a torsion balance (see Figure.1.8.1.).
Textile Handbook 6-23 Figure 1.8.1 Pressley Fibre Strength Tester
s Pressley Index (P.I.)= w where S: measured breaking force (lb); W : weight of specimen (mg).
Fibre Strength expressed in gram/tex or pound/in2: gram/tex = P.I. x 5.36 1000 lb/in2= 10.8116 x P.I. - 0.1200 (U.S.D.A.) ~ = 10.81 x P.I. For Zero Inch Gauge: 1000 lb/in2 (1000 psi)=
Breaking force(lb) x 10.81 Fibre bundle weight (mg)
Fibre Strength (g/tex) = 1000psi x 0.496 P.I. = 1000psi ÷ 10.81 P.I. = g/tex ÷ 5.36 For 1/8 Inch Gauge: FibreStrength (g/tex)=
Breaking force(kg) x 15 Fibre bundle weight (mg)
Note : For Zero Inch Gauge, specimen length = 1.18cm (0.464in) For 1/8 Inch Gauge, specimen length = 1.50cm (0.590in)
Textiles Testing and Quality Control
Calculation:
6-24
Textiles Testing and Quality Control
1.8.2 Stelometer A random sample of cotton fibres is prepared, short fibres being removed by combing so that all the fibres in the test specimen extend all the way through the jaws of the Stelometer. One of the jaws is mounted in the adjustable jaw holder carried by the beam. When the instrument is started, the beam rotates in a clockwise direction and the breaking load is read from the pointer over the scale. The percentage of elongation can also be read by the other pointer (see Figure.1.8.2). Generally, the ratio between the tenacity at 1/8 inch and at zero is approximately 0.5 but will vary with the nature of the cottons tested; for long, staple, uniform cottons the ratio will be higher than for short, less uniform cottons. Usually, about sixteen specimens should be tested in order to obtain average values with confidence limits of about 1.5%. Figure 1.8.2 Stelometer Fibre Bundle Strength & Elongation Tester
Textile Handbook 6-25
1.8.3 Pressley Index and Fibre Strength (lb/in2) Conversion Table Strength 53938 55019 56100 57181 58263 29344 60425 61506 62587 63668 64750 65831 66912 67993 69074 70155
P.I. 6.6 6.7 6.8 6.9 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8.0
Strength 71237 2341 73399 74480 75561 76642 77724 78075 79886 80967 82048 83129 84210 85292 86373
P.I. 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 9.0 9.1 9.2 9.3 9.4 9.5
Strength 87454 88535 89616 90697 91779 92860 93941 95022 96103 97184 98266 99347 100428 101509 102590
P.I. 9.6 9.7 9.8 9.9 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 11.0
Strength 103671 104753 105834 106915 107996 109077 110158 111239 112321 113402 114438 115564 116645 117726 118080
Note : Specimen length is Zero Inch Gauge: 1000psi = 10.8116 x P.I.- 0.1200
Table 1.8.4 Strength Ratings for Medium- Staple Cotton - 1 inch (25mm) to 1-3/32 inch (28mm)
Description
Pressley 0 MPSI (1000) lb/in2
Pressley 1/8 (g/tex)
Stelometer 1/8 (g/tex)
Using International Calibration Cottons Very low Low Average High Very High
70-76 77-83 84-90 91-97 98-104
Below 21 21-23 24-26 27-29 Above 30
Below 17 17-19 20-22 23-25 Above 26
HVI 1/8 (g/tex) Using HVI Cal. Cottons Below 21 22-24 25-27 28-30 Above 31
Textiles Testing and Quality Control
P.I. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0 6.1 6.2 6.3 6.4 6.5
6-26
Textiles Testing and Quality Control
1.9 Fibre Dust and Trash 1.9.1 Definition of Dust and Trash The ITMF (International Textile Manufacturers Federation) recommends the following classification for trash, dust, microdust and respirable dust, which is based on the particle size. This has found a broad international acceptance: Figure 1.9.1 Trash/Dust Definition According to ITMF
Respirable dust
0
Microdust
15
Trash
Dust
50
500
(µm)Particle Size
Trash and dust (particles larger than 50µm) are often combined under the term Visible Foreign Matter (VFM). ITV/ Hollingsworth and Rieter suggest the following classification for trash and dust measurement results in case for rotor spinning: Trash in cotton bale:
Trash in card or drawframe sliver:
up to 1.2% 1.2% to 2.0% 2.0% to 4.0% 4.0% to 7.0% above 7.0% up to 0.05% 0.05% to 0.10% 0.10% to 0.15% 0.15% to 0.20% above 0.20%
very clean clean average trashy very trashy very clean clean average fair high
Textile Handbook 6-27
Dust content:
up to 0.01% very low 0.01% to 0.03% low 0.03% to 0.05% average 0.05% to 0.09% fair above 0.09% high No classification for fibre fragments has been established so far.
1.9.2
Trash And Dust Measurement By Using Shirley Analyzer
A sample of about 100 gram is placed on the feed table and presented to the taker-in by the feed roller. Owing to its high speed and large number of teeth, the taker-in cylinder opens up the cotton almost to the single hair state. The separation of the cotton and the trash takes place as the two travel with the air stream through the setting chamber. The heavy particles fall to the trash tray while the single cotton hairs are carried along with it into the delivery box; the lighter particles fall into another trash tray. By weighing the trash and clean cotton, the trash content can be calculated as the following formula: Trash Content (%)=
W-W’ x100 W
where W : weight of specimen (g); W’: weight of clean cotton (g)
Textiles Testing and Quality Control
Cotton consists of foreign matter or trash such as broken leaf and pod, seeds, sand, and dirt. The percentage of trash content can be measured by using a Shirley Analyser.
6-28
Textiles Testing and Quality Control
a) Machine Setting of Shirley Analyzer (Source : ASTM D2812-95) (1) Speeds of Various Parts: Part Licker-in-cylinder Feed roll Cage Fan Motor
rpm 900 0.9 80 1500 1400 (approx.)
(2) Settings of Various Parts: Part Feed plate to licker-in Streamer plate (lead-in edge) to licker-in. Streamer plate (lead-off edge) to licker-in. Stripping knife (bottom edge) to licker-in. Stripping knife (bottom edge) to cage. Licker-in to cage Separation Sheet (top edge) to cage Separation sheet (top edge) to licker-in. Delivery plate to cage •
Table 1.9.3
in. 0.004 0.004 0.007 0.004 5/16 7/32 1/4 9/16 1/16
mm 0.1 0.1 0.2 0.1 7.9 5.6 6.4 14.3 1.6
Note : for details on the use of Shirley Analyzer, please refer to ASTM D2812-95 Standard Test Method for Nonlint Content of Cotton. Relationship of Trash Measurement to Classer’s Leaf Grade
Relationship of Trash Measurement to Classer’s Leaf Grade Classer’s Trash Measurement Leaf (4-yr. Avg.) Grade (% Area) 1 0.12 2 0.20 3 0.33 4 0.50 5 0.68 6 0.92 7 1.21
Textile Handbook 6-29
1.10 Fibre Identification Table 1.10 (1)
Shirley Stain Test
Table 1.10 (2)
Shirlastain D Cold 5 min Blue Green
Shirlastain A-D Hot 2 min Dark blue Dark blue Deep brown
Shirlastain E Hot 2 min
Green Pale greenish yellow Deep brown Greenish blue Green Blue Golden brown Grey Deep brown Brownish black Golden brown
Bright orange Bright yellow Green. Red Pinkish yellow Red Green Dull yellow Brown Deep brown Brown
Dull pink Dull pink Green
Ultra Violet Test
Wool Silk Cotton Viscose rayon Acetate fibre Nylon Vinylon Orlon(Acrylic) Dacron (Polyester) Cuprammonium Kanekalon
Pale greenish white Pale green Yellow Pale yellow (slightly green) Dark greenish-purple - green Dark greenish-white Dark greenish - yellow Pale purple - pale greenish white Dark Purplish white Pale cream (with greenish purple) Dark greenish- white
Textiles Testing and Quality Control
Shirlastain A Hot 2 min Cotton Purple to blue Viscose rayon Lavender Wool Bright golden brown CelluloseBright, secondary acetate greenish yellow Cellulose triacetate Greenish yellow Acrilan (standard) Brown Acrilan 16 Cream Courtelle Cream Orlon 42 Fawn Orlon 44 Orange brown Terylene Pale fawn Nylon 66 Brownish yellow Nylon 6 Golden brown Nylon 1 Yellow Rinen Blue Hemp Reddish blue Ramie Deep lavender Jute Bronze Cuprammonium Pale blue Silk Orange Vinylon Brown Pale yellowish
Table 1.10 (3)
Fibre Identification by Solubility Test (ASTM D276-87)
6-30
Textiles Testing and Quality Control
1.11 Typical Fibre Testing Equipment .................................... 6-34 1.11.1 1.11.2 1.11.3 1.11.4
High Volume Instrument (HVI) .................................. 6-34 Advanced Fibre Information System (Uster AFIS) .... 6-38 MicroDust and Trash Analyser (Uster MDTA 3) ........ 6-40 Comparison Between USTER® MDTA 3 and ........... USTER® AFIS-T ........................................................ 6-41 1.11.5 Recommendations for Fields of Application .............. 6-43 1.11.6 Statistics on Raw Cotton Fibre Properties Determined with Uster HVI ............................................................ 6-44
Section 2 - Yarn Testing .............................................. 6-49 2.1
Yarn Conditioning ............................................................ 6-49 2.1.1 2.1.2 2.1.3 2.1.4 2.1.4
2.2
Basis of Unscoured Yarn .............................................. 6-49 Basis of’ Scoured Yarn ................................................ 6-49 Preconditioning (Options 1 and 4 only) ...................... 6-49 Conditioning (Options 1 and 4 only) ........................... 6-50 Oven-Drying (Options 2, 3, 5, and 6, and 7 only) ...... 6-50
Yarn Numbering Systems ................................................. 6-50 2.2.1 2.2.2 2.2.3
Direct and Indirect Systems ........................................ 6-50 Conversion Between yarn Numbering Systems .......... 6-52 Yarn Diameter ............................................................. 6-52
2.3
Testing Plan ....................................................................... 6-53
2.4
Yarn Count Testing ........................................................... 6-61 2.4.1 2.4.2 2.4.3
2.5
Instruments .................................................................. 6-61 Sampling ..................................................................... 6-61 Instruments .................................................................. 6-61
Lea Yarn Strength ............................................................. 6-62 2.5.1 2.5.2
Lea Yarn Strength Testing ........................................... 6-62 Yarn Strength Conversion ........................................... 6-62
Back to Table of Content
Fibre Identification by Infra Red Spectrum Analysis (ASTM D276-87)
Textiles Testing and Quality Control
Note : for details of fibre identification, by solubility test, and intra-red spectrum analysis, please refer to ASTM D276-87(1999) Standard Test Methods for Identification of Fibres in Textiles
Table 1.10 (4)
Textile Handbook 6-31
6-32
Textiles Testing and Quality Control Table 1.10 (5)
Textile Fibre Burning Tests
Wool
Melts Shrinks Burns near from in flame flame flame No Yes Yes
Silk
No
Yes
Yes
Cotton No
No
Yes
Flax No (Linen) Rayon No
No
Yes
No
Yes
Acetate Yes
Yes
Yes
Strong odour of burning feather Yes (Slowly) Strong odour of burning feather Yes (Rapidly) Odour of burning paper Yes (Rapidly) Odour of burning paper Yes (Rapidly) Odour of burning paper Acid Yes
Nylon Yes
Yes
Yes
Yes
Celery
Polyester
Yes
Yes
Yes
Yes
Olefin Yes
Yes
Yes
Yes
Acrylic No
Yes
Yes
Yes
Mod- Yes acrylic Rubber Yes
Yes
Yes
No
Yes
Yes
No
Spandex Yes
No
Yes
Yes
Sweet characteristic odour Odour of burning plastic Odour of burning plastic Odour of burning plastic Odour of burning plastic Odour of burning plastic
Fibre
Continues to burn
Odour
Yes (Slowly)
Appearance of ash Black soft flake Black soft bead Light-grey soft flake Light-grey soft flake Light-grey soft flake Black hard irregular bead Grey hard round bead Black hard round bead Tan hard round bead Black hard irregular bead Black hard irregular bead Black or grey fluffy irregular mass Black or grey fluffy irregular mass
Textile Handbook 6-33 Table 1.10 (6) Typical Values of Physical Properties Useful for Identifying Fibres
Fibre
371 425 ...
1.790 2.322 15-1.57
1.662 1.637 1.49
0.128 0.685 0.01-0.08
1.37 1.42 2.1-2.8
6.5 3.5 ...
dnm dnm 288 (s)570 dnm dnm
1.596 1.580 1.37 1.547 1.536 1.650
1.528 1.533 ... 1.547 1.531 1.648
0.068 0.047 ... 0.000 0.005 0.002
1.54 1.54 2.1 2.47-2.57 1.28-1.37 1.29
12.0 7.4 0.0 0.1 1.3 6.0
219 254 275 265 185 176
1.568 1.582 1.554 1.550 1.55 1.484
1.515 1.519 1.510 ... 1.51 1.476
0.053 0.063 0.044 ... 0.04 0.008
1.1 1.14 1.03 1.25 1.04 1.20
4.0 4.2 2.5 9.1 1.0 2.5
135 170 194
1.556 1.530 1.626
1.512 1.496 1.566
0.044 0.034 0.060
0.93 0.90 1.21
0.0 0.01 0.3
256 227 283 225
1.710 1.690 1.632 1.662
1.535 1.524 1.534 1.568
0.175(10) 0.166 0.088 0.094
1.38 1.32 1.24 1.34
0.4 0.3 0.2 0.5
dnm dnm 170 dnm 230 288 dnm dnm dnm
1.548 4.547 4.603 1.591 1.5 1.472 1.543 1.541 1.556
1.527 1.521 1.611 1.538 ... 1.471 1.513 1.536 1.547
0.021 0.026 0.008 0.053 ... 0.001 0.030 0.005(4) 0.009
1.53 1.52 1.62-1.75 1.53 1.2 1.30 1.30 1.40 1.31
13.0 13.3 0.0 9.4 1.3 2.5 3.0 0.2 13.0
Textiles Testing and Quality Control
Acetate Acrylic Anidex Aramid Nomex Kevlar Abestos Cellulosic Flax Cotton Fluorocarbon Glass Modacrylic Novoloid Nylon Nylon 6 Nylon 6.6 Qiana Nylon 4 Nylon 11 Nytril Olefin Polyethylene Polypropylene Polycarbonate Polyester 2GTF(6) 4GTG(7) CHDM OxybenzoateI(9) Rayon Cuprammonium Viscose Saran Silk Spandex Triacetate Vinal Vinyon (PVC) Wool
BireRefractive Index(8) (2)(3) Melting(1) Parallel to Perpendicular fringence(8) Density3 Moisture mg/mm Regain Fibre Axis to Fibre Axis point˚C ε-ω ε ω 5.0 1.32 1.477 1.479 200 0.002 1.8 1.17 1.520 1.524 dnm 0.004(4) ... 1.22 (5) (5) (s) 190 (5)
6-34
Textiles Testing and Quality Control
Notes : (Table 1.10(6)) 1. dnm indicates the fibre does not melt, (s) indicates softening point. 2. The listed values are for specific fibres which warrant the highly precise values given. For identification purposes these values should be regarded as indicating only the relative values of the properties. 3. Measured at 65% relative humidity. 700F(210C). Listed values may not agree with the commercial moisture regains, which are arbitrarily set. 4. Varies, always weak, sometimes negative. 5. The fibre is opaque. 6. Ethylene glycol type. 7. 1,4-Butanediol type. 8. 1,4-Cyclohexanedimethanol type. 9. p-Ethylene oxybenzoate type 10. Staple and fully-oriented filament yarns (FOY), partially oriented (POY), and undrawn yarns may have much lower values of birefringence and refractive index.
1.11 Typical Fibre Testing Equipment 1.11.1 High Volume Instrument (HVI) The HVI system is designed to measure large quantities of bale cotton samples within a minimum time frame, as determining cotton fibre properties on a per-bale basis is a necessary pre-requisite for computerized bale management in modern spinning mills. Typical HVI measurements include Micronaire, Fibrogram length and length uniformity, 1/8 inch gauge length bundle tenacity, reflectance and yellowness on Hunter’s scale as well as optical trash particle counts and trash area. Before processing any measurement, the instrument should be calibrated using standard calibration cotton.
Textile Handbook 6-35
a) HVI Calibration Two different sets of calibration cottons are available from the US Department of Agriculture, Agricultural Marketing Services (USDAAMS) in Memphis, Tennessee: USDA HVI Calibration Cotton Standard (HVI-CC) and International Calibration Cotton Standard (ICC). Either one of these two sets of standards can be used for calibrating the HVI but the instrument readings will be different.
Micronaire calibration should be done with ICC only, since the Micronaire range provided by HVI-CC is not nearly large enough. Elongation calibration is not possible with HVI-CC. Colour tiles are available to calibrate the colorimeter and the grade boxes along with a dot matrix tile should be used for video trash meter calibration. For testing within the framework of the USTER STATISTICS, the HVI was calibrated with ICC, exclusively. From a global point of view, most HVI users in the spinning industry still tend to favour ICC calibration.
b) Length and Strength Parameters Len 1
(mm or in)
50% span length (ICC- mode, Figure. 1.11.b(1))
Len 2
(mm or in)
2.5% span length - classer’s staple (ICC mode) span length length of fibres protruding from a clamping point (Figure. 1.11.1b(1))
Len 1
(mm or in)
Mean length (HVI mode) = mean fibre, length
Len 2
(mm or in)
Upper half mean length (HVI mode) = mean length by weight of the longer 50% of fibres (Figure 1.11.1b(2))
Unif
(%)
Uniformity Ratio = length uniformity of the fibres. The Uniformity Ratio is only valid for the ICC mode.
Textiles Testing and Quality Control
Strength results with ICC calibration, for example, will be on a lower level (Stelometer) than with HVI-CC. Likewise, length will be given as 2.5% span length (SL 2.5%), 50% span length (SL 50%), and uniformity ratio (UR) when the HVI is calibrated with ICC and as upper half mean length (UHML), mean length (ML), and uniformity index (UI) when using HVI-CC.
6-36
Textiles Testing and Quality Control
Len 1x100 =Uniformity Ratio Len 2 The Uniformity Index is based on the same calculation as the Uniformity Ratio. The Uniformity Index is only valid for the HVI mode. Classification of the length uniformity: Uniformity Ratio very low below 40 low 41 - 43 average 44 - 46 high 47 - 48 very high above 49 Strength
(g/tex)
Uniformity Index below 76 77 79 80 82 83 85 above 86
Breaking force of the fibre bundle divided by fibre fineness Assessment of the fibre strength: Stelometer 1/8 (ICC) below 17 17 to 19 20 to 22 23 to 25 over 26
HVI 1/8(HVICC) below 21= very low 22 to 24 = low 25 to 27 = average 28 to 30 =high over 30 = very high
Elongation Amount
(%)
Breaking elongation of the fibre bundle Parameter describing the optically measured number of fibres in the bundle at the time of break
% Crimp
(%)
Fibre crimp, measured simultaneously with the fibre strength
Modulus
(N)
Material constant describing the tensile behavior of the fibre bundle
Brk For (N or lb)
Breaking force of the bundle
Work Peak
(J)
Work to peak, can be represented as area below the force/ elongation curve drawn to the peak point
S. F.
(%)
Short fibre index = percentage of fibres shorter than 12.7 mm
SCI
Spinning consistency index. A coefficient is
Textile Handbook 6-37
calculated by means of various quality characteristics by a multiple regression analysis. The main benefit of the SCI is a simplified selection of bales for a predetermined blend of fibres as well as the long-term check of the raw material blend. CSP
Count strength product = skein strength of a Ne 16 yarn
Ten @
[%]
Tenacity at a specified elongation
Work to %
[j]
Work until a specified elongation is attained
Work Tot
[j]
Total work, can be represented as area below the force/elongation curve
Figure 1.11.1.b. (1)
Span length mode/Fibrogram
Figure 1.11.1b.(2) USDA-mode/Fibrogram
Textiles Testing and Quality Control
The software for synthetic fibre testing provides the following additional parameters:
6-38
Textiles Testing and Quality Control
c) Micronaire Parameter (Mic) Mic Below 3.0 3.1-3.9 4.0-4.9 5.0-5.9 over 6.0
Micronaire Ratings: very fine fine average coarse very coarse
d) Colour & Trash Parameters Rd +b C-G
Area Cnt Trash
Reflectance of the fibres, higher Rd values mean a higher colour grade Yellowness of the fibres (Nickerson/ Hunter scale) Colour grade = Colour classing parameter according to the American Grade Standards (USDA) for Upland and Pima cottons or according to a user-specific classification Area of the sample covered with trash particles Number of trash particles Trash code = trash classing according to USDA
1.11.2 Advanced Fibre Information System (Uster AFIS) The Uster AFIS (Advanced Fibre Information System) is a laboratory instrument for single fibre testing. A pair of pin-type opening rollers, partially surrounded by carding segments, individualize the fibres and separate non-fibrous components. The fibre individualizer unit utilizes the principle of aeromechanical separation to extract trash particles, large seed coat fragments, and other types of foreign matter from the original fibre specimen. These objects are conveyed through the trash channel. Individual fibres, neps and small seed coat fragments (seed coat neps) pass through the fibre channel. Electro-optical sensors are installed in both the trash and the fibre channel and advanced signal processing technology is applied to identify and characterize several thousand individual cotton fibres, fibre entanglements and foreign matter. The modular concept of the USTER AFIS provides comprehensive information on the frequency distribution of pertinent dimensional parameter: single fibre length and the size of neps, trash and dust particles. AFIS also comprises the assessment of single fibre fineness and maturity distributions as well as the discriminative detection of seed coat fragment.
Textile Handbook 6-39
a) AFIS-L&M n w L (n,w) L (n,w) CV
[mm or in] [%] [%]
UQL (w)
[mm or in]
5% (n)
[mm]
2.5% (n)
[mm]
Fine
[mtex]
IFC
[%]
Mat Ratio b) AFIS-T Total Mean size Dust
[µm] [Cnt/g]
Trash
[Cnt/g]
V. F. M.
[%]
Total number of particles per gram Mean particle size Dust particles per gram (<500 µm) Trash particles per gram (>500 µm) Visible foreign matter
c) AFIS-L&D D (n)
[µm]
Fibre diameter
[%]
Coefficient of variation of the fibre diameter
D (n)
[Cnt/g]
Textiles Testing and Quality Control
SFC (n,w)
= by number of fibres = by fibre weight Mean fibre length Coefficient of variation of the fibre length Short fibre content, percentage of fibres shorter than half inch or 12.7 mm Upper quartile length = length exceeded by 25% of the fibres Length exceeded by 5% of the fibres Length exceeded by 2.5% of the fibres Fibre fineness (linear density) Immature fibre content = percentage of immature fibres Maturity ratio
6-40
Textiles Testing and Quality Control
1.11.3 MicroDust and Trash Analyser (Uster MDTA 3) Using the modified opening roller of a rotor spinning unit, the USTER MDTA separates the sample into trash, dust and fibre fragments. The respective contents of trash, dust and fibre fragments are determined with a precision balance. The percentage content of good fibres and trash is subsequently calculated. Lint
[%]
Percentage of fibres found in the lint bin or in the rotor ring
Trash
[%]
Trash content relating to the mass of the original specimen (>500µm)
Dust
[%]
Dust content relating to the mass of the original specimen (50 ... 250µm)
Fibre [%] fragment
Fibre fragment content relating to the mass of the original fragments specimen (250 ... 500µm)
Interpretation of the results A test on the USTER® MDTA 3 will provide the following results (example): Raw material
Sliver
Good fibre (lint) content:
97.67%
99.78%
Trash content (V.F.M.):
2.01%
0.11%
Dust content:
0.11%
0.05%
Fibre fragments:
0,21%
0.06%
Percentages will always add up to 100 %, since the total weight of the sample after processing is defined as 100 % (contrary to, e.g., the Shirley Analyzer, where the sample weight before processing is defined as 100%). Therefore no result for an “invisible loss” will be given.
Textile Handbook 6-41
1.11.4
Comparison Between USTER® MDTA 3 and USTER® AFIS-T
The comparison shows that the MDTA3 includes the microdust measurement in the dust measurement, whereas with the AFIS-T the microdust cannot, at the present time, be measured. Figure 1.11.4 (1)
Measured particle sizes with the USTER® MDTA 3 and USTER® AFIS-T
Fibre fragment MDTA-3
Trash
Microdust+Dust
AFIS-T
ITMFDefinition
0
Microdust+Respirable dust (planned)
Dust
Trash
RespirMicrodust able dust
Dust
Trash
15
50
500 (µm) Particle size
Textiles Testing and Quality Control
Instrument
6-42
Textiles Testing and Quality Control Figure 1.11.4 (2)
Comparison of the two methods
The following table compares several aspects of the two trash measuring systems:
Measuring principle
Measured properties good fibres (lint) trash dust microdust respirable dust fibre fragments Data output
AFIS-T Electro-optical (“single testing”) (=“microscope”)
MDTA 3 Gravimetric (“bundle testing”) (=“magnifying glass”)
No Yes Yes No No No (L-module>1mm) Particle count per gram Particle size Particle size histogram Prediction of gravimetric trash content(V.F.M.%) Integrated software with PC
Yes Yes Yes Yes (together with dust) No Yes
Separate via personal computer
Share in % of total weight
Data protocol System Balance required Test time
Module for AFIS basic unit Regular accuracy (0.01g)
Standalone instrument Precision scale (0.1mg)
15 min.
15-20min
Sample size
Up to 10x0.5 grams
3x10 or 20 grams
Visual assessment Space requirement Acceptance
Possible 108x95cm New method, of increasing importance Collection filter for gravimetric trash determination and visual analysis Input/output analysis to determine cleaning efficiencies
Possible 136x80cm Standard test, used by all major machine manufacturers ROTOR RING 3, as a module in the production line of the short spinning system to directly prepare slivers from bale cotton
Options
Textile Handbook 6-43
1.11.5 Recommendations for Fields of Application Figure 1.11.5
Recommendations for fields of application
(XX = very suitable, X = suitable) USTER USTER AFIS-T MDTA 3 + QUICKSPIN
XX
X
Ginners: Determination of cleaning efficiencies of lint cleaners
X
X
Checking of the ginning process to reduce seed coat fragments, smallest trash particles, etc. in bale cotton Cotton merchants: Determination of weight share of trash with respect to total weight of bale
X
X
Recommendations to customers (cotton with low dust content for rotor spinning, cotton with good cleanability, etc.)
X
X
Machinery manufacturers: Recommendations to customers for optimum machinery and operating element selection
XX
XX
XX
XX
Development of new machinery, operating elements, ginning machinery, spinning machinery components, etc., especially in the field of opening/cleaning, carding and rotor spinning: - for overall assessments - for detailed evaluations Spinning mills: Selection and purchase of raw material suitable for required yarn quality, etc. Checking of raw material and obtaining basic information on best processing procedures (number of cleaning points, suitable for rotor or ring spinning, etc.) Routine process monitoring
XX
XX
XX
XX
Process optimization (i.e., in opening/cleaning and carding or combing) for trash and nep content, particle size, etc,
X
XX
Problem analysis (i.e., different trash/dust deposits in rotor groove despite identical trash content in sliver)
X
XX
Prediction of the number of imperfections in yarns Prediction of the yarn characteristics (with USTER( QUICKSPIN)
XX XX
Textiles Testing and Quality Control
Cotton growers (seed breeding and research institutes): Determination of the influence of different harvesting methods, cotton varieties, etc. based on the trash content of seed cotton
6-44
Textiles Testing and Quality Control
1.11.6 Statistics on Raw Cotton Fibre Properties Determined with Uster HVI (Source: Uster Statistics 1997) Figure 1.11.6 (1) Micronaire, calibrated with ICC
Figure 1.11.6 (2)
50% span length, calibrated with ICC cottons
Figure 1.11.6 (3)
Uniformity ratio, calibrated with ICC
Textile Handbook 6-45 Figure 1.11.6 (4)
Bundle strength, calibrated with ICC cottons
Figure 1.11.6 (6)
Degree of yellowness on Hunter’s scale
Textiles Testing and Quality Control
Figure 1.11.6 (5) Reflectance on Hunter’s scale
6-46
Textiles Testing and Quality Control Figure 1.11.6 (7)
Trash count on surface
Figure 1.11.6 (8)
Percent of sample area covered by trash
Figure 1.11.6 (9)
Nep count per gram
Textile Handbook 6-47 Percentage of fibres ≤ 1/2 inch by number
Figure 1.11.6 (11)
Percentage of fibres ≤ 1/2 inch by weight
Figure 1.11.6 (12)
Number of trash particles per gram (>500(m)
Textiles Testing and Quality Control
Figure 1.11.6 (10)
6-48
Textiles Testing and Quality Control Figure 1.11.6 (13)
Number of dust particles per gram (<500(m))
Figure 1.11.6 (14)
Visible foreign matter content
Figure 1.11.7
Quality Factor Tolerance Quality Factor Tolerance
Micronaire (unit) Color Rd (unit) Color +b (unit) Trash (%area) Length (inches) Uniformity (percent) Strength (grams/tex)
± 0.100 ± 0.400 ± 0.400 ± 0.050 ± 0.007 ± 0.700 ± 0.500
Textile Handbook 6-49
SECTION 2
YARN TESTING
2.1 Yarn Conditioning (Source : ASTM D1907-80)
2.1.1 Basis of Unscoured Yarn
Option 2 - Moisture-free yarn. Option 3 - Moisture-free yarn plus commercial moisture regain.
2.1.2 Basis of’ Scoured Yarn Option 4 - Scoured yarn at equilibrium with the standard atmosphere for testing textiles. Option 5 - Moisture-free scoured yarn. Option 6 - Moisture-free scoured yarn plus commercial moisture regain. Option 7 - Moisture-free scoured yarn plus commercial allowance (commercial moisture regain plus allowance for finishing materials).
2.1.3 Preconditioning (Options 1 and 4 only) Precondition skeins as wound for Option 1 or scoured and air-dried skeins for Option 4 for at least 3 hours in an atmosphere with a relative humidity between 5 and 25% and a temperature not exceeding 50°C (122°F). NOTE: In Option 1, preconditioning and conditioning may be done before reeling. It is usually not convenient, however, to pre-condition large-size packages in an oven or a small cabinet. It is therefore preferable to precondition (and then to condition) the yarn in skein form.
Textiles Testing and Quality Control
Option 1 - Yarn at equilibrium with the standard atmosphere for testing textiles.
6-50
Textiles Testing and Quality Control
2.1.4 Conditioning (Options 1 and 4 only) Condition the preconditioned skeins in the standard atmosphere for testing textiles, 70 ± 2 °F (21 ± 1 °C) and 65 ± 2% relative humidity, until moisture equilibrium for testing is reached, that is until the mass of the specimen increases by no more than 0.1% after 2 hours in the standard atmosphere for testing.
2.1.4 Oven-Drying (Options 2, 3, 5, and 6, and 7 only) Place the skeins as wound, or after scouring in an oven, and maintain the temperature at 105 ± 3°C (221 ± 6°F). Arrange the skeins to permit free access of air. Dry the yarn to constant mass, that is until it loses no more than 0.1% of its mass at 15-min intervals if weighed in the oven or at 30-min intervals if weighed outside the oven.
2.2 Yarn Numbering Systems 2.2.1 Direct and Indirect Systems Direct system is linear density and is always expressed in terms of weight/unit length. Often some of the particular units, such as denier or tex are used. Clearly, as the yarn gets coarser, the number gets larger. The indirect system is expressed in terms of length/unit weight. As the yarn gets coarser, the number gets smaller.
Direct yarn number =
Weight (or mass) Length
Length Indirect yarn number = Weight (or mass)
Textile Handbook 6-51 Table 2.2.1 Yarn Numbering Systems Table Direct Name Fibre Cotton Wool Man-made Intermediate products Picker lap
Indirect Name Units
Micronaire Micrograms/in. Milligrams/cm Denier Grams/9000 m
Lap “weight”
Diameter
Ounces/yd Or pounds/lap*
Sliver “weight” Grains/yd or Grams/meter kilotex**
Yarns Man-made Denier yarns All yarns Tex (scientific) Cotton & blend yarns
Grain/yd**
Hank Hanks/lb roving Nc
Grams/ 9000metres Grams/ 1000metres
Worsted yarns
English cotton count Ne Worsted count Nw
Woolen yarns
Woolen run Nwr
All yarns (European)
Metric count Nm
Note : * for known lap length ** Infrequently in USA
Other Name Units
Hank/lb (hank=840 yds) Hank/lb (hank=560 yds) Hank/lb (hank=1600 yds) metre/gram
microns
Textiles Testing and Quality Control
Sliver Top Comber lap Comber ball Roving (cotton)
Units
6-52
Textiles Testing and Quality Control
2.2.2 Conversion Between yarn Numbering Systems Table 2.2.2 Count conversions tex
dtex
den
dtex÷10
tex
Nm
den÷9
1000÷Nm
den÷0.9
10000÷Nm
dtex
texx10
den
texx9
dtexx10
Nm
1000÷tex
10000÷dtex 9000÷den
NeC
590.54÷tex 5905.4÷dtex 5314.9÷den Nmx0.5905
9000÷Nm
NeC
NeW
590.54÷Nec 885.8÷New 5905.4÷Nec 8858÷New
New÷1.5
NeW
885.8÷tex
NeL
1653.5÷tex 16535÷dtex 14882÷den Nmx1.6535 Necx2.8
Newx1.87
8.3÷Nec
12.5÷New
grains/yd tex÷70.86
dtex÷708.6
den÷637.7
14.1÷Nm
grains/yd
16535÷NeL gr/ydx708.6 5314.9÷Nec 7972.3÷New 14882÷NeL gr/ydx637.7 Necx1.6934 Newx1.13 NeLx0.6048 14.1÷gr/yd
7972.3÷den Nmx0.8858 Necx1.5
8858÷dtex
NeL
1653.5÷NeL gr/ydx70.86
NeL÷2.8
8.33÷gr/yd
NeL÷1.87
12.5÷gr/yd 23.33÷gr/yd
23.33÷NeL
2.2.3 Yarn Diameter Yarn diameter helps determine how closely the yarns can be packed to make a fabric or how well a given yarn will cover in a given fabric. The linear density of a yarn is equal to the product of the number of fibres and the average linear density of the fibres. n y = m x nf where ny = the linear density of yarn, nf = the linear density of fibre, and m = the number of fibres in the cross section. Assume that the fibres are evenly spread throughout the cross section at a rate of b fibres per square inch. A yarn of diameter d inches has a cross-sectional area of πd2/4 sg.ins and contains (πd2/4)b fibres [i.e., m = (πd2/4)b]. Substitute for m in the above eequation and rearrange
√nn
d=
y f
4 bπ
Thus, for a given fibre, d α√ny . Also, referring back, it will be realized that the diameter is also inversely proportional to the square root of the yarn count (i.e. d α 1 ). √ne
Opening line
- Fibre staple - Amount of waste length - Fibre fineness (Micronaire) - Fibre Strength (Pressley) - Waste content - Classification - Colour - Maturity (Caustic Method) - Moisture content
Bale
- Sliver - Lap weight count - CV% 10m sliver - CV% 1cm - Spectrogram - Diagram
- Sliver count - CV% 100m sliver - CV% 1cm - Spectrogram - Diagram
- Neps - Waste amounts
Drawframe
Card Sliver lap machine
Ribbon lap 2.passage Draw-frame
- sliver count - CV% 1m sliver - CV% 1cm - Spectro-gram - Diagram
1.passage Draw-frame
- Sliver count - CV% 10m sliver - CV% 1cm - Spectrogram - Diagram - Comber noil %
Comber
Cone winder - Yarn faults S/ L/T/Yarn breaks - Yarn faults (classimat) - Yarn friction - Moisture content
Ring spinning - Yarn count - CV% 100m - CV% 1cm - Thin & thick places, neps - Spectrogram - Diagram - Variance length curves - Histrogram - Hairness - Breaking force - Breaking elongation - Yarn twist - Yarn faults (classimat) - End breaks
Roving maching - Roving count - CV% 10m - CV%1cm - Spectrogram - Diagram
Textiles Testing and Quality Control
Sliver lap machine
Table 2.3 (1) Quality Test Parameters For Combed Cotton Spinning
2.3 Testing Plan
Textile Handbook 6-53
- Fibre staple length - Fibre fineness (Micronaire) - Fibre Strength (Pressley) - Waste content - Classification - Colour - Maturity (Caustic Method) - Moisture content
Bale
Table 2.3 (2)
Card
- Amount of waste - Sliver count - Micro-dust content - CV% 100m silver - CV% 1cm - Spectrogram - Diagram - Neps - Waste amounts
Opening
2.passage Drawframe
- Sliver count - CV% 1m sliver - CV% 1cm - Spectrogram - Diagram
1.passage Drawframe
Quality Test Parameters For OE - Rotor Spinning
- Yarn faults - Yarn count (classimat) - CV% 100m yarn Yarn faults S/L/T/MO - CV% 1cm - Yarn breaks - Thin & thick - Yarn twist places, neps Yarn friction - Spectro-gram Moisture content - Diagram - Variance - length curves - Histogram - Hairiness - Breaking force - Breaking elongation
OE-Rotor spinning
6-54
Textiles Testing and Quality Control
Textile Handbook 6-55 Table 2.3 (3)
Cleaning line
Test Quality Fibre Testing interval method Parameter assembly 1 per semester - Amount of Fibre flocks/ waste Off-line - Microdust waste content - Sliver Continuous Sliver count - CV% 100m Online sliver - CV% 1cm - Spectrogram 1 per month *Sliver count Sliver 1 per month * CV% 1cm Sliver * Spectrogram Off-line - Diagram - Neps S l i v e r / 1 per semester Web -Amount of S l i v e r / 1 semester waste waste
Note : * For checking the online system
Sample/ size Testing instrument
100% Production
1 x 100m min. 125m
- DenkendorfDust & Trash Analyser or Shirley-analyser USTER Sliverdata
USTER Autosorter USTER Tester
Toenniessen Neps-tester Denkendorf Dust &Trash Analyser or Shirley analyser
Textiles Testing and Quality Control
Card with autolevelling
Combination of Online and Off-line Quality Assurance at Opening Cleaning and Carding
6-56
Textiles Testing and Quality Control Table 2.3 (4) Combination of Online and Off-line Quality Assurance at Combing Test Quality Parameter Fibre method assembly Off-line Lap weight Sliver lap
Sliver lap machine Ribbon Off-line Lap weight lap machine Comber Off-line Sliver count
- CV% 1cm - Spectrogram - Diagram - Comber waste % Drawfr- Online * Sliver count ame as - CV% 1m sliver combing - CV% 1cm prepar- Spectrogram ation Off-line . Sliver count
Sliver lap machine
* CV% 1cm * Spectrogram - Diagram Off-line Lap weight * Sliver count
Comber Off-line - Sliver Count * CV% 1cm * Spectrogram - Diagram Comber waste % * For checking the online system
Testing interval 1 per day
Sample/ size 6 full laps
Testing instrument Balance
Sliver lap
1 per week 8 full laps
Balance
Sliver
1 per week 3 x 10m per delivery 1 per week At least 12.5m per delivery
USTER Autosorter USTER Tester
Sliver / comber Sliver
1 per week Continuous 100% production
USTER Autosorter USTER Sliverdata
Sliver
1 per week 3 x 10m per delivery 1 per week At least 12.5m delivery
USTER Autosorter USTER Tester
1 per week 8 full laps 1 per week 3 x 10m per delivery 1 per week 3 x 10m per delivery 1 per week At least 12.5m delivery
Balance USTER Autosorter USTER Autosorter USTER Tester
1 per week
USTER Autosorter
Sliver
Sliver
Sliver lap Sliver Sliver Band
Sliver/ Comber
Textile Handbook 6-57 Table 2.3 (5)
Combination of Online and Off-line Quality Assurance at Drawing
Test Quality Parameter Fibre method assembly 1.Passage - Sliver count Sliver Drawing - CV% 1m sliver Online - CV% 1cm - Spectrogram * Sliver count Sliver Off-line
Off-line
* CV% 1cm * Spectrogram - Diagram
Testing instrument USTER Sliverdata
1 per week 3 x 10m per delivery 1 per week At least 12.5m per delivery
USTER Autosorter USTER Tester
Sliver
Continuous 100% production
USTER Sliverdata
Sliver
1 per week 3 x 10m per delivery 1 per week At least 12.5m per delivery
USTER Autosorter USTER Tester
Sliver
Sliver
Note : * for checking the online system Table 2.3 (6) Test method
Combination of Online and Off-line Quality Assurance at Roving and Ring Spinning
Quality Parameter Roving count
Testing Sample/ size Testing interval instrument Roving 8 Roving 1 per week Each 1 x 10m USTER machine Off-line bobbins; 4 front Autosorter + 4 back - CV% 1cm 8 Roving 1 per week Each at least USTER 12.5m Tester - Spectrogram bobbins; 4 front - Diagram + 4 back RingUSTER Continuous 100% Yarn Online End breaks production spinning Ringdata machine - Yarn count 1 per week Each 1 x 100m USTER 20 Cops Autosorter - CV% 100m USTER 1 per month Each min. 10 Cops - CV% 1cm Off-line - IPI Tester 1000m - Spectrogram - Diagram USTER 10 Cops 1 per month Each min. Hairiness Tester 3 1000m USTER 1 per month Each 20 - Breaking force 10 Cops Tensorapid samples/ cops - Breaking elongation Fibre assembly
Textiles Testing and Quality Control
* CV% 1cm * Spectrogram - Diagram 2.Passage - Sliver count Drawing - CV% 1m sliver Online - CV% 1cm - Spectrogram * Sliver count
Testing Sample/ size interval Continuous 100% production
6-58
Textiles Testing and Quality Control
Yarn twist
10 Cops
Yarn faults (Classimat)
Cops
Table 2.3 (7)
By change 10 samples/ of style cops 1 per month 300000m and style
Zweigle USTER Classimat
Combination of Online and Off-line Quality Assurance at OE- Rotor Spinning
Quality Parameter OE- CV% 1cm Rotor - IPI Spinning - Spectrogram Machine Online - Yarn faults Yarn faults S/L/T/Mo Yarn breaks Test method
- Yarn count - CV% 100m - CV% 1cm - IPI/ Diagram - Spectrogram Hairiness
Sample/ Testing Fibre Testing interval size instrument assembly USTER Yarn 100% Continuous production Polyguard with Q-Packet Yarn
Continuous
Yarn
Continuous
20 Spools 1 per week 10 Spools 1 per month
10 Spools 1 per month
Off-line - Breaking force 10 Spools 1 per month - Breaking elongation Moisture content Spool Per yarn batch Yarn friction 10 Spools 1 per month Yarn twist
Spool
1 per month
100% USTER production Polyguard USTER Polyguard 100% production & USTER Rotordata Each 1 x USTER 100m Autosorter Each min. USTER Tester 1000m Each min. USTER tester 3 1000m Each 20 USTER samples/ Tensorapid cops 10 Spools Mahlo 10 Spinning Schlafhorst positions 10 samples per spool
Zweigle
Textile Handbook 6-59 Table 2.3 (8)
Combination of Online and Off-line Quality Assurance at Cone Winding
Quality Test Parameter method Cone Online Yarn faults winder S/L/T/ Yarn breaks Yarn faults (Classimat)
Cones
1 per month 10 cones; each min and style 1000m
USTER Tester
Cones
1 per month 10 cones; and style each min 1000m 1 per month Each 20 and style samples per cone
USTER Tester3
1 per month All winding positions Per yarn 10 cones batch
Schlafhorst
- Breaking force Cones - Breaking elongation Yarn friction Cones Moisture content
Cones
USTER Tensorapid
Mahlo
Textiles Testing and Quality Control
- CV% 1cm - IPI - Spectrogram Off-line - Diagram - Hairness
Testing Fibre Testing Sample/ size instrument assembly interval Cops USTER electronic Continuous 100% production yarn clearer/ Conedata 1 per month 300,000m USTER Cones and style Classimat
6-60
Textiles Testing and Quality Control Table 2.3 (9)
Quality Parameter, Testing Conditions and Sample Sizes
Parameter Abbre- Unit viation Micronaire Mic Span Length SL 2.5% SL 50% UR Bundle Strength Tenacity Colour Rd +b Trash CNT Area Neps Neps/g Length SFC(n) SFC(w) UQL(w) Trash Trash/g Dust/g VFM Count CVb variation U% Mass CV% variation CVb H Hairiness SH CVb Imperfections Thin Thick Neps CLASSIMAT A…I defects RH Tensile Properties CVRH
εH
CVε H WH CVWH HV Tensile RH Properties CVRH
εH
CVεH WH CVWH F P=0.1 εP=0.1
Instrument
No. of Tests Testing Duration samples within speed of test (m/min) (min) 10 USTER®HVI 1 10 USTER®HVI 1 mm 10 1 mm 10 1 % 10 USTER®HVI 1 g/tex 10 1 10 USTER®HVI 1 % 10 1 10 USTER®HVI 1 % 10 1 10 USTER®AFIS 1 1/g 10 USTER®AFIS 1 % 10 1 % 10 1 mm 10 USTER®AFIS 1 1/g 10 1 1/g 10 1 % 1 USTER®AUTOSOR- 20 % TER3 2.5 400 1 USTER®TESTER3 10 % 2.5 400 1 10 % 2.5 400 1 10 % 2.5 400 1 USTER®TESTER3 10 2.5 400 1 10 2.5 400 1 10 % 2.5 400 1 1/1000m USTER®TESTER3 10 2.5 400 1 10 1/1000m 2.5 400 1 10 1/1000m 800 USTER®CLASSI10 1/100km MAT2/3 5 20 10 cN/tex USTER®TENSO5 20 RAPID3 10 % 5 20 10 % 5 20 10 % 5 20 10 cNcm 5 20 10 % 1000 400 cN/tex USTER®TENSOJET 10 1000 400 10 % 1000 400 10 % 1000 400 10 % 1000 400 10 cNcm 1000 400 10 % 1000 400 10 cN 1000 400 10 %
Textile Handbook 6-61
2.4 Yarn Count Testing The count of a yarn is a numerical expression which defines its fineness.
2.4.1 Instruments a) Wrap Reel with circumference 54" ± 0.1% (see Figure 2.4.1.a) b) Balance of accuracy within ± 0.2% (see Figure 2.4.1b)
d) Temperature and humidity controller Figure 2.4.1.a
Figure 2.4.1.b
2.4.2 Sampling Usually 8 to 16 samples are taken from a batch. It is recommended that they are from different packs and from different groups. For bobbin cops, some specimens are taken from the top and some from the middle. If it is a cone stage, 2 specimens are taken from each cone with sampling size of 8, one from the outer shell and one from the inner core. Actually, the number of bobbins in the sample may be chosen to suit a particular quality control system.
2.4.3 Testing procedure a) A wrap reel is a simple instrument consisting of a reel, yarn package creel, a yarn guide which has a small sideways traverse to spread the loops of yarn, and a length indicator. For cotton yarn, the reel has a girth of 54 inches, that is 11/2 yards, so that 80 revolutions of the reel produces a skein of 120 yards (a lea).
Textiles Testing and Quality Control
c) Oven which is able to maintain a temperature of 105oC ± 2 oC
6-62
Textiles Testing and Quality Control
b) Where possible, it is recommended that yarn should be allowed to condition in the testing atmosphere. c) The analytical balance used in the determination of count must be accurate with not more than 0.2% accuracy. The balance should be well maintained, and before use it is levelled and checked. d) The leas of yarn of 120 yards are wrapped on the reel at the correct and even tension. e) The specimens are then weighed and their yarn counts are computed.
2.5 Lea Yarn Strength 2.5.1 Lea Yarn Strength Testing A 120 yard hank of yarn is directly wrapped on the wrap reel, with its starting and finishing ends knotted, is placed over the hooks of a lea tester. As the lower hook descends, a load is imposed on the loops of yarn constituting the hank. At some point one of the threads breaks, and ultimately the hank suffers a succession of thread breaks, the pendulum lever tester stops moving and the ‘lea strength’ of the hank is indicated on the dial. The yarn count is also measured and the count strength product, which is a useful measure of the merit of the yarn from a strength point of view can also be computed by multiplying the average yarn count with the average lea strength.
2.5.2 Yarn Strength Conversion 1 hank x 2.05 2 • Lea Strength =Lea Strength of 1 hank x 4.4 4 • Lea Strength (kg) = Single yarn strength (g) x 1 K where K: count in tex; 10-34 Tex K=6.0 38-44 Tex K=6.25 46-85 Tex K=6.5 • Lea Strength =Lea Strength of
Textile Handbook 6-63
• Single yarn strength (oz) = 0.1408xLea strength (lbs) • Lea strength in Metric System (kg) = 0.6xLea strength in English System (lbs) where 1 Lea in Metric system = 100 metres, 1 Lea in English system = 120 yards Table 2.5.3
Correlation between Moisture Regain (M.R.) and Yarn Strength of Cotton Yarn
ASTM formula
M x [100 + (rxR)] 100 + (r x R)
where
S= corrected strength (lbs.) M= tested strength (lbs.) R= standard M.R. (Nominal 7%) A= measured M.R.(%) r = cotton yarn strength variation (%) due to increase or decrease of M.R.% (normally the variation is 6%)
e.g. Measured M.R. is 8%, and tested strength is 94.6 lb 94.6 x [100 + 6 x 7)] Corrected Strength = =90.7lb 100 + (6 x 7)
Textiles Testing and Quality Control
S=
6-64
Textiles Testing and Quality Control Table 2.5.4
Correlation Between Fibre Length, Yarn Count and the Estimated Yarn Strength of Cotton Yarn
Sheldon’s Formula [1+0.1(L-16)+0.01(28-C)] C where K= 1600 (carded yarn) K = 1750 (combed yarn) L = fibre length (1/16") C = English cotton count Lea Strength (S)=
Carded Cotton Warp Yarn Strength (lb) Count 10 14 16 20 30 32 36 40 42 50 60
7/8"
1"
150.5 106.0 90.0 68.0 40.0 35.5 30.5 25.5 23.5 17.0 11.5
186.5 130.0 111.5 85.5 52.5 48.0 41.0 35.5 33.0 25.0 17.5
Fibre length (in) 1-1/8" 218.5 154.0 133.0 103.5 64.5 60.0 51.0 44.0 41.0 32.0 23.0
1-1/4"
13/8"
254.0 178.0 155.0 122.5 75.0 69.0 60.0 52.5 49.0 39.0 30.0
/ 205.0 176.5 140.5 86.0 80.0 70.0 62.0 58.5 46.5 36.5
Combed Cotton Warp Yarn Strength (lb) Count 20 30 32 36 40 42 50 60 80 100
1-1/8" 113.0 70.5 64.5 56.0 48.0 45.0 35.0 26.5 15.5 8.5
1-1/4" 1132.5 82.5 76.5 66.5 57.5 54.0 43.0 32.5 20.5 12.5
Fibre length (in) 1-3/8" 151.5 96.0 89.0 77.5 68.0 64.0 51.0 39.5 25.5 16.50
1-1/2" 270.0 108.0 100.0 88.0 77.5 73.0 58.5 45.5 30.0 20.0
1-5/8" 189.0 121.5 112.0 99.0 87.0 82.0 65.5 51.0 34.5 24.5
2.6
Yarn Twist Testing ............................................................ 6-65
2.7
Yarn Appearance Characteristics ................................... 6-66 2.7.1 2.7.2 2.7.3 2.7.4 2.7.5
2.8
Count Variation ........................................................... 6-66 Mass Variation ............................................................. 6-66 Hairiness ...................................................................... 6-67 Imperfections ............................................................... 6-67 Testing of Yarn Appearance Characteristics (USTER Yarn Testing Series) ...................................... 6-67
Tensile Properties .............................................................. 6-71
2.8.1 Uster Tensojet .................................................................... 6-72 2.9
Classimat Defects .............................................................. 6-73
2.10 Yarn Quality Statistics of 100% Cotton Carded Ring Spun Yarns ......................................................................... 6-74 2.10.1 2.10.2 2.10.3 2.10.4
Yarn Quality ................................................................ 6-74 Imperfections ............................................................... 6-77 CLASSIMAT Defects ................................................. 6-77 Tensile Properties ........................................................ 6-78
Back to Table of Content
Textile Handbook 6-65
2.6 Yarn Twist Testing As twist is not usually distributed uniformly along a yarn, it has been recommended that the twist should be determined at least one yard between consecutive tests along the yarn. Normally, equal number of tests from the packages should be taken. The minimum number of tests to carry out is given in Table 2.6(1). Table 2.6(1)
Yarn Twist Testing
Plied and cabled yarn Continuous filament yarn (single) Grey yarn (single) spun from long bast fibres Spun single yarn
Minimum number of tests
Length of test specimen (inch)
20 20
10-20 10-20
50 50
10-20 10-20
A twist tester has a pivot and carries a pointer (see Figure 2.6(2)). Firstly, the yarn is gripped in the left hand clamp on a pivot. The yarn is then led through the rotating jaw on the right hand side. The yarn is pulled through on the right side until the pointer on the left side lies on a zero mark on a small quadrant scale. The rotating jaw is then closed. The specimen is under a small tension and has a nominal length of 10 inches or 20 inches. As the rotating jaw rotates, the twist is untwisted, the yarn extends and the pointer drops to the left. While testing single spun yarn, eventually all the twist is taken out and the jaw is kept rotating in the same direction until sufficient twist has been inserted to bring the pointer back to the zero mark again. The total number of turns registered on the revolution counter should be divided by 2, and by the length of the specimen for calculation of twists per inch.. When testing plied yarns the pointer has freedom to move over the quadrant scale. The scale is graduated, in tenths of an inch, so that the contraction can be noted. While all the doubling twist is being removed, the number of turns is noted on the revolution counter; the reading should be divided by the length of the specimen in order to obtain the number of twists per inch.
Textiles Testing and Quality Control
Type of yarn
6-66
Textiles Testing and Quality Control
The required tension is applied by clipping a weight to the end of the yarn. Usually Tension = tex / 2 gm ± 10% To prevent the yarn from being stretched when the twist has been removed, an adjustable stop on the quadrant restricts the swing of the pointer towards the left end. Figure 2.6(2)
Twist Tester
2.7 Yarn Appearance Characteristics 2.7.1 Count Variation The term count variation (CVb) denotes the between-sample coefficient of variation of yarn count in percent. Count variation can be determined semi-automatically with the USTER AUTOSORTER by reeling 100m or 120 yards of yarn off each bobbin or package and placing each skein on the balance. The calculation is performed by the instrument. The fully automatic module of the USTER TESTER provides a fully automatic determination of the yarn count and count variation. It is a well documented fact that a count variation of CVb >3.0% can impair fabric appearance, primarily in knitting.
2.7.2 Mass Variation Mass variation includes nomograms on the mean linear irregularity (U%), the coefficient of variation of yarn mass (CV%) and the between-
Textile Handbook 6-67
sample coefficient of variation of the CV% (CVb) In the last few years, the USTER CV% has clearly become more popular than the USTER U%, the classic measure of yarn evenness. A factor of 1.25 has been derived from the theoretical considerations which are based on the assumption that the yarn mass signal corresponds to a perfect normal distribution.
2.7.3 Hairiness
2.7.4 Imperfections The sensitivity settings for the detection of imperfections are -50% for thin places, +50% for thick places, and +200% for neps. These settings are commonly used for all yarn types except rotor-spun yarns. Neps in rotor-spun yarns tend to be spun into the solid yarn body which represents a short mass defect, and therefore the +280% sensitivity setting for neps has become a common convention for the testing of rotor spun yarn.
2.7.5 Testing of Yarn Appearance Characteristics (USTER Yarn Testing Series) Mass variations, count variations and imperfections have a decisive influence on the utility and market value of a yarn. The USTER TESTER determines these quality parameters on yarns, rovings and slivers very quickly. The capacitive measuring system permits fast and reproducible measurements. Based on spectrograms and diagrams, it is easy to eliminate the sources of defects. In recent years. the hairiness measurement has become more and more important, because hairiness can also affect the quality of a woven or knitted fabric, The modular design of the USTER TESTER permits simultaneous testing of all parameters. With the USTER, TESTER 4 additional optical sensors have been introduced (sensors OM and OI).
Textiles Testing and Quality Control
Yarn hairiness is expressed in the form of the hairiness value H, which is an indirect measure for the number and the cumulative length of all fibres protruding from the yarn surface. High or low hairiness is not necessarily a quality deficiency. The yarn hairiness requirements are strictly governed by the end use. Yarns with higher hairiness are usually produced for end uses in knitting, such as underwear, knitted outerwear and sportswear. Most weaving applications call for a smooth yarn surface, especially with warp yarns.
6-68
Textiles Testing and Quality Control
a) Parameters Measured by Capacitive Measuring Unit Figure 2.7.5.a.(1)
Irregularity U
Figure 2.7.5.a (2)
Coefficient of Variation CV
Textile Handbook 6-69
Um
[%]
Mean linear irregularity now obsolete, CVm is more common today, Figure 2.7.5a (1))
CVm
[%]
Coefficient of variation of the yarn mass (Fig 2.7.5 a (2))
CVm(L)
[%]
Coefficient of variation of the yarn mass at cut lengths of 1, 3, 10, 50, 100 m and in the Inert and Half Inert modes
Mass deviation
m(max)= maximum mass
cut lengths for the calculation are 1, 3, 10 m or Half Inert Index
Ratio between the ideal and actual evenness of staple fibre strands
Imperfections
Number of thin places, thick places and neps at selected sensitivity settings (staple fiber yarns only)
- thin places:
-30% , -40%, -50%, -60%
- thick places:
+35% , +50% , +70%, +100%
- neps:
+140%, +200%, +280%, +400%
Rel. count
Abs. count
[%]
Count deviation relating to the length of yarn tested; the mean corresponds to 100% Linear density of the yarn e.g. tex, Ne
b) Hairiness Measuring Sensor (sensor OH) The receiver detects only the light transmitted by the protruding fibres (Figure 2.7.5b). The yarn body remains black and does not transmit light. The light intensity at the receiver, therefore, measures the light intensity which is proportion to the hairiness of the yarn.
Textiles Testing and Quality Control
m(min)= minimum mass
6-70
Textiles Testing and Quality Control Figure 2.7.5 b
Protruding Fibres Detected by Sensor OH
Hairiness
The hairiness H corresponds to the total length of protruding fibers divided by the length of the sensor of 1 cm, therefore the hairiness is a figure without a unit.
sh
Standard deviation of hairiness
sh (L)
Standard deviation of hairiness at cut lengths of 1, 3, 10, 50, 100 m
Hairiness deviation h(max)= maximum hairiness h(min)= minimum hairiness cut lengths for the calculation are 1, 3, 10 m
c) Multifunctional Measuring Unit (sensor OM) This is an optical sensor which illuminates the yarn from 2 different directions and with an angle of 90 degrees.
2DØ
[mm] Mean value of the two-dimensional diameter over the measured yarn length
s2D8mm
[mm] Standard deviation of the diameter over the reference length of 8 mm
CV2D8mm [%]
Coefficient of variation of the diameter over the reference length of 8 mm
Textile Handbook 6-71
CV2D 0.3mm [%] Coefficient of variation of the diameter over the reference length of 0.3 mm CV FS
[%] Coefficient of variation of the fine structure, assessment of short-wave variations
CV1D 0.3mm [%] Coefficient of variation of the onedimensional yarn diameter, related to 0.3 mm Non-dimensional value between 0 and 1, which describes the roundness of a yarn (1 = circular, 0.5 = elliptical)
D [g/cm3]
Mean yarn density related to the nominal count
2.8 Tensile Properties The term CRE serves as an abbreviation for ‘constant rate of extension’. CRE describes the movement of the moving clamp which is displaced at a constant velocity. The velocity of the moving clamp, also referred to as the testing speed, must be exactly 5m/min. The gauge length, i.e. the length of the specimen, or the distance between the stationary and the moving clamp, should be 500mm and a pre-tension of 0.5cN/tex must be applied. In general, there are two fundamental criteria which affect the compatibility between different measurements of tensile yarn properties: testing conditions, i.e. the testing principle (CRE, CRL), testing speed, gauge length and pre-tensioning; and the specific stress/strain characteristic of the yarn itself, which is determined by the fibrous materials, the blend ratio, and the yarn construction. The breaking tenacity is calculated from the peak force which occurs anywhere between the beginning of the test and the final rupture of the specimen. The peak force or maximum force is not identical with the force measured at the very moment of rupture (force at rupture). The breaking elongation is calculated from the clamp displacement at the point of peak force. The elongation at peak force is not identical with the elongation at the very moment of rupture (elongation at rupture). The work to break is defined as the area below the stress/strain curve drawn to the point of peak force and the corresponding elongation at
Textiles Testing and Quality Control
Shape
6-72
Textiles Testing and Quality Control
peak force. The work at the point of peak force is not identical with the work at the very moment of rupture (work to rupture) (see Figure .2.8). Figure 2.8
Tensile Strength Testing
2.8.1 Uster Tensojet The USTER TENSOJET is a laboratory instrument which provides highvolume and high-velocity features in tensile testing (see Figure2.8.1) . The mechanism to load, elongate and finally break the test sample consists of two pairs of counter-rotating rollers, which are arranged at a distance of 500 mm. The measuring cycle consists of four phases: continuous yarn take-up and intermediate storage, insertion of the yarn by a compressed air nozzle, clamping and extension to rupture by the rollers, and removal of the broken end into the waste bin via an air flow. The USTER TENSOJET operates according to the CRE principle at a testing speed of 400m/min. The actual time-to-break is about 3ms for a 100% cotton yarn. The instrument is capable of performing 30,000 individual breaks per hour. Parameters measured by Tensojet are: B-Force
[cN]
Breaking force = maximum tensile force measured
Elongation
[%]
Breaking elongation = elongation at maximum force
Tenacity
[cN/tex]
Breaking force divided by the linear density of the specimen
B-Work
[cNcm]
Work to break = work at breaking force (area below the force/elongation curve drawn to the point of maximum force
Max values
Maximum value of force, elongation, tenacity or work within one test series
Textile Handbook 6-73
Min values
Minimum Value of force, elongation, tenacity or work within one test series
Percentile Values e.g. P. 0.01
0.01%, 0.05%, 0.1%, 0.5%, 1.0% of all measurements are below the reported value
Figure 2.8.1 Uster Tensojet
There are basically two types of yarn faults. Firstly, there are the frequent yarn faults, known as imperfections, which are detected with an evenness tester. Secondly, there are rate yarn faults, which occur at such irregular intervals that at least 100 km of yarn has to be tested to ensure reliable detection. For open-end yarns, a test length of 1,000 km is recommended. As a yarn fault classifying installation, the USTER CLASSIMAT detects all seldom-occurring yarn faults and classifies these into the respective classes of the CLASSIMAT system. Using the CLASSIMAT matrix, it is possible to define or control the most suitable yarn clearer settings. The defect classification matrix covers short thick places (A, B, C, D), long thick places (E, F, G) and long thin places (H, I). The classification system is illustrated in Fig 2.9. Figure 2.9
Classimat Defect Classication Matrix
Textiles Testing and Quality Control
2.9 Classimat Defects
6-74
Textiles Testing and Quality Control
Where : Fault lengths A: B+TB C+TC D+TD E F+H G+1 Fault sizes 0 1 2 3 4 E F+G TB1/TC1/TD1/H1/I1 TB2/TC2/TD2/H2/I2 Fault channels of the clearers N channel for very short thick places S channel for short thick places L channel for long thick places T channel for long thin places C channel for count deviations
shorter than 1 cm 1 to 2 cm 2 to 4 cm 4 to 8 cm longer than 8 cm 8 to 32 cm longer than 32 cm +45 to +100% +100 to +150% +150 to +250% +250 to +400% over +400% over +100% +45 to 100% -30 to -45% -45 to -75%
Sensitivity +100% to +500% +50% to +300% +10% to +200% -10% to -80% % to 0%
Reference length 1 to 10 cm 1 to 200 cm 10 to 200 cm 12.8 m
2.10 Yarn Quality Statistics of 100% Cotton Carded Ring Spun Yarns (Source: Uster Statistics 1997) 2.10.1 Yarn Quality Figure 2.10.1(1)
Between-bobbin coefficient of variation of yarn count
Textile Handbook 6-75 USTER U%, mean linear irregularity of yarn mass
Figure 2.10.1(3)
USTER CV%, coefficient of variation of yarn mass
Textiles Testing and Quality Control
Figure 2.10.1(2)
6-76
Textiles Testing and Quality Control Figure 2.10.1 (4)
Between-bobbin coefficient of variation of USTER CV%
Figure 2.10.1 (5)
Hairiness
Textile Handbook 6-77
2.10.2 Imperfections Figure 2.10.2(1) Thin places -50% per 1000m, Thick places +50% per 1000m, Neps +200% per 1000m
Figure 2.10.3(1) CLASSIMAT defects
Figure 2.10.3(2)
CLASSIMAT defects (Non-cleared)
Textiles Testing and Quality Control
2.10.3 CLASSIMAT Defects
6-78
Textiles Testing and Quality Control
2.10.4 Tensile Properties Figure 2.10.4(1)
Breaking tenacity (CRE, 5m/min)
Figure 2.10.4(2)
Total coefficient of variation of breaking tenacity
Textile Handbook 6-79 Breaking elongation(CRE, 5m/min)
Figure 2.10.4(4)
Total coefficient of variation of breaking elongation
Textiles Testing and Quality Control
Figure 2.10.4(3)
6-80
Textiles Testing and Quality Control Figure 2.10.4(5) Work-to-break (CRE, 5m/min)
Figure 2.10.4(6)
Total coefficient of variation of work-to-break
2.10.5 HVI Tensile Properties ................................................ 6-81
2.11 Standard Tolerances for Yarn Spun on the Cotton System .................................................................. 6-85 2.11.1 2.11.2 2.11.3 2.11.4 2.11.5 2.11.6
Strength ....................................................................... 6-85 Yarn Number ............................................................... 6-85 Twist ............................................................................ 6-85 Extractable Matter ....................................................... 6-85 Appearance .................................................................. 6-85 Uniformity ................................................................... 6-86
2.12 New Developments in Testing .......................................... 6-86 2.12.1 Uster Qualiprofile ........................................................ 6-86 2.12.2 USTER® Lab Expert .................................................. 6-87
Section 3 3.1
Woven Fabric Testing ....................................................... 6-88 3.1.1 3.1.2 3.1.3 3.1.4
3.2
Woven Fabric Inspection and Testing .. 6-88
Fabric Construction ..................................................... 6-88 Durability, Aesthetics and Environmental Resistance ... 6-91 Fabric Strength ............................................................ 6-94 Relationship Between Strip Test & Grab Test ............. 6-95
Woven Fabric Inspection System .................................... 6-95 3.2.1 3.2.2 3.2.3
4 Point System ............................................................. 6-95 10 Point System ........................................................... 6-98 Graniteville “ 78 ” System of Visual Quality Evaluation for Woven and Knitted Fabrics ................. 6-99
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Textile Handbook 6-81
2.10.5 HVI Tensile Properties Figure 2.10.5 (1) Breaking tenacity (CRE, 400m/min)
Textiles Testing and Quality Control
Figure 2.10.5 (2) Total coefficient of variation of breaking tenacity
6-82
Textiles Testing and Quality Control Figure 2.10.5(3) Breaking elongation (CRE, 400m/min)
Figure 2.10.5(4)
Total coefficient of variation of breaking elongation
Textile Handbook 6-83 Figure 2.10.5(5) Work-to-break (CRE, 400m/min)
Textiles Testing and Quality Control
Figure 2.10.5(6) Total coefficient of variation of work-to-break
6-84
Textiles Testing and Quality Control Figure 2.10.5(7)
Breaking force percentile value 0.1% (CRE, 400m/min)
Figure 2.10.5(8) Breaking elongation percentile value 0.1% (CRE, 400m/min)
Textile Handbook 6-85
2.11 Standard Tolerances for Yarn Spun on the Cotton System (Source: ASTM D2645-85) 2.11.1 Strength The average breaking load of each lot shall be equal to or greater than the specified minimum.
2.11.2 Yarn Number
2.11.3 Twist The direction of twist in each package or end shall be S or Z, as specified. In all cotton-system yarns, except single yarns made of cotton, the average twist conforms to the limits: specified value ± 5.0% of the specified value. In single cotton yarns, including the single yarn components of plied cotton yarns, the average twist shall conform to the limits: specified value ± 10.0% of the specified value. In yarn spun on the worsted system the average twist shall conform to the limits: specified value ± 7.5% of the specified value.
2.11.4 Extractable Matter The average percent of extractable matter in yarns spun on the worsted system shall not exceed the following values: Oil-spun yarns
4.0%
Dry-spun yarns
1.75%
2.11.5 Appearance (Applicable to 100% cotton single yarns only, except by agreement) At least 80% of the specimens examined shall be equal in appearance to the standard for the specified grade. The remaining 20% shall not fall below the next lower grade.
Textiles Testing and Quality Control
The average yarn count of yarns spun on the cotton system or the worsted system shall conform to the limits: specified value ± 4% of the specified value.
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Textiles Testing and Quality Control
2.11.6 Uniformity Yarns spun on the Cotton System - The coefficients of variation of individual observations shall not exceed the following limits:
Yarn number Breaking load, skein Breaking load, single strand Twist (direct-counting method) Twist (untwist-twist, 5 in.) Twist (untwist-twist, 10 in.)
Carded % 5 8 18 25 14 12
Combed % 4 6 16 22 12 10
Notes : Higher coefficients of variation than those listed may indicate either poor control of the manufacturing processes or mixed yarn from two or more production lots.
2.12 New Developments in Testing 2.12.1 Uster Qualiprofile Describes total quality with regard to structure, seldom-occurring events, mechanical characteristics, type of yarn and customer-specific parameters. Radius and colour show the quality, and the width of the segment relates to the weighting of the respective yarn parameter. The dots in the segment show the distribution of single test values. USTER® QualiProfileTM is the metric by which all yarn quality is rated. Figure 2.12.1
Uster Qualiprofile
Textile Handbook 6-87
2.12.2 USTER® Lab Expert USTER® LAB EXPERT provides unique support by managing and evaluating the extensive amount of data which is typically handled in the textile laboratory: • Checking the measurement values with regard to exception values. • Detection and interpretation of periodic faults. • Comparison of the produced quality with a specific quality profile.
• Simulation of yarn boards, woven and knitted fabrics. • Presentation of long-term reports. • Preparation of exception reports and quality certificates. Figure 2.12.2
USTER LAB EXPERT
Textiles Testing and Quality Control
• Comparison with the implemented USTER® STATISTICS.
6-88
Textiles Testing and Quality Control
SECTION 3
WOVEN FABRIC INSPECTION AND TESTING
3.1 Woven Fabric Testing 3.1.1 Fabric Construction a) Fabric Length Fabric should be conditioning first before processing the fabric length testing. Testing Methods: • ISO 3933:1976 Textiles - Woven fabrics - Measurement of length of pieces • ASTM. D3773-90(1996)e1 Standard Test Methods for Length of Woven Fabric b) Fabric width Fabric should be conditioning first before processing the fabric width testing. Testing Methods: • ISO 3932:1976 Textiles - Woven fabrics - Measurement of width of pieces • ASTM: D3774-96 Standard Test Methods for Width of Textile Fabric c) Fabric Weight Fabric must be fully conditioning before processing the fabric weight testing and the bone dry weight is the key measurement weight. Testing Methods: • ISO 3801:1977 Textiles - Woven fabrics - Determination of mass per unit length and mass per unit area • ISO 7211-6:1984 Textiles - Woven fabrics - Construction - Methods of analysis - Part 6: Determination of the mass of warp and weft per unit area of fabric • ASTM D3776-96 Standard Test Methods for Mass Per Unit Area (Weight) of Fabric
Textile Handbook 6-89
d) Fabric Count Determination of Number of Threads per unit Length. Testing Methods: • ISO 7211-2:1984 Textiles - Woven fabrics - Construction - Methods of analysis - Part 2: Determination of number of threads per unit length • ASTM. D3775-98 Standard Test Method for Fabric Count of Woven Fabric
Pressing weight and time duration should be noted while processing the fabric thickness testing and thickness evenness. Testing Methods: • ISO 5084:1996 Textiles - Determination of thickness of textiles and textile products • ASTM. D1777-96 Standard Test Method for Thickness of Textile Materials f) Fabric Crimp or Take up Provides technological data for weaving design and for computation of yarn usage. Testing Methods: • ISO 7211-3:1984 Textiles - Woven fabrics - Construction - Methods of analysis - Part 3: Determination of crimp of yarn in fabric • ASTM. D3883-99 Standard Test Method for Yarn Crimp or Yarn Take-up in Woven Fabrics g) Filling Bow and Skewness Measurement of the angle and curvature between the fabric selvage and the weft. Testing Method: • ASTM. D3882-99 Standard Test Method for Bow and Skew in Woven and Knitted Fabrics
Textiles Testing and Quality Control
e) Fabric Thickness
6-90
Textiles Testing and Quality Control
h) Moisture Regain As a reference and a correction variable for fabric weight testing and strength testing. Testing Method: • ASTM D2654-76 Moisture Content & Moisture Regain of Textile Material. i) Yarn Count from Fabric Testing Methods: • ISO 7211-5:1984 Textiles - Woven fabrics - Construction - Methods of analysis - Part 5: Determination of linear density of yarn removed from fabric • ASTM. D1059-97 Standard Test Method for Yarn Number Based on Short-Length Specimens j) Yarn Twist from Fabric Testing Methods: • ISO 7211-4:1984 Textiles - Woven fabrics - Construction - Methods of analysis - Part 4: Determination of twist in yarn removed from fabric • ASTM. D1423-99 Standard Test Method for Twist in Yarns by Direct-Counting k) Weave Diagram Woven Fabric Structure Analysis. Testing Method: • ISO 7211-1:1984 Textiles - Woven fabrics - Construction - Methods of analysis - Part 1: Methods for the presentation of a weave diagram and plans for drafting, denting and lifting
Textile Handbook 6-91
3.1.2 Durability, Aesthetics and Environmental Resistance a) Air Permeability Fabric Permeability per second under 1cm H2O pressure. Testing Methods: • ISO 9237:1995 Textiles - Determination of the permeability of fabrics to air
b) Wear and Abrasion Measurement on abrasion and wear ability. Testing Methods: • ISO 12947-1:1998 Textiles - Determination of the abrasion resistance of fabrics by the Martindale method - Part 1: Martindale abrasion testing apparatus • ISO 12947-2:1998 Textiles - Determination of the abrasion resistance of fabrics by the Martindale method - Part 2: Determination of specimen breakdown • ISO 12947-3:1998 Textiles - Determination of the abrasion resistance of fabrics by the Martindale method - Part 3: Determination of mass loss • ISO 12947-4:1998 Textiles - Determination of the abrasion resistance of fabrics by the Martindale method - Part 4: Assessment of appearance change • ASTM. D3884-92 Standard Test Method for Abrasion Resistance of Textile Fabrics (Rotary Platform, DoubleHead Method) • ASTM. D3885-99 Standard Test Method for Abrasion Resistance of Textile Fabrics (Flexing and Abrasion Method) • ASTM. D3886-92 Standard Test Method for Abrasion Resistance of Textile Fabrics (Inflated Diaphragm Method) • ASTM. D4157-92 Standard Test Method for Abrasion Resistance of Textile Fabrics (Oscillatory Cylinder Method) • ASTM. D4158-92 Standard Test Method for Abrasion Resistance of Textile Fabrics (Uniform Abrasion Method)
Textiles Testing and Quality Control
• ASTM. D737-96 Test Method for Air Permeability of Textile Fabrics
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Textiles Testing and Quality Control
c) Stiffness Measurement on Fabric handle and Fabric drape. Testing Method: • ASTM. D1388-96 Standard Test Method for Stiffness of Fabrics d) Crease Resistance and Crease Recovery Measurement on crease recovery level. Testing Methods: • ISO 2313:1972 Textiles - Determination of the recovery from creasing of a horizontally folded specimen of fabric by measuring the angle of recovery • ISO 9867:1991 Textiles - Evaluation of the wrinkle recovery of fabrics - Appearance method • AATCC 66-1984 Wrinkle Recovery of Fabrics: Recovery angle method • AATCC 128-1985 Wrinkle Recovery of Fabrics: Appearance Method • AATCC 88C-1984 Appearance of Creases in Wash and Wear items after Home Laundry. • JIS L1059-1985 Crease Recovery of Woven Fabrics. e) Thermal Properties Testing Methods: • ISO 5085-1:1989 Textiles - Determination of thermal resistance - Part 1: Low thermal resistance • ISO 5085-2:1990 Textiles - Determination of thermal resistance - Part 2: High thermal resistance • ASTM. D1518-85(1998) Standard Test Method for Thermal Transmittance of Textile Materials f) Pilling Testing Methods: • ASTM.D3511-99 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Brush Pilling Tester
Textile Handbook 6-93
• ASTM.D3512-99 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Random Tumble Pilling Tester • ASTM.D3514-99 Standard Test Method for Pilling Resistance and Other Related Surface Changes of Textile Fabrics: Elastomeric Pad • ISO 12945-2:2000 Textiles - Determination of fabric propensity to surface fuzzing and to pilling - Part 2: Modified Martindale method
g) Water Repellency and Wetting Testing Methods: • ISO 4920:1981 Textiles - Determination of resistance to surface wetting (spray test) of fabrics • ISO 9865:1991 Textiles - Determination of water repellency of fabrics by the Bundesmann rain-shower test • ASTM.D3779-95a Standard Performance Specification for Women’s and Girls’ Woven Rainwear and All-Purpose, Water-Repellent Coat Fabrics. • ASTM. D3781-95 Standard Performance Specification for Men’s and Boys’ Knitted Rainwear and All-Purpose, Water-Repellent Coat Fabrics h) Dimensional Stability Testing Methods: • ISO 675:1979 Textiles - Woven fabrics - Determination of dimensional change on commercial laundering near the boiling point • ISO 3005:1978 Textiles - Determination of dimensional change of fabrics induced by free-steam • ISO 7771:1985 Textiles - Determination of dimensional changes of fabrics induced by cold-water immersion • ISO 9866-2:1991 Textiles - Effect of dry heat on fabrics under low pressure - Part 2: Determination of dimensional change in fabrics exposed to dry heat
Textiles Testing and Quality Control
• JIS L1076-1985 Pilling of Woven and Knitted Fabrics
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Textiles Testing and Quality Control
3.1.3 Fabric Strength a) Fabric Tension and Elongation • ASTM. D1775-94 Standard Test Method for Tension and Elongation of Wide Elastic Fabrics (Constant-Rate-ofLoad Type Tensile Testing Machine) b) Grab Test • ISO 13934-2:1999 Textiles - Tensile properties of fabrics - Part 2: Determination of maximum force using the grab method c) Strip Test • ISO 13934-1:1999 Textiles - Tensile properties of fabrics - Part 1: Determination of maximum force and elongation at maximum force using the strip method d) Tongue Tear Test • ASTM. D2261-96 Standard Test Method for Tearing Strength of Fabrics by the Tongue (Single Rip) Procedure (Constant-Rate-of-Extension Tensile Testing Machine) e) Ballistic Tear Test • ASTM. D1424-96 Standard Test Method for Tearing Strength of Fabrics by Falling-Pendulum Type (Elemendorf) Apparatus f) Bursting Test • ISO 13938-1:1999 Textiles - Bursting properties of fabrics - Part 1: Hydraulic method for determination of bursting strength and bursting distension • ISO 13938-2:1999 Textiles - Bursting properties of fabrics - Part 2: Pneumatic method for determination of bursting strength and bursting distension • ASTM D3786-87 Bursting Strength, Hydraulic of Knitted Goods & Nonwoven Fabric - Diaphragm Bursting Strength Tester Method. • ASTM D3787-80a Bursting Strength of Knitted Goods Constant Rate of Traverse (CRT), Ball Burst Test.
Textile Handbook 6-95
g) Strength of Seam • ISO 13935-1:1999 Textiles - Seam tensile properties of fabrics and made-up textile articles - Part 1: Determination of maximum force to seam rupture using the strip method • ISO 13935-2:1999 Textiles - Seam tensile properties of fabrics and made-up textile articles - Part 2: Determination of maximum force to seam rupture using the grab method
• ASTM D1683-81 Failure in Sewn Seams of Woven Fabrics. • JIS L1093-1078 Seam Strength of Clothes
3.1.4 Relationship Between Strip Test & Grab Test (By Mr. H. A. Mereness) Material Used in Fabric Silk Rayon Staple fibre Cotton Wool
Warpwise S = 0.8 G S = G - 12 S=G-9 S = 0.83G - 4.4 S = 0.75G - 2.5
Fillingwise S = 0.75 G S = G - 12 S = G - 14 S = 0.83G -3.8 S = 0.75G - 2.5
where S=Strip Test; G=Grab Test; Unit: pound force (lbf)
3.2 Woven Fabric Inspection System 3.2.1 4 Point System This standard is issued by the American Society for Testing and Materials with reference to the designation : ASTM D5430-93. Faults are scored with penalty points of 1, 2, 3 and 4 according to the size and significance.
Textiles Testing and Quality Control
• ASTM D434-95 Standard Test Method for Resistance to Slippage of Yarns in Woven Fabrics Using a Standard Seam
6-96
Textiles Testing and Quality Control
Size Of Defect-(Length In Inch)
Penalty Points
3 inches or less over 3 but not over 6 inches over 6 but not over 9 inches/half width over 9 inches/full width
1 2 3 4
Note (i) Assign no more than a total of 4 points to any one linear yard of fabric, regardless of the number or size of the detected individual defects. (ii) Assign 4 points to each consecutive linear yard in which a continuous running defect exceeds 9 inches. (iii) Assign 4 points to each linear yard of fabric where the useable width is less than the minimum specified. Assign 4 points to each seam or other full width defect if applicable. A piece is graded as “passed” if the total penalty points do not exceed (xx) points per 100 square yards. A piece is graded as “failed” if the total penalty points exceed (xx) points per 1 00 square yards. The entire lot shall be rejected if the average penalty points exceed (xx) points per 100 square yards. Total points x 100 Average points per 100 linear yds = Piece length Average points per 100 sq yds =
Total points x 36" x 100 Piece length x fabric width
Textile Handbook 6-97
Example:The following condensation of an inspection sheet is given to illustrate the use of the formula: Yard
slub slub smash 1 /2 mispick to 49 bias to 61 flat
1
/2
stain slub slub slub
1 1 4 0 16 12 3 1 1 1
95 bar 1 98-99 /2 shaded Total
Penalty
} }
}
4 8
(small defects, each less than 3".) (note, no yard is penalized more than four points.) (4 yards of exceptional defect at 4 (points per yard.) (defect runs through yards.) (defect from 6 to 9 inches long.) (small defects, each less than 3 inches long - all penalized within the same yard since the total is not more than four.) (defect full width-i.e., over 9".) (Exceptional defect entering 2- yards penalized four points per yard.)
52
Width of fabric 40 inches. Total yardage 120 yards. Formula applied: 52x100 = 43.4 points per 100 linear yards 120 Alternate formula applied: 52x3600 120x40
= 39 points per 100 square yards
Textiles Testing and Quality Control
12 14 28 28 45 58 3 64 67 67 68
Defect
6-98
Textiles Testing and Quality Control
Supposing a contract for an average quality level of 20 points and a shipment of 10 rolls of 40-inch fabric, the quality level would be found as follows: Piece 1 2 3 4 5 6 7 8 9 10 Total
Points/100 yards 24 40 28 32 25 25 15 35 20 12 256
256 ÷ 10 = 25.6 quality level of shipment
3.2.2 10 Point System This standard is jointly approved and adopted by The Textile Distributors Institute, Inc. and The National Federation of Textiles, Inc. Faults are scored with penalty points of 1, 3, 5 and 10 according to the size and significance. Size of defect (length in inch) 1 inch or less over 1 but not over 5 inches over 5 but not over 10 inches/half width over 10 inches/full width
penalty points 1 3 5 10
Note : (i) Assign no more than a total of 10 points to any one linear yard of fabric regardless of the number or size of the detected individual defects. (ii) Assign 10 points to each consecutive linear yard containing a continuous running defect. (iii)Assign 10 points to each linear yard of fabric where the usable width is less than the minimum specified.
Textile Handbook 6-99
(iv)Assign 10 points to each splice or other full width defects. A piece is graded as “first quality” if the total penalty points do not exceed the yardage of the piece. A piece is graded as “second quality” if the total penalty points exceed the yardage of the piece. The entire lot shall be rejected if the average penalty points exceed (xx) points per 100 linear yards.
3.2.3 Graniteville “78” System of Visual Quality Evaluation for Woven and Knitted Fabrics a) Inspection Fabrics will be inspected full width, face side only, with no back lighting. All defects having the potential to second end item will be counted. Defect threshold will be that agreed upon between buyer and seller. b) Demerit Points Demerit points will be assigned for defects in increments of nine inches (or 25 centimetres), or parts thereof. Example -
0"- 9" or 0 cm to 25 cm - 1 point 9"-18" or 25 cm to 50 cm - 2 points 18"-27" or 50 cm to 75 cm - 3 points, etc.
c) Maximum Penalty The maximum penalty per square yard (or metre) is four points. The maximum number of points per linear yard (or metre) is determined by the fabric width.
Textiles Testing and Quality Control
An increase of not more than 10% in penalty points will be allowed on “first” quality goods over 50 inches wide.
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Textiles Testing and Quality Control
Per Linear Yard-Divide width in inches by 9. Examples-
48" Fabric - 6 points 60" Fabric - 7 Points
Per Linear Meter-Divide width in centimetres by 25. Examples-
122 cm Fabric (48") - 5 Points 153 cm Fabric (60") - 6 Points
No defect within eighteen inches (or 50 cm) to either side of an extended or running defect shall be counted. No defect within nine inches (or 25 cm) of one point defect shall be counted. d) Computation of Inspection Results Results shall be computed in points per 100 square yards or 100 square metres. Step 1-
Divide yards inspected by 100.
Step 2-
Divide results into total points to obtain points per 100 linear yards or metres.
Step 3-
For points/100 sq. yards - multiply points per 100 linear yards by 36 the fabric width in inches. For points/100 sq. meters - multiply points per 100 linear metres by 100 divided by the fabric wide in centimetres,
e) Conversion Formulae Points/100 sq. yards X.836 = Points/100 sq. metres. Points/100 sq. metres X 1.196 = Points/100 sq. yards.
Section 4 - Knitted Fabric Inspection and Testing...... 6-101 4.1
Knitted Fabric Testing ...................................................... 6-101 4.1.1 4.1.2 4.1.3
4.2
Fabric Construction ..................................................... 6-101 Durability, Aesthetics and Environmental Resistance ... 6-102 Fabric Strength Testing ............................................... 6-102
Knitted Fabric Inspection Systems ................................. 6-102 4.2.1 4.2.2 4.2.3
The KTA System for Circular Knitted Fabrics ............ 6-102 The KTA System for Raschel Knitted Fabrics ............ 6-104 The KTA System for Tricot Fabrics ............................ 6-107
Section 5 - Fabric Quality and Performance........... 6-113 5.1
Quality Standard and Performance Tests for Apparel ... 6-113 5.1.2
5.2
Quality Guideline for Fabrics Containing LYCRA® .... 6-116
US Standard for Flammability ........................................ 6-120 5.2.1 5.2.2 5.2.3
Flammable Fabrics Act Standards - USA ................... 6-120 Federal Test Method Standard 191 - Textile Test Methods ....................................................................... 6-122 Miscellaneous Tests ..................................................... 6-123
5.3
Woven Fabric Defect Description and Cause ................. 6-124
5.4
Illustrations of Woven Fabric Faults .............................. 6-129
5.5
Knitted Fabric Defect Description and Cause ............... 6-136
5.6
Illustrations of Knitted Fabric Faults ............................. 6-140
Back to Table of Content
Textile Handbook 6-101
SECTION 4
KNITTED FABRIC INSPECTION AND TESTING
4.1 Knitted Fabric Testing 4.1.1 Fabric Construction a) Fabric Width
Testing Method: • ASTM: D3774-96 Standard Test Methods for Width of Textile Fabric b) Fabric Weight Fabric must be fully conditioning before processing the fabric weight testing and the bone dry weight is the key measurement weight. Testing Methods: • ASTM D3776-96 Standard Test Methods for Mass Per Unit Area (Weight) of Fabric c) Fabric Thickness Refer to woven fabric testing section 3.1.1e. d) Filling Bow and Skewness Refer to woven fabric testing section 3.1.1g e) Moisture Regain Refer to woven fabric testing section 3.1.1h f) Yarn Count from Fabric Testing Method: • ASTM. D1059-87 Yarn Number based on Short Length Specimen. g) Yarn Twist from Fabric Testing Method: • ASTM. D1423-82 Twist in Yarns by the Direct Counting Method.
Textiles Testing and Quality Control
Fabric should be conditioning first before processing the fabric width testing.
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Textiles Testing and Quality Control
4.1.2 Durability, Aesthetics and Environmental Resistance Refer to Woven fabric testing section 3.1.2
4.1.3 Fabric Strength Testing Bursting Testing Methods: • ISO 13938-1:1999 Textiles - Bursting properties of fabrics - Part 1: Hydraulic method for determination of bursting strength and bursting distension • ASTM D3786-87 Bursting Strength, Hydraulic of Knitted Goods and Nonwoven Fabric - Diaphragm Bursting Strength Tester Method. • ASTM D3787-80a Bursting Strength of Knitted Goods Constant - Rate of Traverse (CRT), Ball Burst Test.
4.2 Knitted Fabric Inspection Systems 4.2.1 The KTA System for Circular Knitted Fabrics This standard is approved by Knitting Textile Association Circular Committee and endorsed by the American Textile Manufacturers Institute and Textile Distributors Association. a) Applicability This standard apply to circular knitted fabrics including basic, face finished and novelty types. b) Method Four-Point System- The following schedule of penalty points is based on fabrics 64-66 inches in width for defects visible when inspected on face side of fabric only: Length of Defects Number of Penalty Points 3 inches or less 1 Over 3 but not over 6 inches 2 Over 6 but not over 9 inches 3 Over 9 inches 4
Textile Handbook 6-103
• Four penalty points per linear yard are the maximum assessable for fabrics up to 64/66 inches in width. • For fabrics over 64/66 inches in width, maximum penalty points are to be increased in proportion as the width exceeds 64 inches. • Regardless of the length of the fabric, the quality shall be expressed in the number of penalty points per 100 yard length. (Example: A 40-yard piece with six penalty points is to be rated as 15 points per 100 yards.)
(i) Bias/bowing but bias/bowing is not to exceed five inches per 60-inch width for all knitted fabrics (ii) General aesthetic characteristics are not to be assigned penalty points. (iii) Barre and pin holes are not to be assigned penalty points. These conditions must be judged as to extent and degree to which they affect the garment being produced. c) Quality Determination Determining First Quality Circular Knitted Fabrics Shall Be Done As Follows: • Basic Fabrics shall be classified as first quality if the number of penalty points does not exceed 50 points per 100 linear yards. • Face Finished Fabrics shall be classified as first quality if the number of penalty points does not exceed 60 points per 100 linear yards. • Novelty Fabrics are to be classified by the knitter in relation to difficulties of producing them. (Types of yarns, stitches, fibers, etc. affect the difficulties of production.) Novelty fabrics shall be classified as first quality if the number of penalty points does not exceed the maximum for the type(s) as designated by the seller in the sales contract or by written notice prior thereto:
Textiles Testing and Quality Control
• Penalty points will not be assigned for the following.
6-104
Textiles Testing and Quality Control
Novelty Type
Maximum Points Per 100 Linear Yards
A
70
B
75
C
50
D
85
d) Weight and Length Tolerances (i) Weight of circular knitted fabric may not vary by more than plus or minus five percent from the stated weight. The standard weight is to be stated as a whole number, such as six ounces, not a range such as 6-6.5 ounces. The yield is to be based on individual roll measurements of lengths or pounds, (ii) Length/Weight-If the total length, or, if fabric is bought on a weight basis, the total weight of the delivered quality varies no more than plus or minus ten percent of the stated quality ordered, all such goods shall be deemed in conformity with the order and acceptable. To the extent that the quality exceeds such limit, only the excess over the limit may be rejected; and a deficiency or shortfall of more than ten percent may be deemed a non-delivery to the extent that it exceeds ten percent. (Cutting table measurement of length by the buyer is not in conformity with this standard; measurement shall be made on a knitted fabric examining machine).,
4.2.2 The KTA System for Raschel Knitted Fabrics a) Applicability This standard applies to fabrics for apparel and apparel accessories of basic, flat finished, textured surface and novelty raschel fabrics. Fabrics for other end users made subject hereto by express agreement between buyer and seller.
Textile Handbook 6-105
b) Method Four-Point System: The following schedule of penalty points is based on fabrics 60/62 inches in width for defects visible when inspected on the face side of the fabric only: Length of Defect 3 inches or less Over 3 but not over 6 inches Over 6 but not over 9 inches Over 9 inches
Number of Penalty Points 1 2 3 4
• For fabrics over 60/62 inches in width, maximum penalty points are to be increased in proportion as the width exceeds 60 inches. • Regardless of the length of the fabric, the quality shall be expressed in the number of penalty points per 100 yards length. (Example: A 40 yard piece with six penalty points is to be rated as 15 points per 100 yards.) • Bowing and skewing (bias); bowing may not exceed 3 inches and skewing may not exceed 4 inches per 60inch width, and any yard containing bowing or skewing in excess of these limits shall be penalized 4 points. • Penalty points will not be assigned for the following: (i) General aesthetic fabric characteristics. (ii) Pin holes (whether caused by knitting or by tenter frame pins); they shall be judged by the extent and degree to which they occur and their probable effect on the type of garment or other end use. (iii) Defects appearing outside the selling width, the selling width being centred in the total width of the fabric. (iv) Defects resulting from napping, shearing and other surface treatments (which shall be otherwise evaluated). (v) Irregularities normal to the existing state of the art or beyond reasonable control of the manufacturer, or inherent in Raschel knitted fabrics.
Textiles Testing and Quality Control
• Four penalty points per linear yard are the maximum assessable for fabrics up to 60/62 inches in width.
6-106
Textiles Testing and Quality Control
c) Quality Determination Determining first quality Raschel fabrics shall be done as follows: • Basic fabrics shall be classified as first quality if the number of penalty points does not exceed 40 points per 100 linear yards, • Raised surface fabrics shall be classified as first quality if the number of penalty points does not exceed 50 points per 100 linear yards. • Novelty fabrics shall be classified as first quality if the number of penalty points does not exceed 60 per 100 linear yards, Novelty fabrics are to be so designated by seller. Novelty fabrics are those whose production involves special difficulties including those arising from special types of yarn, stitches, fibres or other factors. Fabrics are to be classified if they are thus designated in the sales contract or in other written notice given by the seller to the buyer. Note:Laps: No more than two laps per 100 yards are allowable and not more than one lap in less than 100 yards. The shortest unlapped portion of a piece shall not be less than 10 yards. d) Length And Width- Measurement Methods (i) Length shall be measured with any surface contact device (Tru-meter or equivalent) that is calibrated regularly. The device shall contact the back or a smooth surface of Raschel fabrics. (Preferred calibration method: Measure a known length of canvas or other stable, lowelongation fabric less than 2% in either direction) through the measuring device. Reference: ASTM D1910-64 hand method. The actual yardage of each piece shall be accurate to within plus or minus 2% when measured by the above method. (ii) Width shall be measured with an accurate tape after laying Raschel fabric flat on a table without tension or elongation. (Reference ASTM 3887-80.) Conformity to the selling width of Raschel fabric shall be determined on the basis of one of the three following methods.
Textile Handbook 6-107
• Width between gummed edges of gummed fabrics, • Width between tenter frame pin marks when pin marks remain in shipped fabrics. • Overall width of Raschel fabric when neither of the above two criteria exist. Note: If width is stated in a range such as 60/62 inches, the lower figure governs.
4.2.3 The KTA System for Tricot Fabrics This standard applies to plain, flat, finished and raised tricot fabrics. b) Method The method for measuring and rating the quality of fabrics according to the number and nature of certain common types of defects affecting their usability shall be known as the Four Point System and is as follows: (i) Penalty points shall be imposed for defects in a piece of fabric according to the size of such defects, as set forth below: Number of Penalty Points 1 2 4
Description of Defects Run, hole or damage in width or warp direction measuring not over 3 inches in its greatest dimension. Run, hole or damage in width or warp direction, over 3 but not over 10 inches in its greatest dimension. Run, hole or damage in width or warp direction, over 10 but not over 36 inches. Defects over 36 inches are to be charged to the extent that each additional yard is affected.
(ii) Point limitation: Regardless of the number of defects no single linear yard of fabric shall be charged with more than 4 points.
Textiles Testing and Quality Control
a) Applicability
6-108
Textiles Testing and Quality Control
(iii)Exclusions: -
This standard evaluates quality only with respect to knitting defects and other distinctly measurable defects including grease, oil and dye spots, slubs, picks and bowing and skewing but not including napping, shearing, surface effects or other general defects which must be otherwise evaluated. Irregularities normal to the existing state of the art or beyond the reasonable control of the manufacturer or inherent in tricot fabrics shall not be classified as defects and shall not bear penalty points.
-
Penalty points shall not be assigned on the basis of general aesthetic characteristics of fabrics.
-
Unless otherwise agreed upon by buyer and seller, fabrics are to be examined for defects only on their face side.
-
Defects appearing within one inch of either edge shall be disregarded.
-
Count shall not be considered.
-
Conditions such as pin holes may not be assigned penalty points, and must be judged by the extent and degree to which they occur and their probable effect on the type of garment to be cut; pin holes are not limited to those caused by tenter frame pins.
c) Quality Determination Tricot fabric shall be classed as first quality if it meets both of the following requirements: In the case of plain, flat, finished tricot the number of defect points shall not exceed the proportion to its length of 40 per 100 linear yards; and in the case of tricot with a raised fibre surface the number of defect points shall not exceed the proportion to its length of 48 per 100 linear yards. The fabric shall come within the tolerances allowed for other characteristics as set forth below:
Textile Handbook 6-109
-
Selling width of tricot fabric shall be determined on the basis of one of the three following methods: • Width between gummed edges of gummed fabrics. • Width between tenter frame pin marks when pin marks remain in shipped fabrics. • Overall width of tricot fabric when neither of the two above exist.
-
Weight: Weight of tricot fabrics per linear yard may not vary by more than plus or minus 5 per cent from the weight stated in the contract.
-
Wales: Variation in wales per inch may not exceed five across the actual width of the fabric measured as provided in above.
-
Bias/Bowing: Bias or bowing may not exceed 3 inches of bias per 60 inches of width.
-
Laps: No more than two laps per 100 yards are allowable and not more than one lap in less than 100 yards. The shortest unlapped portion of a piece shall not be less than 10 yards.
Textiles Testing and Quality Control
Note: If width is stated in a range such as 60-62 inches, the lower figure governs.
7
5 6
4
3
2
1
No.
Defect Counting Conversion of Defect Size and Count to Point Definition of Defects Counted
Scope- Product
Importance
4 Points
10 Points 78 System
5-10 ins Over Over half-full 10 ins width Direct count 1,3,5,10
Over 6-9 ins Over 9 ins
Defects counted should be Nil changed with different fabric types since same defect may cause different reactions
Imperfections are defects which can be prevented under normal conditions or with reasonable care.
5- half width
All defects having the potential to second and end item
Direct count 1,2,3
Over 18-27 ins
0-9 ins Over 9-18 ins
0-1 ins 1-5 ins
0-1 ins 1-5 ins
Over 3-6 ins
0-3 ins
Any direction
Weft
Visual
Warp
Visual
Any direction
Visual
Grey and Plain dyed Grey and finished woven fabric Woven and Knit Fabric woven fabric All Around 50 ins Around 50 ins
Defect seriousness Direct count Combine size and Qty into 1,2,3,4 a single index
Different fabric have different important criteria Fabric width will affect the Scope - Fabric first fabric Width Evaluation method Hidden defects will not be counted Defect Size Range Defect seriousness Definition
Criteria
Table 4.2.3 Comparison of Different Inspection Systems (Size and Quantity) BS 6395
KTA
Visual
Any feature within the usable width of a fabric which, if it appeared in a finished product would down grade that product.
Direct count 1
0-25 cm
Nil
1,2,3,4
Direct count
Over 9 ins
6-9 ins
0-3 ins 3-6 ins
Any direction Any direction
Visual
All kinds of Circular fabric Knit fabric All 64-66 ins
6-110
Textiles Testing and Quality Control
F i r s t q u a l i t y Acceptance level should be a d j u s t m e n t t o sensitive to area of fabric, different fabric not length of fabric only width
Side of inspection Depends on End-Product Piece length Depends on Cutting Table, wastage can be minimized
11
12 13
—
Total penalty points <= Total linear length e.g. If fabric width is 50 ins or smaller than 50 ins, max. 100points per 100yd for First Quality roll. 1) Per 100yd2: Fabric width>50 ins Continuous Total penalty poinst <= 110% Proportional of total linear yd length 2) Per 100yd: width (Discrete) > 50 ins total points e.g. If fabric width is >50 ins, then Max. 110 points per 100 <=45/100yd yd for First quality roll. Face Face As ins second if Nil continuous length <40yd, no matter the penalty points.
Maximum penalty Omit localized serious — defects from overall result points per area and take consideration of fabric width Definition of First Acceptance level 1) total penalty points Quality fabric roll <=40/100yd2 2) total penalty points <=40/100yd
9
10 /yd
—
4/m2
Nil
Face
Nil
Nil
Face Nil
Nil
Face Nil
No single level of acceptance
4/yd
—
No single level No single of acceptance l e v e l o f acceptance
4/yd2
—
Textiles Testing and Quality Control
10
Maximum penalty Omit localized serious 4 /yd points per linear defects from overall result. length
Comparison of Different Inspection Systems (Size and Quantity) Continued
8
Table 4.2.3
Textile Handbook 6-111
17
16
15
14
No.
Importance
4 Points
Bow & Bias (Skewness)
1) No backlighting 2) 9 feet viewing distance
1) North daylight 2) Free from reflection 3) Fabric 45° to the vertical
KTA
Nil Nil
Nil
Nil
Bias/ bow <=5 ins per 60 ins width
Nil
Nil
Nil Nil
Nil
BS 6395
Nil
78 System
Nil
<=0.5 ins from selvage
Nil
10 Points
Comparison of Different Inspection Systems (Size and Quantity) Continued
-efficiency of Fabric Up to 60 ins width:1) bow max. 1 ins up Laying -Fabric Wastage to 60 ins -Hidden Garment Shape 2) bias max. 1.5 ins Stability up to 60 ins 3) over 60 ins bow <=1.02 ins and bias <= 1.54 ins Area not counted -ncontrolled damages Nil during production Approved sample -Colour and Surface Recommended Texture C o n d i t i o n o f -Colour 3 feet viewing inspection -Surface Texture distance -Efficiency
Criteria
Table 4.2.3
6-112
Textiles Testing and Quality Control
FABRIC QUALITY AND PERFORMANCE
Appearance after -Washing or Drycleaning
Mand- Fibre Labelling atory Testing Flammability Flammability Test (1) Care Labelling Dimensional Stability -Washing or drycleaning (2) Colour fastness -Washing or Drycleaning (2) -Chlorine Bleach (3) -Non-chlorine Bleach (3)
Test item Fibre Analysis
Apparel
X X
X X
X X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Shirt, Sport Trousers Dress, Skirt Blouse Shirt, T-Shirt
X
X X
X
X
X
X
X
X X
X
X
X
X
X
X X
X X X X
X
X X
X X X X
X
X X
X
X
X
X
X
X X
X X X
•
X
X X
X X X X
Jacket, Skiwear, Underwear, Sweatshirt, Swim- Lining AccesBlazer, Anorak, Lingerie, Knitwear wear sories Coat, Rainwear Nightwear Suit
Guidelines For Selection Of Quality Performance Tests For Major Types Of Apparel
Textiles Testing and Quality Control
Table 5.1.1
5.1 Quality Standard and Performance Tests for Apparel
SECTION 5
Textile Handbook 6-113
Quality and Performance Testing
• • •
X
•
• • •
•
X X X
X X X
X X X
•
•
•
•
•
X
X
X
X X
X
X
•
X
X
X
X
X
X X X X X X
X X X X X X
X X X X X X
X X X X X X
•
Banned Azo Colorants (4) Formaldehyde content (5) Cadmium content (6) PCP content (7) Release of nickel (8) Colour fastness Rubbing (crocking) tests Light - 10-hr exp - 20-hr exp - 40-hr exp Perspiration Water Chlorinated Water Sea Water Strength tests Tensile Strength (9) Tearing Strength (9) Seam Properties (9) Bursting Strength (10) Seam Bursting Strength (10) Bonding Strength of fused collar Other tests Pilling Resistance (11) Abrasion Resistance (12) Spray test Durable Press Rating (13)
• • X
X
•
X
X
•
X
X
X X X X X X
X
•
X
X X X X X X X X X X X X
X X X
•
X
X
X
X X
•
X
X X X X X X
X
X
Hazardous Chemicals
X X X
X X X
X
X X X X
X
•
X X X
X
X
X
X
X X X
X X
X X X X
X
6-114
Textiles Testing and Quality Control
Textile Handbook 6-115 Note: X •
(1)
Essential Test Optional Test to be required on basis of fabric materials and apparel style Flammability USA/Canada U.K./The Netherlands Australia Sweden
(13)
Either washing or drycleaning procedure is performed For USA only For Germany and the Netherlands Mandatory test for Finland and Japan Mandatory test for Sweden Mandatory test for Germany, suitable for leather goods Mandatory test for Europe, suitable for metal accessories Woven articles only Knitted articles only Hairy, brushed or cellulosic blended articles Essential test for corduroy and easy-care articles, optional test for other Permanent press finished articles only
Textiles Testing and Quality Control
(2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
: Childrens; sleepwear and other wearing apparel : Nightwear only : Childrens’ nightclothes : All wearing apparel
TTM 033
LYCRA® content
TTM 079A or TTM 079B
Dimensional stability (%) In length x width directions
Warp Knits Fabric Minimum LYCRA® content 23 g/m2 Minimum elongation 80% Dimensional stability +/- 8% x +/- 8%
Table 5.1.2 (2) Warp Knits Fabric
Note : *for ribs above 1 x 1
TTM 076 or LTM-30
Elongation (%) in length direction
Fabric weight
Test to be conducted
Item
5x5
50% 5x5
5x5
160 g/m2 4.8 oz/yd2
60%
160 g/m2 4.8 oz/yd2
160 g/m2 4.8 oz/yd2 80%
3 g/m2 0.08 oz/yd2
8 g/m2 0.25 oz/yd2
Single Jersey Body Single Jersey Non-Body Double Jersey fabric Hugging fabric Hugging fabric
Circular Knits Fabric
Table 5.1.2 (1) Global quality Standard for Ready-to-Wear
5.1.2 Quality Guideline for Fabrics Containing LYCRA®
5 x 12*
50%
160 g/m2 4.8 oz/yd2
Ribs
6-116
Textiles Testing and Quality Control
Min 20% Min 15% Max -3% x -3%
TTM 076
TTM 079A or TTM 079B tumble dried
TTM 077
TTM 035
Machine elongation (%) -1 direction -bi-elastic
Wash shrinkage
Growth in direction of stretch
Tear strength
Max +4%
Max -5% x -5%*
Min 20% Min 15%
Min 2%
Washable fabric
1.3 daN
Max +4%
Max -5% x -5%*
Min 20% Min 15%
Min 2%
Shirtings
Textiles Testing and Quality Control
Additional comments: • Minimum 2% LYCRA® content is recommended to meet the standard unless specified. • Because of the specific fibre’s composition and construction of linings with LYCRA® spandex, it might be difficult to meet dimensional stability and growth criteria. In that case, we advise the garment maker to cut the fabric more ‘generously”. • For denim fabrics and fabrics which are not heatset and are to be washed / dyed in garment forms, the above quality criteria will be reached only after garment washing/ dyeing treatment • TTM 033, 076, and 077 are Du Pont methods
Max +3%
Min 2%
TTM 033
LYCRA® content
Non washable fabric
Woven Fabric
Test to be conducted
Woven Fabric
Item
Table 5.1.2 (3)
Textile Handbook 6-117
* minimum LYCRA content -bare: 2% -covered: 1% * complies with care label
* LYCRA® must be every feed except: -3D/ surface effect (max 25 courses without LYCRA®) -links-links stitch -multi-colour jacquard
Minimum wet-sag recovery
Minimum Elongation -length -width Dimensional stability
Minimum LYCRA® weight
Minimum fabric weight
Item
-6%
50%
Intimate Apparel 1 x 1 Rib Knits 110 g/m2
70% 100% -5%
7 g/m2 0.2 oz/yd2
Plain Jersey 110 g/m2 3.3 oz/yd2
70% 100% -5%
5 g/m2 0.15 oz/yd2
Surface effects 90 g/m2 2.7 oz/yd2
Circular Knits Fabric
40%
100% 120%
20 g/m2 0.6 oz/yd2
120% 120% -6%
20 g/m2 0.6 oz/yd2
Activewear Swimwear Chlorine resistant Type “B” 200 g/m2 200 g/m2 2 6.0 oz/yd 6.0 oz/yd2
Table 5.1.2 (5) Global Quality Standard for Intimate Apparel/ Swimwear/ Activewear
®
Flat Knits
Table 5.1.2 (4) Flat Knits
6-118
Textiles Testing and Quality Control
2
100% 70% -5%
14 g/m 2 0.42 oz/yd
2
90 g/m 2 2.7 oz/yd
70%
10% content
Lace
Intimate Apparel
Tricot Plain/ Pattern
120% *100%
50%
50%
23 g/m 2 0.69 oz/yd
2
Swimwear Tr i c o t s u r f a c e effect (Chlorine resist TYPE “B”) 2 180 g/m 2 5.4 oz/yd
120% *100%
2
28 g/m 2 0.84 oz/yd
180 g/m 2 5.4 oz/yd
2
Tricot Plain (Chlorine resist TYPE “B”)
40%
120% 120% 120%
2
23 g/m 2 0.69 oz/yd
2
2
180 g/m 2 5.4 oz/yd
Activewear
23 g/m 2 0.69 oz/yd
2
180 g/m 2 5.4 oz/yd
Raschel (Chlorine resist TYPE “B”)
Textiles Testing and Quality Control
Woven Fabric (for Swimwear) Minimum LYCRA( (chlorine resistant type) content 5% Minimum machine elongation (%) - l direction >50% - Bi-elastic >50% Wash shrinkage max -5% x -5% (tumble dryed) Growth in direction of stretch max +5%
Table 5.1.2 (6) Woven Fabric (for Swimwear)
Minimum Elongation -length -width Dimensional stability Minimum wet-sag recovery
Minimum LYCRA weight
®
Minimum fabric weight
Item
Warp Knit Fabric
Textile Handbook 6-119
6-120
Textiles Testing and Quality Control
5.2 US Standard for Flammability 5.2.1 Flammable Fabrics Act Standards - USA In 1953, the Flammable Fabrics Act was passed to regulate the manufacture of highly flammable clothing under the jurisdiction of the Federal Trade Commission. It was amended in 1967 to permit regulation of a wide range of clothing and interior furnishings. In 1972, the Consumer Product Safety Act was passed. This act created the Consumer Product Safety Commission(CPSC) with broad jurisdiction over product safety, and transferred responsibilities under the Flammable Fabrics Act to the CPSC. a) 16 CFR Part 1610 - Standard for the Flammability of Clothing Textiles (CS 191-53) This standard became effective in 1954, when made mandatory by the Flammable Fabrics Act. It established a minimum flammability standard for wearing apparel, excluding interlining fabrics and certain hats, gloves and footwear. It was designed to keep highly flammable apparel off the market. The test requires that when a fabric specimen (2" x 6") is placed in a holder at a 45°C angle and exposed to flame near the lower edge for 1 second, there is no flame spread, with base burn, up the length of the specimen in less than 3.5 seconds for smooth fabrics or 4.0 seconds for napped fabrics. The National Fire Protection Association 702 Flammability of Wearing Apparel is a similar test method. b) 16 CFR Part 1615 - Standard for the Flammability of Children’s Sleepwear: Sizes 0 Through 6X (FF 3-71) The children’s sleepwear standard became effective in 1972, and includes any garment (sizes 0-6X) worn primarily for sleeping or activities related to sleeping such as nightgowns, pajamas, robes, etc., but excludes diapers and underwear. Fabrics intended or promoted for children’s sleepwear must also meet this standard. The test requires 5 specimens to be individually hung vertically in a cabinet, and exposed to a gas flame along the bottom edge for 3 seconds. To pass the test, the specimens
Textile Handbook 6-121
cannot have an average char length greater than 7 inches; no single specimen can have a char length of 10 inches. This test is also required after the fabric or garment has been washed 50 times. c) 16 CFR Part 1616 - Standard for the Flammability of Children’s Sleepwear: Sizes 7 through 14 (FF 5-74) This standard became effective in 1974 and includes the same clothing articles covered in Part 1615 but in sizes 714.
d) 16 CFR Part 1630 - Standard for the Surface Flammability of Carpets and Rugs (FF 1-70) This standard became effective in 1971 and includes carpets which have one dimension greater than 6 feet and a surface area greater than 24 square feet, but excludes linoleum, vinyl tile and asphalt tile. In this test, eight 9 inch square specimens are individually exposed to a burning methenamine tablet which is placed on the centre of each specimen. The test requires that 7 of the 8 specimens must not char more than 3 inches in any direction. e) 16 CFR Part 1631 - Standard for the Surface Flammability of Small Carpets and Rugs (FF 2-70) This standard also became effective in 1971 and includes carpets with a surface area less than 24 square feet and no dimension greater than 6 feet, but excludes linoleum, vinyl tile and asphalt tile. The test requires the same burning methenamine tablet test which is used for large carpets and rugs. As an alternative to compliance, the standard provides for use of a warning label.
Textiles Testing and Quality Control
The test specified in this standard is identical to the test in Part 1615.
6-122
Textiles Testing and Quality Control
f ) 16 CFR Part 1632 - Standard for the Flammability of Mattresses and Mattress Pads (FF 4-72, Amended) This standard became effective in 1973 and includes ticking filled with a resilient material intended or promoted for sleeping upon, including mattress pads. Pillows, boxsprings, and upholstered furniture are excluded. The test requires that the surfaces be exposed to a total of 9 burning cigarettes on the bare mattress and the char length on the mattress surface must not be more than 2 inches in any direction from any cigarette. Tests are also conducted with burning cigarettes placed between 2 sheets.
5.2.2 Federal Test Method Standard 191 - Textile Test Methods The Federal Test Method Standard 191 describes methods for testing textile products for conformance with the requirements of federal and military specifications. All federal agencies are required to use this standard. Pass/fail test criteria are not specified in these test methods. Requirements are usually listed in individual contracts. a) FTMS 191-5903 Flame Resistance of Cloth: Vertical This test is used in determining the resistance of cloth to flame and to glow propagation, and tendency to char. It is designed primarily for cellulosic fabrics treated with a flame retardant, but may be utilized in other applications. The test requires 10 specimens to be individually hung vertically in a cabinet and exposed to a gas flame along the bottom edge for 12 seconds. Each specimen tested shall be evaluated for after-flame time, after-glow time and char length as specified in the- applicable procurement document. ASTM specifies a similar test method, F501-77 Aerospace Materials Response to Flame, with Vertical Test Specimen. This method specifies exposure time as the period of time required by the applicable material specification,
Textile Handbook 6-123
b) FTMS 191-5905 Flame Resistance of Material: High Heat Flux Flame Contact This test method is used in determining the resistance of textiles and other materials to flame propagation. It provides a means to identify changes that occur in thermoplastic materials on flame contact, such as melting or shrinking from the flame source. The method is intended to complement FTMS 191-5903 and provides higher heat flux flame contact and a longer exposure time.
% Consumed =
Original length - length of uncharred portion x 100 Original length
5.2.3 Miscellaneous Tests a) ASTM D4151 Flammability of Blankets The purpose of this test is to determine the ignitability of blankets. It is the result of industry anticipating mandatory standards and implementing voluntary standards. The test requires 10 specimens (2.75"x 2.75", positioned horizontally) to be subjected individually to a standard flame impinged on their surface for 1 second. The blanket passes if no individual specimen ignites, surface flashes, or burns enough to char or burn a paper monitor bordering the area. b) Limited Oxygen Index This test provides a precise method for determining a numerical measure of the relative flammability of plastics, textiles and other materials. ASTM defines Oxygen Index to be the minimum concentration of oxygen expressed as a percent by volume, in a mixture of oxygen and nitrogen which will just support combustion of a material.
Textiles Testing and Quality Control
The test requires 10 specimens (2.75" x 12") to be individually hung vertically over a gas flame with crucible tongs and exposed along the bottom edge for two 12 second periods. The after-flame for each 12-second exposure is reported along with the percentage consumed:
6-124
Textiles Testing and Quality Control
c) Thermal Protective Performance Test This test rates textile materials for thermal resistance and insulation. Heat is applied to one side of the material, and the heat transfer through it is measured. The thermal protective performance value is defined as the predicted time to second-degree burn in seconds multiplied by the heat flux. d) NFPA 701-1989 Standard Methods of Fire Tests for Flame-Resistant Textiles and Films Small Scale This test is used to determine if flame-resistant materials are comparatively difficult to ignite and may propagate flame beyond the area exposed to the ignition source. It applies to flame resistant materials which are used extensively in the interior of buildings, in protective clothing and for tarpaulins and tents. This test requires 10 specimens (3.5" x 10") to be individually hung vertically in a cabinet and exposed to a gas flame (Bunsen or Tirrill burner at a 25o angle from vertical) for 12 seconds. e) UFAC Cigarette Ignition Test The Upholstered Furniture Action Council (UFAC) Cigarette Ignition Test determines the ignition resistance of upholstered furniture when exposed to a lighted cigarette. It is also the result of industry anticipating mandatory standards and implementing voluntary standards. Cover fabrics are divided into two categories of ignition propensity. Fabrics with vertical surface char of less than 1.75" above the crevice are Class I. All other fabrics are Class II. f ) California Technical Bulletin 133 TB 133 is a full-scale fire test for furniture manufactured for use in certain public buildings in California. The test measures the amount of heat generated and the rate at which it is generated. In addition, smoke opacity, carbon monoxide generation and temperature are measured in the test room, as well as the weight loss of the product being tested. Many states are adopting TB 133 as a seating standard for public buildings, but the specific types of buildings and the definition of public buildings may vary from state to state.
Excessive curvature of the weft in a fabric. that may or may not extend over the full width Coloured weft yarns appearing in the fabric in the wrong sequence A warp-wise line where a warp yarn is absent for part or all of the piece In a fabric made from multi-filament yarns, a fibrous or hairy surface appearance that may be localized or general A weft yarn which is present for only part of the fabric width
Bow, weft
Broken colour pattern
Cockled yarn
Clip mark (centering marks; pin marks; stenter mark) Chopped weft Coarse end (thick end) Coarse pick (thick pick)
Bruise
Broken pick
Broken filaments
Broken end (end out; missing end)
Colour paste falling on to the fabric, or contamination from printing rollers or a screen Lack of control of during warping resulting in a variation in warp tension across the width during weaving Lack of control in fabric manufacture or processing (uneven tension across the fabric width during stenter processing) Failure to reset the pattern control after a loom stoppage Warp yarn break which has not been repaired This defect is caused by rupture of individual filaments, usually during winding or weaving A weft yarn breaking, running out, or being prematurely released during insertion The squeezing or crushing of the fabric
Weft that has been partially severed A warp yarn thicker than the adjacent warp yarns A weft yarn of substantially greater thickness than that of the adjacent weft yarns Small slub-like irregularities in the yarn that are readily extensible
This defect is often caused by the unintentional introduction of stretch into some fibres during drafting and the subsequent relaxation of these fibres to form loops or crimps in the yarn.
Cutting by the reed during beat A wrong yarn being entered or a yarn of long-term unevenness Variation in the yarn count of the weft yarn
An area that has been subjected to impact or pressure, that differs from the adjacent normal fabric A visible deformation of the selvage due to pressure from a stenter clip Hooked blunted or poorly adjusted stenter pins
Excessive curvature of the warp in a fabric
Bow, warp
Blot
Bias weft; skew
Variation in weft yarn characteristics such as linear density, tension, twist, etc. Inadequate control of the fabric during open-width finishing (uneven side speed of stenter; side holding points on selvedges are shifted)
Defect Cause By chafing or oblique impact with a hard or rough surface Occurs in an undersett fabric, or through poor finishing
Textiles Testing and Quality Control
Bar (weft bar)
Defect Description An area damaged by friction Warp yarns generally showing between the weft yarns unintentionally, or vice versa A band or stripe which differs in appearance from the adjacent normal fabric. A fabric condition in which the warp and weft yarns are straight but vary from the perpendicular to the one another by a degree which is unacceptable in that fabric type An area of uniform colour appearing incorrectly in a printed design
Defect Name Abrasion mark (chafe mark) Bad cover (poor cover)
Table 5.3 Woven Fabric Defect Description
5.3 Woven Fabric Defect Description and Cause
Textile Handbook 6-125
Foreign fibres
Ending Fine yarn (thin yarn) Float
A difference in colour between the bulk and one end of a piece of fabric A yarn whose is noticeably less than that of the adjacent yarns In a fabric, a length of yarn that is unbound over two or more successive ends or picks Fibres of a different type and / or colour from the other fibres in the fabric
Loss of colour from a dyed fabric when immersed in water, or other liquid medium with consequent colouring of the liquid medium colours missing from an area of design in a printed fabric Colour out A narrow steak running parallel to the warp threads, characterized by the Crack existence of a marked space between two adjacent threads A hard fold in a fabric, i.e. one that cannot be readily removed by those Crease means normally available to a garment maker, e.g. by steam pressing A dyed-in mark of a crease, usually along the warp direction, of a lighter Crease streak colour within the crease area and often with edges darker than the adjacent normal fabric Wrinkles of varying degrees of intensity and size that give the overall Crows’ feet effect of birds’ footprintsabric C u t s e l v e d g e ( r i p p e d Cuts or breaks that occur in the selvage only selvedge; torn selvage) Conspicuous pin stenter marks appearing in the body of the fabric and Deep pinning so reducing the usable width of the fabric Doctor blade (doctor streak) On a fabric, a lengthways steak of excess colour or excess coating Warp yarns in fabric which exhibit an approximately sinusoidal waveform Double bow, warp for more than three quarters of the wavelength Weft yarns in a fabric which exhibit an approximately sinusoidal wave Double bow, weft form for more than three quarters of the wavelength A disruption of the weave pattern similar in appearance to a thick pick Double pick where two yarns are in the same shed A weave distortion characterised by tight and slack places in the same Draw back warp yarn Dye mark (dye spot, dye stain) In a piece-dyed fabric, a discrete area of different colour Emboss mark (seam mark) A small area of the fabric standing out in relief
Colour bleeding
Contamination of the fabric by extraneous fibre which is either included in the yarn or woven into the fabric
The insertion of two weft yarns in the same shed when only one was inteded. Entanglement behind the harness, putting tension on several adjacent warp threads A contamination with concentrated dyestuff or dyeing assistants The relief print-off of defects, such as slubs, or of seams used to join lengths of fabric, under excessive rolling tension, or contraction on the roll during wet processing The premature exhaustion of the dye bath in continuous dyeing Variation in the linear density of the yarn A slack warp end or a faulty pattern card
A lack of control in fabric manufacture or processing
A damaged or incorrectly set doctor Lack of control during warping (uneven tension of warp yarn)
Incorrect feed-on to a pin stenter
By mechanical damage or unbalanced warp tensions
During wet processing or by careless folding of finished goods
The fabric being pad-dyed whilst creased
Distortion of the yarns during wet processing
A blocked screen or a faulty colour supply An imperfect reed, or a worn or maladjusted temple
Poor wet fastness of the dyeing or printing
6-126
Textiles Testing and Quality Control
A lumpy, asymmetrical fault in a spun yarn of a fabric An area of light colour surrounding a defect
An extra length of weft yarn that has been inserted for a part of the fabric width Exposed loops of weft yarn A difference in colour between the selvedges and the centre of a fabric Waste fibres created during weaving that are woven into a fabric
Jerked in weft
A reed misdraw or by a damaged or defective reed
poor carding or combing of fibre or by contamination during preparation for spinning Abrasion during prolonged finishing processes By irregularities of pressure during the finishing process
Accumulation of undrafted waste fibre into the yarn during spinning Migration of dye during drying or by less dye reaching the area around the defect during pad dyeing Weft yarns catching on a prominent warp yarn knot for a split second during beating up or until the knot has reached the fell of the cloth The stopping of a printing machine, allowing more paste than normal to penetrate the fabric Due to very many causes, amongst which are: careless handling of the fabric, defective machine elements, chemical damage, insect damage or damage during finishing, etc On conventional loom, after a pirn change due to a loose tail being woven in with a subsequent pick because cutters or suction devices were inactive An incorrect sequence of weft insertion Uneven batching -up of the fabric or by difference in temperature from the selvedges to the centre of the fabric during dyeing and finishing Weaving in close proximity without adequate precaution against contamination Excessive warp tensions or poor control of the selvedge at the fell of the fabric Incorrect balance of fabric structure between the selvedge and the body of the fabric, selvedge warp yarns being woven at too low a tension, or careless handling of the fabric Yarns being drawn into the heald wires in the wrong sequence By printing rollers or screens not being synchronized An interruption of the weft supply, a faulty weft stop motion, or drawing through The mixing of yarn batches or by the use of different yarn types Uneven application or penetration of dye or by surface distortion
Textiles Testing and Quality Control
Warp yarns that do not conform to the required draft plan Misdraw (wrong draft) Misregister; (out of register) In a printed fabric, colours not correctly positioned with respect to each other A bar across the fabric or the weave design is broken by the absence of Missing pick a weft Two or more different yarns appearing adjacent to one another Mixed weft Variation in colour or surface effect, localized or general, which is not Mottled appearance specifically orientated in the length or width directions An excessive number of small tangles or knots of fibre appearing on the Nep fabric surface small accumulations of fibre on the surface of a fabric Pilling An area of greater lustre, or of reduced thickness, in a fabric when compared Pressure mark to the adjacent normal fabric A crack between groups of warp ends either continuous or at intervals Reed mark which is not associated with missing yarns
Loose selvedge (slack Slack ends in the fabric edge selvage)
Loopy selvage (beaded selvedge; An improperly woven selvage of uneven width or a selvage containing corded selvedge, rough selvage) irregular weft loops extending beyond the outside selvages
Kinky weft Listing Loom fly
A breakdown in the fabric where two or more adjacent yarns are severed to create an aperture
Hole
Hang pick
A pick, caught on a warp yarn knot for a short distance, producing a triangular-shaped hole in the fabric Heavy colour (machine stop) Excess colour smudged in a weftways band
Gout Halo
Textile Handbook 6-127
Appears in a fabric which has been stretched excessively weft-wise during stentering
An abrupt, narrow indentation in the selvage Warp stripes which occur at regular intervals across all or part of the fabric width Selvage doubling (selvedge A length-wise crease mark along the selvage caused by an edge being folded or doubled turndown) A side-to-side change in colour across the width of the fabric Shading
An unwanted pate area in a piece-dyed fabric
Fine weftways cracks distributed randomly across the whole or part of the fabric
Weft which is distinctly different form the normal weft in a fabric
Undyed crease Water mark
Water spot
Weft crackiness
Wrong weft
Tight weft
A weft yarn which is under greater tension, or exhibits less crimp, than the adjacent weft yarns In a printed fabric, a well defined lengthways streak from which the colour in missing Irregular light and dark bands giving a rippled effect similar to rnoire
Small hole or disortion adjacent and parallel to the selvedge A selvedge that is shorter than the adjacent fabric
Fracture or damage of the warp yarns, weft yarns or both, adjacent to the edge of the fabric
A discrete area of discoloration of a fabric A continuous change in colour along the length of a piece
Stain Tailing Temple cutting Temple mark Tight selvedge
Snag
Skitteriness Smash
A disturbance of the weave or a localized pucker of the fabric that extends over an area corresponding to the dimensions of a shuttle An undesired speckled effect in a fabric or in a yarn within a fabric A relatively large hole in a fabric characterized by many broken warp ends and floating picks, or a prominent mark left behind after repairing such a hole A yarn or part of a yarn pulled or plucked from the surface
Shuttle trap mark
Scallop selvage Section marks
A yarn or fibres or filaments from a yarn, catching a sharp projection and being drawn out from the structure Contamination with extraneous substances such as dirt, oil or rust A gradual change in dye-bath concentration or temperature By hooked, flattened, or otherwise damaged temple pins during weaving A poorly adjusted temple Incorrect balance of fabric structure between the selvedge and the body of the fabric, selvedge warp yarns having been woven at too high a tension, or careless handling of the fabric A weft yarn having been inserted under a greater tension than that imposed on the other weft yarns, or relaxation of picks subsequent to insertion Passing a creased fabric through the printing machine The fabric having been subjected to excessive beat and or pressure and occurs more often in fabrics having a ribbed or corded weave Contamination with water prior to tinting or dyeing on a pad mangle, which results in a reduction of uptake of dye liquor Variations in warp let-off and fabric take-up when weaving an underset fabric, or irregularities of cohesion points in man-made intermingled continuous-filament yarns A lack of control of incoming material
Several heald wires breaking or by a defective picking motion
Differences in the depth of dyeing between adjacent fibres or portions of the same fibre
Tension differences within sections during sectional warping or by differential dyeability of the yarns or variations in yarn linear density The selvedge having folded over, thus shielding the edge of the usable fabric during processing Uneven concentration of dyestuffs or by temperature variations during dyeing and finishing An incomplete cycle of the picking motion, causing a trapping of the shuttle between the reed and the fell of the cloth
Overloading machinery for wet processing fabric in rope form, resulting in uneven liquor penetration or the formation of creases along which abrasion or felting may occur
Long, irregularly shifting, longitudinal markings on dyed or finished fabrics
Rope marks
6-128
Textiles Testing and Quality Control
Textile Handbook 6-129
5.4 Illustrations of Woven Fabric Faults Neppy
Figure 5.4 (2)
Gout
Figure 5.4 (3)
Warp Float
Textiles Testing and Quality Control
Figure 5.4 (1)
6-130
Textiles Testing and Quality Control Figure 5.4(4) Drawback
Figure 5.4(5)
Weft float
Figure 5.4(6) Double pick
Textile Handbook 6-131 Figure 5.4(7) Coarse Pick
Figure 5.4(9)
Mixing Weft
Textiles Testing and Quality Control
Figure 5.4(8) Thin place
6-132
Textiles Testing and Quality Control Figure 5.4(10)
Chopped weft
Figure 5.4(11)
Stop mark
Figure 5.4(12)
Jerk-in
Textile Handbook 6-133 Figure 5.4(13)
Warp burl
Textiles Testing and Quality Control
Figure 5.4(14) Thick place
Face
Figure 5.4(15)
Back
Soiled wefts
6-134
Textiles Testing and Quality Control Figure 5.4(16)
Double end
Figure 5.4(17) End out
Figure 5.4(18)
Coarse end
Textile Handbook 6-135 Figure 5.4(19) Open reed
Figure 5.4(21)
Broken pick
Textiles Testing and Quality Control
Figure 5.4(20) Slack end
See Clip mark in 5.3. A yarn of unacceptably greater thickness than that of the adjacent yarns. See Cockled yarn in 5.3 Crinkled, shriveled or ridgy fabric which prevents it from lying flat. See Colour Bleeding in 5.3 A small quantity of coloured fibre unintentionally incorporated into the structure of a fabric of a different colour.
See Colour Out in 5.3. See Crease in 5.3. See Crease Streak in 5.3. See Crow’s Feet in 5.3.
Clip mark (pin mark, stenter mark Coarse yarn
Colour out Crease Crease streak Crows’ feet
Colour bleeding Coloured fly
Cockled yarn Cockling
Broken filaments Bruise Bursting
During wet processing or by careless folding of finished goods,
Small amounts of coloured waste fibre being spun into a yarn of another stock, or by different fibres or colours running or being knitted in close proximity without adequate precaution against contamination.
Stitch distortion, uneven yarn relaxation or shrinkage.
Variation in the yarn evenness
The knitting elements cutting or damaging the yam during stitch formation and may not become apparent until tensions are imposed during finishing,
Feeder variation or variation in yarn characteristics. A malfunctioning needle forming random tuck stitches Incorrect take-down tension during knitting or Incorrect feeding during finishing.
Birdseye (pinhole) Bow
Defect Cause
Defect Description
See Abrasion Mark in 5.3. An unintentional, repetive visual pattern of continuous stripes usually parallel to the courses of cirucalr knit fabric Small apertures occurring occasionally in a wale. Excessive curvature of the courses in a fabric that may or may not extend over the full width. See Broken filament in 5.3 See Bruise in 5.3. The presence in a fabric of several individual stitches which have been severed.
Defect Name
Abrasion mark (chafe mark) Barre
5.5 Knitted Fabric Defect Description and Cause
6-136
Textiles Testing and Quality Control
See Dye Mark in 5.3. See Emboss Mark in 5.3. See Ending in 5.3. A warp-wise streak in a warp-knitted fabric in which some of the laps are missing. A length of yarn extending unbound over a number of wales with which it should be intermeshed. An inclusion of non-textile matter.
See Foreign Fibres in 5.3. See Gout in 5.3. See Halo in 5.3. See Heavy Colour in 5.3.
See Hole in 5.3. See Dropped Stitch in this section See Listing in 5.3. See Misregister in 5.3. See Mottled Appearance in 5.3. A vertical crack which is different from the adjacent normal wales. See Nep in 5.3.
Dye mark; dye spot; dye stain Emboss mark; (seam mark) Ending End out
Foreign fibres Gout Halo Heavy colour (machine stop)
Hole Ladder Listing Misregister (out of register) Mottled appearance Needle line
Neppy fabric
Foreign body
Float
Dropped stitch (run)
See Doctor Blade in 5.3. One or several wales in a warp-knitted fabric in which the laps appear shorter than those in the adjacent normal wales. A stitch has not formed due to malfuncion of a needle
See Deep Pinning in 5.3. The appearance on the face side of a fabric of the wrong one of two yarns knitted simultaneously at a feeder. A break in the intended pattern of an inlay pile fabric.
A misaligned or broken needle which forms distorted stitches.
The stopping of a printing machine allowing more paste than normal to penetrate the fabric.
A needle failing to take the yarn, or by yarn casting off from the knitting elements prematurely, Insufficient attention to the cleanliness of the knitting machines and of the knitting room.
A warp yarn breaking or running out.
A needle failing to take the yam, or by the yarn casting off from the knitting elements prematurely,
Excessive tension in one or more warp yarns,
Poorly differentiated feed heights or tension during plating. A disruption in the synchronization of the knitting elements that control the position of a fleecy yarn in a laidin fabric.
Textiles Testing and Quality Control
Doctor blade (doctor streak) Dragging end
Displaced inlay yarn
Deep pinning Defective plating
Textile Handbook 6-137
A breakdown in the knitted structure over a discrete area or the fabric falls off the machine. See Rope Mark in 5.3. See Scallop Selvage in 5.3. See Selvage Doubling in 5.3. See Shading in 5.3. Courses that are straight but off square to the wales
Press-off
Stripiness; warp-wise bars
Length-wise areas of several wales width appearing darker in colour from normal fabric.
See Snag in 5.3. A distortion in a weft-knitted fabric in which the wales are clearly not at right angles to the courses. See Stain in 5.3. A band of several courses having stitch characteristics different from those in the normal fabric.
Snag Spirality
Stain Start-up mark (stop mark)
See Skitteriness in 5.3. In a yarn, a thickened place having tapering ends and a diameter several times that of the adjacent normal yarn
Skitteriness Slub
Rope marks Scallop selvage Selvedge doubling (selvage turndown) Shading Skew
See Pilling in 5.3. See Pressure Mark in 5.3.
Pilling Pressure mark
A change in yam tension resulting from the deceleration and standing time when a machine stops. Wale-consolidation or distortion arising from uneven width tension during knitting that is subsequently accentuated by dyeing and finishing, or from poor width control during open-width processing.
Twist-lively yam (due to insufficient setting).
Presence in the yarn of fragments of undrafted roving or slubbing that have not been cleared during winding
Uneven take-down during knitting or a failure to line up the fabric edges during open-width finishing.
Irregularities of pressure during the finishing process Fabric coming off the knitting needles due to a failure in the yarn supply.
6-138
Textiles Testing and Quality Control
See Tailing in 5.3. A prominent band in which an increase in stitch density, compared to the rest of the fabric, is apparent. A prominent band in which a decrease in stitch density, compared to the rest of the fabric, is apparent. A yarn of unacceptably thinness than that of the adjacent yarns. See Undyed Crease in 5.3. See Water Mark in 5.3. See Wate Spot in 5.3. In a warp-knitted fabric, a yarn that differs from normal yarns in respect of composition, thickness, filament or colour. See Wrong yarn in 5.3. A lack of control of incoming material,
A poor start-up of the machine, or uneven let-off or take-up. Uneven yarn let-off or fabric take-up.
Textiles Testing and Quality Control
Note: For further information on fabric defects, Please refer to ASTM D3999, ISO 8498 and ISO 8499
Wrong yarn
Thin yarn Undyed crease Water mark Water spot Wrong end
Thin place
Tailing Thick place
Textile Handbook 6-139
6-140
Textiles Testing and Quality Control
5.6 Illustrations of Knitted Fabric Faults Figure 5.6 (1)
Needle line
Figure 5.6 (2)
Bird’s eye
Figure 5.6 (3)
hole
Textile Handbook 6-141 Drop stitches
Figure 5.6 (5)
Cloth Press off
Figure 5.6 (6) Tuck loop
Textiles Testing and Quality Control
Figure 5.6 (4)
6-142
Textiles Testing and Quality Control Figure 5.6 (7)
Loose course (Thin yarn)
Figure 5.6 (8)
Vertical stripe
Figure 5.6 (9)
Barre
APPENDIX
I
BUSINESS STRATEGIES FOR THE TEXTILE AND APPAREL 1
Quick Response 1.1
The Objective of Quick Response
The objective of Quick Response is to shorten the cycle time of the entire apparel production and distribution chain, from fibre production through to the retail point of sale. Quick response is a partnership strategy in which the retailer and supplier work together to respond more quickly to consumer needs. This includes sharing information on electronic point of sale activity, jointly forecasting future demand for replenishment items and continually monitoring trends to detect opportunities for new items. This partnership strategy calls for investments in information systems and mutual trust among participants. Information technology has an important role to play in achieving quick response.
1.2
Five Stages of Implementation
1.2.1
Stage 1 deals with the technical aspects and includes technologies such as Electronic Data Interchange (EDI), Point of Sales (POS), and Universal Product Code (UPC). Purchase orders, acknowledgements, shipping notices, payment orders and invoices are the typical documents that are sent through EDI. Retailers gather daily sales data at the electronic point of sales terminals and report these to the supplier. The product flow can then be fine-tuned by eliminating slower selling items.
1.2.2
Stage 2 relates to the automatic replenishment of sold goods. Purchase orders are automatically generated from known lead times that are fed into the system and forwarded to suppliers. Suppliers can achieve a just-in-time manufacturing system by issuing more frequent orders with fewer units, thus eliminating safety stocks and increasing inventory turnover.
1.2.3
Stage 3 concerns the trading partners forging closer alliances through mutual inspection of their supply chain and identifying areas for improvement, e.g. reducing buffer stock in the supply
chain. Common forecasting models are used, and the same data is used for forecasting future demand. 1.2.4
Stage 4 involves major changes to the product development process and is based on continuously monitoring POS activity to detect trends, and constantly testing new product concepts in a limited number of stores. The POS information is particularly important because it allows retailers to retain product-specific information about consumer spending patterns and methods of purchase.
1.2.5
Stage 5 defines a partnership scenario where the supplier is handed full responsibility of the supply chain right up to the point of purchase by the customer. In this case the supplier is given allocation of shelf space by the retailer and it is his responsibility to provide full stock replenishment, in-store promotion and staff training where necessary. It is in the interests of both parties to see that the shelves are replenished as efficiently as possible since both are receiving profits from the sales.
1.3
Technologies a)
Electronic Data Interchange (EDI) is the ability to exchange business data between trading partners electronically. Billing and shipping orders, acknowledgement, and reorders are all done without exchange of paper. To further enhance the Quick Response system, manufacturers are setting up EDI systems with their major retail accounts. For the systems to work, retailers provide the manufacturer access to sales and inventory data for the manufacturer’s specific product lines
b)
Point of Sale (POS) is a terminal that records sales against inventory
c)
Universal Product Code (UPC) is a special scannable bar code system adopted as a standard labelling system for the apparel and retail industry; the code can be integrated into all types of packaging, labelling, and hang tags.
Supply Chain Management Interest in the concept of supply chain management has steadily increased since the 1980’s when companies saw the benefits of collaborative relationships within and beyond their own organisation. Definition of the supply chain is that all the activities involved in delivering a product from raw material through to the customer, including sourcing raw materials and parts, manufacturing and assembly, warehousing and inventory tracking, order entry and order management, distribution across all channels, delivery to the customer, and the information systems necessary to monitor all of those activities. Supply chain management co-ordinates and integrates all of these activities into a chain process. It links all of the partners in the chain, including the departments within an organisation and the external partners including vendors, carriers, third-party companies, and information systems providers. Table 2
Supplier
Designer
Manufacturer
Branding Marketing and Promotion Distribution Centre Shops
Dyeing Printing Finishing Cut/MakeTrim (Quota)
Research and Design Manufacturing Process Design Fashion Design Colour and Finishing requirements
Sample Supply Chain for Textile and Apparel
Fibers Yarn Fabrics Trimmings and Accessories
2
Retail
Supply chain management assumes that a company’s supply chain is a competitive resource. The company must understand their internal and supplier core competencies in meeting customer needs in terms of production capabilities, flexibility and overall organisation competence. They must develop relationships and alliances with suppliers who have key competencies that strengthen, supplement, and enhance internal core competencies.
3
Enterprises Resources Planning (ERP) ERP is the integrated business planning and execution process for managing the operations and support functions of a manufacturing enterprise. The ERP system is an accounting oriented information system for identifying and planning the enterprise-wide resources needed to take, make, ship, and account for customer orders. An ERP system differs from the Manufacturing Resources Planning (MRP II) system in technical requirements such as Graphical User Interface (GUI), relational database, use of fourth generation languages and computer-aided software engineering tools in development, client-server architecture, and open system portability.
3.1
ERP Components
ERP is a closed-loop planning and execution process. The scope of ERP begins with business planning, and includes all of the support functions and operations of the enterprise. It is completed with key performance measures (financial and operational) that close the planning loop and become an integral part of the next business planning cycle. The enterprise functions in an ERP process include: • Business Planning Vision Mission Strategic planning • Forecasting • Operations processes Master planning Production planning Purchasing Inventory management Shop floor control Manufacturing performance measures • Financial Payroll Product costing Accounts payable Accounts receivable
Capital/fixed assets General ledger • Human Resources • Information Systems • Engineering • Plant and Equipment • Tooling
3.2
The Material and Information Flow in ERP Operation
The material and information flow in ERP is a closed loop planning and control system that covers the three key cycles in a manufacturing business, and associates all activities in these three cycles with financial information. The three cycles of manufacturing are: Revenue Generation, Production and Procurement Cycles.
Table 3.2 Typical ERP System
4
E-Commerce Online commerce or E-Commerce is a unique way of doing business on the Internet. With E-Commerce, companies can now do financial business on the Internet 24 hours a day, all year round. E-Commerce allows the suppliers to not only display its products / services on the Internet, but also perform real-time sales online (financial transactions). In essence the supplier will be able to make an online sale with credit card transactions approved in 15-20 seconds, and the supplier’s bank instantly crediting the amount to the supplier’s account. The supplier can even conduct banking online from the web. (E-Commerce) essentially has two facets when transactions/business take place: Business-to-Consumers (B2C) and Business-to-Business (B2B). B2C are consumer oriented services tailored to meet large numbers of users / visitors. Per Transaction dollar value is low. The retail market is what B2C is all about. B2B are transactions between businesses tailored to meet mid-to-high volume transactions, where each transaction carries a high-dollar price. In an ideal B2B transaction financial settlement can be made online, although that will not usually be the case.
APPENDIX
2
WEB SITES RELATED TO TEXTILES www.aatcc.org
www.inda.org
www.acad.polyu.edu.hk
www.itaaonline.org
www.acimit.it
www.iso.ch
www.amtex.sandia.gov
www.i-textile.com
www.apparelcircle.com
www.itmf.org
www.apparelkey.com
www.itt.edu
www.asiafabric.net
www.tx.ncsu.edu
www.astm.org
www.portugaltextil.com
www.atma.org
www.sdc.org.uk
www.atmi.org
www.tc2.com
www.btma.org.uk
www.texi.org
www.bttg.co.uk
www.textile.fr
www.chinatextrade.com
www.textiles.org.tw
www.cotton.org
www.textilesolutions.com
www.cottoninc.com
www.textiles.umist.ac.uk/textiles/
www.cottonusa.org
www.textileweb.com
www.ctei.gov.cn
www.textileworld.com
www.custom.ustreas.gov
www.textrade.com
www.econcentral.org/wcd/
www.texwatch.com
www.fabriclink.com
www.ucmtf.com
www.fas.usda.gov
www.unicate.com/mainmenu.html
www.fcc.co.jp/jcfa
www.vdma.org
www.fibersource.com
www.wool.com
www.gesamttextil.de
www.wronz.org
www.hubcap.clemson.edu
www.wto.org
APPENDIX
3
THE HONGKONG COTTON SPINNERS ASSOCIATION 2000/2001 – Member List Central Textiles (HK) Ltd East Asia Textiles Ltd Eastern Cotton Mills Ltd Far East Cotton Ind Ltd Guestkeen Enterprises Ltd Nam Hwa Textiles Ltd Nan Fung Textiles Ltd Nanyang Cotton Mil Ltd South Management Ltd Tai Hing Cotton Mill, Ltd Textile Alliance Ltd Woodard Textile Manufacturing Co, Ltd
APPENDIX
4
THE HONGKONG COTTON SPINNERS ASSOCIATION Committee Members of 2000/2001 Mr. Alexander Woo (Chairman) Mr. Albert Chang (Vice Chairman) Mr. Clement Chen Mr. Sam T S Chen Mr. S S Fan Mr. Standford Kuo Dr. Richard Lee Mr. James S Wan Mr. James St Wong Mr. Julian Wong Mr. Jerry Yu Mr. Lincoln Yung
APPENDIX
5
CHAIRMAN AND VICE CHAIRMAN LIST OF THE HONGKONG COTTON SPINNERS ASSOCIATION Year
Chairman & Vice-Chairman
1955-56
C. Y. Wong * P. Y. Tang *
1956-57
S. H. Yang * H. K. Liu *
1957-58
C. C. Lee, J.P. H. J. Shen *
1958-59
Mou Lee * V. J. Song *
1959-60
T. Y. Wong, O.B.E., J.P. * H. T. Liu, J.P.
1960-61
T. Y. Wong, O.B.E., J.P. * H. C. Yung, J.P.
1961-62
H. T. Liu, J.P. H. C. Yung, J.P.
1962-63
T. Y. Wong, O.B.E., J.P. * Y. F. Wu
1963-64
T. Y. Wong, O.B.E., J.P. * T. K. Ann, C.B.E., LL.D., J.P. *
1964-65
T. Y. Wong, O.B.E., J.P. * Y. F. Wu
1965-66
T. K. Ann, C.B.E., LL.D., J.P. * Vincent Woo, J.P. *
1966-67
T. K. Ann, C.B.E., LL.D., J.P. * S. C. Fang *
1967-68
T. K. Ann, C.B.E., LL.D., J.P. * Y. F. Wu
1968-69
Vincent Woo, J.P. * S. C. Fang *
1969-70
T. Y. Wong, O.B.E., J.P. * H. C. Tang, O.B.E., J.P.
1970-71
T. Y. Wong, O.B.E., J.P. * H. C. Tang, O.B.E., J.P.
1971-72
T. Y. Wong, O.B.E., J.P. * S. C. Fang *
1972-73
Vincent Woo, J.P. * H. C. Tang, O.B.E., J.P.
1973-74
Vincent Woo, J.P. * H. C. Tang, O.B.E., J.P.
1974-75
H. C. Tang, O.B.E., J.P. Y. C. Chen, O.B.E., LL.B., J.P.
1975-76
H. C. Tang, O.B.E., J.P. Y. C. Chen, O.B.E., LL.B., J.P.
1976-77
Y. C. Chen, O.B.E., LL.B., J.P. C. S. Loh *
1977-78
Y. C. Chen, O.B.E., LL.B., J.P. C. S. Loh *
1978-79
Y. C. Chen, O.B.E., LL.B., J.P. C. S. Loh *
1979-80
C. S. Loh * T. Z. Wang *
1980-81
C. S. Loh * T. Z. Wang *
1981-82
T. Z. Wang * H. L. Ho
1982-83
H. T. Liu, J.P. Lincoln C. K. Yung, J.P.
1983-84
H. T. Liu, J.P. Lincoln C. K. Yung, J.P.
1984-85
Lincoln C. K. Yung, J.P. Sam T. S. Chen
1985-86
Sam T. S. Chen Herbert C. F. Woo
1986-87
Y. C. Chen, O.B.E., LL.B., J.P. Alexander C. H. Woo, O.B.E.
1987-88
Alexander C. H. Woo, O.B.E. Albert H. Y. Chang
1988-89
Alexander C. H. Woo, O.B.E. Lincoln C. K. Yung, J.P.
1989-90
Lincoln C. K. Yung, J.P. Clement C. J. Chen
1990-91
Lincoln C. K. Yung, J.P. Clement C. J. Chen
1991-92
Clement C. J. Chen Fan Sze Shun
1992-93
Clement C. J. Chen Paul H. Y. Cheng
1993-94
Clement C. J. Chen Julian W.C. Wong
1994-95
Clement C. J. Chen James S.J. Wan
1995-96
Clement C. J. Chen Jerry J. H. Yu
1996-97
Clement C. J. Chen Jerry J. H. Yu
1997-98
Clement C. J. Chen Jerry J. H. Yu
1998-99
Clement C. J. Chen Jerry J. H. Yu
1999-00
Alexander C. H. Woo, O.B.E. Albert H. Y. Chang
2000-01
Alexander C. H. Woo, O.B.E. Albert H. Y. Chang * = (deceased)
