False Twist Textured Yarns: Principles, Processes and Applications By C. Atkinson


False Twist Textured Yarns: Principles, Processes and Applications
By C. Atkinson

False twist textured yarns


Woodhead Publishing Series in Textiles ix
Preface xvii
1 The development of textured yarns 1
1.1 Artificial silk: an early history 1
1.2 The arrival of melt spinning 3
1.3 The melt spinning process 4
1.4 Achieving desirable fabric properties through texturing 10
1.5 References 13
2 Basic principles of false twist texturing 14
2.1 The concept of false twist texturing 14
2.2 The false twist mechanism 19
2.3 Twist application methods 21
2.4 References 27
3 Yarn texturing machine design 28
3.1 The evolution of yarn texturing machines 28
3.2 Yarn heating and residence time in the primary texturing zone 30
3.3 Vapour phase heaters 31
3.4 High-temperature (HT) heaters 33
3.5 Intermediate-temperature heaters 39
3.6 Comparison summary of heater types 39
3.7 Yarn cooling in the texturing zone 41
3.8 Secondary heaters 46
3.9 Machine profi les 47
3.10 References 57
4 Yarn twist application methods 59
4.1 Friction disc twisting 59
4.2 Friction disc materials 64
4.3 Infl uence of friction disc twisting parameters on texturing performance 72
4.4 Friction disc systems advances 74
4.5 Belt twisting 77
4.6 Improving yarn elasticity by torque generation (self twist) 81
4.7 References 85
5 Process performance issues in yarn texturing 86
5.1 Friction and surface texture of yarn contact surfaces 86
5.2 Process instability: tension transients and speed limitations due to ‘surging’ 90
5.3 Creel design and management 98
5.4 Package build specifi cations 103
5.5 Oil application systems 108
5.6 Automatic doffi ng systems 110
5.7 References 113
6 Newer yarn texturing machine designs 115
6.1 Factors affecting machine design 115
6.2 Examples of new designs 118
6.3 References 123
7 Air jet intermingling in yarn texturing 124
7.1 The concept of air jet intermingling 124
7.2 The intermingling process 125
7.3 Downstream process issues 133
7.4 References 134
8 Optimisation of process parameters in yarn texturing 135
8.1 Influence of texturing parameters on yarn characteristics and performance 135
8.2 Single-position to plant-scale operation 141
8.3 Resolving process quality issues 147
9 Draw textured yarn variants and speciality yarns 152
9.1 Double-density machines 152
9.2 Machine variants for draw textured speciality yarns 152
9.3 References 155
10 Process control and quality assurance in yarn texturing 156
10.1 In-process controls 156
10.2 At yarn package doff 159
10.3 Laboratory controls 159
10.4 Final product inspection and packing 163
10.5 Statistical process control 165
10.6 References 165
11 Process costs in yarn texturing operations 167
11.1 Factors affecting costs 167
11.2 Opportunities for yarn texturing outside low labour-cost countries 170
11.3 Reference 171
12 End uses for draw textured yarns 172
12.1 Property benefi ts of textured yarns 172
12.2 Nylon 174
12.3 Polyester 179
12.4 Polypropylene 189
12.5 References 190
13 The future of false twist texturing 191
13.1 Global production trends 191
13.2 Machine development 193
13.3 Process integration 194
13.4 Raw material yarns 195
13.5 References 196
Index 197

As a descendant of a hemp and flax spinning mill owning family; having graduated with a degree in textile science; and having later obtained a PhD in man-made fi bre extrusion at Bradford University, it was inevitable that I should pursue an industrial career in textiles. In 1977, my industrial career started in the Synthetic Fibres Laboratory of Courtaulds Plc, Coventry, England, where I was involved in various development activities for the company’s POY and LOY polyester spinning operations in Northern Ireland and Eire.

Three years later I joined Ernest Scragg and Sons Ltd (later in 1982, Rieter-Scragg Ltd) as Senior Textile Technologist. ‘Scragg’ was a leading manufacturer of draw texturing machines for the international market and was renowned for its process know-how and innovations. For a young industrialist, the global world of texturing machine manufacturing provided a wealth of international contacts and excitement. Unknowingly at the time, Scragg was to become highly infl uential in my industrial career, providing a foundation for both process knowledge and practical experience in draw texturing. In particular, it brought into my life a fascinating textile process, where complex process parameter interactions infl uence texturing performance and where hands-on experience, together with a systematic approach, are vital for achieving optimum results. Moreover, during the mid-1970s to 1980s research and development activities in texturing were extremely active throughout Europe, both in machine manufacturing and yarn processing. As a consequence, I was fortunate to work alongside many of the leading international fi gures in research institutions and companies who were associated with draw texturing at the time.

My interests in the draw texturing process grew rapidly during my employment in Scragg and it was not surprising that my career advance evolved around draw textured yarns. To acquire experience in a disciplined yarn production environment I moved to Germany, working for a number of years in polyester and nylon textured yarn process development at Rhodia AG. Yarn end-user experience was also essential, so a period followed in hosiery manufacturing as Technical Director, Aristoc, Courtaulds Textiles. Finally, I returned to the texturing process itself as Technical Director, Rieter-Scragg Ltd and Managing Director, Intex Yarns Ltd, a textured- and dyed-yarn manufacturer in the UK. Since 2000, I have been operating as an independent consultant in the texturing industry, continuing my international involvement in development activities, process performance improvements and novel yarns.

In recent years there has been a rapid demise of the continuous fi lament industry in the Western world coupled with a move to lower cost countries, predominantly in the Far East and Asia. Basically, the draw texturing process is currently on a plateau, where a signifi cant advance in process technology is diffi cult to realise and profi t margins are squeezed to the extent that draw textured yarn manufacturing can largely survive only in lower labour cost regions. Moreover, a relocation of the draw texturing machine manufacturing industry has followed yarn processing due to the same cost constraints. The machines, however, tend to be copies of past European designs and signifi cant advance in designs is restricted due to lack of fundamental draw texturing process knowledge. Indeed, the many people that were involved in the pioneering days of the industry are now retired and the number of draw textured yarn- and machinery-manufacturing companies in Europe has drastically shrunk. Moreover, as a consequence, some fundamental key process knowledge and experiences have been lost. It is of course possible to survey past literature on the subject of draw texturing, but this can be time consuming to locate and retrieve and it is often diffi cult to relate both research and commercially orientated papers to specifi c problems that can occur in every-day industrial practice.

With my experience in machine manufacturing and process technology in draw texturing exceeding 30 years, together with a unique experience in the synthetic fi lament supply chain from extrusion through to retailer, I am able to provide an ideal platform for the conveyance of a broad experience and depth of knowledge to existing persons in, and newcomers to, the draw texturing process. Indeed, I very much welcome the opportunity to pass to others my experience and knowledge gained over the enjoyable years in this industry.

This book provides an overview of the properties of, and the applications for, draw textured yarns. It describes key fundamentals in the draw texturing process, the effects of process parameters on texturing performance, and new developments. The key features of draw texturing are initially described for acquiring a basic understanding of the process, followed by details on process optimisation methods and solutions to problems that are commonly encountered in draw texturing. It is a practical guide to the draw texturing process.

Colin Atkinson

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