Yarn Texturing Technology | J W S Hearle, L Hollick and D K Wilson


Yarn Texturing Technology
By J W S Hearle, L Hollick and D K Wilson

Yarn texturing


Preface ix
About the authors xii
1 The origins of texturing 1
1.1 Introduction 1
1.2 Twist-texturing 4
1.3 Jet-screen texturing: BCF yarns 13
1.4 Air-jet texturing 14
1.5 The future 15
2 Scientific and engineering principles in twist-texturing 16
2.1 Introduction 16
2.2 Fibre science: Heat-setting 16
2.3 Mechanics of twisting 41
2.4 Structural mechanics of twisted yarns 57
2.5 False-twist texturing process 62
2.6 Twisting, bending and buckling 70
2.7 Variability 80
3 Scientific and engineering principles in other texturing processes 83
3.1 Introduction 83
3.2 Bending, buckling and setting 83
3.3 Air-jet texturing 86
4 False-twist process 97
4.1 Introduction 97
4.2 Draw-texturing machine 98
4.3 Process variables 116
4.4 Package dye yarns 141
4.5 Machine types and variations 145
4.6 Plant environment and operating procedures 147
4.7 Safety 149
4.8 Product integrity 150
5 False-twist textured yarns 151
5.1 Introduction 151
5.2 Definition of yarn type 151
5.3 Modification of yarn properties 153
5.4 Spun-dyed yarns 175
5.5 Common modified polymers 176
5.6 Composite or combination yarns 176
5.7 Oops! What went wrong? 178
6 BCF processes and yarns 185
6.1 Introduction 185
6.2 BCF draw-texturing machine 186
6.3 Process variables 194
6.4 BCF yarns 203
6.5 Modification of yarn properties during draw-texturing 206
7 Air-jet texturing and yarns 211
7.1 Introduction 211
7.2 Air-jet texturing machine 212
7.3 Process variables 222
7.4 Air-jet textured yarns 233
8 Quality assurance 244
8.1 Introduction 244
8.2 Raw materials 244
8.3 Quality assurance of textured yarn 251
8.4 Visual inspection prior to despatch 265
9 Textile yarn logistics 267
9.1 Introduction 267
9.2 Handling 268
9.3 Internal transport systems 272
9.4 Packing line 273
9.5 Yarn packaging 274
9.6 Warehousing 275
9.7 Product logging 276
9.8 Load planning 277
10 Retrospect and prospect 278
10.1 Introduction 278
10.2 Past technologies 278
10.3 Current technology 281
10.4 Related technology 283
10.5 New research and development 284
Appendix 1 Textured condition reference chart 289
Appendix 2 Machine speed and general calculations 290
Bibliography 293
Index 297


In 1946, when I started my career in textiles, nylon, which had come to the market less than ten years before, was virtually synonymous with parachute fabrics and ‘nylons’, the ladies’ stockings first brought to Europe by American servicemen. Polyester was being explored in laboratories for competitive uses. Both were flat, continuous yarns, densely packed in fabrics. Over the next few years, nylon and polyester appeared in other markets.Washand- wear was an attraction and so, when I went on a Fellowship to South Carolina in 1953, I bought nylon and polyester shirts, socks and underwear – all made of fabrics that would be unacceptable today, because of their poor comfort and appearance.

It was in South Carolina that I first came across texturing. Hugh Brown, a highly inventive physicist, who had become Dean of Textiles at Clemson, was exploring texturing by running nylon yarn over a hot wire.A few miles away Deering-Milliken researchers were developing edge-crimping, and from Switzerland we heard of the long process for twist texturing.When I returned to Manchester, I introduced textured yarns into my lectures, and, with Malcolm Burnip and Gordon Wray started research into the relation between process conditions and yarn structure and performance in falsetwist texturing.This research continued in various ways until I retired from UMIST in 1985.

Like many of the major advances in textile manufacturing, starting with Arkwright and cotton spinning 200 years ago, texturing has led to fierce patent litigation. I learnt a great deal from tests and studies in my role as an expert witness. I wrote thousands of pages of affidavits, but never went on the witness stand in person. Apart from opposition proceedings on a variety of patents, I was active in three phases of law-suits. First, on a Stoddart and Seem patent, which applied to single-heater false texturing for stretch yarns.This started with a threats action against Fluflon Ltd and continued with infringement actions until it petered out. Second, on another Stoddart and Seem patent, which covered double-heater, false-twist texturing for set polyester yarns.This led to a re-examination of the patent by the US Patent office, almost 20 years after its priority date, and eventually to two trials in Florida.Third on the DuPont Petrille patent for POY yarns, the feed-stock for draw-texturing: a case in India died for want of prosecution after running for a few months, first with oral evidence and then with affidavits, and DuPont versus ICI was settled just before it was due to open in the High Court in London.There were other cases, with which I was not involved, notably a trial in Canada in the1950s on stretch yarns and one in USA in the 1970s on set yarns with Milliken and Burlington as the main opposing protagonists.

My co-author, Keith Wilson, as a student in the Faculty of Technology of the University of Manchester, was introduced to textured yarn technology by my lectures. He then went on to a career in the fibre and textile machinery industries, which progressively took him closer first to false-twist texturing and then to air-jet texturing. Our other co-author, Les Hollick, has a great depth of experience in the manufacture of textured yarns.

For physicists, like myself, working in an academic environment, there is a great temptation to concentrate research on problems that are interesting – and amenable to mathematical theorising or neat experiments – but in industrially related departments, it is important that even basic research should add useful insights to commercial operations, either current or with future potential. Les Hollick makes a similar comment about the place of technologists in business in the following words:

The aim of any manufacturing organisation, no matter what business they are engaged in, is to secure a positive return on investment. A healthy balance sheet benefits the owners, the shareholders or, in the case of a co-operative, the workers themselves. If any organisation is to have sufficient funds to secure full employment and to provide for future investment in plant and equipment, concentration on running a viable business is required. It is very tempting for the technologist to pursue work purely because it is exciting or interesting. If time permits this is fine, but first and foremost continual concentration on product and process improvement is required. This does not mean that such work cannot be fun; far from it, if the work itself becomes mundane and tedious then it is time to find alternative employment.

It is the function of the technologist to examine every detail of the process, the design of the machine itself, the quality and suitability of machine components and ancillaries that are employed, as well as obviously, the quality of the feedstock and the process conditions employed. These must be carefully evaluated to ensure that they are the best available at economic cost. The elimination of sub-standard product and the maximisation of yield of first quality product, which can be sold at a competitive price and still be viable, is of paramount importance. Communication between the technologist and those directly involved with the manufacture of the product, at all levels, must be simple and clear. The temptation to escape into jargon must be avoided. It used to be sufficient to ‘speed up the traverse system to cure some overthrows’; now unfortunately it’s all to easy to ‘realise an increase in the angle of wind in order to secure optimum packaging conditions’.These statements may be impressive, but no one else in the room will have any idea what you are talking about. Clear and concise communication and the ability to motivate others to strive towards a common goal is a skill every bit as important as technical prowess.

Finally, it must never be forgotten that the contribution by well trained and well motivated operatives, who understand the importance of correct yarn handling and operating procedures, is one of the greatest assets that any company involved in the manufacture of yarn can have. Constantly keeping the workforce up to date with the current situation and what improvements are to be implemented is one aspect of the technologist’s work that cannot be ignored.

In this book, we hope that the combination of authors, who range from the detached academic to the involved technologist, has enabled us to provide for students, teachers and the yarn texturing industry, both an explanation of relevant scientific and engineering principles and a wealth of information on industrial practice.

John Hearle

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