Role of Yarn Tension in Weaving | Samir Kumar Neogi


Role of Yarn Tension in Weaving
by Samir Kumar Neogi

Role of Yarn Tension in Weaving


Preface xi
Foreword xiii 

1 Fundamentals of yarn tension 1
1.1 Introduction 1
1.2 Definition of yarn tension 1
1.3 Necessity of tension in textile processing 2
1.3.1 Tension at weaving preparatory 2
1.3.2 Tension at weaving 3
1.4 Yarn tension and yarn breakage 4
1.5 Tensioning system 4
1.6 Tensioner (or Tension device) 10
1.6.1 Disc tensioner 10
1.6.2 Gate-type tensioner 11
1.6.3 Roller tensioner 11
1.6.4 Capstan tensioner 11
1.6.5 Tensioner with automatic control system 11
1.7 Tension measurement 12

2 Yarn tension at the weaving preparatory process 17
2.2 Weaving preparatory processes 18
2.3 Winding process 19
2.3.1 Unwinding 20
2.3.2 Tensioning (and clearing) 26
2.3.3 Winding 27
2.3.4 Pirn winding 28
2.4 Warping process 30
2.5 Slashing (or sizing) process 32

3 Warp tension measurement 37
3.1 Introduction 37
3.2 Passage of warp yarns through the loom 37
3.3 Stretch and strain of warp yarns due to shedding 38
3.4 Warp tension control by let-off motion 42
3.5 Measurement techniques of warp tension 44
3.5.1 Tension measurement of the whole warp sheet 44
3.5.2 Tension measurement of the bunch of warp yarns 47
3.5.3 Tension measurement of single warp yarn 49

4 General form of warp tension variation 59
4.2 Warp tension variation 60
4.2.1 Tension variation of the whole warp sheet 60
4.2.2 Tension variation of the bunch of warp yarns 62
4.2.3 Tension variation of single warp yarn in shuttle loom 63
4.2.4 Tension variation of single warp yarn in shuttleless loom 69

5 Weft tension measurement 73
5.1 Introduction 73
5.2 Weft tension measurement in shuttle loom 74
5.2.1 Measurement during unwinding from pirn 74
5.2.2 Measurement during insertion of a pick 76
5.3 Weft tension measurement in shuttleless loom 79

6 General form of weft tension variation 81
6.1 Introduction 81
6.2 Weft tension variation in shuttle loom 82
6.2.1 Tension variation during unwinding from pirn 82
6.2.2 Tension variation during insertion of a pick 83
6.3 Weft tension variation in shuttleless looms 86
6.3.1 Tension variation in projectile picking 87
6.3.2 Tension variation in rapier picking 88
6.3.3 Tension variation in air-jet picking 90
6.3.4 Comparison of weft tensions in different shuttleless picking systems 92

7 Effects of loom settings and other factors on warp tension 97
7.1 Introduction 97
7.2 Effects of warp beam and let-off motion 98
7.2.1 Warp tension control in negative let-off motion 99
7.2.2 Warp tension control in positive let-off motion 102
7.3 Effects of back-rest 105
7.3.1 Back-rest setting 105
7.3.2 Back-rest movement 108
7.3.3 Back-rest mounting 112
7.3.4 Back-rest type 118
7.4 Effects of warp stop motion setting and warp leasing pattern 119
7.4.1 Warp stop motion setting 119
7.4.2 Warp leasing pattern 120
7.5 Effects of shedding 123
7.5.1 Front shed geometry 123
7.5.2 Heald movement 124
7.5.3 Heald position 128
7.5.4 Warp drafting pattern 129
7.5.5 Shed timing 130
7.6 Formation of clean warp shed 132
7.7 Effects of warp denting pattern 138
7.8 Effects of beat-up 139
7.9 Effects of temple 148
7.10 Effects of looming-in lengths of warp and cloth 151
7.11 Effects of other factors 155
7.11.1 Weave 155
7.11.2 Loom speed 156
7.11.3 Yarn join 157
7.11.4 Weft tension 160

8 Effects of loom settings and yarn characteristics on weft tension 167
8.1 Introduction 167
8.2 Shuttle picking 168
8.2.1 Effects of pirn and shuttle modifications 168
8.2.2 Effects of shed timing 171
8.2.3 Effects of shuttle checking 172
8.3 Shuttleless picking 172
8.4 Effects of weft package 173
8.5 Weft storage system (weft accumulator or weft feeder) 175
8.5.1 Forces acting on the yarn at weft accumulator 177
8.5.2 Effects of weft accumulator 180
8.5.3 Effects of type and setting of weft accumulator 184
8.6 Effects of other loom mechanisms 189
8.7 Effects of loom speed 193
8.8 Effects of weft yarn characteristics 197 

9 Effects of yarn tensions on loom performance 207
9.1 Introduction 207
9.2 Loom performance 208
9.2.1 Warp break 209
9.2.2 Weft break 215

10 Effects of yarn tensions on fabric properties 221
10.1 Introduction 221
10.2 Mechanics of cloth formation in relation to yarn tensions 222
10.3 Beat-up force 225
10.4 Cloth properties 233
10.4.1 Structural and dimensional properties 233
10.4.2 Physical properties 242
10.4.3 Comfort properties 249
10.5 Weave prominence 250
10.6 Roll of yarn tensions on the remedy of some cloth defects 251
10.6.1 Starting mark or setting-on place 251
10.6.2 Repping 258
10.6.3 Reed mark or reediness 260
10.6.5 Selvedge distortion 268

In the process of weaving, warp and weft yarns are interlaced to produce a cloth and proper interlacement of these two sets of yarns are possible if both of them remain under some tensions. Again, to ensure continuity of the production of the cloth, the warp and weft yarns are needed to be fed from their respective packages and smooth feeding of the yarns can be assured if their packages are prepared under certain tensions of the yarns. Furthermore, the magnitude and nature of tension variations of both the warp and weft yarns are significantly infl uenced by the settings of different loom mechanisms. Working performances of the looms as well as many of the physical properties of the cloths woven are also determined by the tensions under which the warp and weft yarns are woven. Yarn tension, therefore, plays the most vital role in weaving and each and every person associated with this process ought to have a clear knowledge and perception about this. Hence, discussing weaving without referring to warp and weft tensions is akin to cooking without salt.

Over the long years, warp and weft tensions at weaving have been the subject of many investigations and discussions by many researchers including myself and workers of weaving. The fruitful outcomes of these have improved and enriched, a great deal, the art of weaving. Unfortunately, many of these have not yet been collated and presented in the proper manner under one cover for the benefit of the readers. A sincere attempt has, therefore, been made to write a textbook titled Role of Yarn Tension in Weaving. As mentioned, the contents of the book written in 10 Chapters is primarily the compilation of different published work on yarn tensions at weaving preparatory, weaving and the related matters.

With a view to presenting the topics in proper perspective and enabling the readers to understand the subject more clearly, the book starts with the fundamental of yarn tension which then follows with the important aspects of yarn tension at preparatory stages to weaving, the techniques of measurement of tension and the general form of tension variations of both the warp and weft yarns, effects of loom settings on warp and weft tensions, effects of warp and weft tensions on the loom performance and fi nally the infl uences of warp and weft tensions on the various cloth properties. For the purpose, fairly exhaustive review of literature has been made. I do not, however, claim that I have reviewed all the literatures published so far on this subject, but I have nonetheless made an honest and sincere effort to study as many number of published papers and books on this subject as possible. The text in each chapter has been substantiated by numerous photographs, diagrams, graphs and tables for understanding the subject better. However, if any reader kindly makes any valuable suggestion on further reference on this topic or on necessary correction or modification for upgrading the quality of the book, these will definitely be considered with due importance in future publication.

In epilogue, I wish to express my sincere gratitude to the Director, Indian Jute Industries’ Research Association, Kolkata; the Director, Ahmedabad Textile Industries’ Research Association, Ahmedabad; and the Principal, Institute of Jute Technology (presently Department of Jute and Fibre Technology, University of Calcutta), Kolkata for providing me with their library services for survey of the literatures during the course of writing the book.

Dr. Samir Kumar Neogi

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