A Practical Guide to Quality Management in Spinning | Purushothama

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A Practical Guide to Quality Management in Spinning
By B. Purushothama
A Practical Guide to Quality Management in Spinning

Contents
Preface xiii
1 Introduction to quality management 1
1.1 Introduction 1
1.2 Understanding customer needs 4
1.3 Quality objectives of the product 5
1.4 Balancing the processes – quality planning 7
1.5 Quality control 7
1.6 Quality assurance 8
1.7 Quality improvement 9
1.8 Five Golden Questions 9
2 Product quality objectives 11
2.1 Introduction 11
2.2 Quality objectives of yarns 13
2.2.1 Combed yarns 14
2.2.2 Carded yarns 17
2.2.3 Miscellaneous yarns 18
2.3 Communications of quality objectives 19
3 Impact of yarn features at customer’s end 21
3.1 Looking from customer’s perspective 21
3.2 Knitting applications 21
3.2.1 Grey yarns for knitting T-shirts 21
3.2.2 Dyed yarns for knitting T-shirts 23
3.2.3 Grey yarns for socks knitting 23
3.2.4 Dyed yarn for knitting socks 25
3.2.5 Grey yarns for sweater knitting 25
3.2.6 Grey yarns for underwear knitting 26
3.2.7 Grey yarns for knitting liner materials 27
3.3 Weaving applications 28
3.3.1 Grey yarns for weaving apparels 28
3.3.2 Grey yarns for heavy fabrics and industrial applications 29
3.3.3 Yarns for towels 30
3.3.4 Yarns for carpets and furnishings 30
3.4 Thread applications 31
3.4.1 Yarns for sewing threads 31
3.4.2 Yarns for twines 32
4 Reasons for poor quality in spinning 34
4.1 Raw material 34
4.1.1 Improper selection of raw material 35
4.1.2 Variations in raw material 37
4.1.3 Handling and storage damages 37
4.1.4 Damages due to improper ginning in case of cotton 38
4.1.5 Fused fibres in case of synthetic staple fibres 38
4.1.6 Presence of uncut fibres in staple fibres 39
4.1.7 Packing of cotton bales with polyester cotton cloths/
HDPE/polypropylene cloths 39
4.1.8 Inadequate number of lots in a mixing 39
4.2 Work methods 39
4.2.1 Mixing 40
4.2.2 Blow room 43
4.2.3 Carding 48
4.2.4 Draw frames 54
4.2.5 Combers 62
4.2.6 Speed frames 63
4.2.7 Ring frames 69
4.2.8 Winding 79
4.3 Machinery condition 80
4.3.1 Blow room 81
4.3.2 Carding 82
4.3.3 Drawing 85
4.3.4 Combers 86
4.3.5 Speed frames 88
4.3.6 Ring frames 90
4.3.7 General 98
4.4 Technology and parameters adapted 99
4.4.1 Blow room 99
4.4.2 Carding 102
4.4.3 Draw frames 103
4.4.4 Combers 104
4.4.5 Speed frames 107
4.4.6 Ring frames 110
4.4.7 Winding 114
4.5 Management systems adapted 115
5 Normal problems and non-conformities 120
5.1 Blow room 120
5.1.1 Low cleaning efficiency 120
5.1.2 High nep generation and fibre rupture 121
5.1.3 High variability in the delivered hank 122
5.1.4 Formation of cat’s tail 122
5.1.5 Conical lap 122
5.1.6 Lap licking 122
5.1.7 Patchy lap 123
5.1.8 Holes in lap 123
5.1.9 Soft laps 123
5.1.10 Ragged lap selvedge 123
5.2 Carding 123
5.2.1 Patchy web and holes resulting in uneven card sliver 123
5.2.2 Cloudy web 123
5.2.3 Singles 124
5.2.4 Sagging web 124
5.2.5 Bars in card web 124
5.2.6 Irregular selvedge in card web 124
5.2.7 High card waste 124
5.2.8 Low nep-removal efficiency 124
5.2.9 Higher U% of sliver 124
5.2.10 Medium and long-term irregularity 125
5.2.11 Bulky sliver 125
5.2.12 High breaks 125
5.2.13 Fibre rupture at cards 125
5.3 Combing 125
5.3.1 Inadequate removal of short fibres and neps 125
5.3.2 Short-term unevenness 126
5.3.3 Piecing waves 126
5.3.4 Drafting waves 126
5.3.5 Hank variations 126
5.3.6 Higher sliver breaks at coiler 126
5.3.7 Frequent coiler tube choke-ups 127
5.3.8 Web breakages at draw box 127
5.3.9 Breakages at sliver table 127
5.3.10 Breakages on comber heads 127
5.3.11 Detaching roller lapping 127
5.3.12 Excessive lap licking and splitting 128
5.4 Draw frames 128
5.4.1 Improper sliver hank 128
5.4.2 Uneven sliver 128
5.4.3 Singles 128
5.4.4 Cuts in sliver 128
5.4.5 Good fibres in suction waste 129
5.4.6 Improper coiling 129
5.4.7 Higher breakages 129
5.5 Speed frames 129
5.5.1 Higher U% of rove 129
5.5.2 Higher breakages 129
5.5.3 Soft bobbins 130
5.5.4 Lashing in 130
5.5.5 Hard Bobbins 130
5.5.6 Oozed out bobbins 131
5.6. Ring frames 131
5.6.1 Ring cut cops 131
5.6.2 Hard twisted yarn 132
5.6.3 Uneven yarn 132
5.6.4 Soft twisted yarn 132
5.6.5 Higher hairiness 132
5.6.6 Lean built cop 132
5.6.7 De-shaped cops 132
5.6.8 Sloughing off at winding 133
5.6.9 Undrafted end 133
5.6.10 Higher thin places 133
5.6.11 Idle spindles 133
5.6.12 Slub 134
5.6.13 Crackers 134
5.7 Winding 134
5.7.1 Improper splicing 134
5.7.2 Electronic yarn clearer (EYC) failures 134
5.7.3 Double end 135
5.7.4 Stitches 135
5.7.5 Soft and bulged cones 135
5.7.6 Sunken nose/base 135
5.7.7 Weight variation between cones 135
5.7.8 Shade variation within cones 135
5.8 Rotor spinning 135
5.8.1 Neppy and uneven yarn 135
5.8.2 Stitches 136
5.9 General 136
5.9.1 Stains 136
5.9.2 Contaminations 137
6 Normal complaints from customers 138
6.1 Count and count variation 139
6.1.1 Why customers are bothered about high count CV%? 139
6.1.2 Major reasons for count variation 141
6.1.3 Attacking higher count CV% 151
6.2 Hairiness 155
6.3 Barre 158
6.3.1 What is Barre? 158
6.3.2 Reasons for Barre 158
6.4 Classimat faults 163
6.4.1 What are faults? 163
6.4.2 Classification of faults 164
6.4.3 Sources of faults 165
6.4.4 Misleading readings 166
6.5 Mix ups 166
6.5.1 Losses due to mix up 166
6.5.2 Precautions to be taken 168
6.6 Uneven cone length and higher breaks at tips 170
6.7 Contaminations 174
7 Process control studies 175
7.1 Process control 175
7.2 Mixing and blow room 176
7.2.1 Randomly checking the bales issued and bales planned 176
7.2.2 Checking the tuft size 176
7.2.3 Synchronization study of different machines in a
blow room 177
7.2.4 Speeds of various beaters and fans 177
7.2.5 Checking of air pressures, roller pressures at
appropriate places 177
7.2.6 Grid bar settings 178
7.2.7 Mass variation in lap sheet 178
7.2.8 Total length of lap 178
7.2.9 Lap weight 178
7.2.10 Cleaning efficiency 179
7.2.11 Machine audit 179
7.3. Carding 179
7.3.1 Breakages and snap efficiency 179
7.3.2 Neps removal efficiency and neps per gram in sliver 179
7.3.3 Card cleaning efficiency and trash in card sliver 180
7.3.4 Card-to-card waste variation 180
7.3.5 Trumpet size and hank of sliver 180
7.3.6 Feeding consistency 180
7.4 Draw frames 181
7.4.1 Periodic machine audit 181
7.4.2 Breakages 181
7.4.3 Top roller diameters 181
7.4.4 Functioning of stop motions – delay in functioning,
fail to function 181
7.4.5 Functioning of autolevellers 182
7.4.6 Top roller pressure 182
7.5 Combers 184
7.5.1 Periodic machine audit 184
7.5.2 Head-to-head noil variation 184
7.5.3 Breakages 184
7.5.4 Short fibre removal and improvement in mean length 184
7.5.5 Neps removal efficiency 185
7.6 Speed frames 185
7.6.1 Periodic machine audit 185
7.6.2 Breakages 185
7.6.3 Idle spindles 186
7.6.4 Stretch and draft 186
7.6.5 Evenness 186
7.7 Ring frames 186
7.7.1 Periodic machine audit 186
7.7.2 Breakages 186
7.7.3 Idle spindles 187
7.7.4 Ends down percent 187
7.7.5 Pneumafil waste percentage 187
7.7.6 Spindle wise monitoring 187
7.7.7 Online monitoring of spindles 188
7.8 Winding 188
7.8.1 Breaks per cop 188
7.8.2 Clearing efficiency 188
7.8.3 Hard wastes generated 189
7.8.4 Cone quality 189
7.8.5 Length consistency 189
7.9 Packing 190
7.9.1 Calibration of balance 190
7.9.2 Cone inspection before packing 190
7.9.3 Markings on the packages 190
8 Control points and check points 191
8.1 Concepts 191
8.2 Process-wise control points and check points 195
8.2.1 Mixing 195
8.2.2 Blow room 196
8.2.3 Carding 197
8.2.4 Drawing 199
8.2.5 Combing 200
8.2.6 Speed frame 201
8.2.7 Ring frame 202
8.2.8 Cone winding 204
9 Role of technicians in quality management 205
9.1 Introduction 205
9.2 Routine and special activities 206
9.3 Understanding the requirement of a customer 209
9.4 Understanding the company capabilities 211
9.5 Understanding the legal requirements of the process 212
9.6 Designing the product 213
9.7 Designing the process 214
9.8 Deciding the measuring and monitoring of process 215
9.9 Working out the quality plans 217
9.10 Working out the production programme 218
9.11 Planning for the raw materials, spares, consumables, etc. 219
9.12 Procuring required material in time 219
9.13 Planning the maintenance activities 220
9.14 Tuning the machines as per the process design 222
9.15 Educating and training the men on shop floor 222
9.16 Allocating the suitable competent workmen for the skilled jobs 223
9.17 Monitoring the process periodically to ensure its suitability 225
9.18 Documenting the procedures, actions and the results 226
9.19 Reporting the activities 227
9.20 Analyzing the reasons 227
Notes 228
Further Reading 229
Index 230

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