A practical guide on quality management in spinning A practical guide on quality management in spinning B. Purushothama WOODHEAD PUBLISHING INDIA PVT LTD New Delhi ● Cambridge ● Philadelphia Published by Woodhead Publishing India Pvt. Woodhead Publishing India Pvt., G-2, Vardaan House, 7/28, Ansari Road Daryaganj, New Delhi – 110002, India www.com Woodhead Publishing Limited, 80 High Street, Sawston, Cambridge, CB22 3HJ UK Woodhead Publishing USA 1518 Walnut Street, Suite1100, Philadelphia www.com First published 2011, Woodhead Publishing India Pvt. © Woodhead Publishing India Pvt., 2011 This book contains information obtained from authentic and highly regarded sources.
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ISBN: 978-0-85709-006-5 Typeset by Sunshine Graphics, New Delhi Printed and bound by Sanat Printers, New Delhi Contents Preface xiii 1 Introduction to quality management 1 1.2 Understanding customer needs 4 1.3 Quality objectives of the product 5 1.4 Balancing the processes – quality planning 7 1.8 Five Golden Questions 9 2 Product quality objectives 11 2.2 Quality objectives of yarns 13 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 3.1 Grey yarns for knitting T-shirts 21 3.2 Dyed yarns for knitting T-shirts 23 3.3 Grey yarns for socks knitting 23 3.4 Dyed yarn for knitting socks 25 3.5 Grey yarns for sweater knitting 25 3.6 Grey yarns for underwear knitting 26 3.7 Grey yarns for knitting liner materials 27 3.1 Grey yarns for weaving apparels 28 3.2 Grey yarns for heavy fabrics and industrial applications 29 vi Contents 3.3 Yarns for towels 30 3.4 Yarns for carpets and furnishings 30 3.1 Yarns for sewing threads 31 3.2 Yarns for twines 32 4 Reasons for poor quality in spinning 34 4.1 Improper selection of raw material 35 4.2 Variations in raw material 37 4.3 Handling and storage damages 37 4.4 Damages due to improper ginning in case of cotton 38 4.5 Fused fibres in case of synthetic staple fibres 38 4.6 Presence of uncut fibres in staple fibres 39 4.7 Packing of cotton bales with polyester cotton cloths/ HDPE/polypropylene cloths 39 4.8 Inadequate number of lots in a mixing 39 4.4 Technology and parameters adapted 99 4.5 Management systems adapted 115 Contents vii 5 Normal problems and non-conformities 120 5.1 Low cleaning efficiency 120 5.2 High nep generation and fibre rupture 121 5.3 High variability in the delivered hank 122 5.4 Formation of cat’s tail 122 5.8 Holes in lap 123 5.10 Ragged lap selvedge 123 5.1 Patchy web and holes resulting in uneven card sliver 123 5.5 Bars in card web 124 5.6 Irregular selvedge in card web 124 5.7 High card waste 124 5.8 Low nep-removal efficiency 124 5.9 Higher U% of sliver 124 5.10 Medium and long-term irregularity 125 5.13 Fibre rupture at cards 125 5.1 Inadequate removal of short fibres and neps 125 5.2 Short-term unevenness 126 5.6 Higher sliver breaks at coiler 126 5.7 Frequent coiler tube choke-ups 127 5.8 Web breakages at draw box 127 5.9 Breakages at sliver table 127 5.10 Breakages on comber heads 127 5.11 Detaching roller lapping 127 5.12 Excessive lap licking and splitting 128 5.1 Improper sliver hank 128 5.2 Uneven sliver 128 viii Contents 5.4 Cuts in sliver 128 5.5 Good fibres in suction waste 129 5.1 Higher U% of rove 129 5.6 Oozed out bobbins 131 5.1 Ring cut cops 131 5.2 Hard twisted yarn 132 5.4 Soft twisted yarn 132 5.6 Lean built cop 132 5.7 De-shaped cops 132 5.8 Sloughing off at winding 133 5.10 Higher thin places 133 5.2 Electronic yarn clearer (EYC) failures 134 5.5 Soft and bulged cones 135 5.6 Sunken nose/base 135 5.7 Weight variation between cones 135 5.8 Shade variation within cones 135 5.1 Neppy and uneven yarn 135 5.2 Contaminations 137 Contents ix 6 Normal complaints from customers 138 6.1 Count and count variation 139 6.1 Why customers are bothered about high count CV%? 139 6.2 Major reasons for count variation 141 6.3 Attacking higher count CV% 151 6.1 What is Barre? 158 6.2 Reasons for Barre 158 6.1 What are faults? 163 6.2 Classification of faults 164 6.3 Sources of faults 165 6.1 Losses due to mix up 166 6.2 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 7.2 Mixing and blow room 176 7.1 Randomly checking the bales issued and bales planned 176 7.2 Checking the tuft size 176 7.3 Synchronization study of different machines in a blow room 177 7.4 Speeds of various beaters and fans 177 7.5 Checking of air pressures, roller pressures at appropriate places 177 7.6 Grid bar settings 178 7.7 Mass variation in lap sheet 178 7.8 Total length of lap 178 7.1 Breakages and snap efficiency 179 7.2 Neps removal efficiency and neps per gram in sliver 179 7.3 Card cleaning efficiency and trash in card sliver 180 7.4 Card-to-card waste variation 180 7.5 Trumpet size and hank of sliver 180 7.6 Feeding consistency 180 x Contents 7.1 Periodic machine audit 181 7.3 Top roller diameters 181 7.4 Functioning of stop motions – delay in functioning, fail to function 181 7.5 Functioning of autolevellers 182 7.6 Top roller pressure 182 7.1 Periodic machine audit 184 7.2 Head-to-head noil variation 184 7.4 Short fibre removal and improvement in mean length 184 7.5 Neps removal efficiency 185 7.1 Periodic machine audit 185 7.4 Stretch and draft 186 7.1 Periodic machine audit 186 7.4 Ends down percent 187 7.5 Pneumafil waste percentage 187 7.6 Spindle wise monitoring 187 7.7 Online monitoring of spindles 188 7.1 Breaks per cop 188 7.3 Hard wastes generated 189 7.1 Calibration of balance 190 7.2 Cone inspection before packing 190 7.3 Markings on the packages 190 8 Control points and check points 191 8.2 Process-wise control points and check points 195 Contents xi 8.8 Cone winding 204 9 Role of technicians in quality management 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.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 Preface Quality is demanded by all and customer of spinning is no exemption. The quality has dimensions of product parameters, timely delivery and affordable price and also after sales service. To produce quality is not one man’s job. It is a combined effort of all in the organization and also of the customers.
In my experience of 38 years in various spinning mills, in various positions from Production Supervisor to Production Manager, Chief of R&D and Quality Assurance and also in my interactions with various research associations, professional associations etc, I could learn various aspects responsible for getting the quality. In this book an effort is made to recollect them and put in simple possible way so that people in the industry can take advantage. Some of the new concepts of Quality are explained in this book, which are not normally explained in other books. The book starts with the concepts of quality management system and then the objectives of product.
We normally get various norms for quality of yarns, updated from time to time, by various research associations and also from customers. However, they are not end use specific, but are broadly classified as carded and combed, hosiery and weaving yarns etc. However, in reality the customers are interested in the yarns to meet their specific requirements. Therefore, in this book, the concepts of product objectives and the impact of product features at customer’s end is discussed with some examples.
To produce good quality, one needs to take action at the source of generation of poor quality. Hence the reasons for getting poor quality is discussed in details with four angles viz. the raw material, the work practices, the machinery conditions and adapting of appropriate technology. The Processwise nonconformities normally observed and the normal complaints from the customers are then discussed.
In order to achieve the required results, monitoring the processes with suitable control points and check points are essential. They are discussed in detail. This book has targeted the shop floor technicians and students willing to become a spinner. The developments in the spinning field in terms of latest machinery are not discussed here, but the concentration is on tuning and maintaining the existing machinery and trying to get best out of it by xiv Preface good work practices.
If we do not know how to get best out of the existing machinery and technology, we cannot get success even with latest machineries. I hope the technicians and the industry get some benefit out of this book and would be able to cater to their customers with the quality they require, so that the industry can progress. I am very much thankful to Woodhead Publishing India Pvt., for coming forward to publish this book and encouraging me to write a useful book. Purushothama 1 Introduction to quality management Quality cannot be inspected into a product; it is either there or not.
It must be bred into the making of the product by the operative; this is where quality starts.1 Introduction Quality management consists of four parts, viz., quality planning, quality control, quality assurance and quality improvement. Quality planning deals with planning the activities to meet the customer needs, whereas quality control deals with monitoring the activities using different control points and checks to ensure bad quality does not go to the customer. Quality assurance is focused on establishing systems and procedures to ensure that quality is achieved all the time and quality improvement concentrates on changing needs of the customers and proactively works for improving the levels of quality not only of the product but also of the systems targeting reduction in costs, timely services and delivery in time while adhering to product quality, legal and regulatory requirements and ethical values (Fig.1 Components of quality management. Quality planning is the process of planning the production activities in order to achieve the goals of meeting the customer requirements in time, within the available resources.
Understanding the customer’s needs is the first step in the process.