Optimization of process parameters in spinning mills to meet customer requirements

Winsys Limited

Introduction

Today spinning mills in India are being watched by theirpeers across the globe. Indeed it is a golden chance given to Indian spinnersand many leading garment players are trying to have tie up in some form orother with leading Indian Industries. At least one leading global player tiesup with an Indian Industry every two months. This is a crucial period forIndian spinners and it is high time for them to optimize their processestowards achieving excellence in manufacturing.

Referencepoint / Benchmarking

When we start benchmarking, we should know our point ofreference. For example, in a family there will be achievers in studies, sports,good practices etc. We used to refer the achievers as our point of reference. Similarly,achievers in each business sector become a point of reference to those in thatline of business. For example, when we say Polyester Sewing Threads theimmediate point of reference is a well known company in India. When we say gassed, mercerized and dyed yarns, the leader is the most reputed export house of India.

They should be taken as the leaders and we should benchmarkourselves against them to excel in business through process optimization.

CustomerClassification

The customers of spinning mills can be classified into fourmajor groups.

• Weavers
• Knitters
• Garment manufacturers
• Value addition group

a) Weavers

Weavers can be further divided into two major groups. One isgrey fabric weaver and the other section is yarn dyed fabric weaver.

Grey fabric weaving

Spinners yarn is directly taken to warping to producewarping beams. After sizing, weavers beam is produced for weaving grey fabric .Thisgrey fabric is fully bleached/scoured & dyed/printed.

Grey fabric weaver runs the warping machines at the highestspeed up to 1000 meters per minute and his expectation on warping breaks isbelow 0.5 breaks per million meters in single yarn and zero in the case ofdouble yarn.

Yarn Dyed Fabric Weaving

Yarn dyed fabric weavers runs the warping machines at 600meters per minute only. However the expectations on warping breaks are the sameas that of grey fabric weaver. Average RKM and the 10 percentile RKM from the tensiletesting instruments need attention for achieving this level of performance.

Another important factor worth mentioning for warping islength consistency of the packages (cones). If the length of the packagesdiffers between cones beyond 1%, certainly this is going to affect their costof warping operations.

In weft packages, weavers expect higher size packages withtail ends because high speed looms operate at an insertion rate of 2000 metersper minute. The package defects should be NIL as the loss of utilization ofhigh speed jet looms is going to add manufacturing cost at weavers end.

Todays preferred packages for coarse and medium counts is2.4 kg and fine counts is 1.85 kg without any defects like crushed cones, cutends and rib boning/entanglement.

Yarn dyed fabric weaver demands a very high quality of yarn in terms of yarn hairiness, yarn strength and yarn elongation. This is mainly because yarn undergoes many mechanical / chemical processing before reaching warping machines. Elongation and Single yarn strength of the yarn can be totally spoilt in warping machines if enough care is not taken at the time of warping process optimization.

b) Knitters

Knitters also can be broadly classified into two major groups. One is grey fabricators and another is yarn dyed fabric knitters (Autostripe fabricators). Requirements for both groups are different.

Grey fabric knitters focus on lesser long term faults and optimum twist level. Dyed knitted fabric manufacturers require stronger yarn with a slightly higher twist level. They also demand less hairy yarn with optimum level of lubricity for smooth running of knitting machines.

c) Garment Manufacturers

This group procures Polyester or Cotton Sewing Threads directly or indirectly from spinning mills. The expectations of these customers are,

• Less splice
• Zero knots
• Near zero short thick places
• Zero breakage of yarn at 6500 stitches per minute speed with relevant needle gauge for that count

We should also note high speed stitching machines are now capable of working at 9000 stitches per minute and the expectations could become more stringent in the days to come.

d) Value Addition Group

This class of customers buys single yarn and adds value to the same through,

• Doubling
• Gassing(singeing)
• Scouring, Bleaching ,Dyeing
• Mercerisation

Requirements of this customer base are very stringent and any deviation leads to severe loss to the yarn supplier in the form of compensation. The requirements are,

• Uniform shade through homogenous mixing
• Less long term faults
• Less fluff like faults
• Good single yarn strength to meet the stress during continued operations.

Normal customer complaints

We have seen elaborately our customer group and their requirements. Let us have a quick look at the nature of customer complaints we receive from Knitters.

• Shade variation
• Needle breaks
• Fabric holes
• weight shortage
• Fluff liberation
• Contamination

Normal customer complaints from weavers

• More warping breaks(most of the time due to package defect)
• Entanglements due to sizing(poor splice quality)
• Warp and weft breaks in loomshed(reasons are manifold)

Contamination levels

Spinners have very limited role in controlling the contamination level. Practices in the Indian Ginneries are going in for a tremendous change thanks to the efforts taken by Government of India and few reputed private sector mills in India. Some of the Ginners have even installed Contamination clearers in their post cleaning line after ginning.

A point must be noted here even the cotton from US has contaminations whereas US demands contamination free fabrics from India! If the efforts taken by Indian Ginners continue with still more support from the spinning industry we can definitely become leaders in supplying contamination free cotton/fabrics in the world.

Optimisation of the process

By seeing the customer base, requirements and the type of complaints let us start working on optimizing the process. To start with let us optimize our goals:

• What type of customer is going to use our yarn?
• What are the yarn quality requirements?
• What are the end use performance characteristics?
• What are the implied needs?
• Who are the current suppliers to this customer and what is their quality and performance level?

Secondly, let us examine our current quality level of our product against these requirements. The gap between the requirements and our level has to be identified.

Through process optimization we have to bridge the gap. Once we achieve the goals, let us try to reset our goals for continuous improvement. Only then we can excel others in the race. It alone helps us to establish our Brand.

Guiding sources for the Spinners

When we like to benchmark ourselves, we should have source of information for benchmarking ourselves. What are all the guiding sources of information for the textile industry today?

• SITRAS CPQ findings
• PREMIER/USTER Statistics Issued periodically
• Competitors product quality.

This information helps us to benchmark ourselves and improve continuously thro process optimization. Quality statistics by Uster/Premier Statistics is a voluminous data collection and interpretation of data. These become norms for the industries to excel in Quality. When we say that we have achieved Uster/Premier 10% standards, it means that we have achieved the quality level of the top ten percent of the particular product manufactures across the globe participated in that survey.

Analyzing competitors quality and its performance should be a disciplined continuous affair without which we cannot remain at the top continuously. For assessing performance level of our product against competitors at customers sites, we need to establish a good rapport with our customers.

Product Quality

It can be classified into three:

• Measurable - U%, Imperfections ,RKM etc
• Discrete - Package Quality like entanglement, ribboning etc
• Performance characteristics Warping breaks, Fluff liberation etc.

Cost of Quality

Quality achievement involves cost. Financial implications of process optimization should be understood very clearly. Cost of a product is decided by,

• Raw material
• Wages
• Power
• Stores
• Administration and selling expenses

To achieve better quality, if we extract higher waste levels or use a richer mix, the immediate effect will be on raw material cost. If we use finer hanks in process or reduce production level it is going to affect both power and wages cost.

If we replace critical parts like top combs/card wires prematurely it will have an impact on our Repairs & Maintenance cost.

Hence it is essential to identify our CTQ-critical to quality factors. We have to focus our attention to those factors on top priority for that particular product. While focusing on that, we should benchmark our norms for each level of our process. It is necessary to have the flowchart of our operations covering,

• Blow room and carding
• Combing
• Drawing
• Roving
• Spinning
• Autocone winding

Let us earmark our decision points and its alarm limits. For example, Nep removal efficiency is one of the decision point in Carding and alarm limit could be 60%.

Rework loops

When we set alarm limits we should also specify rework loops for each stage of processing, in case of any non conformers. Non conformers cannot be treated as waste as we have added value up to that particular point of production.

If the above system is implemented, we will come across many internal complaints and this will help us to fine tune the process continuously.

External complaints / Feedbacks

External complaints and feedbacks should not be ignored since they are vital in our proposed system to continuously improve our product quality. Based on the review of our failures and the corrective actions, we should install preventive measures to achieve consistency.

There is a paradigm shift in our todays manufacturing process. In the earlier days:

• We will act on problems to solve. Today we foresee problem areas and take proactive steps to eliminate occurrence itself
• In the earlier days, we used to set norms for waste and monitor the deviation. Today we are planning to optimize the waste itself by controlling the lint loss.
• Similarly today we focus on only unreliability and not reliability levels. For example, 0.1% unreliability in US means 12 babies given to wrong parents and 8,80,000 credit cards with wrong information. Hence it is essential to focus on unreliability and not on reliability levels. Because it is the unreliability level which is going to affect our brand image in the minds of customers.

As a customer, he has every right to get what they want and certainly not what we produce. He has to receive value for the money he pays to the product. They also have the right to demand Right First Time-RFT.

Different approaches of meeting the customer requirements thro` process optimization

• Taylor made products
• Co creation

Taylor made products

When we buy shirts, we expect good handcuffs, matching buttons and threads. We delete certain features like extra pockets etc. That is, it is a Taylor made product for us. Likewise, certain quality characteristics will be given more importance by the customers. As a manufacturer, we should be ready to optimize our process by Taylor making the products to suit his requirements.

Co-creation

In todays market scenario Co creation is wide spread in much industrial activity. It is nothing but creation of the products, building up the quality into the products along with the customers themselves. We should allow him to decide the in-process parameters itself to get the final product to meet his requirements.

However, we have certain issues to be sorted out in Co creation:

• Customers requirements become dynamic
• We should reorient our relationship with the customers
• Our managers fear of insecurity or interference

In a transparent system of management these problems can be easily sorted out to make these systems to work successfully.

Conclusion

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