qc in weaving

Quality Control In Weaving

By: Qurat-ul-Ain

ME-Textiles

NED University

Introduction

to produce top quality woven goods in high volume

must have their planning and organization under control.

Additional criterion is thorough familiarity with the entire production process, from fibre to fabric, to ensure that fabric production is profitable.

Introduction(Cont)

optimum production steps

planning stage that defines process parameters, sequences of operations and working conditions, all of which are relevant to profitability.

optimal installation of the weaving machines, with appropriate transport routes and equipment.

Additionally, capacities must be planned and the necessary infrastructure and resources created, including buffer store, air conditioning, lighting, personnel, quality control etc.

Yarn quality

80% of weaving machine stoppages originates from bad yarn quality.

Not only the uniformity of the yarn is important; damaged packages are a sign of poor transport quality, and on the weaving machine they not only impair productivity but also cause waste.

If there are no yarn reserves in the weft packages the result will be a weft stoppage.

Yarn quality.(Cont)

Thread breaks in weaving are the largest cost factor in the entire production process, because they always involve a machine stoppage

Every stoppage prevented directly improves the company's profits.

Weaving preparation

Faultlessly produced warp beams and precision work on the sizing machine, in combination with the right sizing agent and size application, are the conditions that have to be fulfilled.

According to an old German proverb in the textile industry, "well sized is half woven"

Yarn Breakages:

Importance of yarn breakages in weaving process:

Competitiveness is the main feature of the textile industry in future.

The main issue is the cost of grey cloth per meter.

To lower the production costs yarn breakages are essential to be reduced at every manufacturing stage

breakages of both warp and weft yarns which not only reduce the production rate and also deteriorate the quality of the produced fabric.

Importance of yarn breakages in weaving process.(Cont)

These breakages on the preparatory processes and also on loom produce lots of problems and become labor intensive.

Lesser the yarn breakages lesser will be the defects.

Reducing the warp and weft yarns breakages

increase the productivity of the processes involved to the production of fabrics including warping, sizing etc

maintain quality of the woven fabric

reduces wastages of yarn, and energy

ultimately the cost per meter/yard of the prepared fabric reduces.

Yarn Breakages Effect :

On efficiency:
It is generally observed one breakage per loom per 100,000 picks looses considerably efficiency and at every loom stop there is a chance for a defect to come. So the end breakage rate cone winding, weft winding, warping, sizing and finally onto the loom has to be controlled as minimum as possible.

Yarn Breakages..(Cont)
In order to control end breakage rate different quality control measures are taken in each process.Analysis shows that no more than one stop per 100,000 m of weft yarn should occur. As soon as two or more stops per 100,000 m of yarn are available in the high production weaving mill, costs will increase as a result of a reduction in efficiency.

Benefits of reduction of yarn breakages

Cost Reduction

reduce yarn breakages, reduces the cost.

stoppages at the loom because of any yarn breakages gets repaired and some cost will increase in this manners.

entangling the problem of loom stop, the cost automatically goes down.

Benefits of reduction of yarn breakages(Cont)

Man Power:

Resolving the problem of loom stoppage, man power will also be reduced.

If there is problem of yarn breakage constantly at the loom than a person will be required to handle this situation, and when we solve this problem than there will be no need of person constantly at the loom


Effect on Production:
Problem of yarn breakage or problem in the mechanical part of loom, the loom will stop to work.Productivity of loom will be affected and solving these problems increases production.


Quality of Fabric:

Yarn breakages on the loom, affect the quality of fabric.

Constant breakage of yarn and definite knotting, damages fabric quality.

When these problems are solved the quality will also be improved.


Department Efficiency:

Suppose 10 looms out of 100 looms are not working, it will affect the department efficiency and it reduced 10% straight away.

When the different problems are solved out the department efficiency will also increase in the same proportion.

Loom stoppages:

The loom stoppages occur due to the following reasons.

1. Breakages of warp yarn
2. Breakages of weft yarn
3. Malfunctioning of some important of mechanisms of loom or basic loom motion.
4. Temperature and humidity of weaving depart

Practical measures for the reduction of yarn breakages:

There is need of implementation of following practical steps to reduce the yarn breakages.

Ensure that the yarn coming from spinning must have the suitable characteristics of strength, hairiness, thick places, thin places, neps, and elongation according to the standards for different yarn counts.

Prepare the report of yarn breakages in each preparatory process so the feed back may provided to the beck process for instance to spinning mills etc.

Ensure the proper sizing with different chemicals by appropriate add on percentage.

Practical measures for the reduction of yarn breakages .Cont) :

Study the yarn breakage due to different mechanical, electronic, and electrical parts of the loom and rectify them.

Compare the yarn breakage rate of different looms and position them either they are effective or not.

Study and prepare report of loom stoppages on the different loom having same qualities or not so better awareness may obtain about machine.

Practical measures for the reduction of yarn breakages .Cont)

Prepare & access the report of loom stoppages on the same type of looms having same qualities or not so better information regarding yarn breakages may obtain about loom.

Study and define the defects, quality deterioration cases cause by the yarn breakages

Properties of yarn selection for weaving:

During selection of yarn the following properties are needed to consider in order reducing breakages of yarns. These are as follows

Twist in yarn

Tensile strength
a)Single yarn strength
b)Lea strength

Elongation

Hairiness

Yarn imperfection ( thin, thick places and neps)

Other Quality Measures:

Machine configuration (weaver-room layout)

Excessive material movements.

Correctly dimensioned transport routes and good transport equipment are essential to ensure efficiency.

sufficient stockage space between the weaving machines, movements to transport weft yarn can be reduced.

Floor condition has a crucial influence on the speed of transport. well finished floor, any vehicle can move faster and with less wear.

Air conditioning:

Air conditioning serves to create an optimal climate for weaving.

Correctly adjusted relative humidity is crucial for the running characteristics.

Good air conditioning also fulfils other tasks:

it purifies the ambient air by extracting dust,

by cooling air,creates the right working conditions.

Mainly used for cotton and cotton blends. In some cases, but is also used where manmade fibres are woven

Cleaning:
Efficient and effective cleaning is important in achieving flawless fabric production.For staple fiber yarns, the air conditioning system is not enough, travelling cleaners are used. blow off advisable. for thorough cleaning of weaving machines, using vacuum cleaners and compressed air.

Cleaning (Cont):
Compressed air is efficient but simply blows the dust somewhere else. For this reason, suctioning off is a far more effective method. Central vacuum systems have the advantage that they simultaneously remove dust and waste. Heavy soiling increases wear on machine components and causes stoppages. With scheduled cleaning work, unnecessary costs - of spare parts, stoppages and maintenance can be avoided

Weaving machine stoppages

Weaving machine stoppages adversely affect
the weaving mill's productivity, reduce machine allocation per weaverand increase costs.
To eliminate stoppages, their cause and frequency must be known.

Weaving machine stoppages
Modern and mill management systems provide information on the number of stoppages but not about their exact causes. The efficiencies and stoppage times recorded by these systems are important as benchmarks, in order to detect sudden and gradual changes and thus conclude what action to take. improvements introduced must also be checked. A control loop is thus created, of action taken and verification thereof. To evaluate these analyses, in-depth knowledge of the entire textile production process is needed.

Downtime
The duration of a stoppage is not only important with regard to productivity; it also crucially influences fabric quality. Stop marks, can be prevented if the machine is restarted quickly. Too long stoppage, the width of fabrics may be reduced.

Downtime(Cont)
Complicated yarn breaks or multiple breaks must be avoided at all costs. The weaver's workload can be calculated from the downtime and the number of stoppages. From this data it can be seen how many weaving machines one weaver can look after, which in turn provides information on personnel costs.

Long-term stoppages
Include style and warp changes,machine servicing and repairs. can be reduced to a minimum by planning with foresight, teamwork and personnel training are indispensable. Keeping sufficient quantities of spare and wearing parts in stock to cover consumption will help minimize long-term downtimes and save costs by avoiding rush orders

Efficiency

Two types of efficiencies.
Weaver efficiency provides information on the weaver's workload. It takes the frequency of stoppages (broken ends and weft breaks), downtime and productivity into account. Plant efficiency includes all stoppages (broken ends and weft breaks, warp changes, repairs etc.). The difference between the two figures can be traced back to the long-term stoppages.

Efficiency(Cont)
The plant efficiency reflects the productivity of the weaving facility and can be improved by reducing short-term (yarn breaks) and long-term (organizational) stoppages.Depending on the style mix, increasing efficiency by one percent results in an increase in earnings of up to 1000 Euros or more per weaving machine and year.

Lighting

Correct lighting of production facilities
creates good working conditions, makes work easier and helps prevent mistakes. The lighting must be such that parts of machines or installations do not cast shadows on the cloth. it makes good sense to install a light source behind or below the fabric in order to detect defects quickly and easily.

Machine maintenance
Maintenance must be carried out in accordance with the manufacturers' instructions.Unnecessary repairs and long-term stoppages can thus be avoided, and spare parts costs reduced. Maintenance is carried out on the basis of
checklist,

making a record of the condition of parts and of parts replaced.

Machine maintenance(Cont)
The record file will identify deficiencies and excessive wear of individual weaving machines.Lubrication and greasing require special care and must be carried out by qualified personnel in accordance with the manufacturer's instructions. Machine cleaning must not be neglected under any circumstances

Style and warp changes

Style and warp changes can easily be planned in advance.

It is important to make sure that besides the warp beams, weft yarn and harness, all other necessary materials (temples, cams, weft feeder brushes etc.) are put ready in the order they will be needed.

Style and warp changes(Cont)

Checklists are very helpful and thorough job preparation helps to avoid wasting time.

In addition, machine reports ensure that all machines weaving the same article have the same settings.

Preparation of materials

Good planning benefits
The production process,Helping to avoid unnecessary waiting time. Adequate quantities of warp beams and weft material at intermediate storage points, close to the weaving machines, production losses can be minimized. The weft yarn should be acclimatized for at least 24 hours under the climatic conditions in the weave room.

Cloth inspection
Immediate inspection after weaving, avoids the production of further faulty goods. Avoiding defects is the prime objective.If they occur, it is vitally important to detect and remedy them quickly. Document all defects, so that a subsequent inspection can be carried out efficiently.

qc in weaving

Documents