Textile Learning Details

Types of Defect:

Types of Defects: There are two main types of defects:

Non-sewing defect

And

Sewing defect

Global garments importer.

 

Defects may occur in garments produced on a mass scale. The sources of defects are given below:

Non-sewing Defects

Defects occurring due to faulty raw materials;

Defects due to cutting of fabric, lining, interlining by the wrong pattern;

Defects due to wrong marking, spreading, cutting, bundling, etc.

Defects occurring due to handling, for instance, spoilage, staining, etc.

Defects occurring due to oil marks, etc.

Defects due to wrong ironing, folding, packing, packaging, etc.

Sewing Defects:

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There are generally three types of main sewing defects:

Defects due to the problem of stitch formation.

Defects due to fabric distortion or puckering.

Defects due to fabric damage along the stitch line.

Frequently occurring sewing defects

Sewing defects may be categorized in the following way:

During sewing, defects that occur may be classified in the following way:

Defects occur due to the problem of stitch formation; slipped or skipped stitches are caused due to such a problem.

Defects due to fabric distortion or puckering.

Defects due to damage of fabric along the stitch line.

Defects due to the problem of stitch formation:

 

There are defects that occur due to problems related to stitching formation. Such defects entail rejects which may be enumerated below:

Slipped or Skipped stitches:

Slipped or skipped stitches

Staggered stitches

On balance stitches

Staggered stitches:

Unbalanced stitches: Thread tensions generally cause unbalanced stitches and give a poor appearance.

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Variable stitch density:

It occurs, especially, with sticky or slippery materials and also when material feeding is uneven.

 

Thread Breakage:

Needle and bobbin or looper threads break mainly due to metal surfaces being chipped or otherwise damaged and then causing damage to the thread. The guard over the book in a plain machine or the needle hole in the throat plate can become chipped as a result of needle deflection. This causes thread breakage. Thread breakage is a time-consuming problem arresting productivity.

 

Problems due to fabric distortion or puckering:

Puckering is a wrinkle appearance along a seam line in a smooth fabric. It is one of the most frequently occurring defects. Puckering shows that there is too much fabric and not enough thread in the seam. This is the reason why sewing thread is often blamed for causing puckering though there are other factors as well for the promotion of puckering. They are given below:

Fabric structure,

Seam construction,

Needle size,

Material feeding problem,

Wrong thread tensions &

Unsuitable thread.

 

Puckering may be visible as soon as sewing is complete but some appear later when the garment is ironed or washed. It is generally said that stitching on fabric always leads to some amount of puckering or fabric distortion. Fabrics from synthetic fibers generally have a tendency to show up puckering. A puckering is the most frequently occurring sewing defect and commonest of all defects. The problem was seriously investigated by researchers who found five reasons for puckering.

 

Puckering due to differential fabric stretch:

When two or more plies are sewn together, a simple feeding mechanism finds it difficult to move all plies together. Due to uneven friction between lower fabrics, feed the dog, and upper fabric and that between pressure foot, upper fabric & lower fabric, both upper & lower fabric suffer relative tension and compression before sewing. As a result, puckering develops in the fabric. Such problems may be dealt with by using a special feeding mechanism.

 

Puckering due to differential fabric dimensional instability:

When different types of fabrics are sewn together, they will have different dimensional stability after sewing or after washing the garment. Due to different dimensional instability of fabrics, puckering may occur.

 

Sewing with a plain machine requires two threads, namely, needle thread and bobbin thread. During sewing operation, both threads undergo tensile forces tending to stretch them. The needle thread is subjected to a higher tension than bobbin thread because during sewing, the upper thread has to pull the bobbin thread up from below the fabric to form a loop mid-way between the face and back of the seam. This requires considerable force. The tension of the sewing thread passes on to the seam and puckering results.

 

Puckering due to shrinkage of sewing thread:

Some sewing threads, for example, cotton threads when a wet increase in diameter and shrink in length. Garments sewn with such threads develop puckering when wet or after wash. In such cases, synthetic threads are preferable, because they are stabilized to have negligible shrinkage up to 1500 C temperatures.

 

Puckering due to structural jamming:

If a garment has been woven as close to as practical weaving limit. That is, with very little space left between the yarns, it may prove to be very difficult to force in any more threads in either warp or weft direction. If stitching is introduced in such fabric, puckering develops. In such cases, fine threads may be used to control puckering.

 

Puckering due to mismatched patterns:

Puckering may develop due to mismatched patterns. If there is a discrepancy in the lengths of two parts due to a wrong pattern. These parts may be attached together with a defect of puckering on one play. Probably, on the lower ply, this happens because, during sewing, the operator pulls them together with force. This force shows up in the seam as puckering.

 

Defects due to damage of fabric along seam line:

Sometimes damage to fabric occurs mainly due to a damaged needle, unsuitable needle type, and unsuitable fabric or due to a combination of them. The needle can cause damage to synthetic fabrics if the needle becomes unusually heated. This problem may be controlled in the following way:

By changing the damaged needle,

Removing the cause of needle,

Changing the type of needle.

Defects and their Remedies:

Defective products or services are produced for a variety of reasons. A few of them are given below:

 

Causes of defects:

Not understanding buyer’s specifications or requirements.

Not understanding the increasing requirements of the buyer.

Unsystematic work & non-compliance with work rules lead to major setbacks & defectives.

Defects caused by human or operator error.

An operator performing a job improperly causes a defect.

A worker missing an operation in the job makes a defect.

An operation setting a job improperly causes a defect.

An operator working carelessly may commit mistakes.

A worker hurrying or panicky causes defect.

A worker not complying with work-rule causes defect.

A worker due to indiscipline may cause a defect.

A harassed or humiliated worker may cause the defect.

Absenteeism of operators may cause defects.

The migration of workers may lead to poor quality.

 

Remedy of Defects:

Take elaborate. P. O sheet & specification & special instructions if any.

Set stiffer AQL than the buyer currently requires. Plan for continuous improvement.

Work systematically and as per set rules instead of hurrying or working anarchically.

Keep operators motivated, trained & satisfied. Improve management.

Brief workers and set Work Standard.

Set rigorous in-process quality control.

Motivate workers, Set rigorous in-process quality control.

Motivate workers, Set rigorous in-process quality control.

Motivate workers, Set rigorous in-process quality control.

Set work Standard & TQM.

Train & motivate workers to follow Work Standard.

Train & motivate workers to follow Work Standard.

Declare reward for full attendance. Deliver health care & medication.

Set attractive package & motivation to reduce migration.

Cause of defects:

Machine not well maintained

A machine leaking oil causes the defect

A machine with a blunt or broken needle causes the defect

A machine with un tensioned thread causes the defect

A machine not properly cleaned causes the defect

A machine with the wrong feed mechanism causes the defect

A machine with a defective folder, attachment causes the defect.

Using sub-standard material causes defects.

Not inspecting goods prior to delivery may cause the importation of shoddy goods.

Not importing goods from the right supplier leads to poor goods.

Not inspecting goods prior to taking delivery at the store.

The absence of work standards causes defects.

The absence of a Quality Standard causes defects.

The absence of Maintenance Standard causes defects.

The absence of training for workers may lead to defects.

Lack of motivation of workers leads to defective work.

 

Remedy:

Introduce & maintain preventive maintenance management.

Conduct preventive maintenance. Clean machine from time to time

Mechanic & operators must check needles from time to time. Set in-process QC.

Mechanic & operators must check thread tension from time to time. Set in-process QC.

Conduct preventive maintenance. Clean machine from time to time.

Adjust the feed mechanism for the type of fabric.

Check machinery & set in-process QC.

Use only quality raw materials.

Import goods only with a pre-shipment inspection clause.

Source materials from reliable & authorized suppliers.

Inspect all incoming goods.

Set right work standard.

Set the appropriate quality standard.

Set right maintenance standard.

Train & retrain personnel to acquire skills & workmanship.

Continuously motivate employees.

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