39 Apparel quality analysis – Final inspection, specific testing apparels

S. Natarajan

1. Introduction

Final  inspection  is  the  last  steps  of  garment  inspection  system.  In  this  stage  complete garments are inspected by buyer. Different parts of garments are inspected in this stage such as garments main fabric, accessories, trims, label, fabric faults etc. There are various systems for final inspection in the garment industry. Final inspection is very important for an export order shipment.

Final inspection also consists of inspecting finished garments from the buyer’s point of view, size measurements, form fitting (putting garments on the proper size mannequins to see if they properly fit labeled sizes); and live modeling if necessary (again to see if the garments properly fit the labeled sizes). Final inspection may occur before or after garments are packed in poly bags and cartons. If it is done after garments packed, then proper size and style markings on the package will also be checked.

Buyers always try to ensure that goods delivered to them by the manufacturer must complete with the specified quality standard.

In this system, buyer defines quality standard of goods. Buyer worried only about those major defects which may damage functional quality of goods and thus their sale ability. Renowned buyers generally supply inspecting team with a list of such major defects and inform of the Inspection Sampling Plan that must be pursued.

2. Garment Inspection

The inspections are done to control the quality is means by examining the products without any instruments. To examine the fabric, sewing, button, thread, zipper, garments measurements and so on according to specification is called inspection. There are so many facilities for inspection in every section of garments industries. The aim of inspection is to reduce the time and cost by identifying the faults or defects in every step of garments making.

Inspection Procedure of Garments isas follows:

I. Confirmation of Quantity:

First step of garment inspection start with confirmation of Quantity with the vendors packing list by counting all pieces of each box. If Quantity is not matching to the packing list and written in the box then this discrepancy is informed to the buyer.

II. Confirmation of Accessories:

Next step is the confirmation of accessories, such as sewing thread, buttons, zippers, lining, etc as specified by the buyer andall labels are evaluated based on the specifications outlined in  specification sheet for correct brand name, fibre content, care instruction and country of origin and its placement.

III. Measurements:

Garment measuring is included in the inspection. After confirmation of accessories a minimum of 13 pieces for one order must be measured with at least 1 piece of each size and colour being selected for measuring. All pieces aremeasured as per size specification sheet which is given by the buyer side. If any measurement problem is noticed then we check the original sample and inform the buyer same time.

Measurements out of tolerance are unacceptable and should be marked with a circle on the report as a minor defect. Jumping out of grade should be marked with a triangle as a major defect. If one garment has two or more major defects only, it should be marked as one major defect, and if there are two minor defects in a different garment while in the same size, it should be accounted as one major defect.

1. In Side Inspection:

At this stage garment is checked from reverse side to ensure that there is no fabric defect, poorstitching, and stains etc in the garment.

1. Out Side Inspection:

At this stage garment is checked from outside to ensure that there is no color variation, weaving defect, fabric defect, printing defect, holes, poor stitching, bad smell , dying defect and stains etc in the garment.

1. Final Inspection:

Final Inspection stage is the most important part of inspection process, here garment is rechecked to confirm that inspection is done properly without missing any checking step. VII. Packing:

All “Grade-A” goods are put back into poly bags as per the original packaging and then they are send for needle inspection.

So, depending on the quality of defect some garments are send for repair and some are rejected.During inspection defects are classified into 3 categories:

3. Garment Defects

In practice, three types of defects are categorized such as critical, major and minor depending on the severity. To determine whether a defect is major or minor, the following factors are to be considered:

• Whether the defect will render the garment unsalable
• Whether the defect is easily noticed and
• The location of the defect on the garment

3.1 Critical defects (totally unacceptable: a user might get harmed, or regulations are not respected).

A critical defect is one that is likely to result in hazardous or unsafe conditions when using the product or others in the immediate vicinity of its use. A critical defect is also a deviation from delivery requirements which prevents the product from being received. If one occurrence of critical defect is observed during the inspection, the entire lot will be rejected. A 100%  inspection will be carried-out by the garment factory quality assurance staff to remove the defective products.

3.2 Major defects (these products would usually not be considered acceptable by the end user).

This is a defect which is sufficient to cause the garment to be considered as second’s quality

• A defect which is noticeable
• Affects the salability or serviceability which worsens with wear and time
• Varies significantly from the approval garment specification

3.3 Minor defects (there is some departure from specifications, but most users would not mind it).

This is a defect which does not normally be identified by the customer, but is, however less than the agreed quality standard. A defect which

• Does not affect the performance of the garments in normal conditions
• Is not noticeable to the customer on purchasing
• Is not noticeable to the wearer of the garment, or anyone adjacent to the wearer
• Will not worsen with time and wear

4. Defects Zone in Garment

Generally, defects are classified into three categories in the eye of buyer’s inspection. These are Critical, Major, and Minor defects. In some cases, a major defect can be considered as minor defect based on the location of the defect in a garment. This location is called as zone. Garments zoning is done to get a right evaluation of the garment during visual inspection in the apparel industry. Location of defects zone of garments is not only helpful for the garments final inspection, but it also helpful for a consumer who will try to purchase any types of ready-made garments on the basis of visual inspection.

Defect Zone Classification of Garments during Inspection:

In order to conduct inspection, garments are divided into a three zones.

• Zone-I : Most noticeable
• Zone- II : Average noticeable
• Zone- III : Least noticeable

Three defect zones of garments are also known as Zone- I, Zone-II and Zone-III. At the front sleeves and upper front is considered as zone ‘I’ and lower front considered as zone ‘II’. On the back of the garment, under arms and back bottom is considered as zone ‘III’.

Evidently, Zone-I is the most important part of garments, Zone-II is the next most important area and zone-III is the least important zone.

For instance, a seam puckering or shading in Zone –I makes a garment totally reject while the same defect in Zone-II impairs functional quality to a lesser extent and in Zone-III to the least extent. In the 3rd case, the garment is nearly perfect and saleable.

Illustrative example of defect Zone Classification of shirt and Trousers are given below to understand defect Zone Classification of Garments clearly. Defect Zone Classification for Shirt:

Defect Zone Classification for Trousers

4. Acceptable Quality Level

Inspection is the tool that is used for assessing the conformance of the merchandise to the agreed specifications. Though inspection is important and it gives an idea about the acceptance level of a product, it may not be possible to carry out 100% inspection of all the units in a particular shipment or a lot because it is costlier and excessive handling of goods will result in losing their freshness.

Having known that 100% inspection may not be the best thing to do, the next question is if not 100%, how much to inspect?

The answer is Acceptance Sampling procedure which is used to arrive at a sampling plan and makes an acceptance decision.

Acceptance sampling is a scientific technique and it also tells us the probability of making a wrong judgment while using it.

Acceptance sampling plans help in distinguishing between the acceptable and the unacceptable lots. The basic assumption here is if the proportionate sample is randomly drawn from a lot, the sample would represent the quality level of the lot and based on this the acceptance decision can be made. Acceptance Sampling is the middle of the road approach between 100% inspection and no inspection.

AQL means maximum average defective garments in a lot beyond which a batch is rejected. It is expressed in a percentage number of average defective garments by following a formula,

Average defective garments = No. of defective garments found during inspection / Total no. of garments inspection X 100

The sample plan also provides the number maximum allowed defective pieces. If the defective pieces are less than allowed number the lot is accepted and if the number of defective pieces is greater than allowed the lot is rejected.

Sampling plan is selected in such a way that quality is ensured within a statistical confidences limit of 95% or above. Acceptable Quality Levels (AQL) used in garments industry are 1.5%, 2.5%, 4%, 6.5%.

The AQL level used for inspection depends on the price and the quality of the product. Normally lower level AQL standard such as AQL 1.5% is used for higher price garments and higher level AQL standard such as 6.5% is used for lower quality and lower price garments. As, for example, AQL 2.5% means, maximum average defective item is 2.5%, which is acceptable in the inspection system.

Lot or Batch size: This means total how many pieces inspector is going to check or inspect.

Sample   size  Code letter:    This     code    is     indicative    a     range     of     batch    size.

Sample size: It means that how many pieces will be picked up for inspection from the total offered pieces (Batch).

Ac (Accepted): The number in this column denotes that if the inspector finds up to that much defective pieces the shipment will be accepted by buyer.

Re (Rejected): On the other hand number in this column denotes that if the inspector finds that much defective pieces or more than the listed number, the shipment will be rejected or asked to the manufacturer for 100% inspection and re-offer for final inspection by buyer.

4.1 AQL Requirements Based on the Products:

In general cases the buyer will determine which sampling plan and what AQL to adopt. There are three types of sampling plans: i.e. single, double and multiple sampling plans. Each sampling plan can be performed at three levels, i.e. normal, tightened and reduced, depending on inspection requirements and quality of the products. The apparel industry mainly uses single sampling plans for the acceptance decisions. However, a few buyers also use double sampling procedure. In single sample based on AQL table you randomly draw a sample consisting of specified number of garments from a lot. The sample plan also provides the number maximum allowed defective pieces. If the defective pieces are less than allowed number the lot is accepted and if the number of defective pieces is greater than allowed the lot is rejected. One may say that as the acceptance sampling is scientific, ideally speaking, it must lead to 100% reliable results. In other words, it must always lead to acceptance of lots containing lower defective level than AQL and must reject all the lots that contain more defective products than AQL. But this is not possible, as the acceptance decision is made only on the basis of small sample drawn from the lot and it carries a risk of making a wrong judgment.

4.2 How to Use AQL Table

The AQL tables will help to determine the sampling size according to ordered quantity and specified level of severity. Inspector can choose Levels I, II or III, with Level III being the most stringent testing and Level I being the least. The standard level, most commonly in the apparel industry is the Level II. Though this is up to the client, but it is the most recommended level.

In order to find the necessary sampling size to be inspected, Inspector must first look at the sample size code letter chart and find on the left side the range of items being produced in  total. For example, if Inspector is inspecting 10000 pcs, at Level II he have the letter L, which in the sampling plan table corresponds to a sample size of 200.

4.3 Single sampling plan – Normal inspection procedure:

• Assume AQL is 2.5% to be followed for lot size of 600 garments,
• First, from Table 1 find out the code letter for lot size of 600 and inspection level II is “J”
• From Table 2 (single sampling plan), the letter “J” corresponds to sample sizes of “80”.
• So, 80 samples are needed to inspect out of 600
• At AQL 2.5%, if defective garments are less than or equal to 5, whole lots will be accepted, if it is found to be 6 or more, whole lots will be rejected.

4.4 Double sampling plan – Normal Inspection:

• For Normal Inspection procedure:
• Assume AQL is 4.0% to be followed for lot size of 3,000 garments,
• First, from Table 1 find out the code letter for lot size of 3000 and inspection level II is “k”
• In Table 3, double sampling plan shows the sample size of letter K is 80.
• First inspection, at AQL 4%, the acceptable number is 5, rejection number is 9
• If any number between 5 to 9, second inspection is needed.
• For second inspection, the sample sizes again is 80
• At AQL 4%, the cumulated acceptable number is 12 and rejection number is 13.

If the number of defective garments found in the first sample is 6, and in second sample is 5, making a total of 11, then the whole lot of 2,000 pieces will be accepted.

Today’s educated consumer is focused on finding apparel with the best balance of style, quality, and price, manufactured under the highest possible ethical standards. Increased consumer awareness is making apparel quality control more important than ever.

5. Garment specific testing

   5.1 Seam Slippage:

Seam slippage is a fabric problem especially for fabrics that contain slippery yarns or that have an open structure or where the number of warp and weft interlacing is low. Such factors mean that one set of yarns may be easily pulled through the other. Seam slippage is the condition where a seam sewn in the fabric opens under load. Some of this gap may close on removal of the load but some of it may be a permanent deformation.

5.2 Seam Slippage Test:

This test method is used to determine the resistance to slippage of filling yarns over warp yarns , or warp yarns over filling yarns, using a standard seam.

There are three different types of seam slippage test in existence, each of which has its drawbacks. Firstly there is the type where a standard seam is put under a fixed load and the seam gape is measured. In second type a load extension curve is plotted with and without a standard seam and thedifference between the two curves is taken as the slippage. The third type does away with a sewn seam and measures the force required to pull a set of pins through the fabric. A variant of the first type is to measure the load required to give a fixed seam opening.

5.3 Seam strength

Seam strength is the strength of seam assembly in a garment. It is a function of the strength of the thread used for the seam, type of seam assembly in a garment and type of fabric used, among other factors.

Failure of seam assembly can occur either by breaking of sewing thread, tearing of the fabric at the seam, excessive yarn slippage adjacent to the stitches or a combination of the above mentioned conditions.

The specimen is mounted on the tensile tester. It is operated until the sewn seam or fabric ruptures. The observation is made whether the rupture is caused by Fabric yarn rupture, sewing  thread rupture, sewn seam yarn slippage or a combination of two or more of the foregoing. This will give the seam strength.

Seam strength (gms/cm)= (Individual specimen seam breaking force in gms)/ Width of specimen in JawsSeam Efficiency= Seam Strength (Seamed Fabric Strength) x 100)/ Base Fabric Strength

Snap and Button Strength Tester

In order to ensure buttons/snaps are securely attached to garments, a minimum pull force of 90Newtons or 9.17 kg is required. To determine the holding or breaking strength between the snap/button and the garment sample

The snap/button component is gripped by the Upper Clamp and the garment is fixed to the lower Fabric Clamp.

5.4 Zipper Testing

There are various methods by which to evaluate zipper strength. The basic strength can be determined based on the results of the following inspection methods, from which overall strength appropriate for respective uses can be judged.

5.4.1 Chain crosswise strengthper 2.5cm

To determine ordinary zipper strength: a zipper chain is interlocked, pulled at a fixed speed at a right angle to the chain interlocked direction, and the resistance is measured.

5.4.2 Top stop holding strength

The lower part of an interlocked zipper is fixed and the slider is pulled up to the top stop. Holding strength is measured by pulling the slider tab firmly

5.4.3Bottom stop holding strength

The slider is pulled down to the bottom stop and single chains are opened to the right and left sides. Bottom stop holding strength and resistance of the elements inside the slider are measured.

5.4.4 Separating unit crosswise strength

The open part is fixed to the tensile tester (only the open part as shown in the figure) so that the end of the last element falls into line with the clamp edge and the tensile strength can be measured.

5.4.5Slider lock strength

A slider is locked at the middle of a zipper chain and single chains are opened to the right and left sides.Locking strength and resistance of the elements inside the slider are measured.

5.4.6 Slider tab pull off strength（90 degrees）

For a completed slider, resistance of the slider is measured when the pull tab is pulled away from the lower part of the body. In addition to the 90 degree method of measuring shown in the figure at left, there is one for 45 degrees.

6. Conclusion

Today’s educated consumer is focused on finding apparel with the best balance of style, quality, and price, manufactured under the highest possible ethical standards. Increased consumer awareness is making apparel quality control more important than ever.

REFERENCES and URLs

1. Solinger Jacob, “Apparel Manufacturing Hand Book – Analysis, Principles and Practice”, Columbia Boblin Media Corp., 1988.
2. David J.Tyler, “Materials Management in Clothing Production”, 2000.
3. Herold Carr and Barbara Lathem, “ The Technology of Clothing Manufacturing”, II nd  Edition, Blackwell Scientific Publications, London, 1988.
4. Prodip V.Mehta, “An Introduction of Quality Control for the Apparel Industry”. ASQC quality Press, Marcel Dekker Inc., Newyork, 1992.
5. Managing Quality In Apparel Industry, S.K.Bhrdwaj & Pradip V Mehta. Quality is Free,Philip Crosby.