Garment InspectionGarment Inspection

Jimmy K.C. LamJimmy K.C. Lam

The Hong Kong Polytechnic UniversityThe Hong Kong Polytechnic University

Garment InspectionGarment Inspection

Stage of Garment InspectionStage of Garment Inspection AQL Random Sampling InspectionAQL Random Sampling Inspection

– AQL 1.5 severe inspectionAQL 1.5 severe inspection– AQL 2.5 normal/good quality inspectionAQL 2.5 normal/good quality inspection– Sample Size Code LetterSample Size Code Letter

Single Sampling Plan, normal inspectionSingle Sampling Plan, normal inspection Double Sampling Plan, normal inspectionDouble Sampling Plan, normal inspection

Stages of Garment InspectionStages of Garment Inspection Pre-production CheckPre-production Check

– final check on the raw material used, style, cutfinal check on the raw material used, style, cut Initial Production CheckInitial Production Check

– First batch of garments is inspected, make correction before First batch of garments is inspected, make correction before bulk productionbulk production

During Production CheckDuring Production Check Final Random InspectionFinal Random Inspection

– Checking the total production quality by selecting the samples Checking the total production quality by selecting the samples from the order. AQL sampling inspection may be appliedfrom the order. AQL sampling inspection may be applied

AQL Random Sampling InspectionAQL Random Sampling Inspection The AQL inspection takes the samples from a goods, The AQL inspection takes the samples from a goods,

inspect them and depends on the quality of samples inspect them and depends on the quality of samples inspected and decide to accept or reject them.inspected and decide to accept or reject them.

The standard is based on Military Standard 105D (MIL-The standard is based on Military Standard 105D (MIL-STD-105D)STD-105D)

It provides with the sampling plans, the number of samples It provides with the sampling plans, the number of samples to be inspected and the acceptable quality level (AQL)to be inspected and the acceptable quality level (AQL)

AQL 1.5 is applied to very severe inspection on high-class AQL 1.5 is applied to very severe inspection on high-class expensive item. expensive item.

AQL 2.5 is applied when textiles of normal/good quality AQL 2.5 is applied when textiles of normal/good quality are involved.are involved.

AQL (II)AQL (II)

Three types of sampling plansThree types of sampling plans– single, double and multiplesingle, double and multiple

Each sampling plan can be performed in three Each sampling plan can be performed in three levellevel– normal, tightened and reduced, depending on normal, tightened and reduced, depending on

quality of productsquality of products In garment industry, single and double normal In garment industry, single and double normal

sampling plans are appliedsampling plans are applied

Sample Size Code LetterSample Size Code Letter

The Sample Size Code Letter shows different The Sample Size Code Letter shows different lot sizes to different code letter.lot sizes to different code letter.

There are seven inspection level, four for There are seven inspection level, four for general inspection and three for special general inspection and three for special inspectioninspection

For garment inspection, General Inspection For garment inspection, General Inspection level II would be used.level II would be used.

Sample Size Code LetterSample Size Code Letter

Single Sampling Plan for normal Single Sampling Plan for normal inspectioninspection

Double Sampling PlansDouble Sampling Plans

ExampleExampleSingle Sampling Plan-Normal InspectionSingle Sampling Plan-Normal Inspection

Assume AQL is 2.5% and lot size is 600 Assume AQL is 2.5% and lot size is 600 garments, find out the following :garments, find out the following :

– The total number of samples need to inspectThe total number of samples need to inspect– The acceptable number of the samplesThe acceptable number of the samples– The rejection number of the samplesThe rejection number of the samples

AnswerAnswerSingle Sampling PlanSingle Sampling Plan

First, from Table 1 find out the code letter for lot First, from Table 1 find out the code letter for lot size of 600 and inspection level II is size of 600 and inspection level II is “J”“J”

From Table 2 (single sampling plan), the letter “J” From Table 2 (single sampling plan), the letter “J” corresponds to sample sizes of “80”.corresponds to sample sizes of “80”.

So, So, 80 samples are needed to inspect out of 60080 samples are needed to inspect out of 600 At AQL 2.5%, if defective garments are less than At AQL 2.5%, if defective garments are less than

or equal to 5, whole lots will be accepted, if it is or equal to 5, whole lots will be accepted, if it is found to be 6 or more, whole lots will be rejected.found to be 6 or more, whole lots will be rejected.

Try this oneTry this one

If the garment lot is 300 dozens, and AQL is If the garment lot is 300 dozens, and AQL is 4.0%, find out 4.0%, find out

the number of samples to be inspectedthe number of samples to be inspected the acceptable number and rejection numberthe acceptable number and rejection number

Example IIExample IIDouble Sampling PlanDouble Sampling Plan

Assume AQL is 4% and lot size is 2000 Assume AQL is 4% and lot size is 2000 garments, find out from double sampling plan garments, find out from double sampling plan on the following:on the following:– The total sample sizes need to inspectThe total sample sizes need to inspect– What is the first acceptable numberWhat is the first acceptable number– What is the second acceptable numberWhat is the second acceptable number

AnswerAnswerDouble Sampling PlanDouble Sampling Plan

First, Table 1 of 2000 lots at inspection level II is First, Table 1 of 2000 lots at inspection level II is letter “letter “KK””

Table 3, double sampling plan shows the sample Table 3, double sampling plan shows the sample size of letter K is size of letter K is 8080..

First inspection, at AQL 4%, the acceptable First inspection, at AQL 4%, the acceptable number is 5, rejection number is 9number is 5, rejection number is 9

If any number between 5 to 9, second inspection If any number between 5 to 9, second inspection is neededis needed

AnswerAnswerDouble sampling Plan (II)Double sampling Plan (II)

For second inspection, the sample sizes again is 80For second inspection, the sample sizes again is 80 At AQL 4%, the cumulated acceptable number is At AQL 4%, the cumulated acceptable number is

12 and rejection number is 13.12 and rejection number is 13. ConclusionConclusion

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

Try this oneTry this oneDouble Sampling PlanDouble Sampling Plan

A total of 3,000 dozens of sweaters were A total of 3,000 dozens of sweaters were produced. At AQL 2.5%, find out the produced. At AQL 2.5%, find out the following at double sampling plan:following at double sampling plan:

The total sample sizes need to inspectThe total sample sizes need to inspect The acceptable number at first inspectionThe acceptable number at first inspection The acceptable number at second inspectionThe acceptable number at second inspection