Jimmy K.C. Lam The Hong Kong Polytechnic University Garment Inspection Jimmy K.C. Lam The Hong Kong Polytechnic University

Garment Inspection Stage of Garment Inspection AQL Random Sampling Inspection AQL 1.5 severe inspection AQL 2.5 normal/good quality inspection Sample Size Code Letter Single Sampling Plan, normal inspection Double Sampling Plan, normal inspection

Stages of Garment Inspection Pre-production Check final check on the raw material used, style, cut Initial Production Check First batch of garments is inspected, make correction before bulk production During Production Check Final Random Inspection Checking the total production quality by selecting the samples from the order. AQL sampling inspection may be applied

AQL Random Sampling Inspection The AQL inspection takes the samples from a goods, inspect them and depends on the quality of samples inspected and decide to accept or reject them. The standard is based on Military Standard 105D (MIL-STD-105D) It provides with the sampling plans, the number of samples to be inspected and the acceptable quality level (AQL) AQL 1.5 is applied to very severe inspection on high-class expensive item. AQL 2.5 is applied when textiles of normal/good quality are involved.

AQL (II) Three types of sampling plans single, double and multiple Each sampling plan can be performed in three level normal, tightened and reduced, depending on quality of products In garment industry, single and double normal sampling plans are applied

Sample Size Code Letter The Sample Size Code Letter shows different lot sizes to different code letter. There are seven inspection level, four for general inspection and three for special inspection For garment inspection, General Inspection level II would be used.

Sample Size Code Letter

Single Sampling Plan for normal inspection

Double Sampling Plans

Example Single Sampling Plan-Normal Inspection Assume AQL is 2.5% and lot size is 600 garments, find out the following : The total number of samples need to inspect The acceptable number of the samples The rejection number of the samples

Answer Single Sampling Plan 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.

Try this one If the garment lot is 300 dozens, and AQL is 4.0%, find out the number of samples to be inspected the acceptable number and rejection number

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

Answer Double Sampling Plan First, Table 1 of 2000 lots at inspection level II is letter “K” 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

Answer Double sampling Plan (II) For second inspection, the sample sizes again is 80 At AQL 4%, the cumulated acceptable number is 12 and rejection number is 13. Conclusion 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.

Try this one Double Sampling Plan A total of 3,000 dozens of sweaters were produced. At AQL 2.5%, find out the following at double sampling plan: The total sample sizes need to inspect The acceptable number at first inspection The acceptable number at second inspection