VTMSTONE’s Success in applying Acceptance Quality Level (AQLs) for export products.

One of VTMSTONE’s remarkable achievements in 2006 is deeply applying Quality Assurance Sampling Plan to its export products. This plan is designed to provide maximum inspection productivity while maintaining a high degree of random sampling reliability. Plans are provided for Acceptance Quality Levels (AQLs) of 2.5 percent defective.

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Our Quality Control (Q.C) is highly appreciated and most customers are really satisfied with our products. The export products are always strictly inspected by our Final Inspector before shipment, this final inspection step needs to comply with AQLs. If the conditions are not satisfied, the whole shipment checking will be carried out.

2.5 AQL - INSPECTION

Lot Size
Sample Size
Acc
Rej
Criteria for Continuing Inspection 
1-8
All
*
*
N/A
9-150 
(Cumulative S/S)
8
20
0
1
2
2
If 1 defective found, go to S/S of 20. **
151-280
(Cumulative S/S)
20
32
1
2
3
3
If 2 defectives found, go to S/S of 32.
281-500
(Cumulative S/S)
20
50
1
3
4
4
If 2-3 defectives found, go to S/S of 50.
501-1200
(Cumulative S/S)
32
80
1
5
6
6
If 2-5 defectives found, go to S/S of 80.
1201-3200
(Cumulative S/S)
50
125
2
7
8
8
If 3-7 defectives found, go to S/S of 125.
3201-10,000
(Cumulative S/S)
80
200
3
10
11
11
If 4-10 defectives found, go to S/S of 200.
10,001-35,000
(Cumulative S/S)
125
315
5
14
15
15
If 6-14 defectives found, go to S/S of 315.
Over 35,000
(Cumulative S/S)
200
500
8
21
22
22
If 9-21 defectives found, go to S/S of 500.
* Reject only defectives found.
** If lot size is 20 units or less, inspect all and reject only defectives found.

Here is how the random sampling works:

Let us say that the shipment or lot size is 2,000 items or pieces.
Then,
(1) Take the sample of 50 pieces at random from this shipment.
(2) Inspect all 50 pieces.
(3) If 2 or less defective pieces are found, accept the shipment. 
(4) If 8 or more defective pieces are found, the shipment is not accepted, the whole shipment checking will be carried out.
(5) If 3 to 7 defective pieces are found, then take additional 75 samples at random.
(6) Inspect all 75 samples.
(7) If a total of 7 or less defective pieces are found, accept the shipment.
(8) If a total of 8 or more defective pieces are found, the shipment is not accepted, the whole shipment checking will be carried out.

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