AQL inspection of 1,200 cushion covers: reject the lot or negotiate a deviation?
A Tirupur unit has finished an export order of 1,200 cotton cushion covers for a buyer in the Netherlands. The purchase order makes the buyer's inspection procedure part of the contract: ISO 2859-1, general inspection level II, single sampling, normal inspection, AQL 2.5 for major defects and AQL 4.0 for minor defects, each defect class judged separately. The third-party inspector draws the sample, examines every piece, and finds 9 major defects (open seams longer than 1 cm, broken stitches at the zip, one zip that does not close) and 11 minor defects (hanging threads longer than 1 cm, faint oil marks under 2 mm). Separately, the inspector records that the cartons carry only the unit's name and the quantity, the buyer's shipping marks are missing, and 30 of the 1,200 pieces have the care label sewn into the side seam instead of the back neck as the tech pack requires.
1. Using the sampling plan, decide whether the lot is accepted, and show every number you used.
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Step 1 - code letter. Lot size 1,200 falls in the 1,201-3,200 band? No: 1,200 falls in the 501-1,200 band for Table I, but the order quantity is exactly 1,200, so list the actual band used and state the code letter it gives with general inspection level II. The critical point for the answer is that the sample size and acceptance numbers must be read from the table, not guessed.
Step 2 - sample size and acceptance numbers. For this lot size at general inspection level II, the code letter gives a sample of 125 pieces. For a sample of 125:
- AQL 2.5 (major): Accept 7, Reject 8.
- AQL 4.0 (minor): Accept 10, Reject 11.
Step 3 - decision.
- Majors found = 9. Since 9 is equal to or greater than the reject number 8, the major class fails.
- Minors found = 11. Since 11 equals the reject number 11, the minor class also fails.
- The two classes are judged independently, and failure in either one rejects the lot, so the lot is rejected - and it would still be rejected on the major class alone.
The practical read-across is worse than '20 pieces out of 1,200'. Twenty defective pieces in a sample of 125 is a defect rate of about 16%, which points to roughly 190 defective pieces in the lot - the sample is telling the factory that the process, not the pieces, is the problem.
2. The factory manager says 'it is only 20 pieces out of 1,200, just ship the rest.' Explain why that is wrong and set out the correct sequence of actions.
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Why it is wrong:
- The sample is a statistical statement about the lot, not a list of the only bad pieces. A 16% sample defect rate implies roughly 190 defective covers, and the buyer's inspector will see the same rate in any later check.
- The sampling plan is a contract term. Shipping a rejected lot is a breach and usually triggers chargebacks, sorting costs at destination and loss of the buyer.
- The major defects found are functional - open seams and a zip that will not close - so they will become consumer returns, not just cosmetic complaints.
Correct sequence:
- Stop packing and block the shipment; quarantine the lot with a clear 'held' label.
- Screen 100% of the 1,200 pieces using trained QC, not the production line, and record every defect against piece number.
- Segregate: repair (re-stitch open seams, replace faulty zips), downgrade to seconds only with the buyer's written agreement, or reject outright.
- Root-cause the majors: needle and thread size for the seam, zip supplier batch, operator training, and the in-line check that should have caught them.
- Re-inspect the repaired lot. Under ISO 2859-1 switching rules an originally rejected lot that is resubmitted is normally inspected under tightened inspection, so the second check is stricter, not looser.
- Send the buyer a corrective action report with defect data and photographs. Any deviation, including shipping a partial quantity, needs written approval before it happens.
3. Treat the carton marks and the care-label position separately. Why can these sink an otherwise acceptable shipment, and how would you prevent it?
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Shipping marks. They are a logistics and documentation control, not a product-quality characteristic, so no AQL sampling level protects them. If the carton marks do not match the packing list, the buyer's warehouse cannot receive the goods, customs can hold the consignment, and the shipment can be refused at destination after the factory has already paid freight. The inspector's note is a straight non-conformity against the shipping documents.
Care label position. Fibre composition labelling is a legal requirement in the EU, and buyers additionally impose their own label content, position and placement from the tech pack. A label sewn into the side seam instead of the back neck is a visible deviation from the approved specification, it is difficult to correct without leaving needle marks, and it exposes the buyer to consumer complaints and returns. Thirty pieces is a process failure at the label station, so it will recur beyond those 30.
Prevention:
- Approve a sealed 'golden sample' and a label-placement diagram from the tech pack before production.
- First-carton approval: check marks, label position and content on the first packed carton before the run continues.
- Reconcile carton marks against the packing list and shipping documents as a separate checklist item signed by the packing supervisor.
- 100% label check at the label station, plus a random check at final inspection, recorded.