AQL 2.5 on 5,000 Cushion Covers: 14 Majors in a 200-Piece Sample
An export order of 5,000 cotton cushion covers, 45 × 45 cm with a concealed zip and 1 cm piping, is offered for final inspection. The contract specifies ISO 2859-1, general inspection level II, single sampling, AQL 2.5 for major defects and AQL 4.0 for minor defects. The inspector draws 200 pieces and finds 14 majors (uneven piping, zip not fully concealed, size short by 1.5 cm) and 9 minors. The production manager argues that 14 out of 200 is 7% and that the lot should pass because the defect rate is 'close to 2.5%'. The buyer's QA insists the lot is rejected. The shipment is due in five days and the buyer has already booked freight.
1. Evaluate the production manager's arithmetic and state the correct inspection decision.
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The manager is confusing AQL with a permitted defect percentage. AQL is not the maximum share of defects allowed in a lot. It is the quality level that carries a defined probability of acceptance, about 95% under ISO 2859-1. What decides the lot is the sample plan.
The plan for this lot:
- Lot size 5,000, general inspection level II → code letter L → sample size 200. That matches the 200 pieces drawn.
- Major defects, AQL 2.5, n = 200 → acceptance number 10, rejection number 11.
- 14 majors is at or above the rejection number, so the lot is rejected on majors.
- Minor defects, AQL 4.0, n = 200 → acceptance number 14. Nine minors is within the limit, so minors alone would have passed. The rejection is driven entirely by the majors.
Even the arithmetic is misleading: 14/200 is 7%, while the acceptance number allows about 5% in the sample. And the 1.5 cm short covers are a measurement failure, not a cosmetic one.
2. What disposition would you direct for the 5,000 pieces, and what must happen before shipment?
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- Reject the lot and stop shipment. Inform the buyer in writing the same day, with the inspection record.
- Screen 100% of the 5,000 pieces and sort into major, minor, reworkable and reject.
- Rework what can be reworked - re-piping, re-seating the zip, re-pressing. Covers short by 1.5 cm cannot be reworked and must not be labelled as the ordered size; they are either downgraded with the buyer's written agreement or replaced.
- Re-inspect the reworked lot at a tightened AQL or 100%, and release only after the sample passes the acceptance number.
- Do not let the freight booking force a shipment. Shipping a rejected lot transfers the problem to the buyer and usually costs more in claims and returns than a delayed shipment.
- Check whether the buyer will accept a split shipment of the confirmed-good pieces to protect the delivery date.
3. What root-cause actions would you take so the next lot does not repeat the three defect types?
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Treat each defect separately, because each has a different source:
- Uneven piping - check the piping template, the piping foot and the cut width of the piping strip. If strip width varies, the finished piping will vary no matter how good the operator is.
- Zip not concealed - check the zip foot setting, the seam allowance at the zip and operator technique. A pre-production sample should have locked the setting before bulk.
- Size short by 1.5 cm - measure cut panels against the pattern and check fabric shrinkage. If the panels were correct, the cause is shrinkage or a pattern error, not sewing.
Add in-line checks: measure five pieces every hour at each operation, keep a Pareto chart of defects, and review the pre-production sample approval. Inspection at the end only finds defects; it does not prevent them.