Disposition of a 500-piece shirt lot with a critical finding
A factory has produced 500 cotton school shirts. Final inspection uses general inspection level II and AQL 2.5 for major defects and 4.0 for minor defects. The inspector draws the required sample of 50 shirts. Findings: two open side seams, one mismatched pocket, five loose threads, and one shirt with a broken needle tip embedded in the collar. The acceptable number for major defects is 3 and for minor defects is 5. The production manager argues that the lot should pass because the major count is 3 and the minor count is 5, exactly at the acceptance limits, and offers to re-trim the loose threads. The buyer's delivery deadline is in three days and the shirts are already packed in polybags. The factory has a metal detector but it has not been calibrated for two months.
1. Classify the findings and decide the disposition of the lot. Explain why the acceptance numbers do not settle the matter.
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Classify by severity first. The embedded needle tip is a critical defect because it can injure a child; critical defects are not traded off against AQL acceptance numbers. The two open side seams and the mismatched pocket are major defects; the five loose threads are minor. On the major count alone, 3 is at the acceptance number for AQL 2.5 with a sample of 50, and 5 minor is at the acceptance number for AQL 4.0, so the manager is reading the table correctly but applying it wrongly. Any critical defect found in the sample means the lot cannot be accepted as presented. The sample also has to represent the lot: one needle fragment in 50 pieces suggests a needle-control failure, so the risk in the remaining 450 pieces is unknown. The correct disposition is to reject or hold the lot, quarantine all 500 shirts, and carry out 100% inspection with a calibrated metal detector or other verified metal screening. Rework the open seams and mismatched pockets, trim loose threads, replace the affected shirt, and re-inspect before shipment. Delivery pressure does not override a critical safety defect.
2. What immediate containment and corrective actions should the factory take before any shirts leave the premises?
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Containment comes before correction. Segregate the sampled shirt and all packed polybags in a locked quarantine area. Stop packing and record the lot number, machine numbers and shift. Calibrate the metal detector with known test pieces and then screen every shirt, including collars, cuffs and hems; if the detector is unreliable, use a verified alternative such as X-ray or manual magnet sweep plus visual inspection. Open the polybags for inspection rather than scanning sealed packs blindly. Corrective action must address the cause: introduce a broken-needle policy with needle counts at the start and end of each shift, a signed needle-break log, and a search for fragments immediately after any break. Inspect needle plates and machine heads for damage, and retrain operators not to leave broken needles on the table. Rework the open seams and mismatched pocket, trim loose threads and re-inspect the reworked pieces at a tightened level. Inform the buyer of the hold and the containment plan; do not ship and hope the sample was unlucky.
3. The production manager says the five loose threads can be trimmed and the lot passed. How should the inspector respond, and what records should be kept?
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The inspector should agree that loose threads are minor and can be trimmed, but explain that trimming does not answer the critical finding. The loose threads affect appearance; the needle fragment affects safety. Passing the lot on the minor count would confuse defect severity with commercial convenience. The inspector should record the sample size, lot number, AQL levels, each defect by code and location, the critical finding, the quarantine decision, the metal-detector calibration result and the 100% screening result. Record the rework details for the open seams and mismatched pocket, the number of pieces rejected or replaced, and the final re-inspection sample and result. Keep the broken needle log and the machine maintenance record. If the buyer grants a concession, it should be in writing after the safety screening, not before. The inspector's signature should show that the decision was based on defect classification and containment, not on the delivery deadline. This record also supports traceability if a complaint arises later.