Q: How do I set an AQL level for zipper inspection?
Start from the consequence of the defect. A critical defect, such as a sharp point, a detached slider on a children's item or a needle fragment, is normally set at zero acceptance regardless of lot size. Major defects that make the zipper unusable or unsaleable — a non-locking slider, a chain that separates, a wrong length or colour — are commonly set at 1.0 or 2.5. Minor appearance defects are often set at 4.0.
The AQL works together with the lot size, the inspection level and the sampling scheme in ISO 2859-1 or the equivalent. Choose the inspection level, read the sample size code letter from the lot size, and take the acceptance and rejection numbers from the table for your AQL. Record the plan on the inspection form so the result can be reproduced. The tables, not memory, define the numbers, so refer to the standard text.
Review the level against the process: a stable supplier with good history can justify a reduced inspection, and a new supplier or a new colour should start tightened. Acceptance means the number of defects found is at or below the acceptance number for each class, judged separately.