Inspection is staged across the order rather than concentrated at the end, because a defect caught at the press is cheap and the same defect caught at the packing bench is not.
- Incoming material. Resin is checked against the specified grade and condition before it reaches the press.
- First article inspection. The first parts of a run are measured against the drawing before the run is released, and on a multi-cavity tool this is done per cavity.
- In-process sampling. Parts are drawn at defined intervals during the run and checked for dimensional drift and cosmetic defects.
- Final outgoing QC. The packed order is sampled against the agreed AQL before shipment.
The part of this that buyers most often leave undefined is the acceptance standard itself. Agree the AQL level, and agree what counts as a cosmetic defect on which surface, before production rather than after a disputed shipment. A short written standard naming the visible faces and the acceptable limit for sink, flow marks, and gate vestige removes most of the ambiguity.