DOC KB-QC-016REV 2026-09-21CLASS: PUBLIC
Pre-Shipment Inspection for Protective Cases: What to Check and AQL Basics
Direct answer
A protective case shipment is inspected against a sampling plan — commonly AQL 2.5 for major defects and 4.0 for minor defects under ISO 2859-1 (ANSI/ASQ Z1.4), General Inspection Level II — but sampling only works when the checklist is functional, not cosmetic: latch actuation, gasket compression, hinge play, foam fit, laser/print quality, and the drop or seal tests agreed in the purchase contract.
§01The 8-point functional check
- Latch actuation: open/close 20× per sampled case; no sticking, full preload at close.
- Gasket contact: paper-strip pull test around the lid — uniform resistance everywhere.
- Hinge play: lid must not wobble laterally more than the drawing allows.
- Pressure valve: membrane intact, moves freely; press test for reseal.
- Foam fit: payload (or mock) inserts with defined resistance, notches aligned.
- Surface: sink marks, flash, texture damage logged as defects — distinguish cosmetic vs structural.
- Hardware torque: screws at hinges/handles torqued per spec, thread-lock present where specified.
- Marking: logo, serial and IP marking present and correctly placed per the approved sample.
§02AQL in one minute
You and the supplier agree acceptance quality limits (AQL) in the contract. The inspector draws a sample size from ISO 2859-1 based on lot size, then rejects the lot if defects exceed the AQL table limits. Typical allocations for molded products: critical = 0 (any structural crack or seal failure rejects), major = 2.5, minor = 4.0.
When third-party inspection pays: first order from a new factory, any order above roughly one container load, or whenever the buyer cannot attend in person. Cost is trivial against a rejected container — and it must be named in the contract as a release gate, not booked informally.