Should every snap hook be tested, or is a sample from each lot enough? The answer depends on the failure mode and the test. ISO 2859-1:2026 defines acceptance-sampling plans for inspection by attributes. It helps determine how to accept or reject a lot based on sampled units; it does not guarantee that an accepted lot contains no defects.
Classify defects before choosing a sample size
Separate safety- or function-critical issues from cosmetic variation. A gate that does not close, a sharp edge that damages webbing and a slight color variation should not automatically share one acceptance rule. Write defect definitions with photographs or limit samples, and state how an inspector will classify borderline cases.
An AQL value is part of a defined sampling plan. The inspection level, lot size, sample size and acceptance/rejection numbers all matter. Do not quote an AQL number alone as if it were a percentage of defects permitted in every delivered box.
Use functional checks where function is the risk
Visual sampling cannot establish that a swivel turns under the required conditions or that a buckle holds in a finished assembly. A functional check should reproduce the intended movement or load path. Some checks are nondestructive and can be applied broadly; others consume or damage samples and must be planned by lot or by change event.
The buyer and supplier should decide which checks occur at incoming material, first article, in-process, final lot and finished-product stages. A critical feature may justify a higher inspection frequency or an automated check. A destructive pull test may require a documented sampling frequency and a clear response if one specimen fails.
Define the response to failure
The plan is incomplete unless it states what happens when a sample fails: contain the affected lot, investigate the cause, decide whether additional inspection or rework is appropriate, and document disposition. Repeating the same sample until it passes is not a sound acceptance process.
The Metal Hardware Buyer Guides can help turn an inspection preference into an RFQ requirement. Ask for a one-page control plan that connects each critical defect to a method, frequency and action.
Source: ISO 2859-1:2026 standard overview.
