Glossary

AQL Inspection Levels Explained

Quick Definition: AQL (Acceptable Quality Level) is a statistical sampling method used in quality inspection. It determines how many units to inspect from a batch and how many defects are acceptable before rejecting the shipment.

How AQL Works

  1. Define batch size: Total units in the production run.
  2. Select inspection level: Usually General Inspection Level II (standard).
  3. Look up sample size: The AQL table tells you how many units to inspect.
  4. Set AQL limits: Typically AQL 2.5 for major defects and AQL 4.0 for minor defects.
  5. Inspect and count defects: If defects exceed the accept number, reject the batch.

Common AQL Levels

AQL LevelMeaningUsed For
AQL 0Zero tolerance for critical defectsSafety hazards, electrical dangers
AQL 1.0Very strictHigh-value products, medical devices
AQL 2.5Industry standardMost consumer products — the default for major defects
AQL 4.0RelaxedMinor cosmetic defects

Sample Size Example (AQL 2.5, Level II)

Batch SizeSample SizeAcceptReject
501–1,2008056
1,201–3,20012578
3,201–10,0002001011

Example: For a batch of 2,000 units, you inspect 125 units. If you find 7 or fewer major defects, the batch passes. If you find 8 or more, it fails.

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