AQL Chart

An AQL chart helps inspectors choose the correct sample size and acceptance number based on lot size, inspection level, and defect category.

Chart Purpose

An AQL chart is used to convert a production lot into a clear inspection plan. It helps inspectors decide how many products to check and how many defects can be accepted before the full batch fails inspection.

Lot Size Range

The chart starts with the lot size range, which means the total number of products available for inspection. A small lot needs a smaller sample, while a larger lot usually requires more checked units to support a fair quality decision.

Inspection Level

Inspection level controls how strict the sample selection should be. General inspection levels are commonly used for normal product checks, while special inspection levels may be used for smaller tests, limited checks, or specific product requirements.

Sample Size Code

The AQL chart gives a sample size code after the lot size and inspection level are selected. This code directs the inspector to the correct sample size table, where the required number of checked units can be found.

Sample Size

Sample size shows how many products must be inspected from the batch. Inspectors use this number to select units from different cartons, boxes, pallets, or production areas so the sample can represent the full production lot more accurately.

Acceptance Number

The acceptance number shows the maximum number of defects allowed in the inspected sample. If the defect count stays at or below this number, the batch can pass under the selected AQL level and inspection rules.

Rejection Number

The rejection number shows when the batch fails inspection. If defects reach or exceed this number, the sample result shows that the batch quality has crossed the allowed limit and may need sorting, repair, reinspection, or rejection.

Defect Category

AQL charts are usually applied separately for critical, major, and minor defects. Each defect category can have a different accepted limit because safety issues, functional problems, and small appearance issues do not carry the same quality risk.

Inspection Decision

The final inspection decision comes from comparing the defect count with the acceptance and rejection numbers. This makes the result consistent because the batch is judged through a fixed chart instead of personal opinion or random checking.

To understand what AQL means before using the chart for sample size and acceptance numbers, read the full guide on AQL full form.