Acceptable Quality Level - AQL
Acceptable Quality Level. AQL . Also known as Assured Quality Level.
This publication establishes lot or batch sampling plans and procedures for quality inspection by attributes. The sampling plans described in this standard are applicable to AQL of 0.01 % or higher and are therefore not suitable for applications where quality level in the defective parts per million range cab be realized.
These plans are intended primarily to be used for a continuing series of lot or batch. The plan may also be used for the the inspection of isolated lot or batch.

MIL-STD-105E - AQL Keyword listing

Acceptable Quality Level - AQL - What is AQL?
When a continuous series of lots is considered, the AQL is the quality level which, for the purposes of sampling inspection, is the limit of a satisfactory process average.
A sampling plan and an AQL are chosen in accordance with the risk assumed. Use of the value of AQL for certain defect or group of defects indicates that the sampling plan will accept the great majority of the lot or batch provided the process average level of percentage defective in these lot or batch be no greater than the designated value of AQL sampling plan.

Average outgoing quality - AOQ
For a particular process average, the AOQ is the average quality of outgoing product including all accepted lot or batch, plus all rejected lot or batch after the rejected lot or batch have been effectively 100 % inspected and all defectives replaced by non-defectives.

Classification of Defects
A classification of defects is the enumeration of possible defects of the unit of product classified according to their seriousness.

Lot or batch
The term lot or batch shall mean " inspection lot " or " Inspection batch " . The lot or batch size is the number of units of product in a lot or batch.

Process Average
The process average is the average percent defective or average number of defects per hundred units of product committed by the supplier for original inspecting. Original inspection is the first inspection of a particular quantity of product as distinguished from the inspection of product which has been resubmitted after prior rejection.

AQL Sample
A sample consists of one or more units of product drawn from a lot or batch, the unit of the sample being selected at random without regard to their quality. The number of units of product in the sample is the AQL sample size.

Sampling Plan
A sampling plan indicates the number of unit of product from each lot or batch which are to be insppected and the criteria for determining the acceptability of the lot or batch.

Unit of product
The unit of product is the thing inspected in order to determine its classication as defective or non-defective or to count the number of defects. It may be a single article, a pair, a set, a length or the end product itself. The unit of product may or may not be the same as the unit of purchase, supply or shipment.

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AQL acceptablle quality sampling plan