What is meant by acceptable quality level? (AQL Chart)

A.Q.L (Acceptable Quality Level):

 The acceptable quality level (AQL) is measure applied to products and defined is ISO 2859-1 as the quality level that is the worst tolerable. The AQL tells you how many defective components are considered acceptable during random sampling quality inspections.

 

They followed the following AQL chart. Several times buyer gives the instruction that what type of AQL they have to follow.

AQL CHART

What does AQL of 1.5, 2.5, 4 & 6.5 mean?

In the quality control industry defects are classified per critical, major and minor. If the buyer only mentions AQL like 1.5, 2.5,4 or 6.5 any one, it means that the buyer accepts all kind of defects (Critical, Major, Minor) to be present in the manufactured goods at a level of 1.5, 2.5, 4 or 6.5 (%) of the total order quantity.