Acceptable Quality Level (AQL) is defined by ANSI/ISO/ASQC A3534 as follows: "When a continuing series of lots is considered, a quality level which for purposes of sampling inspection is the limit of satisfactory process average."
The associated AQL and Lot Tolerance Percent Defective (LTPD) are summarized graphically by the operating characteristic curve.
…somebody told me that 0.065% AQL = 650PPM, is it true ???
Strictly speaking, no. But, a case could be made that if the AQL was, in fact, 0.065%, then the PPM might be 650. The problem is, AQL is an Acceptable Quality level, not the Actual Quality Level. AQL is the quality level that would be detectable under a certain sampling plan.
Also strictly speaking, the LTPD * 10,000 = PPM nonconforming.
Regards,
Don