AQL Standard (Single sampling plan for normal inspection)

QCINASIA uses well-proven and widely adopted international standard ISO2859-1 (equivalent of ANSI/ASQC Z1.4-2008, BS 6001, ABC-105, NFX06 –022, NFX 06-022, DIN 40.080, UNI 48.42) Single Sampling Plan. General Inspection Level Normal II is usually applied to determine the inspection sample size for aesthetic and functional check. Special Inspection Level will be applied for safety, reliability, performance or other special test if whereas applicable.

AQL Table

Table A:

Table B:

The inspection level designates the relative amount of inspection. Three inspection levels, I, II and III, are given in Table A for general use. Unless otherwise specified, level II shall be used. Level I may be used when less discrimination is needed or level III when greater discrimination is required. Four additional special levels, S-1, S-2, S-3 and S-4 are also given in Table A and may be used where relatively small sample sizes are necessary (for example, for some destructive test or time-consuming test) and larger sampling risks can be tolerated.

Sample sizes are designated by sample size code letters and the corresponding AQL level. Table A shall be used to find the applicable code letter for the particular lot size, Table B shall be used to find the sample size based on code letter and the prescribed AQL level.

As default, QCINASIA uses general inspection level II, Acceptable Quality Level (AQL) Not allowed / 2.5 / 4.0 of Critical, Major, Minor defect.

For example, there're 6,000 units to be inspected, as per single sampling level II, AQL: Not allowed / 2.5 / 4.0 of Critical / Major / Minor:
According to table A, from quantity 3201 to 10000, the corresponding sample size code letter is "L", therefore in table B, “L” is corresponding to sample size "200". So the maximum allowed number of defective unit is as follow: Critical Defect 0; Major Defect 10; Minor Defect: 14. In other words, if the number of critical defective units is more than 0, or major defective units is more than 10, or minor defective units is more than 14, the lot has to be rejected.