BVIS use the MIL-STD-105E(AQL) tables (also known as AQL tables) to measure acceptable levels of quality of the products they inspect. This method is widely used to decide whether to accept a production lot without checking every single item. This tables standards in all countries of the Organization for Standardization and the International Organization for Standardization has in the same standard. This standard is an effective way to accept or reject a batch of products. These tables are of the US standard with equivalents in all national and international standardization organizations (ANSI/ASQC Z1.4, ISO 2859, NFX 06-022, BS 6001, DIN 40080, GB/T 2828.1-2003).
Acceptance Sampling is used to decide whether to accept or reject a production lot : based on AQL, randomly select samples from the production lot and perform inspection to the samples, then use the result to decide whether or not to accept the lot.
A batch or lot is a collection of products – all identical in size, type, conditions and time of production – from which samples will be taken to decide whether or not it conforms to the acceptance inspection.
General Sampling Level
The Sampling Level represents the overall accuracy level of the Sampling Method. For a given lot size, increasing the Sampling Level means increasing the Sample Size.
The General Sampling Level may be chosen between I, II, or III.
The default General Sampling Quality Level in BVIS is II.
Special Inspection Level
The Special Inspection Level is used instead of the general inspection level when the production has to be special operationally inspected.
Special inspection standards including S1, S2, S3 and S4.
The default Special Sampling Quality Level in BVIS is S2, for weight checking, size checking, technical testing, etc..
Samples size code letter
The code letter is based on lot size and inspection level.
The sampling size is the total number of units to be inspected.
AQL and defect classification
Defects detected during inspections are generally classified in 3 categories:
- Critical defect
- Major defect
- Minor defect
Critical Defect is likely to result in hazardous or unsafe conditions for individuals using.
The default Critical Defect AQL in BVIS is 0.
Major defects does not affect security for the circumstances, could lead to reduced availability of product.
The default Major Defect AQL in BVIS is 2.5.
Minor defects will not damage the products normal use, or deviate from the relevant standard. Minor defect is a quality standard of workmanship.
The default Major Defect AQL in BVIS is 4.0.
How do I determine the right sample size and acceptance number?
For a hypothetical inspection of a 7000-unit lot, with General Inspection Level of II.Table A indicates that the sample size code letter should be L.
Table B indicates that the sample size should be 200 units.
For an AQL of Major2.5/Minor4.0, the corresponding acceptance number is Major 10/ Minor14.
According to 0,2.5,4.0 acceptance quality standards, this batch of defective products can be acceptable standards for:
cirtical defectives acceptable standard is 0 pc;
major defectives acceptable standard is 10 pcs;
minor defectives acceptable standards is 14 pcs.
If critical defectives were not found in the randomly selected samples, but the major defectives were over 10pcs or the minor defectives were over 14pcs, the whole batch result would be failed.