What Does AQL Mean? 'AQL' stands for 'Acceptance Quality Limit', and is defined as the "quality level that is the worst tolerable" in ISO 2859-1. It represents the maximum number of defective units, beyond which a batch is rejected. Importers usually set different AQLs for critical, major, and minor defects. Most Asian exporters are familiar with this type of setting. For example: "AQL is 1.5%" means "I want no more than 1.5% defective items in the whole order quantity, on average over … [Read more...]
The Special Inspection Levels in the AQL Tables
A few years ago I wrote about the inspection levels, but some people are still confused about the "special" levels (S1, S2, S3, and S4). Here is what the ISO 2859-1 standard says (emphasis mine): The inspection level designates the relative amount of inspection. Three inspection levels, I, II and III, are given in Table 1 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 … [Read more...]
How to choose an AQL limit?
A few months ago, I wrote an explanation about the "AQL": what it is and how to use it. I also listed a few frequent questions, but it seems like I forgot one of them: What AQL tolerance is suitable to my products? Unfortunately, it is hard to base this on statistical reasoning. So I don't have any definitive answer. The right AQL depends on two things, I think: The market you are selling into, The kind of risk the users run by using/consuming/getting close to your product. 1. … [Read more...]