Acceptance Sampling Contrasting the LQ vs the AQL for Product Inspections
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- Опубліковано 21 сер 2024
- For a lot of products produced in isolation, you should work with the LQ, not the AQL, which is designed for inspections of a continuous stream of production.
LQ stands for limiting quality. It is the quality level, for a lot in isolation, which, for the purpose of sampling inspection, is limited to a low probability of acceptance.
The tables and all the information needed to use this type of sampling plan are in the ISO 2859-2:2020 standard.
Choosing ISO 2859-1 vs. ISO 2859-2 comes with MASSIVE implications for the supplier. A not-very-good-quality batch is much more likely to get rejected if the LQ (under ISO 2859-2) is used.
This video explains these two concepts for you.
For further information, be sure to read this blog post where this video appears as supplemental information:
This is true. It must also be noted that there is also a conversion table LQ to AQL. Essentially if your LQ = 2, then AQL equivalent = 0.25 which gives you the same amount of pass and fail rates. Essentially you are sampling at a much tighter AQL. The good thing with LQ is that when you set your limit, as the families get larger, the AQL also increases, which means it gives the manufacture some breathing room the more they make in that lot.
AQL provides the manufacture a guide on quality they need to produce, where as LQ looks at the consumer's risk. The standard also says that the LQ needs to be set realistic to what is acceptable (i.e. at least 3x the AQL), so in reality if you did an LQ sample plan, the LQ value would have been 5% to match the AQL of 1% that is aimed for
Very well explained, Thank You.
perfect clarification , thank you and so much appreciated
also I thought the AQL was more like an limit where the majority of lots would be better than AQL (so more like an upper control limit rather than the average centre line)
Why are the AQL values so strange like 0.4 and 0.65?
so what’s the purpose of the next QL? 3.15, 5, etc? in which condition we can use them?
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