Hi, I read the statement "if Cpk> 1,33 then the AQL reduces to 2,5%."
Can you explain how you get to this. I would expect that a Cpk has only 66 pppm defective which would be an AQL of 0,0066%
By the way does anybody knows how to design a sampling plan to guarantee a Cpk of 1,33, rather than quaranteeing an AQL of say 1%?
By the way does anybody knows how to design a sampling plan to guarantee a Cpk of 1,33, rather than quaranteeing an AQL of say 1%?
I used a RQL plan without modifying for a small lot size. An RQL plan will REJECT the lot if it is 66ppm or worse defective. (AQL plans are based on the quality level you will allow to be accepted.) I used a 95% probability of rejecting the lot. If I were to use a 99% probability of rejecting the sample size would be: 69,776.
all sarcasm aside, obviously no attribute (pass/fail) sample plan can 'guarantee' such low defect rates unless the sample is very very large.
You might consider using a variables sample plan such as ANSI Z1.9-2008 However, the best approach is to utilize SPC, mistake proofign and positive process controls to ensure a stable capable process...