Anything higher than AQL 6.5 (ACCEPT/REJECT)?

[QualityMan75]

Hi,
I have an AQL control point, categorised as minor, where I need to have a larger acceptance number, than what AQL 6.5% grants. (Single sampling plan for normal inspection)
I don't want to remove the control point, since I want to track error level, from lot to lot.
Please, advice what is the next number (XX) in the series .....0.065, 0.10, 0.15.......2.5, 4.0, 6.5, XX? (And where can I find the AC/RE levels, corresponding to AQL XX?)

P.S. I fear AQL6.5 is the end station . If so, please suggest what I could do to obtain my goal

Thanks at lot in advance,
QualityMan75

 

[Bev D]

I just uploaded a sampling plan calculator to the resources section.
You can use this to determine a sampling plan for any AQL.

But I must ask why you are looking for such a high AQL? Why do you need a larger acceptance number (c)?

 

[QualityMan75]

Thanks for the calculator, the Excel sheets different fans look interesting, though a bit complicated. However, it was exactly what I need, so I can get the accept/reject level for a higer than 6,5% level.

The defect is minor, so I don't want to reject the lot. And I have to, if I don't go above 6.5%.

 

[Johnny Quality]

Why is the goal less than 6.5%? Costing? Customer requirement?

 

[QualityMan75]

Hi Johnny Quality,
I don't understand what you mean? I am forced to increase the AQL for the control point to above 6.5%, so the ACCEPT/REJECT levels increase high, enough to accomodate the number of rejected items in the sample. For example, if I have a sample of K=125 pieces, and have 25 rejects, the it is above the 15 pieces defined by the ACCEPT level. Thus, I want to increase AQL to for example 15%, so I get maybe 30? defect as ACCEPT level. So, the lot will pass the incomming inspection.

Writing above text, shows basically I am adjusting the incomming inspection, to make the lot pass. One could say, that originally I was not aware of the level of defects for this control point, and I started out to ambitiosly. I cannot be the first, which has experienced such situation?
I believe above is fair for a minor defect, but would not make sense for a major defect.

 

[Bev D]

I am still confused as to waht you are trying to do.
Our concern is that even 6.5% is a very large defect rate even for a minor defect. Teh goal of incoming inspection isn’t to accept lots - it is to protect the organization from a lot that has many defects that will cost more to deal with once they get into production.

What does your organization say about the defect rate?
If this defect is so minor that teh organization doesn’t mind 6.5% or more defects then why inspect at all? Why don’t you just accept all lots and deal with the defects in production?

My other thought is that perhaps you are misinterpreting the accept number in the sample.

 

[QualityMan75]

Hi Bev D,
I agree with your viewpoints, the incomming inspection's purpose is to stop lots with many defects. My organsation wants to overrule the AQL and accept the lot. Then we will deal with it in production, as you suggested.

I guess there is not much to misinterpret regarding accept number in sample. My understanding is that at Single Sampling Plans for normal inspection, then K=125 pieces, 6.5% AQL , then 14 defect pieces is ACCEPT level., 15 defects is REJECTION level. (This is of course allready a high level of defects, so I understand your worry about allowing even higher defects, if using an even higher AQL).

But, what is meant by "Normal Inspection" in the "Single Sampling Plans for normal inspection" (abreviation = SSPFNI)? Meaning, can I use the SSPFNI to find the corresponding sample lot size and acceptance and rejection number given a specific AQL-level, regardless of which
of following GIL-I,II,III and SIL S1, S2, S3 and S4 that I want to apply?
Can you give an example of what a single sampling plan, could be for, if is not for normal inspection?

Thanks in advance,

 

[Bev D]

Single sampling plan is typical.
you don’t need a different type of plan. You need production (QA) to tell you what the actual AQL is and then stick to it.

 

[QualityMan75]

Hi Bev B,
Thanks for informing, that the single sampling plan is sufficient.
Good point with the production QA.