In-Process Inspection Sampling Quantity

[nurhakim]

Hi,

I have this situation during in-process inspection. As part of internal quality control, I took 80 pieces of sample from production, and test for visual defect and freedom from holes. Say, during visual defect inspection, I found 2 defects i.e. the result is 2/80. I have balance of 78 pieces, which I will continue for freedom from holes test. As I took exactly 80 pieces earlier as instructed by my Manager, can I use the 2 defected samples to mark up to 80?

Thanks,
Nur

 

[Bev D]

yes you can. units can have multiple defects so the sample size of 80 can be used for inspecting all defect criteria. the only constraint is that you properly control the two defective units to ensure that they don't get back into the production stream...

curious tho: why 80 pieces for inprocess inspection? that seems a bit high for inprocess. were they randomly selected or sequential pieces?

 

[Michael_M]

Hi,

I have this situation during in-process inspection. As part of internal quality control, I took 80 pieces of sample from production, and test for visual defect and freedom from holes. Say, during visual defect inspection, I found 2 defects i.e. the result is 2/80. I have balance of 78 pieces, which I will continue for freedom from holes test. As I took exactly 80 pieces earlier as instructed by my Manager, can I use the 2 defected samples to mark up to 80?

Thanks,
Nur

I wonder at 80 piece sample as well, however another question comes up (unless I did not understand the statement above). If you found a defect, this should trigger a 100% inspection for this defect as it was found after manufacturing. If an AQL inspection finds a defect, it should require a 100% inspection for that defect.

Again, I may be mis-understanding your question.

 

[PaulJSmith]

can I use the 2 defected samples to mark up to 80?

Yes, and in fact, you should check all sample pieces for all defects. As noted above, there could be multiple defects. If you stop as soon as you find one defect, you may be missing others, which will potentially skew your inspection results.

 

[Chicoria]

It would only make sense to 100% inspect at this point. The purpose of a sample is to prove out the lot. In common use, if the sample does not pass then the lot as a whole could not be considered a pass and would need 100% inspection.