2nd Inspection Sampling Plan

Six Sigma – iSixSigma Forums General Forums Methodology 2nd Inspection Sampling Plan

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    I’ve been searching the web for a sampling plan to incorporate after 100% inspection, and I’m finding nothing. I realize this sound excessive, but one customer which accounts for 40% of our business will allow for 0 defects. We perform 100% inspection on lot sizes of 500, and I’d like to have an additional inspector check smaller sample sizes after the lot has been accepted. Any Suggestions?



    Do you have a good understanding of your current inspection system’s ability to identify defects? Are all inspectors qualified (how?) and the inspection shifts restricted to below the time where their effectiveness rate drops off? What percent of defective products aren’t caught and what percent of good products are incorrectly identified as defective?


    Also depends on your process controls. What kind of historical data do you have on the inspections? Is your process well controlled such that you are not discovering any rejects during inspection? If you consistently have zero rejects in your current lots you should be able to justify a sample inspection with your customer with a fairly high confidence level, along with monitoring of your manufacturing process to assure the process is not deviating. The sample size you choose should be based on some agreed upon confidence level.


    Take a look at MIL-STD-1916…for a lot size of 500 and zero defects…I would recommend a quality verification level IV and inspect a sample 80 by your quality control department.



    1.Only inspection is not solution. its need to find a root cause.Then analysis through statistic.Also to be us a control charts u can catch easy ur process trend.
    2.U can try maximum possible us 50 % tolearnce during process.
    3.implement proper gauges to arrest a defects.

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