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Gage RR problems

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  • #52701

    Currie
    Participant

    Hi All,
    I’m hoping you can advise on a couple of GR&R questions I have.
    We have conducted a study that has indicated the measurement system is no good for either inspection use or for improvement activities (in fact its so bad we question why we are even spending time measuring!). We use the measurement to make accept / reject decison on batches of components and a fail results in rework and re tests.
    In my mind this result has thrown up many issues and my first question is from the results (or other data) is it possible to determine what difference in component we are actually able to detect?
    The second unrelated question is does any one have experience on conducting an MSA on hardness testing where the test is in effect destructive?
    Thanks in advance

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    #185793

    Craig
    Participant

    Question 1: You would need a set of standards for this. (Items of known values). It would be the same approach as a linearity study, but with additional analysis. Example: I have a set of standards for oxide thickness and they are certified at 1000, 1200, 1400, 1600, 1800, and 2000 angstroms.
    Conduct a linearity study, but you could also use a t-test to see if the measurement equipment can detect a difference of 200 angtroms. I’d suggest a series of paired-comparisons. Your null hypothesis would be
    m2– m1  =   200
     
    The biggest challenge is probably obtaining the standards!
    Question 2: There are many threads on GRR for destructive testing already. You might find a solution….The only advantage I see with hardness tesing is that you might be able to take repeated measurements in close proximity on an experimental unit and consider them replications. (Unlike a tensile test, where you use it once and it is toast)

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