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Gage R&R - When to use Part-to-Part Calculation and Tolerance

Discussion in 'Gage R&R and MSA - Measurement Systems Analysis' started by Dejan, Aug 25, 2015.

  1. Dejan

    Dejan New Member

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    Hello everybody!
    I am new here.I have one question related to gage R&R. I kindly ask you if someone can give me short and clear explanation when to use Part to part calculation and when to use Tolerance.Thanks in advance,best regards Dejan.
     
  2. Atul Khandekar

    Atul Khandekar Administrator Staff Member

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    By Part-to-Part varition I understand you mean the Total Study Variation due to parts chosen for the GRR study.

    The basic criteria of 10%-30% as defined by AIAG is based on this variation. There are two ways to evaluate based on the pourpose for which the gage is used.

    If the gage is used for SPC or capability studies, the parts chosen must represent the actual variation in the process. You can also use the Standard Deviation calculated during SPC in place of study variation.

    If the gage is used for final part inspection against tolerance, the %Tolerance metric should be used. If possible parts should be chosen to reflect the tolerance.
     
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  3. Mark Paul

    Mark Paul Member

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    In all seriousness, which would be used if the gage is used for BOTH SPC and final part inspection?
     
  4. Miner

    Miner Moderator Staff Member

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    In that scenario, use both to verify that the gage is suitable for both applications.
     
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