Good GR&R Bad NDC

I recently did an R&R and the GRR turned out to be 9.343% which is good, but the NDC is a .348 (very bad). I'm doing it on a torque wrench and the mark is 10.5 with a ±2.5. This is what is called out in the drawing. How / What can I manipulate in order to get this to come out good? I get readings from 10.4 up to 10.65. Should my resolution be different? I feel I'm missing something, but not sure what it could be.
Thank you for all your advice, in advance.

Timothy B. Hill


  • So I changed the specs to read 3% of the gauge tolerance (10.185 - 10.815) instead of the ±2.5 of the part. The GRR is now a 74.094% and the NDC hasn't moved. Holding steady at .348. This has to be something with my resolution. Can someone please confirm?

  • PQ SystemsPQ Systems PQ Systems Employee
    @TBHill - Torque wrenches may require special consideration when preparing for and conducting a Gage R&R.

    A great resource for this discussion is Dilip Shah's Q&A article: "Gage R&R Study on a Torque Wrench".  HERE is the link. 
  • Thank you for this
  • PQ SystemsPQ Systems PQ Systems Employee
    @TBHill - Sure thing! Hopefully that was the information you needed? 

    FYI - This topic has been moved from the 'Quality Webinars' category to the 'Quality Discussion' category so that it's easier for others to find. 
  • Hi Tim

    If you don't mind me asking, what you end up doing at the end and how was your NDC? I just had IATF 16949 audit and auditor said that another method is to be used for non replicable measurements, as per AIAG MSA book.



Sign In or Register to comment.