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Spring Rate measurement error

Discussion in 'Gage Calibration and Uncertainty' started by kedar, Sep 20, 2015.

  1. kedar

    kedar Member

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    our Spring Rate tester readings & suppliers readings are not matching. hence we asked third party readings through NABL accredited lab. these readings also are not matching with earlier both the readings. all the tester have been calibrated.

    in this case how to go ahead?
    are master springs (having defined values) available?

    Kedar
     
  2. Miner

    Miner Moderator Staff Member

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    I recommend starting by obtaining copies of the three procedures and comparing them carefully. While spring rate is a calculation of two variables (i.e., distance and force), both of which could vary from tester to tester, there are other variables in the test that could have a significant impact also such as preconditioning, preload, etc. I suspect that you will find that the three locations vary in the preconditioning method/conditions or preload.
     
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  3. Bev D

    Bev D Moderator Staff Member

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    In addition to Miner's excellent advice, have you quantified how different they are from each other, perhaps the difference isn't substantial enough to matter...? a Bland-Altman approach will do this for you...
     
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  4. kedar

    kedar Member

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    What is Bland-Altman approach?
     
  5. Miner

    Miner Moderator Staff Member

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  6. BradM

    BradM Moderator Staff Member

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    Hello Kedar! Welcome to the forum.

    A question... you state they are reading "different". Does that imply that the equipment is exceeding tolerance?
    Do the companies provide a statement of uncertainty? If yes, could the error be within the uncertainty ratios between/among the companies?

    I have always observed that despite the best organizations they are going to have some subtle differences. The problems is when one entity says it's within specifications and another (especially if the Out of tolerance entity has a lower uncertainty) says that it exceeds specifications.
     

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