Help GR&R

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  • Help GR&R

    OK this is not PC-DMIS related but know that the knowledge base is at this site.

    We have a gear checker(like a CMM) that I need to do a repeatability test on. I looked at the MSA and Appendix D seems to suffice. I have only one problem - if I run one part 10 times - what should be my d*2 value? Appendix C is where I would look, but the m=the number of appraisers(which in my case is 1).

    I guess it would be no different if it would be repeatability for a CMM, but the MSA kinda threw me here.....Thanks for the expert advice!!!!


  • #2
    1 part 10 times is a Gage R. What are you trying to study. What a Gage R is for Is if the Fixture does not pass a GageR, there is no reason to spend the time on a GR&R.

    What is this MSA you are refering too. I have a excel spead sheet I can send you for a GR&R.
    sigpicSummer Time. Gotta Love it!

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    • #3
      Here is a free down load found on the WEB for GR&R. Hope it helps? We have several internal software to do the job here.

      http://www.mmbstatistical.com/Softwa...0Worksheet.xls

      BS
      Windows 7
      Pc-Dmis 2015
      Global Performance 7-10-7


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      • #4
        The msa is what the AIAG group put out (measurment systems analysis). You are correct for the term gage R. Please send me your spreadsheet as I always find others tools very useful. That might help, but I still would like to get to the bottom of what the MSA is stating as this is what we usually get tied to as to how or why we did something. The bad part is the person who did know and understand the book left and now we are left without that internal source. I will get through it, but that is where I lean on this group to help me out as well. Thanks!!!!

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        • #5
          Ok looked at your link....thanks and if I input n1=1 k1=10 and l1=1 I get a value for d*2 of 3.18.

          but when I only put values in a collection as I only measure 10 parts one time I do not get any values that make sense. It appears the link is more for a GR&R not Gage R as BS had pointed out.

          but that being said is it valid to use the 3.18 value as Appendix C has not shown that in the MSA book.

          thanks

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          • #6
            What software are you using to calculate the GR&R? You can not do an actual GR&R just using yourself in the study .

            You might want to think about conducting a Bias , Linarity , and Stability study on that gage . A gage that can repeat but is not accurate is of little use .

            The d2 that you ask about for the test is correct :3.17905 to be exact . Just a note , The MSA manual states that Gage R study can not be used for Final Gage Acceptance with out more detailed MSA methods .

            The data you get does not probably make sense to you at this point . The formula for calculating Gage R is MR/d2*6/ tol.*100% . This should only be done after you have establised stability of the gage .

            I have to ask , is this gage used for inspection ? If it is , use the inspectors in the lab to conduct your GR&R .

            Let me know if this helps .
            Last edited by pcdmisexpert; 04-27-2006, 01:14 AM.
            Global 3.7 MR3
            Mistral 3.5 MR2
            Windows XP

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            • #7
              There is a difference between GR and GR&R. Some automotive QEs will ask for a Gage R (just repeatability) using 1 part, 1 operator, 10 times. It is mainly used to measure for repeatability for CMMs, vision systems and optical comparators that measure the datums each time the part is measured.

              I have an XL spread sheet that I've tried to upload here but can't for some reason. If you'd like a copy I will email it to you and I've also posted it in CMMTalk in the SPC forum.

              [email protected]
              Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
              Contura Calypso 5.4

              Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

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              • #8
                Originally posted by dwade
                There is a difference between GR and GR&R. Some automotive QEs will ask for a Gage R (just repeatability) using 1 part, 1 operator, 10 times. It is mainly used to measure for repeatability for CMMs, vision systems and optical comparators that measure the datums each time the part is measured.

                I have an XL spread sheet that I've tried to upload here but can't for some reason. If you'd like a copy I will email it to you and I've also posted it in CMMTalk in the SPC forum.

                [email protected]
                My Chrysler SQE's want the GageR, only to determine if we should spend the time on a Gage R&R. They are very complex and time consuming that it just saves time, because if a gage wont pass a GageR it cannot pass a Gage R&R.
                sigpicSummer Time. Gotta Love it!

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                • #9
                  Originally posted by dwade
                  There is a difference between GR and GR&R. Some automotive QEs will ask for a Gage R (just repeatability) using 1 part, 1 operator, 10 times. It is mainly used to measure for repeatability for CMMs, vision systems and optical comparators that measure the datums each time the part is measured.

                  I have an XL spread sheet that I've tried to upload here but can't for some reason. If you'd like a copy I will email it to you and I've also posted it in CMMTalk in the SPC forum.

                  [email protected]
                  Yes , I agree there is a BIG differance between GR and GR&R . Saying that , MSA clrearly states that a dertmination of stablity MUST be found before doing any study.
                  Global 3.7 MR3
                  Mistral 3.5 MR2
                  Windows XP

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                  • #10
                    What software are you using to calculate the GR&R? You can not do an actual GR&R just using yourself in the study .

                    You might want to think about conducting a Bias , Linarity , and Stability study on that gage . A gage that can repeat but is not accurate is of little use .

                    The d2 that you ask about for the test is correct :3.17905 to be exact . Just a note , The MSA manual states that Gage R study can not be used for Final Gage Acceptance with out more detailed MSA methods .

                    The data you get does not probably make sense to you at this point . The formula for calculating Gage R is MR/d2*6/ tol.*100% . This should only be done after you have establised stability of the gage .

                    I have to ask , is this gage used for inspection ? If it is , use the inspectors in the lab to conduct your GR&R .

                    Let me know if this helps .



                    As orignially posted this is a gear checking machine that is very similar to a CMM. All the feedback given iis great!!! I basically want to do a down and dirty Gage R on our part. As you state I agree with the calculation, but was not sure of the d*2 value. I am still open to any spreadsheets that people have to offer as sometimes it can simplify work for everyone!!

                    I should have the data sometime today if all goes well. Thanks again as I know that the knowledge base out here is superior!!!!!!!!!!!!!!

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