Gage R&R for Non-Destructive and Destructive Test Methods

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Thanks so much for reading our publication. We hope you find it informative and useful. Happy charting and may the data always support your position.


Dr. Bill McNeese
BPI Consulting, LLC

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Measurement Systems Analysis/Gage R&R

Comments (35)

  • AnonymousJuly 28, 2014 Reply


  • AnonymousSeptember 8, 2014 Reply

    Please share GR&R Excel template as well so that we can work on it.

  • GordMay 5, 2016 Reply

    I'm currently analyzing the performance of a portfolio of 34 projects to determine how much we unnecessarily spent to give the customer what they wanted. I've asked 13 individuals who can estimate this value, but each for only a subset of these projects. I did repeatability measurements (asked twice) for 6 of those operators. I therefore have some repeatability and some reproducibility data. If I set up a 34 x 13 x 2 table (or even a 34 x 6 x 2 table) however there will be lots of holes. Any idea on how to do a Gage R&R (or similar) test to get an idea as to the accuracy of this measure? Thanks. 

    • billMay 5, 2016 Reply

      Not really a Gage R&R most likely.  You can probably set up an analysis using control charts, but I would need to see the data.  Lots of issues, including the size of the project.  Are you doing as a %?  You can send me the data if you would like me to look at: [email protected].

      • AnonymousMay 5, 2016 Reply

        Thanks Bill. I will send you the data once I have it all which will be by early next week. Still need to get some repeatability measurements. Yes, it is in terms of % unnecessary spend. It is inherently subjective so no real 'standard' to apply it to.

  • MiguelMarch 9, 2017 Reply

    I know that in the industry its commonly used a sample size of 10, but i need to know how can we determin this sample size with an statistical rationale. Does anyone know how to determind the sample size for a Gage study Attribute or Variable?

  • AlessandroMay 23, 2017 Reply

    Hi, I’m currently doing a GageR&R study about Rockwell Hardness on sintered metal products. Since Hardness Test is a destructive test that only alter (not destroy) the piece I’m doing a crossed R&R using 10 pieces of one particular product, 3 trial, 3 appraisers, in the end each piece would be tested 9 times in different locations assuming it is “the same part”.The result on %R&R of the total variation is over 90 with a ndc of 0,5, but using the tolerance range of that particular piece about Rockwell Hardness I have a %R&R of tolerance that is about 5 since all the piece fall within a hardenss between 69 and 72 while the tolerance range is 15 (only a small part of the tolerance range has been used). I cannot understand if ignoring the total variation I can be satisfied since I have a %R&R=5 of the tolerance or I have to consider also the total variation. I know that hardness test has already some inherent problem since a piece is not completely homogeneus but I guess in this case this fact is more relevant since sintered metal product are less homogeneus than a pure metal product. I would be very happy if someone could help me understand the right way to go with this type of study. Thanks.

    • billMay 24, 2017 Reply

      So, your Gage R&R study says that, based on the variation in the  parts you used in your study, there is a large % GRR based on this total variation.  Question – are the parts representative of what you produce?   If you are going to use the total variation base don the parts, this should be the case.  If not, you can use a standard devaition from  your process results for results.   Either do a control chart on the hardness results for the part and estimate the standard deivation (sigma) or simply calculated sigma from a lot of data.  If the parts are reprsentative, it simply means that the Rockwell test is not very good at telling the difference between parts in the process – this means you really can't use it for process control.
      But if you base the results on the tolerance, you have 5% GRR.  This simply means that the test is good enough to tell if the product is in spec or not.  

  • sachin palJune 20, 2017 Reply

    i have to conduct msa study of push pull gauge by applying the load & check at which particular load sample parts lock will break.i cannot divide this part in multiple section because lock will part will one batch.confirm me how the study will done. 

    • billJune 20, 2017 Reply

      You would have to have parts that are similar – the idea of a batch decribed above – so similar that you can consider them to the be the same bar.  It is a destructive test.

  • SandyNovember 21, 2018 Reply

    Kindly share it in proper excel format… ::)  

    • billNovember 19, 2014 Reply

      We don't have a template.  This is part of the SPC for Excel software package.  You can search for free Gage R&R templates on-line but they will have limited ability.

  • LockyDecember 3, 2018 Reply

    Hi Bill,we are seeing poor Assay and Content Uniformtiy results for a product.I want to design a study that explains the varaibility of the measurement system.Our product is typically extacted from its device, and injected by HPLC. i have limited product to use.However, i can spike the known analyte and continue with the extraction and inject by HPLC.As the product is spiked, would the potential study design be classed as "Crossed Gage R&R for Non-Destructive Mesurement Systems"?Also, as this is for Assay (5 devices is 1 sample injected) and Content Uniformity (1 sample is 1 injected), it is expected that outliers may be present. So should i spike at the nominal and also at outlier amounts?My example study:Operators: 2Spike Levels: Low, Nominal and High (each concentration level n=10), prepared by each operator (60 points in total)Replicates: Each operator will inject their own samples on separate HPLC system

    • billDecember 3, 2018 Reply

      I am not familiar with what you  are doing.  Are your samples large enough to split in two and test each part?  If so,  you can use this approach:
      This will give you the measurement system variability.  Not on an operator by operator basis though.  If you have enough in a "batch" for each operator to test at least twice, then you can use the crossed gage R&R method.

  • RosariaMarch 5, 2019 Reply

    I have a question.If we hava only a batch in destructive test, GRR is applied?We designed 3 operators and 6 parts(=regard to repeat) for calculation GRR in destructive test.But above design(18 runs), we can't conform batch to batch variation.That is, we can only calculate the reproducibility and repeatability.(batch to batch variation=0, a batch is homogeneous.)Thanks.

    • billMarch 5, 2019 Reply

      I am not clear on what you are doing. Is part destroyed during testing?  You just have six parts?

      • RosariaMarch 11, 2019 Reply

        In destructive case, we would like to evaluate the gage R&R for measurement system analysis.The design (1 batch) is following as.Analyst1 : part1, part2, part3, part4, part5, part6Analyst2 : part7, part8, part9, part10, part11, part12Analyst3 : part13, part14, part15, part16, part17, part18Repeatability is part to part variation. (compounding repeat & part to part varition)Reproducibility is analyst to analyst variation.Q: Is it possible to evaluate as gage R&R concept?(%GRR shall not exceed 30%)(Unlike the usual gage R&R, repeatability did not caculate from normal design (10 parts * 3analyst * 6 repeat))Q: Is it okay to remove ouliters before Gage R&R?

  • CandaceMarch 22, 2019 Reply

    Question: I am to conduct my first gage r&r and I've been asked to test and compare parts of different width, but doesn't this bias the entire analysis? And I'm not talking about small differences; some parts are three times the width as others. If you compare them in the same gage r&r, the part-to-part difference must overshadow all potential differences between operators etc? Or have I completely misunderstood some fundamentals of this analysis method?

    • billMarch 22, 2019 Reply

      You are correct.  One way to improve the results from a Gage R&R is to throw in some pieces with much more variation.  If you want the Gage R&R to be able to tell the difference between parts with a smaller width, then you need to use those parts in the study.  Otherwise the part-to-part difference dominates.  Focus on what your process produces.  If there are widely different specs or sizes produced, you need to do the gage study for each product.

  • TamilarasanApril 9, 2019 Reply

    Hi, thanks for sharing the knowledge here. I have one doubt for Reproducibility show 0% and how to capture the Reproducibility in this method. please help me.

    • billApril 9, 2019 Reply

      If reproducibility is 0% it means that all the operators got the same result for each part – if i understand what you are asking.

      • TamilarasanMay 2, 2019 Reply

        Hi, Thanks for your reply.1. Our test is destructive test2. We used Gauge R R ( Nested) methord3. Sample results different form each operators, even though we are getting Reroducibility 0% , Why?

  • Mike StevenMay 31, 2019 Reply

    Hi Bill, should the run order be 1 2 3 1 2 3 or can this be 1 1 2 2 3 3 for variable non-destructive test method validation? Does the run order matter?  

    • billMay 31, 2019 Reply

      When you run an Gage R&R study, the runs should be in random order.  So you want to randomize the runs.  You can use Excel's random number generator to that.

  • StianOctober 22, 2019 Reply

    Hi. Reading the articles with interest. I am curious about how you would set it up including another dimension. Lets say the homogenity of the sample taking process is also a suspect. So, you would run multiple sample taking operators, multiple samples, multiple analysis operators, with multiple parts. Let – for simplicity – assume that the sample contains enough material to withdraw enough parts homogenously – or that they are repeatable. Would you simply "add" another layer to the gage R&R layout? (and multiply the required number of trials by the number of "sample taking operators"?) Followup: is there functionality in spcforexcel that allows for this change of "dimensions"?

    • billOctober 22, 2019 Reply

      The SPC for Excel software does not allow changing the level – for Gage R&R. you have mutilpe operators measureing multiple parts, multiple times.  I will have to take a closer look at what you are asking about.  Do you have some exmaple data you can send me?  [email protected]

      • StianNovember 13, 2019 Reply

        Sorry for the late reply, but the answer is – not yet! ;-) We have not decided to run the trial including also the "sample taking process homogenity", we ran w/ 3 sources of variance (part, operator, analysis). It is of interest to also include the sampling process, so that you take an equal amount of parts from a set of sample procedures. By example, drawing a liquid sample from the a) top of the tank, b) bottom of the tank or c) insteam when filling the tank – could introduce separate distributions of results according to whether the sample comes from a type a, b or c sampling process. This variance would be nice to see alongside the standard ones.-Stian

  • Jerry MulkaOctober 30, 2021 Reply

    I have a situation where I need a push out test for a seal.  I have 7 different parts all in several different sizes.  This is a destructive test… Each part can only be tested once. Obviously, It is destroyed…. So based on your writing I should use a nested test structure?  Also, I need a definition of batch.  By batch do you mean same parts from differenct production runs? Or, Batch means different parts run durnig a similar period of production.  As an example 7 different parts, all different sizes, run in week-1. Batch of 7 different parts/sizes.  Then a 2nd batch of 7 different parts/sizes from week-2…   Please clarify…

    • billOctober 31, 2021 Reply

      Hi Jerry,
      A batch is a group of parts that can be considered the “same.” I am not sure about your production process, but most of the time the “same” parts are made in the same production run. You say 7 different parts. Is each part produced in a separate run? or there more parts that size in the run?

  • Jerry MulkaOctober 31, 2021 Reply

    Yes… Each of the 7 parts are produced on the same machine, but at different times.  The Machine accepts different injection molded dies… So between each run a changeover is done and then the next part is run.  All 7 of the parts are he same material, but different sizes and configurations.  A series of tests are to be performed to qualify each production run.  1.) Non-Destructive Inner O-Ring height check.  2.) A Destructive surface roughness check. 3.) A Destrucive push out test of the O-Ring bottom surface.  So to qualify that the equipment is repeatable, reproducible, and capable, we are looking to first quality the test equipment before running a Gage R&R and Capability Study of all 7 parts.  Therefore, I would consider a batch equal to 10 parts, from each production run, tested with different operators.   This should be sufficient to qualify the test equipment as being able to provide repeatable test results.  What is your opinion?

    • billNovember 3, 2021 Reply

      EAch batch consists of the "same" part – so you have seven different batches corresponding to each part.  You make multiple parts per batch and you assume those are the same.

  • FinolaAugust 8, 2022 Reply

    Hi Bill, 3 questions – 1. is there a recommended minimum number of samples per batch and number of operators when the process variation is known to be large? 2. should failing parts be created as a group/batch for inclusion in the study? 3. How do you decide if % study variation or % study tolerance is used as acceptance criteiria? Thanks   

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