This month's newsletter is the first in a multi-part series on using the ANOVA method for an ANOVA Gage R&R study. This method simply uses analysis of variance to analyze the results of a gage R&R study instead of the classical average and range method. The two methods do not generate the same results, but they will (in most cases) be similar.
Any gage R&R study is a study of variation. This means you have to have variation in the results. On occasion, I get a phone call from a customer wondering why their Gage R&R study is not giving them any useful information. And, in looking at the results, I discover that each result is the same - for each part and for each operator. There is no variation. I am asked - Isn't it good that there is no variation in the results? No, not in a gage R&R study. It means that the measurement process cannot tell the difference between the samples. So remember, a gage R&R study is a study in variation - this means that there must be variation.
Anova Gage R Amp;amp;amp;r Template
Three methods for comparing results. One is to compare the gage variation to the variation of the parts used in the study. In this case, the parts should be selected to reflect the range of variation in the process. In other words, don't just take 10 parts off the line right in a row. You need to select the parts so they reflect the variation seen in the manufacturing process. This is the approach to take if you want the test method to be able to tell the differnce between parts (i.e., control the process).
The other two ways to determine the % gage R&R is to use an independent estimate of the process variation or to compare the results to the specification range. If you have an independent estimate of the process variation (e.g., from a control chart kept on the production process), the requirement for the parts spanning the production range is less critical. This is also true if you are comparing the results to the specification range. On the specs, in this case, you are just using the test to accept or reject parts.
Not sure what you mean by wrong reading. A gage R&R is a study of variation. The equipment variation is a measure of the variation in the instrument. The operator variation is a measure of the variation in the operators. You can compare those two variances to see which is larger.
When you run the ANOVA method with SPC for Excel, you select the number of operators, trials and parts. A template is then generated to fill to do the analysis. The software runs based on the tempalte design.
I am doing a gage r r analysis but the variance of error for each operator is different. Is my analysis valid? If not what can I do? If yes, how my interpretation of results is different from the typical gage r r analysis? 2ff7e9595c
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