Gage R&R calculator

The common guideline: under 10% of study variation is acceptable, 10% to 30% may be acceptable depending on the use and the cost of the gage, and over 30% is not acceptable. The number of distinct categories (ndc) should be 5 or more.

Use %study variation when the gage is for process control or improvement, because it tells you whether the gage can see part-to-part differences. Use %tolerance when the gage only sorts good parts from bad. Report the one that fits the job, and say which one it is.

The same person measuring the same part gets different readings. Look at the gage itself: wear, fixturing, resolution, or the part moving during measurement.

Different people get different averages. Look at the method: training, reading technique, clamping force, or a missing work instruction.

Both estimate the same components. ANOVA also separates the operator-by-part interaction and uses the data more efficiently, so it is preferred when software is available. The average and range method is simpler and is what most exam questions use.

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