02/21/2022 Gage R&R: One of Moeller’s Secret Weapons to Precision Machining


“One accurate measurement is worth a thousand expert opinions.”

– Grace Hopper (American Computer Scientist and pioneer of computer programming)

By now, many of you have heard the term “Gage R&R” which stands for Gage Repeatability and Reproducibility.  

For some, this term may have a negative connotation associated with hours of tedious inspections and being watched like a hawk by a data coordinator questioning everything you do.

For others, it’s perceived as a good thing – a break from the everyday routine of tending to machines. 

But for all of us in precision machining, Gage R&Rs are a very good thing. 

A Gage R&R is a statistical tool that measures the amount of variation in the measurement system or inspection method resulting from the measurement device and the individuals taking the measurement.  A Gage R&R helps determine how much variability is caused by the measurement device (repeatability) and how much variability is caused by differences between operators (reproducibility).

A typical Gage R&R involves 3 operators, 5 to 10 of the same part, and 2 to 3 rounds of measurements using a particular inspection method. Each operator measures each part multiple times (this determines repeatability), and their average measurement of each part will be compared to the average of all operators (this determines reproducibility).

The inspection method is considered acceptable if the results of the Gage R&R prove that the variation of repeatability and reproducibility is less than a specific percentage of the tolerance range defined by the customer and AS13003 (Aerospace Standard).

In simple terms, a Gage R&R is a measurement of how reliable an inspection method is.  It ensures that multiple operators can get the same result when checking their parts and that the inspection method provides enough resolution (precision) for the necessary dimensions.

No doubt Gage R&Rs can be tedious and time consuming, however, they provide the critical data required to validate inspection methods as repeatable and reproducible, and their results help ensure the conforming hardware our customers pay for.

Gage R&Rs are a part of our daily lives here at Moeller.  They give us confidence in what we do to accurately machine and measure the products we deliver to our valued customers every day.  All of us are responsible for ensuring conforming hardware leave our facilities and Gage R&Rs are one cross-functional way to ensure this happens.

To learn more about Moeller’s product and process capabilities, check out our website at www.moeller-aerospace.com.

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