GR&R on a In-process gauge installed on a grinder machine?



There is a customer requesting me to perform, a GR&R study on a in-process gauge installed on a grinder machine.

I told him, there is not correct to evaluate an inprocess gauge on this way. The capability machine study is the correct way to do it, but he is not well convinced.

So if someone can tell me where I can get some literature to show him it will be very appreciated.

Thanks for your help in advance.

Bill Ryan - 2007

GR&R study on a in-process gauge


I may not fully understand your definition of "in-process" gage, but I'll proceed on the assumption (favorite word!!!!) that you mean an attribute type of gage (whether "narrow limitted" or not). I'm also assuming that this gage accepts/rejects product.

If those assumptions are correct, I'm afraid I side with your customer (if you don't know that this gage will reject nonconforming product, what faith would you have in a machine capability study?) and an attribute Gage R&R should be required.



Is this in process gage used for automatically making adjustments? If the gage makes adjustments to the machine based on the measurement readings, I would not only perform a machine capability study, but a gage R & R as well. It's very important to prove that the gage is suitable for your application.

This may not be good news for you! Good luck!


thanks for your fast reply

Well, let me explain you the in process gage is just controlling the size of a part grinded during the machine cycle, and there is not making a feedback to the machine CNC.

I'm assuming, if there is an automatic process, where are involved some movements and actions of the machine to hold the part, locate it, rotate it, and to move the gauge from the rest to the part measuring position, this will afect the performing of the gauge to be evaluated with an GR&R.

If there is not any procedure specified to evaluate this kind of application, dont you think the best way is to verify the parts coming out of the process are ok? So, the first evaluation made was a capability study.

Any way I'm here to hear and learn, so your opinions are very much appreciated.


How is the in-line gage calibrated? When the gage measures a component does it give a value? Is it possible to make a number of measurements on the gage without grinding them after?
I may be able to give better direction if you can answer these questions.
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