Gage R&R - What does the % tolerance says about my Gage

P

Philip

Hi,

I am conducting a GR&R studies on my measuring equipment and the results are as follows:

The % tolerance is 31.11 and the number of distinct categories is 9.

Is this gage acceptable? What does the %tolerance tells us about this gage?
Please help.

Thanks.
 

Miner

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Admin
Philip said:
Hi,

I am conducting a GR&R studies on my measuring equipment and the results are as follows:

The % tolerance is 31.11 and the number of distinct categories is 9.

Is this gage acceptable? What does the %tolerance tells us about this gage?
Please help.

Thanks.

The ndc = 9 says that the gage is good for process control, that is the gage can distinguish 9 distinct levels within the process variation.

The percent tolerance of 31.1% is just over the maximum of 30%. This means that the gage is marginally unacceptable for inspection purposes.

Now, a bigger question: To get an excellent ndc and bad P/T ratio can mean one of two things:
1) Your process variation is much greater than your tolerance (i.e., process is not capable). or
2) Your selection of parts for the study greatly exceeds the normal process variation, which inflated the ndc numbers. Your sample parts should reflect the spread of actual process variation.
 
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