Gage RR

Your customer is right – he has a right to know if the SYSTEM used to measure his parts is accurate and precise.

E. Johnson
If it is a production part, you must have alredy done the part approval process, which checks for your process capability and fitness to use.
Customer is right in asking for Gauge R&R report before they start using the part at their production line. THINK from the customer perspective. How do they be confident of your process capability, if the measurement system is not validated. Customer is right in asking for gauge R&R.
Only thing that you can do now, is to apologize to the customer and do the gauge R&R if you want to save your job!. In future be careful…..seek information when in doubt about what to Do!
Hope this help.
Monk

Eric,
Gage R&R is not independent of part variation. If  you refer to any typical gauge R&R analysis output, you will come across the “percentage contribution to total variation” section. which is nothing but the contribution due to the measurement system (Total Gage R&R) and part to part variation. It is Ideal to have less the 7% as total gage R&R and consequently 93% or more part-to- part variation.
Also, while performing gage R&R its imperative that we should include the actual parts to be measured (and not measuring gage blocks). One should include the parts from entire range to capture the total part variation.
So, I would say that the customer is correct when he is asking you to measure the actual part being produced.
Hope this helps..
Amit
 
 
 
 

E,
You have to conduct a gage R&R on each part and every part feature that is different.  The measurement can be affected by part geometry, surface roughness, differences in datum interface with mounting surface, etc.
I ran a whole plant worth of CMMs, and the first time through an inspect routine (program) usually about half the feature Gr&Rs would fail.  The probe would hang up on a chamfer, or the probe tip would be to big/small for the surface finish, etc.
You don’t know what you don’t check.

Hi Eric. .. I think what Amit suggested is right. Gage variation is not independent of the part variation. It is a subset of the total variation which could be due to part-to-part, equipment, or operator.
You need to measure actual parts across the product range to capture variation. For that you can take samples for the entire product range and determine if the equipment is capable of measuring numerous parts. When you analyze the data it will give you R&R output showing percent contribution to TV.
Cheers!!!
RS

Eric,
Your customer is very right in demanding a GR & R for a gage before it being used fot measurements more specifically if it is an critical charatcteristic.
Here in you look for repeatability & reproduceability of your measurement system with the sample size with part variation w.r.t. characteristic of 95%.
 
MSA may be done using some seletced parts or gage blocks, condition being 95% of the tolerance band is covered during analysis.