Adjusting Tolerances because of available tooling?

D

dbulak

#1
Here is the problem we are having. The spec calls for the size of the part to be .648" with a tolerance of +/-.005." When the operator sets up to produce the part he sets the size to be .650." He does this because of the tooling available. When we do the R&R study the results are out because our measurements are closer to the .650" than the .648." Any suggestions on what we have to do to compensate for the fact that we deliberately set up to the plus side? Also, even though we set up to the plus side, none of the product is out of tolerance.

Thanks in advance!
 
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Miner

Forum Moderator
Staff member
Admin
#2
Running off-center will not affect your R&R results. It is based on the spread of the process (variation), not the average. Do you mean the process capability (Cpk/Ppk)?
 
D

dbulak

#6
I apologize for placing both attachments. The one is for width-.748 +/-.005 and the other is for thickness at .025 +/-.001. Sorry to have misled anyone.
 
D

dbulak

#7
I would appreciate advice on this matter. The part size is .748 +/-.005." The operator sets the tooling for .750" which is a standard size. All readings for the part produced are .750-.751. When we did the GRR study on these parts and used these tolerances and entered the measurements we did not get good results.

Any ideas as to what we did wrong?

Is the study flawed in some way? Set up wrong?

Thanks for your help.
 

Stijloor

Staff member
Super Moderator
#8
I would appreciate advice on this matter. The part size is .748 +/-.005." The operator sets the tooling for .750" which is a standard size. All readings for the part produced are .750-.751. When we did the GRR study on these parts and used these tolerances and entered the measurements we did not get good results.

Any ideas as to what we did wrong?

Is the study flawed in some way? Set up wrong?

Thanks for your help.
Can you attach the data and study results?

Stijloor.
 

Golfman25

Trusted Information Resource
#10
What process are you using to produce the width? Is there a chance that the width is different in different locations? Use a gage block to check your measurements and run a study using the block. See what happens.
 
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