Need Help - Runout - Function Gage

[818_qualityguy]

Hello Elsmar Cove.

We have an ongoing discussion with a Quality Rep at our customer in regards to inspection of his parts. We have a very long forging that we use one custom made drill to create an angled hole with varying diameters inside throught the center of this forging. Due to the design of the part, we cannot check runout using indicators as we cannot fit anything within these holes. We also cannot utilize our CMM due to the head unit will not allow a long enough probe for the 9" deep diameters.

The customer rejected the parts due to a runout issue. The runout callout is within .001" so what our tool maker/engineer did here was create an in line function gage. He made a gage that is ground to within .0001" of the diamters, and when we put the gage into these diamters holes, it goes all the way through the part. this to us is showing we simply are not out on the runout of this part.

How can I convey to their QC department that this is a fine way to measure this part? The PO did not state to use CMM and their inspection department refuses to accept unless we provide an actual number. I am more than willing to send to an outside CMM house, granted they pay for it.

 

[Jim Wynne]

How is the customer measuring the part?

 

[818_qualityguy]

How is the customer measuring the part?

The customer is using a CMM with probe's long enough. We have had disagrements in the past with customer on how they align on the CMM as well. So have no other way to verify this currently other than the function in line gage

 

[Michael_M]

Are you measuring run-out or roundness. Run-out is typically not measured with a physical gage (unless the gage is 'holding' the part to measure). By your description, I assume (bad word) they are asking if diameter A is running out to diameter B.

I could be wrong here.

 

[818_qualityguy]

Are you measuring run-out or roundness. Run-out is typically not measured with a physical gage (unless the gage is 'holding' the part to measure). By your description, I assume (bad word) they are asking if diameter A is running out to diameter B.

I could be wrong here.

Correct, runout from the bottom dia which is 9 inches deep to a datum diameter above it.

 

[Proud Liberal]

Your method does not address the effects of form of the features in the runout requirement.

If you could post the print, we could understand your situation better and might be able to provide a better response.

 

[818_qualityguy]

Your method does not address the effects of form of the features in the runout requirement.

If you could post the print, we could understand your situation better and might be able to provide a better response.

Bubble 33 and 52

We made a in line gage that is within tenths of each respective diameter and the gauge goes all the way to bottom smoothly in line.

 

[Proud Liberal]

Without knowing more about the dimensions and design of your "in-line" gage, I suspect that your gage is probably checking position using MMC bonus to facilitate a functional gage. The tolerance zone being on where centerlines lie. The runout tolerance zones lie on the features surfaces.

• Assuming the size and positional tolerancing is intended assure assembly with other precision components, your gage would seem the route to go. The solution here is to change the runout FCF's to position FCF.
  (something like this)
  
• If on the other hand, the function is to house something that rotates, the runout FCF would make sense. This, unfortunately, cannot be checked with a functional gage.