We are having some 8000 lb steel ca

[Tmoose]

We are having some 8000 lb steel castings poured and machined by one Supplier/company.

There are 4 separate bolt patterns with 36 threaded holes on the part. The threaded holes are dimensioned with "basic" bolt circles and angular positions.
The threaded holes' positions are dimensioned using true position tolerances something like this -

https://gdtseminars.com/wp-content/uploads/2008/04/nodiasymbol2.jpg

All the above dimensions are identified as Critical Dimensions on our drawing.

The final inspection report from the Supplier said "OK" beside some of those.

When I asked for more detail they sent the rectangular CNC coordinates for the four bolt patterns, plus the hand written coordinates measured by some means.
A quick visual inspection of the hand written values shows about 18 of 36 tapped holes are not within the true position tolerance. Some by quite a bit.

Our incoming inspect QA will likely NOT be able to measure the threaded hole locations.
It has been suggested that because we cannot inspect some features ( like the threaded hole position), and will not be able to confirm the measurements at our incoming inspection, we should not reject the part.

If the hole position is too far off then four covers and components weighing from 500 to 1000 lbs will not fit on the assembly at the 11th hour, and have to be shipped to a local machine shop for emergency hole elongation or other fixes.

At a previous job there was a better equipped QA department and a sophisticated in-house manufacturing group ( routinely worked with .0001" tolerances). Manufacturing said something similar, like "if we cannot inspect it, the dimension should not be on the drawing."

Is there any basis for those "Just because WE can't measure it" arguments?
In the Eng-tips collective experience have those arguments ever been heard before ?

 

[3DDave]

"In the Eng-tips collective experience have those arguments ever been heard before ?"

Yes. Your QA department should have had a discussion over the inspection plan before the contract was signed so the supplier could not say OK if the part is wrong.

Can you have gauge plates laser or waterjet cut to match the requirement to test-fit in place of the covers?

 

[btrueblood]

Manufacturing said something similar, like "if we cannot inspect it, the dimension should not be on the drawing."

Nope, the correct quote should be "If we can't measure it, you need somebody else to manufacture it, or hire a better QC tech"

 

[r6155]

This is a commercial topic.
Contact a lawyer

Regards

 

[MintJulep]

Is there any basis for those "Just because WE can't measure it" arguments?

No.

If you can't inspect it, or otherwise confirm that it's right, then you shouldn't accept it from your supplier nor deliver it to your customer.

You seem to have evidence that it's wrong. So reject it and make your supplier fix it.

There is a somewhat well known quote:

People don't do what you expect but what you inspect.

https://en.wikipedia.org/wiki/Lou_Gerstner

However I think that it should be: "You don't get what you expect, you get what you accept."