Casting Definition and Inspsection

[jimbod20]

I'm trying to determine if a casting meets an engineering drawing.

The engineering drawing which defines the casting is as follows;

A primary/secondary/tertiary cast datum structure.
Primary datum (E) is a surface defined by three points on a surface of the part. Picture the casting while sitting on a table top fixture with three .150 inch diameter pins on the table top fixture.
Secondary datum (F) is defined by two points on a surface of the part. Picture two .150 inch diameter pins against a surface on one side of the part as the casting sits on the table top fixture.
Tertiary datum (G) is a single .150 inch diameter pin against a third side of the casting as the casting sits on the table top fixture and against the two secondary datum pins.

The casting is fully constrained by datum structure.

The drawing consists of 8 pages of section views with basic dimensions.

A drawing note:
All surfaces shall be simultaneously located within a profile tolerance zone of .060 relative to cast datums E, F, G.

The casting supplier has provided a 'digital image'/scan of a hard part with shades of color showing where the real part is above and below a nominal solid model. The digital image is a best fit with the solid model. The casting supplier states the part does not violate nominal model plus and minus profile tolerance via best fit between the digital image and model, therefore; the part satisfies the engineering drawing.

If I fixture the part via the datum structure and inspect via CMM will I get the same results?

 

[pmarc]

I would say that referencing to E, F, G at RMB (no M, L or [BSC] modifiers after datum letters) means there is no best fit available. The digital image analysis should be provided to you as if the cast was sitting on datum feature simulator pins. That is, when properly oriented and located to E, F, G. The same should be done with nominal model. If comparison of "hard part" and nominal model showed no areas of hard model being at a distance greater than .030 from nominal model, everything would be fine. Otherwise the cast would not meet print requirements.