casting datums
casting datums
(OP)
Hi all,
Has anyone experience with casting datum specification? The part has one flat surface for a primary datum, all else has necessary draft angles. How do I spec B and C datums? On machining drawing, I can add datum surfaces but for casting what is standard practice? Thanks
Has anyone experience with casting datum specification? The part has one flat surface for a primary datum, all else has necessary draft angles. How do I spec B and C datums? On machining drawing, I can add datum surfaces but for casting what is standard practice? Thanks





RE: casting datums
Simplistically, datum targets as explained in section 4.6 of ASME Y14.5M-1994 get used in these types of situations. Y14.8 gives some more 'applied' guidance.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: casting datums
Ten years ago, special cast datums were very common on high production complex cast items like engine blocks, I am not in automotive anymore, but do to the part's complexity and a desire for thinner wall sections, I will assume they still do.
Basically, your choice of approach will depend on the part complexity, the quantity produced and how important it is to you to be able to verify the original established relationship.
Frank
RE: casting datums
I have only done a couple of castings. Let's if one of the experts chip in.
The problem with castings is that they are inaccurate, and their faces are not reliably orthogonal, even if you specified them that way. Read up on datum targets. Make sure everyone is fixturing your part the same way.
Casting manuals recommend designing in physical datum points.
Make sure your datum points or targets are not machined off.
RE: casting datums
RE: casting datums
RE: casting datums
RE: casting datums
Since Y14.5-2009 now includes the use of X, Y, and Z axes to represent a datum reference frame, the use of datum feature letters X, Y, and Z on the same drawing will cause confusion. At least on a drawing with DRF axes labeled, which are very helpful for more than the just the reason described in Y14.5-2009, I think letters other than X, Y, or Z for the datum features would be a better choice.
Dean
www.d3w-engineering.com