control flatness in sand casting?

[BobM3]

We've got some 356 aluminum plates we sand cast that I'd like to get flatter. The foundry does some straightening on it but they do a very inconsistent job. I thought I could add or subtract some material from one side or the other. Would adding material to the convex side reduce the bending? The plate is about 8" x 8" x .56" with bosses.

 

[arunmrao]

Yes it helps. It is called negative cambering. Observe the plate to which side they are bent and to what extent. Now apply this correction exactly on the opposite in the pattern,result you get a flat plate. No need to flatten later.

 

[MikeHalloran]

The traditional way for a foundry to flatten a cast aluminum part is to drop the dead soft cast article on, or hit it with, something that's stiff and flat, and then heat treat it. It's not a real high tech operation.

Your bosses are probably interfering with that operation.




Mike Halloran
Pembroke Pines, FL, USA