A356-T6 internal stresses
A356-T6 internal stresses
(OP)
We purchase tubular A356-T6 castings, nothing special about their geometry, and experience movement when we bandsaw cut through the casting wall (ie. .015" collapse in a 11-1/4 OD x 8-1/4 ID). We've used 713 previously and did not have this problem.
Is A356-T6 known to have internal stresses? I'm trying to determine if it's a processing issue on the part of our vendor or if it's just the nature of the alloy.
TIA
Is A356-T6 known to have internal stresses? I'm trying to determine if it's a processing issue on the part of our vendor or if it's just the nature of the alloy.
TIA





RE: A356-T6 internal stresses
You mention this is a "tubular" casting. Does this mean it was produced using a continuous casting process? Or is it just a sand casting in the shape of a tube?
A356 aluminum is a very castable alloy, and usually is very stable dimensionally if stress relieved and heat treated properly after casting.
Good luck.
Terry
RE: A356-T6 internal stresses
RE: A356-T6 internal stresses
This is a sand casting made using a wooden pattern. It is a simple OD x ID x Length, for example 11-1/4" x 8-1/4" x 3", with no unmachined surfaces on the finished part. After the part is machined it is checked on a mandrel, then band saw cut in half for installation. When we attempt to put each half back onto the mandrel we find that the part is collapsed smaller than the machined diameter and thus won't fit without forcing it.
In order to determine if the dimension change was due to stressed induced by machining we parted off 1" and bandsaw cut just one side. The kerf of the bandsaw blade is about 1/32" and we measured it on the part at .015", therfore we think it's due to internal stresses in the casting/tempering process.
I really just want to make sure that I'm not chasing a problem that is inherent with the A356-T6 material. As I stated previously, we've successfully used 713 in the past with no issues.
RE: A356-T6 internal stresses
RE: A356-T6 internal stresses
RE: A356-T6 internal stresses
RE: A356-T6 internal stresses
RE: A356-T6 internal stresses
swall, CoryPad: It's funny you mentioned "blade pinching" as that's exactly what our machinist called it. I guess my question becomes: Is there something I can suggest to our vendor to reduce this issue or will I simply have to live with it?
Thanks for your responses.
RE: A356-T6 internal stresses
RE: A356-T6 internal stresses
If bandsawing is the only issue, use a larger blade and/or more set in the blade's teeth.
Mike Halloran
Pembroke Pines, FL, USA
RE: A356-T6 internal stresses
If it's from overheating of the part, or the sawblade getting clogged, you can probably double or quadruple the blade speed to good effect. At least measure the blade speed; machinists like to run their tools really slow, so they'll last a lifetime. If the machinist is buying the sawblades, that's understandable. But if the company is buying the sawblades, they should be treated as a consumable, and consumed.
Mike Halloran
Pembroke Pines, FL, USA
RE: A356-T6 internal stresses
Thanks all. Appreciate the assistance.