I have a part that will finish at .700H x .850W x 72.535" and has a slot approx. .280w x .400dp through the length of the part. I am considering sending the stock out for annealing because it's bowing after every cut (cut and release attempts.)

The stock is MIC-6 and is ground to .750"THK (standard) x 1.00 x 73.00"

Any recommendations? The deadline is nearing so any help is greatly appreciated.

Thanks. :cheers:

Is Mic-6 Aluminum tooling material?

If this is the material I'm thinking of, it should already be annealed...
Is is possible that you're inducing stress by either clamping or machining?

Yes, it is indeed the Mic-6 of Alcoa fame. I know that it is already annealed in the process, but because of the size of the stock, they were saw cut to 1.00" wide at the distributor. This is where I am thinking stress was re-introduced to the material -- though I'm not entirely sure.

I went over the other two pieces of stock and they look a lot more straight/flat than the first bar that we used. We are getting ready to rough out the slot in the first piece of material to see how that reacts before we start on the next two pieces.

I believe that is a cast material as well. It may have distorted some, but I don't believe it actually has "stress" in it.

Annealing the stock has no guarantee of producing a "relaxed straight piece" of stock. If it comes back all crooked, then what?

The part would have to be clamped to some relatively massive straight edges during the anneal. I wonder if they would go to that much trouble for you?

You milling method might be inducing some stress, too. If you are taking a simple single pass, there could be some hammering effect on one side of the slot (because of "conventional" milling which is unavoidable in the first pass) that induces a stress skin. It might be worth a shot to mill the slot first with a smaller tool dia, and then finish with a perimeter pass that takes a few thousandths off each side in climb milling mode.

We are finding that the warpage/bowing seems to be related to the sawing that was done to cut our stock to the desired size. Our efforts (facing both sides) so far are yielding a bow of approx. .007" on the 72.5" length. This leaves us with only .03 to finish the height -- it is looking pretty good at this point (or at least good enough that we can proceed with the finishing ops.)

Drawing calls out .010 Flatness over the length.