Plasma Warpage Problem

[FCDL36X7S3]

This is a general CNC Plasma question. I have a Tracker, which I'm very pleased with, but
I am having a problem forming material after it has been burned. Any ideas?

1- Burning 6” wide x 9’ long strips. They have approximately 12 holes in each one.
7-2- Material is 10 ga. Hot roll sheet.
2- Form to a 4” wide channel with 1” legs.
3- After pcs were cut, they lay flat on the table.
4- When one leg was formed, they looked pretty good, but a little bow.
5- When the second leg was bent, it bowed up like a banana.
6- There was almost an inch of bow in the 9’.
7- If we flipped the pcs over, so that the slag side (bottom when burning) was up, the bow was not as bad, maybe ¼” to 3/8”.
8- We already had all the pieces burned, so we did some experimenting. We ended up putting the strips through the roll, and rolling them to a 5’ radius (see picture), and then forming them. They still had a tiny bow, but were acceptable.
9- For kicks, we formed one as a “Z” before rolling. This piece had almost no bow.
10- We had this problem before, but not nearly so severe when doing similar pieces from 14 ga. Those had a slight bow, but were able to be pulled out in the jig.


I feel our problem is coming from the heat along the edges. The only solution I see is to lay out the holes on a whole sheet, let it burn the holes, then come back and shear the strips. Do you have any other suggestions?

[DSL PWR]

If you have a water table try running the water so it just covers the plate. Make sure it is shallow enough that the air blows the water away from the torch during cutting. This should reduce the heat in the plate, and the warping.

Also try lowering your amperage and uping your feed rate.

[FCDL36X7S3]

Thanks for the info. Unfortunately we're in the middle of our busy season, so no time to make a water table. We have found a couple of ways to work around it. One is to delete the long burns, and come back and shear the strip. The other is to oversize, and shear off 1/4" from each leg. This isn't preferable, but we tried a test, and after forming it came out straight.

The machine has surprised me how much we are using it. I bought it figuring on a few hours a week. We've been running on average of 4-5 hours / day.

[Dale Heart]

It's the heat-affected zone on the cut edges. A way around it is to give the edges a light grind but shearing (like you are doing) is going to be quicker. There is also a lot of internal stresses in the material as well.

Edit: You could try and run the plasma slower... a lot slower... and see if that helps *wink*