We do a job every so often where we mill .19" thick 5052 aluminum plates about 34" by 26". We take about 3/16" off the edge all the way around, notch a couple of corners, and put miscellaneous holes in the interior. The first time we ran some they curled up 3/16 to 1/4" when we released the vacuum plate and took them out of the mill so we found a company with a plate straightener and after they ran the plates through they stayed flat after we milled them. They were flat to start with but the extra stress relieving did the trick. Unfortunately, after about 9-10 years of running our plates they realized that their machine was only rated for 0.090" thick mild steel and they were seriously abusing it with our plates and now they won't run them, sigh :-(. I have called about a dozen shops in the Baltimore/DC area and found lots of shops with three roll rollers and press brakes who claim "yeah, we can straighten anything", but no one with a real straighener (pair of entry pinch rollers, a series of say two over three or three over four rollers that bend the plate back and forth, and a pair of exit rollers). Our plates are plenty flat to start with, it is the extra stress relieving that we need. Does anyone know of a shop anywhere close to us that can do this for us? Does anyone know of any other way we can keep the plates from curling up after machining?
----- Regards, Carl Ijames