Vacuum Fixture Problems

[KLP1190]

I run a family of parts at my current shop that are all 3mm thick aluminum with varying features. I recently convinced the foreman to buy me a vacuum chuck for my mill to make the work holding a little easier. I picked a 3mm thick part with a 0.85mm pocket on both sides as my first vacuum project. I made a top plate for my vacuum chuck that would hold the parts nicely with clearance for the drilled holes and proper vacuum pressure. Everything is going well except the parts are coming out looking like a potato chip. They are curled pretty bad. 

Does anyone on here have experience with working with the vacuum chuck for a part like this? Any suggestions to get the curl out of the parts. As it is right now I have 500 to make and I have to flatten all of them on a press when I am done machining. It would obviously be nice to not have to do that. 

Any input would be greatly appreciated. 

[JParis]

The vacuum chuck isn't the issue. It's the material...

You don't list the part material spec but I'll guess 7075, or the required flatness  but when you are cutting, it is stress relieving..there are several ways to get around it...

If the part can be stress relieved, it can help with stress relief, you would then need to cut it in as free a state as possible to not re-introduce stress, or, you may need to buy thicker stock and machine stock off of both sides to bet it flat...

You also might try skimming one side clean, then placing that side fixture face down

[Newbeeee™]

As old bear says - what's the mtl and a pic of both sides of the part will be helpful