What kind of material are you machining? We machine very thin teflon sheets all the time. Industrial double sided tape works very well to hold it down. And you think anything stuck to teflon. It sounds crazy, but man it works!! We have also done this for steel shim stock with sucessful results.
make your own
start with a 1 inch thick alu plate
.125 slotx.275deep around the edge(.125 inside the 7x7)
buy retangluar gasket from vac-u-form .125x.3125 rockford il. about 50 bucks
brush or cut pattern in inside area for vacuum
add vacuum (side or bottom)from a cheap pump can be done with a hand pump
or surplus pumps can be found on the net
i have built a few for maching .385 7x10 alu plates with lots of deep pockets-thin wall
We making Aerospace parts. Minimum thicknes is 0,31" from 1" thicknes. 0.018 is very small thicknes. You need very accurate clamping devices becouse you will have corrugated sheet. Which side, place you will cut. Wery wery carefull.
Good Luck Libor Pírko Czech Republic
If you are only profiling the .018" don't even bother with the vacuum.
Punch it out / laser cut it / waterjet cut it.
Require a milled finnish? leave 0.5mm /0.020" on the edges to clean up on a machine centre
bolt it down with service lugs you add to the profile and crop them off when you are finished.
It is even possible just to mill it from solid use high cobalt hss I find carbide snaps too easy I use 6mm HSS Tin coated.
You might need a vacuum fixture(+/- .0002 flatness) without vacuum bleeding groove which may cause conductivity changed or cutter will leave marks. Vacuum pressure should be at 20 to 25 pounds/ square inch. Locate part on suface fixture, use industrial white tape to seal the vacuum around part. That may hold the parts good enough to machine them. I recommend You should reduce the helix angle to minimum or Straight Flute End Mill so tool not suck the parts up and reduce heat while tool in processing. Remember Speed/Feed and Percentage of coolant are really important. Good luck! I had been machine alot of Satelite and aircraft part with thickness to .012 and tolerance +/- .001.
Advanced Grinding has done similar parts with a series,really a multitude, of very small holes, cross drilled below the locating surface and using a factional hp electric motor and vacuum pump from grainger
