I'm looking for some ideas on how to mill slots and holes in .040 aluminum sheet. My problem is, I need something to "back" the aluminum while it is being milled. I intend to cut dry. Plywood came to mind, but it's kind of hard on the end mill, as there is significant heat in cutting the wood. HDPE was a thought too, but I'm thinking it might melt, and create a gummy blob of plastic and chips.
Static-dissipative UHMW allows tape adhesion, can be threaded, and mills like butter. I've never had a problem with it melting using sharp end mills/drills.
Whats wrong with Aluminum backing? I now keep scrape aluminum just for that reason. I am also setting up a vacuum system to cut about .04 SS myself. So will have aluminum backing for it as well.