Hi everyone. I would like to know if anyone has any suggestions, as far as CNC milling of aluminum without liquid lubricants or coolants.

I am operating a Taig benchtop CNC mill in laboratory / cleanroom environment. Mostly I'm machining various plastics, and for these I've by now figured out how to choose types of endmills, feeds,speeds, depths of cut, and so forth, to reliably machine with high precision and excellent surface finish. (What I've discovered, with plastics at least, is that by far the most critical requirement is to prevent chips from being dragged back into the cut by the rotating endmill.)

Occasionally I cut brass, steel, or even stainless on this machine, and I can get excellent results with these materials also, as long as I respect the limits of the machine and go about things in the right ways.

All of the above, by the way, I can do without any liquid lubricants or coolants.

With aluminum though, I almost always have troubles. The aluminum sticks to the flutes of the endmill in a way that I've not seen with any other material; this seems to be the basis of my troubles. I seem to get the best results with new, razor sharp HSS mills, though I've tried different forms of carbide as well as HSS with various coatings. Sometimes things work out okay and I will get a clean surface finish, though I don't completely understand why and this has been hard for me to predict. Other times I end up with little "scrubs" of material sort of mushed against the machined aluminum surface, no matter what I do.

Now, I know there are many who will want to say to me: Use a lubricant! It only takes a little bit! You have to use a lubricant with aluminum! Try WD-40, or this, or that, just a few drops here or there!

But thank you, I know all that. If I use lubricants, everything is okay, the endmill stays clean and shiny, and if I keep the chips out of the way then cuts come out beautiful and clean.

However, what I'm often doing, is taking a piece of fixturing out of an ultra-clean vacuum chamber, and machining a little off here or there, then putting it right back into the chamber to try how something fits. I can take the part out of this room, over to a big and dirty mill next door, do the machining with flood coolant or whatever, then bring it back, clean it with alcohol, and acetone, then high-grade methanol, then half a day later I can be ready to put it back in the chamber; then maybe have to repeat all of that several times. Well this doesn't work, so for now I just suffer with frequently poor surface finishes, and using up a brand new endmill almost for every cut where I need dependable surface quality.

I've thought of trying even to use wax as a lubricant, which can work, but still it leaves residues of wax on my parts, which later will liquify at elevated temperatures, so in the end it's really no better than oil anyway.

Okay - any suggestions are most welcome!

--dave