[DerekSSS]

I have a pretty complicated vacume head to make and it is mostly made of Teflon.

I am wondering what speeds and feeds to run...150SFM? .001-.004 feed?

I have a sharp 30 degree diamond style insert with a positive rake and a .008 nose radius.

Do you use oil/flood coolant/air blast to keep it cool?

I have about .5" to take off the OD before finishing, should I leave .03 to .05 for a finishing pass or take a light .005 skim final pass?

My tolerances aren't super critical but I like to make everything within .001-.003 regardless. Also I want the finish as glass-like as possible as it will be used in a pharmaceutical environment.

[JimBoyce]

Heat will not be the main problem deflection will be, depending on diameter. SFM could be 600 or even more, a 0.005 or more feed rate will work. Any coolant or none will work, but oil will probably get the best finish. I can't help on a finishing cut, but I think less then 0.015" probably will not work. This stuff is soft, so as I said watch for deflection.

[txcncman]

As said, heat is not a problem on teflon. I doubt you can push it hard enough to even get close to a melting point. If I remember correctly, teflon is a short chain polymer, not long chain. Unless dealing with 4X diameter stick out or more, run it like you would aluminum. Coolant is not needed unless you are trying to use it to blast the stringers away from the tool and part to prevent wrapping. Air works better for this anyway in most cases. If you are running part off, M00 to clear chips before part off if needed or you will lose parts in the chip pan.

[Geof]

...I have a sharp 30 degree diamond style insert with a positive rake and a .008 nose radius....

How sharp is sharp? If it is one of the micrograin carbide inserts made for aluminum which have highly polished finish and almost a razor edge it will probably be sharp enough. If it is one intended for steel it may not be sharp enough. Teflon tends to flow around the cutting edge of a tool unless the tool is really sharp.

[shearder]

Now THAT is interesting and logical. Will remember for when i ever need to cut Teflon.

..... Teflon tends to flow around the cutting edge of a tool unless the tool is really sharp.