Titanium on an X2?

[tooManyHobbies]

Someone my wife works with asked if I could mill titanium on my X2. I immediately assumed it couldn't and told my wife to tell him that, but I really don't have enough experience to know.

What do the experts think?

tom

[LongRat]

I'm not an expert at Ti machining, but I have done it on an X2. Actually got a decent result too. It was a test, to see if it could be done.
I used a 2 flute carbide end mill (diameter 2mm), 2500 RPM, 1000mm/min feed and a shallow depth of cut of only 0.2mm. I was stepping over at about 60% if I recall. My tool extension from the collet was about 10mm, to keep the set up as stiff as I could.
The key with Ti is keeping out of the work-hardened zone created when a tooth shears off a chip. This means you need a high chip loading to avoid that zone with the subsequent tooth of the tool. I did not use coolant but used quite a bit of GT85 (like WD40). It would have been a lot better with proper coolant.
I think some alloys of Ti machine much more easily than others. Not all are equally prone to work hardening. Another tip I picked up from several web sources was that dwelling on the work piece must be avoided. The localised heating caused by friction with the tool will very quickly harden that area and make it very difficult to continue machining.