Hi all,

I own a high speed mill and am working on machining a cylindrical cavity 6" in diameter and 0.25" deep into a 12x12 piece of A-2 steel. I have a TiAlN coated solid carbide toric endmill, 1/2" in diameter that can machine say 1" deep. I have programmed the roughing path for a Vc of 1300 sfm, Fz of .002", stepover of .05", DOC of 0.0375". When I ran the path it looked like I was burnishing slightly, at lower feed override I had sparking. After say 200" along the path the carbide was starting to heat significantly (slight glow, some loss of tool coating observed after path was canceled). The mist oil/air coolant was turned on.

I tried varying feed and speed +/- 30% but it looks like I'm not even in the ballpark.

Do you have any recommendations for HS cutting annealed A2? I can't go lower than 3000 rpm with my spindle, max speed is 42k rpm (obviously not necessarily with a long holder and 1/2" cutter) and max feed is 840 ipm. Books, formulas, any ideas would be generously received.

Thanks,

Dylan