I was machining a cast iron component with a 0.25 4 flute end mill at 1200 rpm and 20 ipm and all seemed well, good finish.
I then did a helical circular cut to enlarge a hole and thinks went south in a hurry with the mill becoming red hot and wearing dramatically. I was advancining 50 thou per revolution with this cut.
Any thoughts on what went wrong with this second approach? I was cutting at 50 thou depth at constant z without difficulty.
Wayne