This ones a little long, but stick with me on it!


Hello. I have a customer who needs me to machine 75 pieces of stainless. They are 8x7.5x1/2 thick. I need to make a 6x7 pocket in the center of the part .250 deep. I commonly work on a lathe and this is my first time maching stainless on a mill. I believe it is series 303, however it is from a lightbulb coating plant and it has been run through a heating oven that is roughly 600 degrees, Im not sure the hardness on the stainless, but Im sure its at least slightly hardened even from those temps. Problem is : My endmills are getting destroyed. Attempt 1 was a .5 dia 5 flute centercutting stub style endmill. Solid Carbide with a AlTiN coating; the purple looking color. Ran at 2.0 IPM and about 1800 RPM .100 DOC; made it about...10 maybe 15 minutes in and completely broke down; no cutting edges to examine to see what happened. I believe a couple chips got " recut " if you will and caused excessive heat, but thats just my guess. Second try I used same speed/feed/doc, except only other endmills I had around were Uncoated carbide. Used same size endmill, and it was shooting fire after only 1-2 inches worth of cut. Im stuck here. Any help is greatly appreciated. Thanks a lot.