Latest advances in tool technology make milling of high carbon and tool steels as reliable and predictable as benign aluminium alloys.

In this video a large 4140 steel component is being roughed out at 2700RPM and 600 inches per minute.
While achieving  impressive material removal rate (20 pounds of steel machined off in a matter of half an hour!) the tool life puts the old school square shoulder endmills to shame.

Yes, it could(and should) have been machined using a bigger cutter, but I wanted to put the tool to the test.
And it performed beautifully: Was able to surpass the recommended starting speeds and feeds by at least 170%!