View Full Version : End Mill Entry Angles and Approachs

11-14-2012, 11:05 PM
I had a long repetitive job this afternoon which allowed time to ponder the effects of how an end mill approaches a work piece and the impact on the effectiveness of the cut and wear on the end mill cutter. There are a number of ways to approach the work - end on from the side etc. Each has a different effect on the cut and the wear on the cutter.

I'm sure you’re more experienced forks have thought this thru. Is there ea rule of thumb about the best way to approach the work? I understand the basics of climb cutting and non-climb cutting. Is there a rule about the number of teeth in contact with the work?

As always, all thoughts would be appreciated THANKS

Jaakko Fagerlund
11-14-2012, 11:50 PM
I usually come in with a tangential radius when entering from the side (APPR LCT in Heidenhain), or feed in downwards with a helical movement or with a linear staircase (coming down in a small angle). Rarely if ever straight plunging, most usually dictated when the space prohibits other styles. This is all in a CNC mill with manual/CAM operations.

Edit: Rule of thumb would be a maximum of cutters half diameter in depth and in sideways, but this depends very much on the cutters manufacturing, material, setup rigidity and cutter size.

11-15-2012, 12:08 AM
Well in general, the high speed CNC toolpaths have the tool hitting the work at glancing angles, i.e. the opposite of plunging straight in vertically or horizontally.

11-15-2012, 01:54 AM
FWIW, Mastercam defaults to a 3*° entry angle for pocketing or ramp contours. I presume that since the primary clearance angle on the end of an end mill is typically 5°, that leaves 2° clearance so the heel of the cutting edge doesn't rub.