The Exit Failure of Cemented Carbide Face Milling Cutters Part I — Fundamentals and Phenomenae

In an earlier paper it was reported that in interrupted turning chipping of the cutting-edge only occured in the exit. The mechanism, called “foot forming”, was described and explained. This dangerous “foot forming” occured in a range of exit geometries. The present paper shows that the same is true for face milling. When the position of the cutter relative to the exit face of the workpiece is a dangerous one, the cutter starts to fail practically immediately. Proof is given that a one tooth-cutter gives the same results as a full teeth-cutter. The failure mode of a multi tooth-cutter differs from existing theory. A cutter with extra large clearance angles, thought to be weak, last however longer. New edges fail quicker than worn edges. Some cutters fail in a wide range of exit geometries, others only in a small range. Up to now we found no cutter to be 100% safe.