Investigation and Optimization of the Clearance Geometry of End Mills

Abstract

Recent investigations into the effect of the peripheral clearance geometry of end mills on tool life, have shown that higher clearance angles than normally found on commercial end mills can significantly improve tool life. Two types of peripheral clearance profiles were investigated: flat and eccentric. Different makes of end mills were tested using a variety of machining conditions and workpiece materials. The test results show an increase in tool life, based on flank wear, in relation to clearance angle; the optimum clearance angle being in the region of 20°. In most cases commercial cutters are produced with clearance angles of between 8 and 13 degrees. It is further shown that the improvement of tool life with higher clearance angles occurs when milling up, or down, with or without coolant. The paper sets out the test procedures adopted and test results of tool life versus clearance angles are presented.