Effect of Ball Nose End Mill Geometry on High Speed Machining of Ti6Al4V

Abstract

The application of Titanium alloys are increasingly seen at aerospace, marine, bio-medical and precision engineering due to its high strength to weight ratio and high temperature properties. However while machining the titanium alloys using solid carbide tools, even with jet infusion of coolant lower tool life was vividly seen. The high temperatures generated at the tool-work interface causes adhesion of work-material on the cutting edges and hence shorter tool life was reported. To reduce the high tool work interface temperature positive rake angle, higher primary relief and higher secondary relief were configured on the ball nose end-mill cutting edges. However after a initial working period the growth of flank wear facilitates higher cutting forces followed by work-material adhesion on the cutting edges. Therefore it is important to blend the: strength, sharpness, geometry and surface integrity on the cutting edges so that the ball nose end mill would demonstrate an extended tool-life. This paper illustrates the effect of ball nose end mill geometry on high speed machining of Ti6Al4V. Three different ball nose end mill geometries were configured and high speed machining experiments were conducted to study the influence of tool geometry on the metal cutting mechanism of Ti-6Al-4V alloy. The high speed machining results predominantly emphasize the significance of cutting edge features such as: K-Land, rake angle and cutting edge radius. The ball nose end-mills featured with a short negative rake angle of value −5° for 0.05–0.06 mm i.e., K-Land followed by positive rake angle of value 8° has produced lower cutting forces signatures for Ti-6Al-4V alloy.