Effect of variation in edge geometry on wear and life of coated carbide face milling inserts

Abstract

Brittle tools such as carbides and ceramics usually fail by wear and often by brittle fracture. Wear is a systematic process and predictable but, because brittle fracture is random and catastrophic in nature, it is very detrimental in all respects, particularly for machining expensive jobs in sophisticated machine tools. The problem of such premature tool failure becomes more acute in intermittent cutting such as face milling which is characterized by both thermal and mechanical shock loading. It has been reported earlier that proper edge bevelling retards tool failure, particularly by fracturing, mainly through edge strengthening, controlled contact cutting and better heat dissipation. The present authors have experimentally studied the effects of bevelling the major cutting edge with varying land geometry on the magnitude and pattern of chipping, fracturing and wear of coated carbide face milling inserts under high speed-feed machining of low carbon steel. Based on the experimental results a mathematical model has also been developed depicting the role of the major geometrical and process parameters on the tool life. It has been observed that the land geometry and edge radius play significant roles in the wear pattern and life of such milling inserts. Scope exists to optimize the geometry of the cutting edges for the best performance of such tools for different levels of cutting speed and feed.