The effect of cutting tool material and edge geometry on tool life and workpiece surface integrity

Titanium alloys are used extensively in the aerospace industry and are generally classified as 'hard to machine'. The combination of high strength at elevated temperatures, low thermal conductivity, low modulus of elasticity, and high chemical affinity with all available cutting tool materials means that there are inherent difficulties when machining. The extensive literature detailing all aspects of the machinability of titanium alloys is briefly reviewed; however, little of this refers specifically to surface integrity, which is critical to industries such as aerospace. This paper focuses on the effects that insert geometry had on tool life and workpiece surface integrity when cutting speed, feed rate, and depth of cut were varied. Specifically the effects of edge radius, side cutting edge angle, and edge land are considered. The findings show that whatever combination of tool geometry and operating parameters were used, the surface integrity is remarkably similar, even at relatively high cutting speeds and feed rates.