An Experimental Investigation Into the High Speed Turning of Ti-6Al-4V Titanium Alloy

Titanium and its alloys have seen increased utilization in military and aerospace applications due to combination of high specific strength, toughness, corrosion resistance, elevated-temperature performance and compatibility with polymer composite materials. Titanium alloys are difficult to machine due to their inherent low thermal conductivity and higher chemical reactivity with other materials at elevated temperatures. In general, temperature related machining difficulties are encountered at production speeds in the range of 60 m/min and high-speed machining of these alloys has created considerable interest to researchers, tool manufacturers and end users. This paper provides recent results obtained during turning operation with the aim of improving machinability of titanium alloys. Several tests have been conducted using (i) micro-edge prep geometry of the inserts, (ii) ultra-hard PVD coated, and (iii) nano-layered coated inserts and the effects of speeds and feeds during turning of Ti-6Al-4V titanium alloy are discussed. The initial tests have been conducted under orthogonal (2-D) cutting conditions with no coolant application. Based on these results, several oblique cutting (3-D) tests have been designed and conducted to study the effect of various types of ultra-hard and nano-layered coatings at higher cutting speeds under flooded coolant conditions. The effects of speed and feed on cutting force and tool wear are presented in this paper.