Evolution of tool wear and its effect on cutting forces during dry machining of Ti-6Al-4V alloy

Variation of cutting forces has been investigated and correlated with the development of tool wear during dry machining of Ti-6Al-4V alloy at cutting speeds of 150 and 220 m/min, respectively. Both the average and maximum flank wear increased more significantly with volume of material removed at higher cutting speed. The tool failure mode is flank wear at both cutting speeds; however, the mechanisms for the excessive flank wear are different. The average width of flank wear reaches the criterion at cutting speed of 150 m/min after 57.2 cm3 of material has been removed as a result of the gradual recession of cutting edge due to crater wear, which led to significant rise of feed force only at the end of tool life. Both average width and maximum width of flank wear exceeds the criteria at cutting speed of 220 m/min after 20.8 cm3 of material has been removed because of severe plastic deformation of cutting edge at the nose radius, which resulted in dramatic increase in all three components of cutting forces at the end of tool life. The cutting edge at the nose radius was pushed up from the flank face in the chip flow direction due to the oversized built-up edge-induced compressive stress applied from the flank face.