On cutting temperatures in high and ultrahigh-speed machining

Since Dr. Carl Salomon proposed the well-known hypothesis on cutting temperatures in 1931, the debate on the hypothesis has never stopped. It shows that evolutions of temperatures with the increase of cutting speed measured at different points are different. From the tool wear and surface integrity point of view, this paper focuses on the evolutions of chip temperature (Chip temp.), tool-chip contact temperature (T-C temp.), and tool-workpiece contact temperature (T-W temp.) with the increase of cutting speed from low (100 m/min) to very high (7000 m/min). First, the cutting heat generation and the temperature increment in machining are theoretically analyzed. Then the influences of chip shape and mechanical property variations with the increase of cutting speed on the temperatures are analyzed. Finally, the cutting temperatures are semiquantitatively derived from chip colors and other heat characteristics in the chip and cutting tool obtained in cutting experiments: evolutions of Chip temp., T-C temp., and T-W temp. with the increase of cutting speed are presented based on the experiment results. The influence of chip shape and temperature variation on tool wear are also discussed.