The Effect of Cutting Speed on Chip Formation Under Orthogonal Machining

Abstract

Orthogonal machining experiments were conducted at different cutting speeds ranging from 8.5 × 10−2 cm/s (0.17 ft/min) to about 2.5 × 102 cm/s (492.1 ft/min) with 6061-T6 aluminum, 4340 steel, and Ti-6A1-4V titanium to examine the chip formation process. The most pronounced effect of the cutting speed on chip morphology was observed with the titanium alloy; the chips remained segmented at all speeds, but became continuous macroscopically at high cutting speeds. The steel chip also became continuous and oxidized, showing the effect of localized heating. The changing chip morphology that is accompanied with decreasing normal force at the high cutting speed is rationalized on the basis of localized adiabatic heating, which is dependent on the thermal-mechanical properties of each material.