The Nature of Chip Formation in Orthogonal Machining

Abstract

Orthogonal machining experiments were conducted at the cutting speed of 8.5 × 10−2 cm/s with 6061-T6 aluminum, 4340 steel and Ti-6Al-4V titanium to measure strain distributions in the deformed chip using a grid analysis technique. While the aluminum alloy with low strength and the steel with high strain hardening coefficient displayed large uniform strains with a continuous chip morphology, the titanium alloy exhibited highly nonuniform strain distributions within segmented chips. Some of these observations as well as published machining test results could be rationalized on the basis of a shear failure criterion where a specific level of critical shear strain might be estimated on the basis of a thermal-mechanical instability analysis.