Study of segmented chip formation in cutting of high-strength lightweight alloys

Chip segmentation results in fluctuation of the cutting force, deteriorated tool wear and surface finish, thereby plays an important role in the machining process. Although extensive research has been carried out on studying the segmented chip formation, the mechanism of chip segmentation has remained under debate. This paper aims to investigate the mechanism by combining numerical and experimental methods. Finite element (FE) models of the orthogonal cutting process of A2024-T351 aluminum alloy and Ti6Al4V titanium alloy were developed with three numerical formulations: Lagrangian (LAG), arbitrary Lagrangian-Eulerian (ALE), and coupled Eulerian and Lagrangian (CEL). The appropriate model for predicting the segmented chip formation process was selected by systematic comparison. The mechanism of chip segmentation was thoroughly investigated by the selected numerical model. It revealed that the adiabatic shear band (ASB) is generated not only from the chip root but also from the free chip surface. The finding was then validated by observing the microstructure of chips from high-speed dry-cutting tests.