Extrusion-like chip formation mechanism and its role in suppressing void nucleation

Abstract

The mechanism of chip formation transforms from concentrated shearing to an extrusion-like behavior at a critical combination of undeformed chip thickness and tool edge radius. Finite element analysis shows that material is removed by severe deviatoric stress within the boundary of elastic-plastic deformation during extrusion-like chip formation while this boundary is constantly redistributed to accommodate chip growth. Simultaneously, the deformation region is contained within active compressive components and hydrostatic pressure as chips are extruded. Under such operating conditions, void nucleation is prevented according to the Le-Chatelier's principle. Exceptional surface finish was produced experimentally through the extrusion-like chip formation mechanism. © 2010 CIRP.