Cutting Depth Dictates the Transition from Continuous to Segmented Chip Formation

The process of material cutting emerges from a series of nonlinear phenomena including frictional contact, plastic deformation, and fracture. While cutting dominated by shear deformation is of interest to achieve a smooth material removal and a high-quality surface finish, the fracture-induced chip breaking is of equal importance to prevent the formation of long chips. Here we show that discrepant observations and predictions of these two distinct cutting mechanisms can be reconciled into a unified framework. A simple analytical model is developed to predict the mechanism of chip formation in a homogeneous medium as a function of work piece intrinsic material properties, tool geometry, and the process parameters. The model reveals the existence of a critical depth of cut, below which the chip formation is gradually progressed by plastic deformation in the shear plane, and above which chips break off by abrupt crack propagation. The models' prediction is validated by systematic in situ orthogonal cutting experiments and literature data for a wide range of materials over multiple length scales.Received 13 July 2021Accepted 20 October 2021DOI:https://doi.org/10.1103/PhysRevLett.127.235502Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasContinuum mechanicsFractureMechanical deformationPlastic deformationPlasticitySurface & interfacial phenomenaTribologyWearCondensed Matter, Materials & Applied Physics