A Slip-Line Field for Ploughing During Orthogonal Cutting

Daniel J. Waldorf, ATF, Inc.
Richard E. DeVor, University of Illinois at Urbana-Champaign
Shiv. G. Kapoor, University of Illinois at Urbana-Champaign

Article comments

Copyright © 1998 ASME. Please contact ASME at permissions@asme.org for permission to reuse this article. Publisher website: http://store.asme.org

NOTE: At the time of publication, the author Daniel Waldorf was not yet affiliated with Cal Poly.

Abstract

Under normal machining conditions, the cutting forces are primarily due to the bulk shearing of the workpiece material in a narrow zone called the shear zone. However, under finishing conditions, when the uncut chip thickness is of the order of the cutting edge radius, a ploughing component of the forces becomes significant as compared to the shear forces. Predicting forces under these conditions requires an estimate of ploughing. A slip-line field is developed to model the ploughing components of the cutting force. The field is based on other slip-line fields developed for a rigid wedge sliding on a half-space and for negative rake angle orthogonal cutting. It incorporates the observed phenomena of a small stable build-up of material adhered to the edge and a raised prow of material formed ahead of the edge. The model shows how ploughing forces are related to cutter edge radius—a larger edge causing larger ploughing forces. A series of experiments were run on 6061-T6 aluminum using tools with different edge radii—including some exaggerated in size—and different levels of uncut chip thickness. Resulting force measurements match well to predictions using the proposed slip-line field. The results show great promise for understanding and quantifying the effects of edge radius and worn tool on cutting forces.