Analysis of the metal cutting process using the shear plane model

Abstract

The objective of the metal cutting process is to reshape a piece of metal, or workpiece, of initial geometry into a new geometry of desired shape. Although there are a variety of ways to cut metal, this study focuses on the type of cutting where metal is sheared away from the workpiece as is commonly done with machine tools such as the lathe or mill. Typically, the correct machine settings can be found from reference guides that summarize a great amount of empirical data on metal cutting. Trial and error when combined with experience, often suffices to select the proper process parameters. The aim of this study is to predict the outcome of a metal cutting process given the properties of the workpiece, feed and cutting speed in order to understand the cutting process and predict optimum conditions. The shear plane model is well known, having been developed in the early and mid-20th century. However the empirical nature of the model and approximations made in making predictions of the metal cutting process serve to limit the usefulness of this model. A calculation routine devised by P.L.B Oxley to predict how to cut steel was created with modifications allowing predictions of the metal cutting process with any metal. A comparative study was done with 1006 steel, 6Al-4V titanium, 2024-T3 aluminum and OFE copper regarding the differences in tool forces and temperatures that would result if each metal was cut with the same process. A quantitative prediction of the metal cutting process was made for the four metals under study. Although there is no experimental data with which to evaluate these predictions, a number of case studies were performed. These case studies involved the prediction of experimental data presented in literature from other laboratories. The metal cutting model presented here has great promise as a guide to predict the best machine tool parameters.