Analysis of the thermo-mechanical load and productivity during force-compliant grinding of pcBN

Abstract

Superhard cutting tool materials such as polycrystalline cubic boron nitride (pcBN) are increasingly demanded in the aerospace and automotive industries. Although grinding is a common manufacturing technology for pcBN cutting tools, the lack of knowledge regarding thermal and mechanical loads during grinding of pcBN can cause workpiece damage and high grinding wheel wear. Therefore, this work presents a new approach of force-compliant grinding (FCG) of different pcBN specifications considering the thermal and mechanical load as well as the productivity. During the FCG approach, the normal force between the grinding wheel and the pcBN workpiece was set to a predefined value before material removal starts. Based on an evaluation of the grinding force ratio, the temperature of contact and the material removal rate, a modification of Preston’s theory of polishing was found to be applicable to predict the productivity. Accordingly, both an increasing grinding normal force and grinding force ratio lead to an increasing productivity during FCG of pcBN. However, the quantitative models developed in this work enable to predict the productivity as well as the mechanical and thermal load during FCG of pcBN. These models hence contribute to the extension of process knowledge for grinding pcBN and thus to prevent damage to the workpiece and high wear of the grinding wheel.