Stress characteristics and fracture wear of brazed CBN grains in monolayer grinding wheels

Abstract

Compared to electroplated cubic boron nitride (CBN) grinding wheels, monolayer-brazed CBN wheels have a distinguished advantage in high bonding strength to super-abrasive grains. However, fracture-induced grain wear can occur during grinding. This study aims to understand the mechanism of such fracture, and hence to predict the fracture based on a stress analysis. A two-dimensional finite element (FE) model was developed to investigate the stress characteristics and fracture wear of the grains. The effects of grain embedding depth, grain wear, bond wear, grain size and grinding load on the stress distribution were investigated. It was found that grain macro-fracture wear is dominated by the brazing stresses in the junction region of a CBN grain, and that the peak brazing stress reduces with the increase in the grain embedding depth, grain size and undeformed chip thickness. This suppresses the possibility of grain macro-fracture wear in grinding.