Wear of Electroplated CBN Grinding Wheels

Abstract

An investigation is reported on the wear of single-layer electroplated cubic boron nitride (CBN) grinding wheels and how the wear process affects the wheel topography and grinding behavior. Internal cylindrical and straight surface grinding experiments were conducted over a wide range of conditions on hardened bearing steel with wheels containing different abrasive grain sizes. The radial wheel wear was characterized in each case by an initial transient at a progressively decreasing rate to a steady-state wear regime at a nearly constant rate until the end of the wheel life. Wheel wear during the initial transient was found to be mainly due to pullout of the most protruding weakly held grains, and the radial wheel wear in the steady-state regime was dominated by grain fracture. The wear rate in the steady-state regime for various grinding conditions and grain sizes was found to be directly related to the undeformed chip thickness. Dulling of the grain tips by attrition and fragmentation caused an increase in the grinding power. Wheel wear was accompanied by a progressive increase in the active grain density and a corresponding decrease in surface roughness. The surface roughness was found to depend mainly on the active grain density and is insensitive to the operating parameters.