An experimental study on grinding of Zr-based bulk metallic glass

There are limited studies in the literature about machinability of bulk metallic glass (BMG). As a novel and promising structural material, BMG material machining characteristics need to be verified before its utilization. In this paper, the effects of cutting speed, feed rate, depth of cut, abrasive particle size/type on the BMG grinding in dry conditions were experimentally investigated. The experimental evaluations were carried out using cubic boron nitride (CBN) and Al₂O₃ cup wheel grinding tools. The parameters were evaluated along with the results of cutting force, temperature and surface roughness measurements, X-ray, scanning electron microscope (SEM) and surface roughness analyse. The results demonstrated that the grinding forces reduced with the increasing cutting speed as specific grinding energy increased. The effect of feed rate was opposite to the cutting speed effect, and increasing feed rate caused higher grinding forces and substantially lower specific energy. Some voids like cracks parallel to the grinding direction were observed at the edge of the grinding tracks. The present investigations on ground surface and grinding chips morphologies showed that material removal and surface formation of the BMG were mainly due to the ductile chip formation and ploughing as well as brittle fracture of some particles from the edge of the tracks. The roughness values obtained with the CBN wheels were found to be acceptable for the grinding operation of the structural materials and were in the range of 0.34-0.58 lm. This study also demonstrates that conventional Al₂O₃ wheel is not suitable for grinding of the BMG in dry conditions.