Center-injected Polishing for Efficient Slurry Utilization

Abstract

Polishing is one of the most crucial finishing processes and usually consumes a sufficient slurry to achieve an ultra-fine surface. However, excess slurry consumption is environmentally costly, as it generates a large amount of wastewater. Given the growing environmental concerns, it is essential to improve the process efficiency and minimize the environmental burdens. Considering this, a novel polishing system, herein referred to as center-injected polishing, is proposed by injecting slurry into the center of the polishing pad. Here, it is aimed to utilize the centrifugal force of the rotating pad, with the aim of efficient slurry utilization. The slurry is directly introduced between the pad and the workpiece, then dispersed across the pad by centrifugal force. A simple experiment was conducted with computational analysis using the specially designed polishing tool to prove the concept; slurry was distributed more uniformly in center-injected polishing when compared to the conventional process. The polishing system was then constructed to evaluate polishing performances. Based on sets of experiments in the polishing of silicon carbide (SiC), slurry efficiencies and productivity were analyzed with respect to different rotational speeds and slurry supply rates. The material removal rate (MRR) was more than twice the rate achieved by conventional polishing at the same processing conditions; whereas the slurry consumption was approximately 60% less at the same MRR. The extended Preston equation was used to predict the MRR of the new process. It is expected that efficient slurry utilization will reduce the environmental footprint of abrasive processes.