A study on PCD tool surface reconditioning technique for SiC micromachining

In this study, ultra-precision machining using a polycrystalline diamond (PCD) micro end mill was carried out on high-purity silicon carbide. The machined surface was observed using scanning electron microscopy, and the three-dimensional surface profile and surface roughness were measured using scanning interferometry. In addition, an elemental analysis of PCD tool surface was performed using energy dispersive X-ray spectrometry (EDX). It was found that a smooth surface with nanometer-scale roughness was obtained when the undeformed chip thickness was small enough to achieve ductile mode machining. However, nanometer-sized chips produced during machining adhered to the PCD tool surface, and were difficult to be removed using conventional methods such as ultrasonic cleaning. An EDX analysis showed that the adhered material was silicon dioxide. In order to remove it, a tool surface reconditioning technique was developed, based on electrolytic treatment using sodium hydroxide and the generation of hydroxide ions. The results indicated that this was effective at removing the adhered material, and led to a recovery of the performance of the PCD tool.