Investigating the machining characteristics of sapphire using polycrystalline diamond end mills and effects of tool surface reconditioning process

Abstract

In this study, the differences in machining characteristics of sapphire between polished and unpolished polycrystalline diamond (PCD) tools with different diamond abrasive protrusion heights were examined. An unpolished PCD tool with a cut depth of 0.2 μm and feed rate of 2 mm/min was utilized to achieve a high-quality machined surface with arithmetic mean roughness of 3.2 nmRa. Machining by brittle fracture was dominant with the polished PCD tool, and the arithmetic mean roughness of the surface after machining was 242.4 nmSa. The presence of adhesive materials that adhered strongly to the tool surface was confirmed after long-distance machining. These adhesive materials on the tool surface were eliminated using an alkaline electrolysis reconditioning method. Furthermore, reconditioning by microdrop peening using saturated water vapor also successfully removed the adhesive materials on the tool surface, and a higher quality machined surface was obtained after compared to that before treatment.