Machining of silicon using high-speed miniature diamond cutters

Abstract

This paper presents the results of an investigation into the machining of single crystal silicon using miniature diamond cutting wheels. To achieve high surface velocities and a large dynamic stiffness, cutting pins are rotated at a speed of between 90000 and 100000 RPM using a commercial air turbine spindle. It is shown that surface degradation due to the grinding process is related to the dynamics of the process and, more importantly, to the geometry of the specimen/cutter interface. The surfaces generated by this process have been assessed using optical microscopy, etching, X-ray diffractometry, stylus techniques and scanning electron microscopy. This analysis provides further indications that the as-machined surface consists of an outer layer of submicrometre thickness that is under a high compressive stress. This is followed by a highly distorted and/or fractured layer that extends with decaying intensity into the bulk material.