Ion beam machining of single-point diamond tools for nano-precision turning

In order to obtain single-point diamond tools (SPDT) with cutting edges of sharp or small negative land for ultra-precision turning of soft materials, machining of the SPDT by an argon ion beam of 1.0 keV has been investigated. The edge radius of the SPDT was measured using a profile SEM (scanning electron microscope having two secondary electron detectors). By this processing method, mechanically lapped or polished SPDTS which have a mean edge radius of 70 nm were sharpened, and their edge radii became of the order of 20-30 nm. Moreover, is is found that the processing method can be useful for improving the surface topography of the SPDT formed by mechanical lapping removing micro-chippings on the cutting edge of the SPDT, and improving the straightness of the cutting edge of the SPDT. The processing method, also, can result in the formation of a small negative land of sub-micrometer width on the cutting edge of the SPDT.