Microgrooving and microthreading tools for fabricating curvilinear features

This paper presents techniques for fabricating microscopic, curvilinear features in a variety of workpiece materials. Microgrooving and microthreading tools with cutting widths as small as 13 μm are made by focused ion beam sputtering and used for ultraprecision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide to create a number of critically aligned facets. Sputtering produces rake facets of desired angle and cutting edges having radii of curvature equal to 0.4 μm. Clearance for minimizing frictional drag of a tool results from a particular ion beam/target geometry that accounts for the sputter yield dependence on incidence angle. It is believed that geometrically specific cutting tools of this dimension have not been made previously. Numerically controlled, ultraprecision machining with microgrooving tools results in a close match between tool width and feature size. Microtools are used to machine 13-μm wide, 4-μm deep, helical grooves in polymethyl methacrylate and 6061 Al cylindrical workpieces. Microgrooving tools are also used to fabricate sinusoidal cross-sectional features in planar metal samples.