Kazuo Nakamoto, Tojiro Aoyama, Kazutoshi Katahira, Peter Fonda, and Kazuo Yamazaki

Abstract:
The demand for high quality micro-scale molds for the production of high value-added miniature parts is rapidly growing. The fabrication of such molds requires highly productive and high quality micro milling of hard and brittle materials, such as tungsten carbide (WC). Such micro milling processes have not yet been studied well, however, so their fundamental nature is not yet well understood. This paper reports the results of a study on the basic nature of the micro milling process when WC is machined with a custom made PCD (poly-crystalline diamond) micro tool. The study includes the design and fabrication of a custom micro end mill tool with a single cutting edge, experimental procedures to find the optimal machining conditions for high quality surface generation, and an evaluation of the quality of the machined surface in relation to tool wear. The results of the experimental study indicate that machining conditions exist for the generation of a surface with nanometer-level roughness. Normal tool wear is maintained over long cutting lengths while tool wear grows continuously on the axial clearance face of the end mill.

Keywords: micro milling, surface finish, PCD tool, tungsten carbide