COMPARISON BETWEEN NUMERICAL SIMULATIONS AND EXPERIMENTS FOR SINGLE POINT DIAMOND TURNING OF SILICON CARBIDE John A. Patten, Jerry Jacob and Biswarup Bhattacharya Department of Manufacturing Engineering Western Michigan University Kalamazoo, Michigan Andrew Grevstad Thirdwave Systems Minneapolis, Minnesota KEYWORDS Silicon Carbide, critical depth of cut, nanometer, High Pressure Phase Transformations, Ductile-to-Brittle transition, simulation, Drucker-Prager. ABSTRACT Single Point Diamond Turning (SPDT) experiments conducted on single crystal 6-H Silicon Carbide (SiC) has shown chip formation similar to that seen in the machining of metals. The ductile nature of SiC is believed to be the result of a high pressure phase transformation (HPPT), which generates a plastic zone of material that behaves in a metallic manner. This metallic behavior is the basis for using AdvantEdge, a metal machining simulation software, for comparison to experimental results. Simulations (2-D) were carried out by matching the SPDT experimental conditions, conducted at nanometer (nm) depths of cut and varying tool rake angles. The experiments were performed by machining the circumference of the single crystal wafer, thereby conforming to a 2-D orthogonal cut. The cutting and thrust forces generated from the experiments under ductile cutting conditions compared favorably with the simulation. As the depth of cut is decreased (250 nm, 100 nm, and 50 nm), the experimental conditions transition from a brittle to ductile environment, with the 50 nm cuts being dominated by ductile events. INTRODUCTION The mechanical and thermal properties of silicon carbide (SiC) have traditionally allowed for its use in refractory linings and heating elements for industrial furnaces, as an abrasive in manufacturing processes, and in wear resistant parts in rotating machinery such as pumps and engines. There is currently some interest in the use of SiC in the optics industry for space based laser mirrors, as a replacement for beryllium. Also in the electronics industry SiC is being used for high-powered/high temperature devices, where the high thermal conductivity, high electric field breakdown strength, and high maximum current density make it more promising than silicon (Si). The successful use of SiC in these industries impose stringent requirements on form accuracy and sub-surface damage (O’Connor et al., 2005) where surface finishes better than 10 nm are considered standard specifications (Blake et al., 1988).