Research on the ductile-mode machining of monocrystalline silicon using polycrystalline diamond (PCD) tools

This article presents an experimental investigation on high-efficiency machining monocrystalline silicon by polycrystalline diamond (PCD) end mills with a tool diameter of 5 mm. The milling experiments were carried out on a self-made five-axis numerical control machine tool. A super-high magnification zoom lens 3D microscope, white light interferometer, and dynamometer were applied to qualitatively and quantitatively characterize the performance of processed surfaces and cutting force. A surface roughness of Ra = 9.9 nm, better than most previously reported value on silicon, was obtained. Also, greater plastic removal efficiency was achieved under a small axial depth of cut and feed rate (less than 60 and 0.3 μm/tooth, respectively) and high spindle speeds (50,000 rpm). Moreover, surface characterization studies were explored which reveals that faster spindle speed, lower feed rate, and smaller cut depth can provide an easy access to ductile machining. At last, note that the shape structure and amplitude of cross-cutting force kept a close relation with the processing mode of single-crystal silicon, and a stable cross force contributed to improve surface quality as well as inhibiting micro-crack initiation.