Fabrication of CVD diamond micro-milling tool by hybrid machining of laser-induced graphitization and precision grinding

Abstract Owing to exceptional hardness and wear resistance, Chemical Vapor Deposition (CVD) diamond material is broadly used for micro-milling tools. However, the fabrication of CVD diamond micro-milling tool by a traditional grinding process is less efficient in terms of productivity and edge quality. In this manuscript, a novel hybrid machining process combining laser-induced diamond graphitization with precision grinding is performed to attain high-quality production of CVD diamond micro-milling tools. The effects of laser parameters on the phase transformation depth of the diamond, and the maximum peak-to-valley height of the boundary contour (Rt), are investigated. The influence of Rt on the cutting-edge quality is studied. Results have indicated that single pulse energy is directly proportional to the diamond phase transformation depth and Rt. In addition, the scanning speed and track displacement have an inverse relation with phase transformation depth and the Rt. Furthermore, a low value of Rt has provided better cutting-edge quality after conducting precision grinding. In order to improve the fabrication efficiency, a solution for roughing, semi-finishing and finishing processes is proposed. Based on the optimum parameters, a sharp CVD diamond micro-milling tool with cutting-edge radius of 2.5 μm and tool tip radius of 3.5 μm is fabricated. The case study has demonstrated that the proposed hybrid machining process improves the process efficiency.

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