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

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 (R-t), are investigated. The influence of R-t on the cutting-edge quality is studied. Results have indicated that single pulse energy is directly proportional to the diamond phase transformation depth and R-t. In addition, the scanning speed and track displacement have an inverse relation with phase transformation depth and the R-t. Furthermore, a low value of R-t 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 mu m and tool tip radius of 3.5 mu m is fabricated. The case study has demonstrated that the proposed hybrid machining process improves the process efficiency.