Simulation and experimental researches on the substrate temperature distribution of the large-capacity HFCVD setup for mass-production of diamond coated milling tools

Abstract

To improve the precision and homogeneity for mass-production of HFCVD diamond coated milling tools, the simulation of substrate temperature field generated by the HFCVD setup was conducted, adopting a 3D simulation model well in accordance with the actual equipment. Firstly, the deviation of the simulation model is assessed by comparing the simulated temperature and measured temperature based on a validation test. The comprehensive influences of various critical setup parameters on the fabrication of diamond coatings are illustrated systematically according to the Taguchi simulation scheme (L16, five factors and four levels), including the filament diameter d, the filament temperature Tf, the separation between two adjacent filaments D, the filament height H, and the material of sample holder M, in order to obtain an optimal HFCVD setup. The results indicate that filament diameter d and the separation between two adjacent filaments D can effectively contribute to adjusting the average temperature; the distance between filaments and tool tips H, and the material of sample holder M exhibit remarkable effects on the temperature uniformity; the filament temperature Tf shows obvious influences on both the average temperature and the temperature uniformity. Furthermore, the optimal HFCVD setup has been proposed, based on which a more uniform temperature field around all the tool tips can be acquired, contributing to the mass-production of high-quality and high-precision diamond coated milling tools. Afterwards, the mass-production experiments of depositing MCD and NCD diamond coatings on WC-6% Co milling tools were conducted in the actual HFCVD reactor, and tool-tip temperature were measured, revealing that the optimal setup can produce an extremely uniform temperature field. Moreover, the characterizations and cutting performances of MCD and NCD diamond coatings deposited on milling tools were evaluated, indicating that high-quality and high-precision diamond coatings with quite satisfactory homogeneity of thickness, surface and cross-sectional morphologies, chemical compositions and phases can be acquired during mass-production of diamond coated milling tools on the base of the optimal HFCVD setup.