Preparation and cutting performance of ultra-smooth CVD composite diamond coated ladder-shape drilling tools

Abstract

The preparation of ultra-smooth composite diamond (USCD) coated ladder-shape drilling tools is studied. These are produced by growing microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) layers employing the hot filament chemical vapor deposition (HFCVD) method on WC-Co parts. A double hot-wire arrangement apparatus is adopted, the complex shape tool is placed between upper tantalum wires and lower tantalum wires so that all parts of the tool can be coated with diamond. The drilling experiments are conducted for assessing the cutting performances of the MCD and USCD coated tools using carbon fiber reinforced plastics (CFRP) as the workpiece, the uncoated tool is also used in the drilling experiments for the sake of contrast. The results show that the MCD and USCD coated tools exhibit a better cutting performance than the uncoated one, besides, the USCD coated tool displays the best wear resistant. The workpiece is precisely machined with a smooth and bright surface by the USCD coated tool, and there are no defects such as crackle and burrs in the hole exit, the durability of the USCD coated tool and the processing quality of the workpiece have been greatly improved.