Cutting performance of Ti-Al-Si-N-coated tool by a hybrid-coating system for high-hardened materials

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high-speed machining. Unfortunately, the development of cutting tool for high-speed machining is not enough in machining of difficult-to-cut material. New superhard Ti-Al-Si-N films, characterized as a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous Si3N4 matrix, was successfully synthesized on WC-Co substrates by a hybrid-coating system of arc ion plating (AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ∼50 GPa at the Si content of 9 at.%, respectively. In this study, Ti-Al-Si-N coatings were applied to end-mills made of WC-Co material by a hybrid-coating system. The tool performances for the high-hardened material were studied under high-speed cutting conditions. Additionally, the relationship between the machining characteristics and the Si contents were investigated under various high-spindle speeds. It showed the tool life was improved up to 50% at the Si content of 9 at.%.