Investigation of the wear and failure modes of surface engineered multipoint cutting tools

Most of the studies todate into the wear mechanisms associated with cutting tools have been undertaken on single point tools which invariably operate under conditions of high speed and stress. The application of PVD coatings has been claimed to confer great benefits in terms of tool life by reducing friction on the rake face and slowing down diffusion wear. Multipoint cutting tools, notably handsaws and circular saws, have been mostly neglected in these studies despite the fact that these are the basic tools used throughout many industrial environments. Wear is recognised as a serious problem in metal cutting operations and surface engineering via the application of plasma vapour (PVD) film is an established technology. It finds current applications deposited on many areas of industry, including high speed steel drilling, gear cutting and mulling. The current work is a study of the wear and failure modes of both standard and simulated wear tested bandsaw and circular saw blades. A range of PVD thin films are critiqued from both the Magnetron Sputtered and Arc Evaporated Systems. The most suitable candidate coatings are prepared for the surface engineering of multipoint cutting tools. The tool wear and failure modes are identified for the surface engineered simulated wear test specimens in order to gain a greater understanding of the benefits obtained from the application of thin films in multipoint cutting applications. The most notable benefits in cutting performance and wear behaviour were recorded at increased cutting speeds on selected coating-substrate systems. This finding was supported via an examination of the resulting tool wear and failure modes. In conclusion the optimum coating-tool systems at the more efficient cutting speeds are recommended for further work as the key to the full exploitation of surface engineered multipoint cutting tools