Factors affecting chemical wear during machining

Very substantial tool wear may arise during machining processes because of chemical affinities between tool and workpiece. Studies have been made of this type of wear by observing the performance under various conditions of diamond tools turning steel, nickel and graphite, of tungsten tools turning graphite, and of CuNi tools turning sulphur. The reactions involved in the wear processes are insensitive to thermal activation and appear to be due to the reactivity of the atomically clean surfaces generated by the machining. The rates of wear are considerably modified both by changes in the chemical composition of tool and workpiece and by changes in the gaseous environment. It is clear that reactions between solid surfaces are at present not well understood and are worthy of further study. The results suggest possible ways of reducing tool wear both in turning and in other operations.