The effect of coatings on the cutting process, friction, forces and predictive cutting models in machining operations

Abstract

The effects of the popular TiN and TiCN coatings on the cutting process, friction and predictive mechanics of cutting models for forces and power in machining operations are investigated. Extensive orthogonal cutting and turning tests on steel work materials have shown that the cutting process and predictive force models are not qualitatively affected by these coatings. Quantitatively, both coatings are equally effective in reducing the friction, forces and power in orthogonal cutting when applied to high-speed steel (HSS) tools and equally ineffective when applied to carbide tools. Both TiN and TiCN coatings applied to HSS tools resulted in modest reductions in the power force component and power of 12–30 per cent ‘on average’ with larger reductions in the thrust force component of about 50 per cent ‘on average’. Considerably more research seems necessary to understand better and to predict quantitatively the effects of the many coating-substrate combinations on the technological performance of machining operations, essential for optimizing the economic performance of these operations.