PVD-coated tools and native ester – an advanced system for environmentally friendly machining

This paper presents results from the turning of stainless steel and the drilling of the nickel-based alloy, Inconel 718, using carbide tools coated with different PVD coatings. Newly developed coating systems like finecrystalline TiAlN resp. AlTiN, nanocomposites based on TiN/a-AlN and crystalline γ-Al2O3 have been analysed during these cutting tasks. Instead of an emulsion, synthetic esters are used which are readily biodegradable. The phenomena and the causes of tool wear have been studied. In the cutting experiments, the tested hard material coating systems demonstrated significantly enhanced wear behaviour in comparison to a conventional coating based on TiAlN. In combination with adapted coating systems, synthetic esters may represent an efficient alternative to conventional water-based lubricoolants, even in difficult machining operations. They are not only able to contribute to environmental protection and to improve the working environment, but also enhance tool performance.