Substitution of commercially coated tungsten carbide tools in dry cylindrical turning process by HiPIMS coated niobium carbide cutting inserts

The deposition of a thin film tool coating as wear resistant layer on tungsten carbide (WC) cutting tool material marks the industrial standard for machining of various workpiece materials. Recent developments on alternative cutting materials show the potential of niobium carbide (NbC) for machining of iron-based materials and its use in cutting tool applications. In this study the tool behavior of two NbC substrates, defined as NbC0.88-12Co and NbC1.0-12Ni4Mo4VC respectively, is compared to commercial, submicron grained WC-6Co tool material. The wear performance of uncoated and physical vapor depositioned (PVD) coated cutting tools is analyzed by scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and energy-dispersive x-ray spectroscopy (EDS) during adhesion tests and machining trials of carbon steel C45E. In uncoated condition, NbC1.0-12No4Mo4VC shows an average increase of material removal VW by 3% combined with a lower crater wear depth KT by 32% compared to industrial WC-6Co standard. Although microstructural defects are evident in NbC substrates, a similar tool performance of coated NbC cutting tools attests the successful substitution of WC-6Co cutting tool material for industrial machining processes.