Factors influencing the milling performances of Ti(C,N)-based tools against carbon steel

A newly developed Ti(C,N)-based tool with Ni-Co-based binder (~9 wt%) was compared with two commercial tools in high speed milling (470 and 600 m/min) against carbon steel. Under the adopted experimental conditions, the new tool suffered a wear lower than the commercial ones. Among the wear mechanisms, those thermally related, i.e. diffusion and oxidation, strongly affect the resistance to abrasion and material degradation, leading to sudden failure of the cutting edge. These mechanisms, under the hypothesis of acceptable fracture toughness and hardness of the tool, emphasise the material microstructure as the key aspect that can be used to understand the comparative behaviour of the various tools. The amount and stoichiometry (particularly C/N ratio) of the Ti(C,N)-based hard phase influence both the thermal conductivity, consequently the temperature at the working edge on service, and the oxidation behaviour. An additional important factor is the reduction of metal binders at the minimum level that allows the achievement of high final densities and suitable mechanical properties