Influence of grain size and cobalt content on machinability of tungsten carbide with diamond-coated tools

Tungsten carbide is an important material for manufacturing cutting tools, molds and dies due to its combination of high hardness and high resistance to mechanical loads and wear. The primary restriction associated with utilizing this material pertains to the time-consuming and costly machining process, which is attributed to its low machinability. As an alternative to conventional electro discharge machining, milling with diamond-coated carbide tools has shown promising results. Due to a lack of knowledge about the interactions between the tungsten carbide to be machined, the tool and the process parameters, the economic advantages of the milling process are currently not fully utilized. In application of the cutting tools, a self-sharpening effect due to flaking of the coating on the rake face occurs, which results in improved cutting conditions. The present study addressed the prevailing knowledge cap regarding the interaction between material composition, parameter selection and tool design. Tungsten carbides with different compositions were machined in orthogonal cutting tests. In the investigations, increasing grain size and cobalt content caused a reduced thermomechanical process load and therefore delayed a favorable self-sharpening effect.