Size and speed of ejected particles from different cemented carbide grades machined with sinking EDM

The application of cemented carbides is desired in several fields due to their superb mechanical properties. The downside of the large strength and wear resistance occurs upon machining, which, especially for conventional machining, is expensive or even impossible. Hence, Electrical Discharge Machining (EDM) is used since it works independently from the mechanical properties of the workpiece. However, the ED-machining of cemented carbides is also characterised by low productivity and high tool wear when it is compared to the machining of steel. This paper investigates the material removal phenomenon of different cemented carbide grades by means of a high speed video camera. In order to allow observation, the single discharges are conducted in air. A large number of experiments with different energy levels is analysed by an algorithm to identify the particle size, particle speed and the ejection angle. The results can be used to identify the dominant material removal mechanism. This should in the future be used to create a machining technology which is dedicated to the specific cemented carbide grade.