Physical and electrical characteristics of EDM debris

In EDM, debris plays a key role in the electrical conditions of the discharge gap prior to each spark. Despite this, analysis of debris at all length-scales has not yet been performed, and therefore the nature of debris produced by electrical discharge processes is not fully understood. In this study debris created by the machining of two electrode materials set as negative polarity, silicon and titanium carbide, was centrifuged and imaged using SEM and TEM. From this analysis it was shown that electrode debris is 1 nm or lower and up to 10 μm in size. Population analysis of the particle size distribution was used to inform an electric field model based on a lattice Boltzmann method framework, simulating the effect of the presence of such debris on the electric field strength. This method is shown to be able to capture the local variation of the electric field and predict qualitatively the correct trend of the electric field strength increasing against the debris concentration. Such data is important for prediction and control of discharge gap size, as well as understanding the impact of a build-up of debris on uncontrolled sparking.