EDM performance of electroformed Cu‐ZrB2 shell electrodes

Abstract

PurposeCu‐ZrB2 shell electrodes were fabricated by composite electroforming to improve the spark‐resistance of the electrical discharge machining (EDM) electrodes made by rapid tooling.Design/methodology/approachCu‐ZrB2 shell electrodes were fabricated using composite electroforming, separating and backing. EDM performance evaluation of the Cu‐ZrB2 shell electrodes is performed using tool steel as the cathode workpiece and the Cu‐ZrB2 composite as the anode tool. The effects of ZrB2 content on the electrode and workpiece removal rate, wear ratio of the electrode to workpiece, and surface quality of workpiece and electrode were studied.FindingsCompared with the conventional electroformed copper tools, Cu‐ZrB2 shell electrodes yield higher workpiece removal rate and lower tool wear ratio. Scanning electron microscopy (SEM) and electron microprobe analysis reveal that, due to the large difference between the melting point of ZrB2 and copper, the heat generated by the sparks is conducted mainly through the copper matrix, reducing the erosion of ZrB2 particles. The refractory ZrB2 particles then act as barriers to the flowing and outburst of melted copper and enhance the resistance to erosion of the electrodes.Originality/valueThe use of Cu‐ZrB2 shell electrodes improves the anti‐erosion properties of the EDM electrodes made by rapid tooling, especially in finish machining conditions. Such electrodes will not only reduce the failure of the EDM electrodes but also improve the machining precision due to the less dimension loss of the electrodes during machining.