EDM performance of electroformed Cu-ZrB{sub}2 shell electrodes

摘要

Purpose - Cu-ZrB{sub}2 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/approach - Cu-ZrB{sub}2 shell electrodes were fabricated using composite electroforming, separating and backing. EDM performance evaluation of the Cu-ZrB{sub}2 shell electrodes is performed using tool steel as the cathode workpiece and the Cu-ZrB{sub}2 composite as the anode tool. The effects of ZrB{sub}2 content on the electrode and workpiece removal rate, wear ratio of the electrode to workpiece, and surface quality of workpiece and electrode were studied. Findings - Compared with the conventional electroformed copper tools, Cu-ZrB{sub}2 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 ZrB{sub}2 and copper, the heat generated by the sparks is conducted mainly through the copper matrix, reducing the erosion of ZrB{sub}2 particles. The refractory ZrB{sub}2 particles then act as barriers to the flowing and outburst of melted copper and enhance the resistance to erosion of the electrodes. Originality/value - The use of Cu-ZrB{sub}2 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.