Enhancing performance of electrical discharge machining by ultrafine-grained Cu-0.5%Cr electrode

The electrode is an important component of electrical discharge machining (EDM), playing an important role in machining efficiency, surface quality and geometric accuracy. In this work, a new method combining equal channel angular pressing (ECAP), deep cryogenic treatment (DCT) and aging treatment (AT) was proposed. The ultrafine-grained Cu-0.5%Cr electrode has high strength and high electrical conductivity through this process, so as to improve the machining characteristics in EDM. The surface roughness ( Ra ), the workpiece corner sharpness (WCS), and the electrode wear rate (EWR) were investigated. The results showed that the treatment of the electrode with 4 passes of ECAP + DCT (12h) + AT (550℃ × 1h) can reduce the EWR and WCS by 63.6% and 49.7%, respectively. It also contributed to the enhancement of electrical conductivity and microhardness of the Cu-0.5%Cr electrode by ECAP + DCT + AT. Meanwhile, it revealed that the processing of the Cu-0.5%Cr electrode resulted in the excellent machined surface quality ( Ra was reduced by 53.5%) which was confirmed by the results of the scanning electron microscopy (SEM). The ultrafine-grained Cu-0.5%Cr electrode with an excellent combination of strength and electrical conductivity has an outstanding EDM performance.