Investigation on the electrical discharge machining of cryogenic treated beryllium copper (BeCu) alloys

Abstract

Introduction. In modern manufacturing world, industries should adapt technological advancements for precision machining of difficult-to-machine metals, especially for beryllium copper (BeCu) alloys. The electrical discharge machining of alloys has proven its viability. The purpose of the work. A literature review indicated that the investigation of electrical discharge machining of BeCu alloys is still in its infancy. Furthermore, the cryogenic treatment of workpieces and electrodes in electrical discharge machining has not received much attention from researchers. Moreover, the impact of magnetic field strength on surface integrity and productivity during electrical discharge machining has not attracted much attention from researchers. The methods of investigation. This paper describes the use of electrolytic copper with different gap current values, pulse on periods, and external magnetic strength for electrical discharge machining of BeCu alloys. This paper examines how the material removal rate, the thickness of the white layer, and the formation of surface cracks are affected by cryogenic treatment of the workpiece and tool, pulse-on time, gap current, and magnetic strength. Results and Discussion. The combination of the cryogenically treated BeCu workpiece and the untreated Cu electrode had the highest material removal rate among all the combinations of workpieces and tools used in this study. The pulse on-time and the strength of the magnetic field had little influence on material removal rate, whereas the gap current had the greatest effect. The maximum achieved material removal rate was 11.807 mm3/min. At a high material removal rate, the observed thickness of the white layer on the horizontal surface ranged from 12.92 µm to 14.24 µm. In the same way, the maximum and minimum values for the vertical surface were determined to be 15.58 µm and 11.67 µm, respectively. According to scanning electron microscopy, the layer thickness was less than 20 µm, and barely noticeable surface cracks were observed in specimens with low, medium and high material removal rates. Obviously, due to the cryogenic processing of the workpiece and the external magnetic strength, there was a slight cracking of the surface and the formation of a white layer.