A machinability evaluation of cryogenically treated beryllium copper in a magnetic field assisted by electrical discharge machining

Abstract

Beryllium copper is known by its high fatigue strength, excellent wear and corrosion resistance and, non-magnetic material. And it finds application in electronic and electro-mechanical devices. But there are some problems in machining of beryllium copper by conventional machining processes. Thus, as a substitute for the conventional machining process die-sink, electrical discharge machining has gained importance for machining such materials. This study investigates the effects of work piece (Beryllium copper), tool electrical conductivity, magnetic strength, gap current and pulse time on the material removal rate, tool wear rate, white layer thickness and crack density. One-variable approach at-a-time was employed to find out the level of the process parameters. Response surface methodology has been used to develop the empirical models for response characteristics. Parametric analysis revealed that electrical conductivity, magnetic strength, gap current, and pulse-on-time affect the responses. Empirical model can predict material removal rate with R2 value of 97.69% and tool wear rate with R2 value of 93.75%. White layer thickness formed is less with a maximum value of 15 µm and negligible surface cracks were observed on the work piece using SEM images at 850X and 1000X.