An investigation on the effect of different coated electrodes on the surface quality of WEDM by varying discharge energy level

Abstract

The quality of WEDM surface is still a concern to the researcher. Due to the uneven spark, the energy discharge transferred to the workpiece surface is not accurate for high-quality machining. Such energy is mainly controlled by process variables and electrode parameters. The selection of proper wire electrode and the proper combination of process variables can extend the surface quality into a much higher limit. In the present investigation, machining quality of brass wire, silver-coated brass wire, and zinc-coated brass wire is compared at different discharge energy levels. The quality of machining is measured in terms of average roughness, maximum roughness, kerf width, recast layer thickness, workpiece surface, and elemental inclusions in both wire and workpiece surface. The surface morphologies of the wire have also been investigated. The research material has been carefully chosen as one of the expensive grades of steel named maraging steel 300 due to its wide applicability in the aerospace and automobile industries. From the investigation, it has found that a minor coating of silver over plain brass significantly improves the surface quality. It has also found that, for better quality machining, discharge energy should be kept in a lower limit. Zinc coating over brass improves the strength of the wire as well as machining rate but simultaneously is responsible for the poor quality of surface. Brass wire is neither a good choice for high surface quality machining nor good for high-speed machining. The majority of copper and some zinc elements have been flush out from wire and adhered to the workpiece surface.