Investigation of the effects of electrochemical polishing on EDM surfaces

Any surface generated by a manufacturing process bears a number of ‘scars’ due to the inherent nature of the process. In the electro discharge machining (EDM) process, the extremely high temperature generated, and the quenching effect of the dielectric at the end of each discharge lead to the formation of a hard and brittle white layer. It is important to remove the defects introduced by a manufacturing process so as to improve the functionality of the component/part. The aim of this work is to study the effect of parameters of electrochemical polishing on the 3D surface texture parameters of EDM surfaces of tool steel specimens. The results have shown a dominant effect due to the direct current of the cell, and there is a limiting value of the interelectrode gap for any given value of current density. A high influence of the interactive effect of current density and electrode gap was also observed. This information would be very useful in choosing the appropriate magnitude of the process parameters in order to engineer the surface to meet the in-service requirements, since the 3D surface texture parameters, particularly, the S ds, S dr and the volume parameters can give quantitative information with respect to the functionality of a surface, such as the load bearing and fluid retention capabilities as well as running in wear, etc.