Structural analysis of electrodischarge machined surfaces of EN31 tool steel

During the last two decades, there has been a rapid growth in the development of harder and difficult to machine metals and alloys to fulfill the need of industries. For these alloys, the conventional cutting and machining have been found to be uneconomical. Further, the degrees of accuracy and surface finish attainable by conventional process have been poor. In view of the seriousness of this problem, there is a need for development of newer concepts in metal machining. Electrodischarge machining (EDM) is a non-conventional process which is used for machining of such alloys. This paper presents the details of machining and structural analysis of EDMed surfaces with respect to material removal parameters of the workpiece. Experimental work has been conducted on EN31 tool steel with copper, brass and graphite as tool electrodes. Kerosene oil of commercial grade has been used as dielectric fluid. The data compiled during the experimentation have been used to check the responses in respect of material removal rate (MRR) and surface roughness (Ra). Further, the detailed analysis of structural features of machined surface has been carried out by scanning electron microscope and optical microscope to understand the mode of heat transfer which alternatively affects the structure of the machined workpiece and hence the life of the tool.