A STUDY ON INFLUENCE OF POLARITY ON THE MACHINING CHARACTERISTICS OF SINKER EDM

Electrical discharge machining (EDM) has been recognized as an efficient production method for precision machining of electrically conducting hardened materials . Electrical Discharge Machining is a machining method primarily used for hard metals or those that would be impossible to machine with traditional techniques. One critical limitation, however, is that EDM only works with materials that are electrically conductive. Sometimes referred to as spark machining or spark eroding, EDM is a nontraditional method of removing material by a series of rapidly recurring electric arcing discharges between an electrode (the cutting tool) and the work piece, in the presence of an energetic electric field. The most important study of this paper is the effect of the polarity on the machining tool / work piece using electrical discharge machining to the material removal rate, electrode wear and surface roughness, to determine the optimum condition , and to determine the most significant factor. In this paper an elaborative methodology is suggested to choose option between electrode and work piece as terminal positive or terminal negative for different categories of tools and work pieces. The wrong polarity can have significant implications on wear, and stability. A set of experiments are conducted and the results are represented numerically and graphically. The most important output parameters are material removal rate, electrode wear and surface roughness. From the obtained data one can easily determine the optimum parameters and most significant factors related to material removal rate (MRR), electrode wear and surface finish very easily.