Experimental Investigation of Material Removal Rate on H-13 Using Powder Metallurgy and Conventional Electrodes.

Electric discharge machining is most widely used method for machining materials which are used mostly for making tools such as Die steel, tool steel which are difficult to machine by simple methods. It was found that considerable research has been done on various aspects of electrical discharge machining of low carbon steels, carbides and a few die steels but sufficient data is not available on H-13 even though it is widely used in pressure die casting tools, extrusion tools, forging dies, stamping dies, plastic molds etc. Hence there is a need to investigate the machining of this material with copper chromium (CuCr) electrodes (made through powder metallurgy technique) by varying different machining parameters such as discharge current, gap voltage, duty cycle, polarity, retract distance and flushing pressure and their effect on Material Removal Rate ( MRR). It was found that Machining rate increases with the increase in current due to predominant increase in spark energy. Positive polarity with powder metallurgy electrode (80%Cu 20%Cr) at current value (10A) and duty cycle (0.9) gives the best results for MRR.