STUDIES ON ELECTRIC DISCHARGE MACHINING OF METAL MATRIX COMPOSITES

Abstract

Metal Matrix Composites (MMC's) are playing a very important role in the industrial growth because of their superior properties such as high toughness, high specific strength, high temperature resistance, high stiffness etc. The superior properties of these materials cause the difficulty in their machining. In order to achieve an economic machining of MMC's and other hard to cut material (Inconel, titanium, tool steel, etc.), non conventional machining is the best alternative. This report explains the machining of MMC's with a newly developed process know as Electrical Discharge Sawing (EDS). Electric discharge sawing is similar to conventional EDM process, but extra reciprocating motion is given to the tool which enhances the flushing efficiency of the process which ultimately yields high MRR. Scotch yoke mechanism is used to generate reciprocating motion. There still exist numerous difficulties in cutting advanced materials, super alloys and metal matrix composite materials. EDS is a competent sawing process for cutting difficult to cut materials. A modified setup has been designed and developed. The sawing process has been investigated with the developed setup. The EDS setup has been developed in a Machine tool lab in MIED at lIT Roorkee. Experimental studies have been conducted on MMC with input parameters as current, pulse on time, pulse off time, gap voltage, lift, stroke length and RPM, keeping other parameter constant. Material removal rate and tool wear rate of developed EDS process has been evaluated through standard test procedures. II has been found that the EDS process is quick as compared to the conventional cutting process. These days there is massive demand of MMC shaft's in automobile industry. EDS may be an effective way to cut keyways and other operation in MMC shafts.