Metal matrix composites refer to a material system composed of discrete constituent(s) called reinforcement(s) dispersed in a continuous phase of the metal called the metal matrix. The advantages of metal matrix composites over unreinforced metals are high specific strength, high Young’s modulus, high temperature strength, good conductivity, and good abrasion and wear resistance etc. By virtue of their superior properties, not seen in monolithic materials, they are used in structural and functional components for high performance applications such as aerospace vehicles and racing automobiles.
 
However their machining has been an impediment to their widespread application The inclusion of the ceramic reinforcement in the composite causes excessive tool wear. The dominant wear mechanism is impact at the cutting edge and thermal stresses  For these reasons non-conventional machining techniques such as EDM are employed to machine mmcs to guarantee dimensional stability and economic machining.
 
EDM is a thermal process whereby material is removed by the action of high-energy electrical sparks. The spark melts and vaporizes a small area on the electrode surface. At the end of the pulse-on time, a small amount of molten material is ejected from the surface. The main advantage of this process is that complex shapes can be machined on very hard materials as mmcs without any contact between the tool and work piece.
 
            The present work reports on the experimental investigation into the electrical discharge machining of Al-B₄C-SiC hybrid metal matrix composite. The composite is developed through powder metallurgy route. The effects of EDM parameters namely current (C) and pulse on time (P) on the metal removal rate (MRR) and surface roughness (SR) are analyzed. Taguchi’s and ANOVA (Analysis of Variance) are used to analyze the effects of machining characteristics such as MRR and SR. The machined surface characteristics are studied using Scanning Electron Microscopy (SEM).