Effect of SiC and rotation of electrode on electric discharge machining of Al-SiC composite

Metal matrix composites (MMCs) contain certain amount of secondary reinforcement, which makes it difficult to machine with conventional cutting tools and methods. The present study analyses the effect of electric discharge machining (EDM) parameters namely polarity, current, electrode material, pulse duration, and rotation of electrode on metal removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) value in EDM of Al-SiC MMCs with 20 and 25 vol.% SiC. Irrespective of the electrode material, polarity of the electrode and volume percentage of SiC, the MRR increased with increase in discharge current and for a specific current it decreased with increase in pulse duration. Increase in the volume percentage of SiC had an inverse effect on MRR, and positive effect on TWR and surface finish. Increasing the speed of the rotating electrode resulted in a positive effect with MRR, TWR and better SR than at stationary. Optimum parameters for EDM drilling were also developed to summarize the effect of machining characteristics such as MRR, TWR and SR. (C) 2002 Elsevier Science B.V. All rights reserved.