Electro-discharge machining of metal matrix composite materials

Following a review on the classification and applications of metal matrix composites (MMCs) and the use of unconventional machining processes to cut MMCs, the paper presents experimental results for electro-discharge machining of an aluminium matrix reinforced with silicon carbide particle composite. A modified fractional factorial experimental design based on Taguchi orthogonal array L9 was employed. This involved three control variables at three levels each, namely discharge current, spark gap and electrode type (varying size and geometry). Process responses included material removal rate (MRR), tool wear rate (TWR) and average surface roughness of the eroded surface. Maximum MRR/TWR ratio of 21.36 was achieved when 3 A and 10 μm discharge current and sparking gap respectively were used with 5 mm diameter solid electrode (with a corresponding R _a of 1.8 μm).