Blasting erosion arc machining of 20 vol.% SiC/Al metal matrix composites

Abstract

Machining of metal matrix composite is a big challenge in industry for the high cutting tool cost and limited machining efficiency. In this study, blasting erosion arc machining (BEAM) was applied to improve the machining efficiency of SiC/Al composite. The performance of BEAM under negative and positive electrode machining conditions was investigated, and two sets of 3-factor, 2-level full factorial experiments were conducted to disclose the effects between the machining parameters. When the peak current was 500 A and the tool polarity was negative, the obtained MRR (material removal rate) was greater than 8270 mm3/min, and the TWR (tool wear ratio) was about 2 %. The competitive efficiency and economy of BEAM indicate the potential of electrical arcing in handling difficult-to-cut composite materials. The optimization of machining conditions can result in a high MRR which arrived to 10, 200 mm3/min, and the specific MRR was nearly three times of that of EDM. Furthermore, it was disclosed that the MRR in both negative and positive machining was sensitive to the peak current, pulse duration, and pulse interval while the TWR was appeared to be stable as the machining conditions varies within a certain range. The surface topography of the machined workpiece indicates that compared to the negative BEAM, positive BEAM creates a smoother surface under the same machining conditions. Furthermore, in order to study the influence of SiC particles on the machining performance, a complementary experiment was conducted to compare the craters formed on 20 vol.% SiC/Al and pure aluminum. Based on the comparison results, it can be deduced that the discharging condition is possibly influenced by the SiC particles and result in smaller craters. Finally, a workpiece was machined to demonstrate the advantages of BEAM for the machining of SiC/Al composites.