Investigation of the Thermophysical Simulation and Material Removal Mechanism of the High-Volume-Fraction SiCp/Al Composite in Wire Electrical Discharge Machining

SiC particle reinforced aluminum matrix composites (SiCp/Al) are widely used in aviation, weaponry, and automobiles because of their excellent service performance. Wire electrical discharge machining (WEDM) regardless of workpiece hardness has become an alternative method for processing SiCp/Al composites. In this paper, the temperature distribution and the discharge crater size of the SiCp/Al composite are simulated by a thermophysical model during a single-pulse discharge process (SPDP) based on the random distribution of SiC particles. The material removal mechanism of the SiCp/Al composite during the multi-pulse discharge process (MPDP) is revealed, and the surface roughness (<i>Ra</i>) of the SiCp/Al composite is predicted during the MPDP. The thermophysical model simulation results during the MPDP and experimental characterization data indicate that the removal mechanism of SiCp/Al composite material consists of the melting and vaporization of the aluminum matrix, as well as the heat decomposition and shedding of silicon carbide particles. Pulse-on time (<i>T_on</i>), pulse-off time (<i>T_off</i>), and servo voltage (<i>SV</i>) have a great influence on surface roughness. The Ra increases with an increase in <i>T_on</i> and <i>SV</i>, but decreases slightly with an increase in <i>T_off</i>. Moreover, compared with experimental data, the relative error of <i>Ra</i> calculated from the thermophysical model is 0.47-7.54%. This means that the developed thermophysical model has a good application and promotion value for the WEDM of metal matrix composite material.