Machining characteristics of 65 vol.% SiCp/Al composite in micro-WEDM

Abstract Wire electrical discharge machining (WEDM) has been proven as an effective way for machining various hardness conductive materials, such as tungsten steel or particle reinforced metal matrix composite (PR-MMC). However, the machining characteristics of high-volume content (>50 vol.%) silicon carbide (SiC) reinforced aluminum (Al) matrix composite (SiCp/Al) in WEDM are often unsatisfactory due to the frequent wire rupture and unstable processing. Addressing this issue, this paper proposes micro-WEDM to steadily machine 65 vol.% SiCp/Al composite with high process efficiency and adequate good surface quality. The workpiece surface is characterized by SEM, optical microscope, EDS and XRD to clarify the removal mechanism of the SiCp/Al composite which consists of melting, vaporization, shedding, oxidation and thermal decomposition. In addition, the influences of processing parameters on material removal rate (MRR) and surface roughness (Ra) is investigated. Experimental results indicate that MRR increases with the increasing of pules-on time and wire tension, the decreasing of pulse-off time and servo voltage. Ra increases with the increasing of pules-on time, servo voltage and wire speed, the decreasing of pulse-off time. Furthermore , a hybrid optimization method is proposed to obtain the optimal processing parameters combination for fast machining speed with low surface roughness based on support vector machine (SVR) and particle swarm optimization (PSO). Verified experimental results indicate that SVR-PSO optimization algorithm can effectively improve the machining characteristics in WEDM of 65 vol.% SiCp/Al composite. Furthermore, the Pareto optimal solution sets based on the SVR-PSO are found to have high precision and reliability.