Micro-EDM machinability of conductivity-
engineered PMMA/MWCNT/Ag hybrid 
nanocomposites for micro-hole fabrication

Polymer-based nanocomposites with engineered electrical conductivity have attracted considerable attention for precision micro-manufacturing applications. However, the micromachining behavior of hybrid conductive polymer nanocomposites, particularly under nontraditional processes such as micro-electrical discharge machining (micro-EDM), remains largely unexplored. To address this research gap, a novel hybrid nanocomposite comprising polymethyl methacrylate (PMMA) reinforced with 10 wt.% multi-walled carbon nanotubes (MWCNTs) and 2.5 wt.% silver nanoparticles was synthesized and evaluated for micro-EDM machinability, with potential applications in biomedical and precision engineering sectors. Using a solution-mixing technique, the nanocomposite was created, resulting in the fillers being evenly distributed throughout the PMMA matrix. Structural and electrical characterization were performed using X-ray diffraction over a defined 2θ range, scanning electron microscopy (SEM) for morphological assessment, and dielectric spectroscopy across a broad frequency spectrum to evaluate conductivity enhancement and interfacial polarization behavior. Dielectric spectroscopy revealed enhanced electrical conductivity and interfacial polarization within the nanocomposite matrix, indicating improved charge transport pathways necessary for stable spark initiation during micro-EDM. The composite was successfully micromachined using micro-EDM using brass (0.5 mm), tungsten (0.5 mm), and copper (0.4 mm) wire electrodes in a hydrocarbon-based electrical discharge machining oil dielectric with varying input voltages (100–150 V) and pulse on-time ratios (10%–50%). The maximum material removal rate achieved was 0.0063 mm³/s using a tungsten electrode. SEM revealed hole diameters ranging from 450 to 555 µm, with tungsten electrodes showing the lowest roundness error (~40 µm), corresponding to approximately 8% deviation relative to the 0.5 mm nominal electrode diameter. Tool wear analysis showed minimal degradation for tungsten electrodes compared to copper and brass. In this study, a PMMA/MWCNT/Ag hybrid nanocomposite was synthesized, characterized, and systematically evaluated for micro-EDM machinability under varying discharge parameters.