Enhancing μ-slots fabrication on Cu-based shape memory alloy via B 4 C-assisted micro-electrochemical machining

Abstract

Electrochemical micro-machining (µECM) enables highly localized, burr-free and thermally damage-free fabrication of precision micro-features, offering superior dimensional control compared to conventional ECM. While ECM is effective for machining complex macro-scale geometries in hard-to-machine conductive materials, its localization is limited at micro-scales. Consequently, µECM has become essential for biomedical, aerospace, and microelectronics applications requiring accurate micro-fabrication. Despite its advantages, conventional µECM often faces challenges such as low material removal rate (MRR), limited dimensional accuracy and surface irregularities, which restrict its overall effectiveness in microscale manufacturing. In the present study, µECM of Cu-based shape memory alloys (Cu-SMAs) was carried out using both a conventional NaCl solution and an abrasive-assisted electrolyte containing boron carbide (B₄C) with mesh size 500 mesh. The effects of applied voltage, tool feed rate and electrolyte concentration on machining responses MRR, surface roughness (SR) and width overcut (WOC) were systematically analysed. Experimental findings indicated that the incorporation of abrasives significantly enhanced machining efficiency. The best combination of MRR, SR and WOC was obtained at a voltage of 16 V, feed rate of 0.35 mm/s and electrolyte concentration of 30 g/L under abrasive-assisted (B₄C) µECM conditions. This condition provided a balanced performance, characterized by a relatively high MRR (0.505 mg/min), improved surface finish (1.438 µm) and minimum overcut (0.008 mm). These results confirm that abrasive-assisted µECM offers improved material removal, surface finish and geometric control, making it a more reliable method for precision machining of Cu-SMAs.