Effect of coated and geometrically modified tools on performance of electrochemical micromachining

Micro-holes are the basic features which are found in various components of medical devices, electronics, and biotechnology devices. The existing machining methods in ECMM for making micro-holes are generally accompanied with higher overcut (OC). Therefore, it is important to suppress OC and improve the machining rate (MR) which predominantly depend on electrode size, electrical parameters, tool electrode insulation, and electrolyte type. Hence, in this research, the suitable tool geometry and coating for the tool electrode is proposed, namely, ceramic, hot melt adhesive (HMA), and hollow wedge, short solid tools, respectively. The effect of electrolyte concentration in g/L, machining voltage in V and duty cycle in % on the OC and MR was studied. The results show that the ceramic tool produces 43.1% lesser OC than normal tool at the parameter combination of 23 g/L, 15 V, and 85% and short solid tool produces 74.3% higher MR for former with same parametric combination. The scanning electron microscope pictures of micro-holes were analyzed to study the effect of tool geometry and its coating. The ceramic and HMA coated tools control the leakages of current and shape modified tools to enhance the flow of current in the inter-electrode gap.