Effect of disk-shaped tools on ECDM performance in micro-hole drilling

Abstract

Electrochemical discharge machining (ECDM) is a non-conventional machining process popular for creating microfeatures such as micro holes and microchannels in non-conductive materials like glass and alumina samples. However, the quality of the drilled holes through ECDM severely decreases as the machining depth increases due to the scarcity of electrolytes and the challenges of debris removal from the machining zone. The present study aims to enhance the machining efficiency and improve the quality of blind holes at higher depths. The disk-shaped tools are fabricated to improve electrolyte supply at higher depths, ensuring effective gas film formation and providing better electrolyte circulation for debris removal. The effect of disk-shaped tools is compared with cylindrical tools using material removal rate (MRR), hole entrance overcut, and aspect ratio as response parameters. The input variables are the applied pulse voltage, pulse frequency, and machining depth. The ANSYS Fluent computational fluid dynamics (CFD) software is used for numerical simulation of the crater profile and mushy zone in single-discharge machining. The mushy zone properties are modeled in between the solidus (<893 K) and liquidus (>1093 K) temperatures of the workpiece. The temperature-dependent physical properties of the borosilicate glass, including thermal conductivity, viscosity, and specific heat, are considered in the range of 500 °C–1500 °C. Results showed that disk tools improved the MRR by 34.5 % and aspect ratio by 26 %, compared to the cylindrical tools. The experimental and simulation results are consistent, with an average deviation of 10 %.