Investigation of the influence of different types of electrolytes on the performance of the Electrochemical Discharge Machining process during micromachining of molybdenum

Abstract

Electrochemical Discharge Machining (ECDM) is a hybrid process that integrates the principles of Electrochemical Machining (ECM) and Electrical Discharge Machining (EDM) to create micro-holes in both conductive and non-conductive materials that are typically difficult to machine. Given the unpredictable nature of this hybrid method, the composition of the electrolyte emerges as a critical factor influencing the accuracy and performance of the machining process. Consequently, the optimization and analysis of electrolytes are pivotal for the efficient utilization of energy during ECDM and for ensuring machining precision. This study aims to experimentally investigate the impact of various types of electrolytes and their concentrations. These are divided into two categories: neutral solutions, which include sodium nitrate (NaNO₃) and sodium chloride (NaCl), and alkaline solutions, comprising sodium hydroxide (NaOH) and potassium hydroxide (KOH), as well as a mixture of both NaOH and KOH. The evaluation metrics considered include the Material Removal Rate (MRR), Tool Wear Rate (TWR), overcut (OC), Heat Affected Zone (HAZ) and surface quality. It was observed that alkaline solutions, particularly the mixed electrolyte, resulted in higher MRR and HAZ, reduced TWR, and the production of micro-holes with minimized overcut compared to using KOH and NaOH separately or neutral solutions, while also enhancing surface quality. Further analysis using Scanning Electron Microscopy (SEM) images and Energy-Dispersive Spectroscopy (EDS) of the brass tools used with different electrolytes revealed that tools used in KOH and mixed electrolytes exhibited less wear and material erosion compared to those used in NaOH and neutral solutions.