Experimental investigation on machining accuracy of polycarbonate material using vibro-magnetic electro chemical discharge machining (VM-ECDM) process

Polycarbonate (PC) material is extensively used in the medical, aerospace, defense, and automotive sectors. However, machining PC to create micro features using conventional methods poses significant challenges. To address this issue, Electro Chemical Discharge Machining (ECDM) has been explored for machining PC. Recent advancements have focused on enhancing ECDM performance by incorporating ultrasonic vibrations and magnetic fields. This study presents an experimental analysis of the Vibro-Magnetic ECDM (VM-ECDM) process for machining non-conductive PC polymer material. The investigation examines the ECDM process with varying configurations of ultrasonic vibration frequency and magnetic flux. Experiments were conducted using a Taguchi L 27 orthogonal array, with controlling factors including electrolyte concentration, voltage, duty cycle, ultrasonic vibration frequency, and magnetic flux. The study measured Material Removal Rate (MRR), Tool Wear Rate (TWR), and Over Cut (OC) as output response factors. Grey Relational Analysis (GRA) was employed to optimize the machining parameters, using Grey relational grade to consider MRR, TWR, and OC simultaneously as desired objectives. The optimal combination of process parameters determined through GRA included a 70 V applied voltage, 20% electrolyte concentration, 40% duty cycle, 21 kHz ultrasonic vibration frequency, and 0.000329 Wb magnetic flux. A confirmation test with these parameters showed that the experimental data matched the expected values satisfactorily. Microstructural analysis using a Scanning Electron Microscope revealed resolidified globules, deep grooves, and micro cracks on the workpiece surface.