Intelligent optimization of micro-electrical discharge machining of aluminum nitride ceramics using nano abrasive zirconium oxide-enhanced biodegradable dielectric.

This study explores the use of nano-enhanced Canola Oil Methyl Ester (COME) formulated with 0.5 wt% of zirconium oxide (ZrO2) nanoparticles as a biodegradable dielectric fluid in sustainable micro-electrical discharge machining (micro-EDM) of aluminum nitride (AlN) ceramics. The Box-Behnken design was employed to test the voltage (100-150 V), capacitance (10-20 nF) and electrode geometry (O-shaped, D-shaped) using Response Surface Methodology (RSM) and Artificial Neural Networks (ANN) to optimize several objectives simultaneously. Analysis of Variance (ANOVA) has identified dielectric type the most significant contributor to the variation in Material Removal Rate (MRR), Relative Wear Rate (RWR), and Surface Roughness (SR), with a contribution of 33.0%, 37.4% and 45.2% correspondingly (p < 0.0001). Optimal conditions at 125.4 V and 15.2 nF with O-COME (+) denoting an O-shaped tool electrode operating at positive polarity with COME dielectric achieved a predicted MRR of 26.89 mm³/min and RWR of 0.43 and SR of 4.87 μm, demonstrating significantly better material removal and wear behavior compared to the conventional electrode metalworking fluid (EMWF). The ANN model was found to be highly predictive (R2 = 0.96, mean squared error (MSE) = 0.002) with an average prediction error of less than 3.5%. Nonetheless, the experimental variability (CV = 19.9-53.6%) was considerable among conditions, which implies that better control of the processes and higher sample size should be implemented before complete implementation in industries. CFD confirmed the superior dielectric flow behavior of the COME variants, and thus, the important formation of conductive layers needed to machine non-conductive AlN. There is a slight reduction in surface quality compared to EMWF. However, nano-enhanced COME shows strong potential for sustainable precision manufacturing. This work improves precision machining processes and replaces petroleum-based dielectric fluids with biodegradable vegetable oil-based alternatives. It also reduces emissions and improves safety in the working environment.