Unveiling the Effects of Machining Parameters on Material Removal Rate, Surface Roughness, and White Layer Formation in Hardened Steel

Abstract

This study investigates the impact of Wire Electrical Discharge Machining (WEDM) parameters on Material Removal Rate (MRR), Surface Roughness (SR), and White Layer Thickness (WLT) in hardened tool steel, particularly focusing on enhanced XW42 steel variants. A two-level full factorial design (FFD) and Analysis of Variance (ANOVA) were used to examine the influence of pulse-on time (Ton), voltage (V), and wire tension (WT) on machining performance. Among the modified steels, enhanced XW42 (M3)— enhanced with cerium (Ce), lanthanum (La), and niobium (Nb)—exhibited superior machinability. Enhanced XW42 (M3) demonstrated the lowest WLT (144.32μm) and SR (1.92μm) under optimized conditions (Ton: 2μs, V: 6V, WT: 120N), along with a high MRR of 0.00811kg/s. SEM and EDS analyses confirmed the formation of a smooth recast layer with minimal defects such as cracks, voids, and residual debris, indicating stable machining. The presence of cerium and lanthanum contributed to grain refinement and enhanced thermal stability, while niobium improved hardness and resistance to white layer formation. Predictive modelling for enhanced XW42 (M3) further validated the machining response trends, confirming its suitability for precise process optimization. Regression models showed strong predictive accuracy with R² values exceeding 93% for SR and WLT, and low average errors (SR: 0.7%, WLT: 8.2%). Voltage was identified as the most significant factor affecting WLT (69.23%), whereas Ton had the highest influence on SR (64.45%). These findings underscore the importance of alloying elements and optimized WEDM parameters in achieving high-performance surface integrity and machining efficiency, particularly for applications in the tool and die industry.

Keywords: Cerium, Niobium, Material Removal Rate, WEDM, White Layer Thickness