Original Article

Multi-response optimization of wire-EDM parameters for austempered ductile iron using RSM and desirability function analysis

¹ Panimalar Engineering College, Chennai, 600123, India
² Higher Colleges of Technology, Sharjah, 7946, UAE
³ Sri Sivasubramaniya Nadar College of Engineering, Chennai, 600020, India

^* e-mail: sharunvictor@gmail.com

Received: 12 August 2025
Accepted: 24 September 2025

Abstract

Austempered ductile Iron (ADI) has gained significant attention in various engineering applications owing to its unique mechanical properties, such as wear resistance, high strength and ductility. On the other hand, the machining of this material presents challenges due to its complex microstructure and higher hardness. WEDM (Wire Electrical Discharge Machining) is a potential unconventional machining which offers potential precision and surface quality advantages. This research work focuses on achieving higher material removal rate (MRR) with the lower surface roughness (Ra) and less formation of recast layer thickness (R_LT) through the Wire EDM method. In the Wire EDM process, pulse on time (T_on), wire feed (WF), servo voltage (SV) and pulse off time (T_off) were selected as input process parameters. In the current work the Response Surface Methodology (RSM) based central composite design (CCD) technique with the desirability approach was used. The ANOVA was used to check the significance levels of the developed models. MRR increased by 62.41% and Ra decreased by 48.77% with increasing pulse on time (6 μs) and applied wire feed (6 m/min) but decreased with increasing Servo voltage (45V) and pulse off time (4 μs). Under varying depths of penetration, the microhardness value falls between 362 HV and 434 HV for lower level machining parameters and between 382 HV and 465 HV for higher level machining parameters. The surface morphology indicated that the surface roughness of the WEDM samples improved by proper selection of machining variables especially pulse on (T_on) and pulse off (T_off).