Dimensional accuracy and surface quality in Wire-Cut EDM of Ti6Al4V: experimental study and optimization

Abstract Ti6Al4V is widely recognized for its exceptional strength-to-weight ratio and is extensively used in aerospace and biomedical applications. This study focuses on optimizing the Wire-Cut Electrical Discharge Machining (WEDM) parameters to minimize geometrical and dimensional errors, such as cylindricity, perpendicularity, dimensional deviation (DD), and taper. The main objective is to enhance machining precision, improve surface integrity, and extend the performance and lifespan of the assembled components. The experimental design was developed using the Taguchi L9 Orthogonal Array (OA) for three key process parameters Pulse-on Time (T ON ), Pulse off Time (T OFF ), and Control of Servo (CS) each at three levels. This approach effectively reduced the number of required experiments while maintaining a robust analysis. The Gray Relational Analysis (GRA) technique was subsequently applied to obtain a global optimum for multiple response optimization. Regression equations were developed to establish relationships between the process parameters and responses, and validation was performed at a 95% confidence level. The experimental results revealed that the optimal parameter combination for the square geometry was a T ON of 110 µs, T OFF of 60 µs, and CS of 70%, whereas for the circular geometry, the best results were obtained at a T ON of 106 µs, T OFF of 58 µs, and CS of 80%. Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) confirmed surface roughness values of 4.47 μm and 4.11 μm for the square and circular holes, respectively. The findings demonstrate that the optimized WEDM parameters significantly improved the machining quality, reduced the inspection time, and minimized the production costs while achieving high dimensional accuracy and superior surface finish.