Experimental Investigation and Optimization of WEDM Process Parameters for Al7075-SiC-Graphite Hybrid Composite Based on Surface Roughness and Material Removal Rate

Abstract

Now-a Wire Electrical Discharge Machining (WEDM) is an advanced non-traditional machining process extensively used for fabricating intricate and high-precision components from difficult-to-machine materials. In this study, an experimental investigation is conducted to analyze the influence of key WEDM process parameters on surface roughness (SR) and material removal rate (MRR) during machining of an Al7075-based hybrid composite reinforced with silicon carbide (7.5%) and graphite (2%). The primary process parameters considered include pulse-on time, pulse-off time, servo voltage, and wire feed rate, each varied at three levels. Experiments were systematically designed using the Taguchi method with an L9 orthogonal array to ensure efficient experimentation and reliable analysis. Other machining conditions such as wire diameter (0.3 mm), peak current (1.1 A), dielectric medium (distilled water), and wire tension (7 kgf) were maintained constant. Statistical analysis was carried out using Minitab software to evaluate the significance and contribution of input parameters on SR and MRR. The results reveal that pulse-on time and servo voltage significantly influence machining performance. An optimal combination of process parameters was identified to achieve improved surface quality and enhanced material removal rate. The findings of this study provide valuable insights into the optimization of WEDM parameters for hybrid composite materials, contributing to improved productivity and surface integrity in advanced manufacturing applications.

Introduction

This study focuses on Wire Cut Electric Discharge Machining (WEDM), a non-traditional machining process used for cutting hard and electrically conductive materials that are difficult to machine using conventional methods. WEDM is widely applied in tool and die manufacturing, mold making, aerospace, and electronics industries because it can produce complex shapes, contours, and cavities in materials such as hardened steel, titanium, Inconel, Hastelloy, and other advanced alloys.

The literature review highlights previous research that investigated the influence of machining parameters such as pulse-on time, pulse-off time, voltage, wire feed, wire tension, and flushing pressure on Material Removal Rate (MRR) and Surface Roughness (SR). Researchers used the Taguchi method and ANOVA analysis to identify optimal machining conditions while minimizing the number of experiments.

The objective of this work is to examine how four WEDM parameters—pulse-on time (100, 150, 200 µs), pulse-off time (52, 56, 60 µs), servo voltage (30, 50, 70 V), and wire feed rate (2, 3, 4 mm/min)—affect MRR and surface roughness of a composite workpiece. Other parameters, including wire diameter, peak current, coolant type, and wire tension, were kept constant. Optimization was performed using the Taguchi L09 orthogonal array and Minitab software.

Experiments were conducted on a CNC Sprint Cut 734 Wire EDM machine. Nine experimental runs were designed according to the Taguchi method, and measurements of surface roughness and MRR were recorded. The results showed noticeable variations in machining performance depending on the selected parameter combinations. Surface roughness values ranged approximately from 3.27 to 4.69 µm, while MRR values ranged from about 249.59 to 346.19 mm³/s.

Finally, the collected data were analyzed using Signal-to-Noise (S/N) ratio plots in Minitab to determine the optimal machining parameters for achieving maximum material removal rate and minimum surface roughness. The study demonstrates the effectiveness of the Taguchi optimization technique in improving WEDM machining performance.

Conclusion

Here in this thesis we are going to investigate the effect of various parameters used in wire cut EDM process on MRR and surface roughness to obtained the optimal set of parameters on the machined work piece. So here the experiments are conducted on the composite work piece material using the respective parameters i.e., pulse on time - 100µsec, 150 µsec, 200µsec &Pulse Time off – 52µsec, 56µsec, 60µsec, servo voltage – 30V, 50V, 70V & Wire Feed – 2mm/min, 3mm/min, 4mm/min. Other parameters are kept constant such as Wire dia - 0.3mm; peak current – 1.14Amp and Coolant is Distilled water, Wire Tension – 7Kgf.So the optimization process is done using taguchi technique using Minitab software. So finally for the taguchi method, for the MRR here the optimal result is pulse on time is at 150µsec, pulse off time is at 52µsec, servo voltage should be set at 70V and wire feed has to beat 2mm/min So when we consider the SR MRR here the optimal result is pulse on time is at 100µsec, pulse off time is at 60µsec, servo voltage should be set at 50V and wire feed has to be at 2mm/min So when we have verified the hardness of this composite material (Al 6061 (90.5%) + SCi(7.5%)+Graphite(2%)) herewehaveachieved110BHN,whencomparedwiththebasematerial aluminum alloy block ranges form 75 – 89BHN.

References

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Copyright

Copyright © 2026 Rekadi Srinivasa Rao, Mr. Dangeti Mahesh, Mr. K.V. Ramana Murthy. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.