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Surfactant and graphite powder-assisted electrical discharge machining was proposed and experiments were performed on titanium alloy in this investigation. Analysis was carried out to observe changes in dielectric fluid behaviour, material removal rate, surface roughness, recast layer thickness, surface topography and energy-dispersive X-ray spectroscopy. It was found out that the addition of surfactant to dielectric fluid (electrical discharge machining oil + graphite powder) improved the material removal rate and surface roughness. It was noticed to have reduced the recast layer thickness and agglomeration of graphite and sediment particles. Biface material migrations between the electrode and the workpiece surface were identified, and migration behaviour was powerfully inhibited by the mixing of surfactant. Surfactant added into dielectric fluid played an important role in the discharge gap, which increased the conductivity, and suspended debris particles in dielectric fluid reduced the abnormal discharge conditions of the machine and improved the overall machining efficiency.

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The present study deals with the machining of hybrid Al 7075/B4C/Gr composite using Abrasive Aqua Jet Machining. The effects of selected input factors, i.e., water jet pressure (WJP), stand-off distance (SOD), and traverse speed (TS) on the performance characteristics, namely taper angle (TA), surface roughness (Ra), and the material removal rate (MRR) are investigated. The experimental runs and test strategies are formulated using the Response Surface Methodology-Central Composite Design approach. Analysis of Variance (ANOVA) was used to examine the effect of input factors and their interactions with performance characteristics. MRR, Ra, and TA optimum condition and mathematical equations were also developed. Further, the multi-optimization method “Technique for Order of Preference by Similarity to Ideal Solution” is considered to find out the best combinations of input factors for optimized output factors on the hybrid composite. The ANOVA results confirm that among the input factors, WJP and SOD are the most significant factors, and the percentage distribution of input factors are found to be jet pressure (55.21%), stand-off distance (23.36%), and traverse speed (2.56%). The multi-objective optimum conditions of the input factors are WJP (A1) 210 bar, SOD (B1), and TS (C3) 30 mm/min, that produce optimal values of the considered responses, i.e., MRR up to 4.8703 mm3/min, Ra up to 3.57 μm and TA up to 0.189°. The TA has improved by 49.6% through the multi-objective optimum results when compared with single parameter optimized results. Article Highlights Hybrid Al7075/B4C/Gr composite fabricated through the rotary stir casting technique Experimental planning and designing layouts using Response Surface Methodology scheme and mathematical equations are produced with Design Expert 11.0. The best TA was obtained by RSM-TOPSIS approach, found at a lower WJP and SOD and a higher TS.