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The LM24–7.5ZrB₂–2.5FA hybrid composite presents machining difficulties as it has excellent durability and low-temperature conductivity, making it challenging to machine using standard methods. In spite of this aspect, Electrical Discharge Machining (EDM) is well-suited for machined materials made of aluminum alloys, including LM24–7.5ZrB₂–2.5FA. LM24 aluminum alloy-based hybrid composite prepared using 7.5wt% of zirconium diboride (ZrB₂) and 2.5wt% of Fly Ash (FA) by stir casting route. This study explores the machinability of the hybrid composite and the primary goal is to establish a connection between the process variable’s key efficiency indicators, which include Material Removal Rate (MRR), Surface Roughness (SR), and Tool Wear Rate (TWR), which collectively reflect dimensional accuracy and machining efficiency. The experimentation involves three adjustable process parameters, namely pulse current (I), pulse-on time ($T_{\text{on}}$), and pulse-off time ($T_{\text{off}}$). These variables are subjected to variation, and a total of 20 experimental runs are set up utilizing the Response Surface Methodology (RSM) and a full-factorial Central Composite Design (CCD). Analysis of Variance (ANOVA) is employed to determine which operating variables substantially influence performance characteristics. The analysis reveals that current has a strong influence on MRR, SR, and TWR by 49.5%, 37.7%, and 36.1%, respectively, followed by pulse-on time and pulse-off time. The developed quadratic regression models for MRR, SR, and TWR demonstrated good performance in predicting the responses, as evidenced by the $R^2$ values of 0.9030, 0.9890, and 0.9302 obtained from ANOVA results.

This study deals with the investigation on the effect of Electrical Discharge Machining (EDM) parameters during machining of hybrid composite (Al 7075/TiC/B₄C). The optimum process parameters of die sinking EDM like pulse current, pulse duration and gap voltage on metal removal rate, tool wear rate and surface finish were investigated. Full factorial experimental design was selected for experiments. Analysis of variance was employed to study the influence of process parameters and their interactions on response variables. Among the process parameters considered, it was observed that the pulse current was found to be more influential in affecting MRR, TWR and SR. The other parameters have little effect on the response variable. Multi-objective optimization study was also performed using genetic algorithm to find the optimum parameter setting for controversial objective function combination such as high MRR and low SR and High MRR and low TWR. Scanning electron microscope study was performed to study the surface characteristics.

In the present work, an investigation has been made into the electrical discharge machining process during machining of precipitation hardening stainless steel PH17-4. Taguchi method is used to formulate the experimental layout, to analyze the effect of each process parameter on machining characteristics and to predict the optimal choice for each electrical discharge machining process parameters namely, peak current, pulse on time and pulse off time that give up optimal process performance characteristics such as material removal rate, surface roughness, tool wear rate and surface hardness. To identify the significance of parameters on measured response, the analysis of variance has been done. It is found that parameters peak current and pulse on time have the significant affect on material removal rate, surface roughness, tool wear rate and surface hardness. However, parameter pulse off time has significant affect on material removal rate. Confirmation tests are conducted at their respective optimum parametric settings to verify the predicted optimal values of performance characteristics.

Inconel 718 superalloy is widely used in aerospace industries for fabrication of the various components for aircraft engine because of its high strength at elevated temperature. It is an extremely difficult-to-machine material due to its work hardening nature and poor thermal conductivity. Creating micro-holes of high precision in this material is beyond the capability of conventional twist drill due to its low thermal conductivity. Micro-electrical discharge machining (micro-EDM) is a well-established process for the machining of any electrically conductive hard and brittle material, but due to very small feature size and narrow discharge gap, removal of debris becomes difficult, causes arcing and short-circuiting. In order to solve this problem, authors indigenously developed an innovative ultrasonic-assisted micro-EDM setup for workpiece vibration. The machining performance characteristics of Inconel 718 superalloy was studied using the developed setup in sinking configuration in terms of material removal rate (MRR), tool wear rate (TWR) and hole taper ($T_a$) considering the effect of ultrasonic power, gap current, pulse on time and pulse off time. It was observed that higher ultrasonic power was more suitable for higher MRR, lower TWR and $T_a$. It was also found from the results that 3 A gap current at 6$\mu$s pulse on time was appropriate for better MRR and 12$\mu$s pulse on time was more appropriate for low TWR and $T_a$. The scanning electron microscope (SEM) analysis of created micro-holes was also performed with and without ultrasonic vibration to ensure the quality as well as accuracy.

Electrical discharge machining with rotary tool is known as electric discharge drilling (EDD) which is being widely used for machining the difficult-to-cut materials like super alloy, ceramics and composite materials. Present research work has been introduced to find the impact of four influencing input factors discharge current (C), pulse off time ($T_{\mathrm{\text{off}}}$), pulse-on time ($T_{\mathrm{\text{on}}}$) and drill speed (S) on the response, tool wear rate (TWR), metal removal rate (MRR) and Centre line average value of surface roughness (R_a). The spark erosion drilling was performed on the Inconel 718 with rotating copper electrode. The major performances characteristics material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) are to be evaluated with consultation of Response Surface Methodology (RSM) techniques. The central composite rotatable design (CCRD) has been reported to plan the experimental design and developing the model for prediction of data within the range of investigation. ANOVA test was also carried out to check the adequacy for development of models. It has been evaluated that discharge current, $T_{\mathrm{\text{on}}}$, and $T_{\mathrm{\text{off}}}$ have been found as most significant factors that effects on the performance measures. The models have 86.02, 84.29, and 83.15% values of correlation coefficient (R²) for MRR, TWR and R_a whereas the adjusted R² (R² adj) are 73.80%, 70.55%, and 68.41% for MRR, TWR and SR, respectively.