# Effectiveness of Electrode Design Methodologies for Fast EDM Slotting of Thick Silicon Wafers
## 1 Introduction
[PERSON] et al. [26] analyzed the influence of ultrasonic EDM, powder-mixed EDM, and powder-mixed ultrasonic EDM on the machining of Ti-6 Al-4V for an increased material removal rate and reduced surface roughness. Silica (SiO\({}_{2}\)) nano powder was mixed with dielectric fluid, and tools vibrated at a 20 kHz ultrasonic frequency. Two different types of dielectrics (i.e., with and without nano powder) and two different electrode modes (i.e., with and without ultrasonic vibration) and their combinations were used. Each hybrid machining method was found to have a higher rate of material removal than the standard EDM. For powder-mixed ultrasonic EDM (PM-US-EDM), the vibration was magnified in the presence of nanoparticles. As a result, it generated the roughest surface roughness (SR) and highest MRR among ultrasonic (US) EDM, powder-mixed (PM) EDM, and standard EDM. Meanwhile, PM-EDM exhibited the least surface roughness among all the processes discussed. The addition of nanoparticles to the dielectric resulted in an increase in the machining gap and spark frequency, which generated low and uniform energy for each spark, causing smaller sparks, shallower cavities, and a smoother surface finish. [PERSON] et al. [27] investigated the effect of pressure flushing in the EDM of X153 CrMoV12-1 using brass electrodes. The dielectric flow rate varied from 5 to 25 L/h. It was found that the feed rate increased with the increasing flow rate of the dielectric fluid. However, there was a limit in the maximum feed rate, and after that, there was a reduction in the feed rate, which was seen as being over this maximum. The superior cooling behavior of the dielectric during pressure flushing is thought to be the cause of the decreased electrode wear. Higher flow rates increased the removal of the heat that developed during discharge and reduced the wear in the tool electrode. The surface properties gradually deteriorated at the increasing flow rates due to hydraulic pressure, which resulted in poor surface quality. [PERSON] et al. [28] investigated the effects of side flushing and multi-aperture inner flushing on machining performance during the EDM of AISI P20 plastic mold steel using copper electrodes. The flushing pressure was set to 0.098 MPa for both side flushing and multi-aperture flushing. Side-flushing and multi-aperture flushing were found to improve the MRR process with increasing pulse on time, current, and electrode rotation. The electrode rotation and pulse on time had an inverse relationship with the TWR of side flushing and multi-aperture flushing, but a positive relationship with the current. [PERSON] et al. [29] analyzed the EDM of nickel-based alloy MARM247 using two different graphite electrodes, EDM-3 and HK-6, with and without the assistance of vibration. It was found that the vibration amplitude had a significant influence on the machining time and MRR and a negligible influence on the TWR. The maximum rate of material removal with the optimal amplitude and frequency was reported to be 53.71 mm\({}^{3}\)/min, whereas it was 50.6 mm\({}^{3}\)/min in the absence of vibration. Therefore, when utilizing the HK-6 electrode, there was an increase in the MRR of about 6.15% when vibration-assisted EDM was employed. When vibration-assisted technology was applied using EDM-3 electrodes as opposed to HK-6 electrodes, the rate of material removal dramatically increased. The MRR was 32.9 mm\({}^{3}\)/min without vibration and 56.6 mm\({}^{3}\)/mm with vibration. Compared to HK-6, the rate of tool wear of the EDM-3 electrode increased significantly with vibration. It was found that neither the electrode material nor the vibration had an impact on the surface roughness, which was mostly influenced by the electrical parameters. Moreover, [PERSON] et al. [30] also investigated the effect of polarity on the MRR for graphite and copper electrodes where the workpiece was AISI P20 tool steel and found that the performance of the EDM process can be manipulated by the selection of electrode polarity. [PERSON] et al.