Papers by Keyword: Electric Discharge Machining (EDM)

Abstract: In the previous many years, several attempts have been made to enhance the effectiveness of the Spark erosion machining process. This review clearly mentioned all the work outputs of Vibration Assisted Electric Discharge Machining at a glance. One of these non-traditional machining techniques, called electric discharge machining (EDM), produces higher surface finishes, high levels of precision, and machinability. Ultrasonic vibrations are used in many industrial processes, such as material removal operations for form generation on material surfaces. Lately, there has been an increasing trend toward using ultrasonic vibration to enhance process performance. Ultrasonic vibration finds noteworthy application in industrial processes such as spark erosion machining, where vibration is enhanced by using ultrasonic waves as a medium. The electrode's ultrasonic vibration modifies the discharge gap and improves the chip removal capability, making it a very effective technique for raising EDM efficiency. An overview of the literature on the application of ultrasonic vibrations in electric discharge machining is presented in this article. Review work has been done on how ultrasonic vibrations can be applied, their ability to affect performance metrics, how to predict and optimise processes, and how to use them with advanced materials that can be difficult to cut. Future requirements for research have been highlighted to increase the ability and potential for the technique of electric discharge machining based on an evaluation of the present state of ultrasonic-assisted electric discharge machining.

Abstract: The paper reviews machining of CoCr alloys by electric discharge machining and ultrasonic aided discharge machining. The removal mechanism is discussed, modeled with Comsol Multiphysics and validated using experimental data.

Abstract: A well-designed experimental were conducted with L₁₈ Orthogonal Array (OA) based on the Taguchi method with input factors discharge current, pulse on time, lift time and flushing pressure. Micro hardness was measured and the mean of the observed values were plotted. The factors effecting the micro-hardness of the work-piece has been obtained. It is inferred that micro-hardness value increases with increase in discharge current and decreases with increase in Pulse on Time. The optimal condition for minimum hardness was found to be discharge current (Ip) = 2A, pulse on time (Ton) = 500μs, lift time (Tup)= 1.4 ms and flushing pressure (Fp)= 0.2 kgf/cm².

Abstract: Electric discharge machining process is an unconventional machining process primarily used for machining the materials such as difficult to machine in conventional machining process, hardest material and composite materials. In the present work, a study is made to find out the optimum EDM process parameters during machining of AA6061-15% boron carbide composite fabricated through stir casting technique. Three process parameters such as Current, pulse on time and pulse of time are opted as machining parameter variables. Response surface methodology is used to formulate the mathematical model for material removal rate, tool wear rate and surface roughness. Response surface methodology and genetic algorithm are applied to optimize the machining parameters individually by taking combined objective function and compared. Genetic algorithm optimization techniques yields better results than desirability approach. Key words: Electric discharge machining, MRR, TWR, Ra, RSM, Genetic algorithm

Abstract: The main requirements of carbide metal working are higher precision and high quality surface which can be fulfilled by electrical discharge machining. This procedure is accompanied with formation of heat affected zones (white layers) during the discharge process negatively. Therefore, the essential post-processing reduces the efficiency of this process and shows the importance of process energy sources (PES) with ultra short discharge in favor of a clearly differentiated cutting volume. By means of simulations of crater geometry and channel expansion the influence of discharge rise time is defined as determining factor for the cut volume and formation of white layers. The technological section presents two different approaches of realizing ultra-short pulses.

Abstract: In order to slice the larger size ingot toward 6 inch of silicon carbide (SiC), we are developing Multi-wire Electric Discharge Machining (EDM). To prevent wire break during slicing, we have developed the electric discharge pulse control system. So far, with 10 multi-wires, we have succeeded in slicing of 4 inch SiC balk single crystal without wire break. High quality slicing surface (e.g. small value of around 10 μm of SORI for 3 inchi wafer) was also achieved. By polishing methode, EDM-sliced wafer was estimated to have the uniform thickness of damaged layer over the entire surface. We confirmed that the wafer sliced by EDM can be processed in the later process, by grinding the 3 inch wafer. And it was confirmed that 6 inch ingot can be sliced with 10 multi-wire EDM, by slicing the boule of SiC poly crystal. For the larger diameter ingot than 4 inch, Multi-wire EDM will be practically used by the effective removal of machining chips from the machining clearance between the wire and work.

Abstract: The damage induced at the cut surface of SiC crystal by slicing were investigated by Raman scattering method and transmission electron microscopy. Electric discharge machining (EDM) predominately forms cracks, silicon, carbon and 3C-SiC by 6H-SiC pyrolysis and wiresawing with loose abrasive (WSLA) induces triangular crystal disordered area, stacking faults and dislocation loop bundles by stressing at the cut surfaces of SiC crystal.

Abstract: In recent years, a lot of effort has gone into many researchers making components of specific functions, mimicking various microstructures in nature. In this study, a super hydrophobic surface on injection-molded liquid silicone rubber was fabricated, mimicking micro-bumps on a lotus leaf. Original patterns were machined by electric discharge machining and liquid silicone rubber was injection-molded by using the original patterns as molds. The hydrophobic characteristics of injection-molded liquid silicone rubber surface replicated from the original electric discharge machined surface were studied. According to variations of injection molding process parameters like mold temperature, injection speed, injection pressure, vacuum, etc. the variations of water contact angles, as a hydrophobic index, measured on the injection-molded surfaces were examined. The liquid silicone rubber surface molded from wire-cutting electric discharge machined surface at mold temperature 120°C, injection speed 5 mm/sec, injection pressure 70 bar and in a vacuum cavity showed water contact angle of 148°, which is close to super-hydrophobic level.

Abstract: Electrical Discharge Machining (EDM) is the most extensive non-conventional material removal processes used. In recent years, EDM researchers have been explore several sparking efficiency improvement methods including some unique experimental concepts that begin from the EDM traditional sparking phenomenon. This paper reports the use of layered cylindrical electrodes combined with jatropha curcas as dielectric fluid which is not widely used in the EDM process. The results are compared with the EDM process using kerosene dielectric fluid and single electrode (conventional). Dielectric fluid jatropha curcas is expected to substitute the commonly used dielectric fluid. Dielectric strength was tested by the impulse method. Furthermore, the EDM process is measured using surface roughness and microhardness of white layer values at various cutting conditions on the material SKD 61 as an indicator. The highest value of white layer hardness using jatropha curcas dielectric fluid is provided by three layers of electrodes, whereas the lowest is resulted of two layers of electrodes. Meanwhile, the use of kerosene dielectric fluid, the highest hardness value is achieved by two layers of electrodes, and the lowest is produced by three layers of electrodes. This study shows that jatropha curcas dielectric fluid is potential to be used in the EDM process since it produces a smoother surface and higher white layer hardness value.

Abstract: In the present study, the powder mixed EDM (PMEDM) process was simulated using FE approach to obtain simulated temperature profiles for estimating the crater dimensions and volume removed during formation of each crater. The craters formed in PMEDM process had higher diameter and shallow depth resulting in improved MRR and better surface finish. The addition of powder increased the amount of heat available at the workpiece between 20-25% as compared to conventional EDM process. The results were subsequently validated experimentally to compare the actual measurements with the simulation output. Predictor equations for crater radius and depth incorporating the significant factors were developed and also validated with the experimental results.