Electrical discharge machining is a non-contact process based on thermoelectric energy between the electrode and workpiece. It is an efficient machining process to machine an advanced, difficult-to-machine material with high precision, complex shapes and high surface quality. Realizing the advantages and abilities of this machining method, electrical discharge machining research has caught the interest of many researchers. This paper reviews the electrical discharge machining process, including recent research fields and inventions that have been developed in order to improve workpiece surface quality and integrity, machining time, tool wear and material removal rate. Electrical discharge machining apparatus and its servomechanism system, including mechanical structure developments using computer numerical control, a lead-screw mechanism and linear motor driven and piezoelectric actuators, are also reviewed. Furthermore, control strategies that are applied to electrical discharge machining systems, including servo-drive control and optimization techniques, such as fuzzy, genetic algorithms and artificial neural networks, are also discussed.

Methane conversion to higher hydrocarbons by pulsed glow discharge at the atmospheric pressure was investigated. The energy efficiency up to 10 % was obtained which is higher than any value ever published for nonequilibrium plasma conversion of pure methame. This method has a potential for development and it is expected that the energy efficiency will be improved further if the plasma parameters are optimized.

Rapid prototyping with Low Frequency Selective Electrical Discharge Sintering (SEDS) is a new method in manufacturing of parts and masters. In this method, an electrical plasma arc provides the required thermal energy for initial binding. A polymeric coated metal powder as raw material is used in SEDS and initial binding is constructed by liquid phase sintering. Sequential layers are manufactured according to their CAD models. A moving electrode scans entire of the surface and the generated thermal energy of the plasma arc is exerted to the particle powders in the selective points of the powder bed. After manufacturing of all of the layers, the green part is removed from the built-chamber of the SEDS system and is put in the appropriate furnace to complete the sintering process. Then for decreasing the porosity and increasing the strength of the part, the infiltration process is done. The manufactured part in the SEDS method is a functional part. The SEDS method has some valuable potential which provide the manufacturing of the large parts and masters.

The creation of modified layer on metal surfaces using new methods is one of the procedures in surface engineering which can improve the surface mechanical properties. The electrical discharge process is a new method that can form a modified layer on the metal surfaces. This study aims to improve of pure aluminum surface properties through Electrical Discharge process with Monel 400 electrode. In order to design the experiments, the pulse on time and the pulse current were considered as input parameters. The SEM images indicated that the increase in the pulse on time and the pulse current can increase the thickness of the modified layer. Based on the obtained results, the thickness of improved layer varied between 35 to 75 microns. The results of the EDX analysis showed the diffusion of the copper and nickel to the aluminum surface. Moreover, the results of microhardness testing of the surface layer showed that after Electrical discharge process, the surface hardness has increased and the surface hardness as 35 Vickers has reached more than 400 Vickers.

This paper deals with the application of discriminant analysis in an electrical discharge machining (EDM) process to determine the comparative contribution of each of its input parameters on the measured responses. It also identifies the most significant EDM process parameters influencing those responses. For this process, voltage, current, pulse-on time and pulse-off time are considered as the input parameters, whereas, material removal rate, electrode wear rate and surface roughness are the responses. Based on the past and simulated experimental data, both simultaneous and step-wise estimations are carried out for each of the three responses showing the relationships between the EDM process parameters and the considered responses. It is observed that in both these estimations, pulse-off time, current and pulse-on time respectively evolve out as the most significant parameters for material removal rate, electrode wear rate and surface roughness. Step-wise estimation identifies voltage as the least significant input parameter for all these responses. The developed discriminant functions, which can also help in predicting the responses, are finally cross-validated.

In this study, electrical discharge process was used to increase surface wear resistance of pure aluminum. Pulse-on-time and pulse current were considered as the input parameters of the electrical discharge process. Experimental results revealed that the electrical discharge process is a successful method for improving the surface wear resistance of aluminum, to the effect that it has greatly increased the surface wear resistance of aluminum parts. The results indicate that with increasing the input parameters (pulse-on-time and pulse current), weight loss of the aluminum specimens is reduced and wear resistance increases. The XRD analysis demonstrated that Al3Ni2 and AlCu intermetallic compound and Al4C3 were formed on the alloyed surface. The presence of these compounds and hard particles on the surface increases the wear resistance. Also, friction coefficient measurements showed that after electrical discharge process and improving surface wear resistance, the friction coefficient slightly increased due to the presence of hard particles on the alloyed surface.