Electrical discharge machining (EDM) is a well-established machining option for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining processes. The non-contact machining technique has been continuously evolving from a mere tool and die making process to a micro-scale application machining alternative attracting a significant amount of research interests. In recent years, EDM researchers have explored a number of ways to improve the sparking efficiency including some unique experimental concepts that depart from the EDM traditional sparking phenomenon. Despite a range of different approaches, this new research shares the same objectives of achieving more efficient metal removal coupled with a reduction in tool wear and improved surface quality. This paper reviews the research work carried out from the inception to the development of die-sinking EDM within the past decade. It reports on the EDM research relating to improving performance measures, optimising the process variables, monitoring and control the sparking process, simplifying the electrode design and manufacture. A range of EDM applications are highlighted together with the development of hybrid machining processes. The final part of the paper discusses these developments and outlines the trends for future EDM research.

http://zclient.persiangig.com/ScienceDirect/M02.pdf

State of the art electrical discharge machining (EDM)

Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and an electrode. A pulse discharge occurs in a small gap between the work piece and the electrode and removes the unwanted material from the parent metal through melting and vaporising. The electrode and the work piece must have electrical conductivity in order to generate the spark. There are various types of products which can be produced using EDM such as dies and moulds. Parts of aerospace, automotive industry and surgical components can be finished by EDM. This paper reviews the research trends in EDM on ultrasonic vibration, dry EDM machining, EDM with powder additives, EDM in water and modeling technique in predicting EDM performances.

A review on current research trends in electrical discharge machining (EDM)

Advancing EDM through fundamental insight into the process

This paper provides a roadmap of development in the thermal and fabrication aspects of microchannels as applied in microelectronics and other high heat-flux cooling applications. Microchannels are defined as flow passages that have hydraulic diameters in the range of 10 to 200 micrometers. The impetus for microchannel research was provided by the pioneering work of Tuckerman and Pease [1] at Stanford University in the early eighties. Since that time, this technology has received considerable attention in microelectronics and other major application areas, such as fuel cell systems and advanced heat sink designs. After reviewing the advancement in heat transfer technology from a historical perspective, the advantages of using microchannels in high heat flux cooling applications is discussed, and research done on various aspects of microchannel heat exchanger performance is reviewed. Single-phase performance for liquids is still expected to be describable by conventional equations; however, the gas flow may...

Evolution of Microchannel Flow Passages-Thermohydraulic Performance and Fabrication Technology

Wire electrical discharge machining (WEDM) is a specialised thermal machining process capable of accurately machining parts with varying hardness or complex shapes, which have sharp edges that are very difficult to be machined by the main stream machining processes. This practical technology of the WEDM process is based on the conventional EDM sparking phenomenon utilising the widely accepted non-contact technique of material removal. Since the introduction of the process, WEDM has evolved from a simple means of making tools and dies to the best alternative of producing micro-scale parts with the highest degree of dimensional accuracy and surface finish quality. Over the years, the WEDM process has remained as a competitive and economical machining option fulfilling the demanding machining requirements imposed by the short product development cycles and the growing cost pressures. However, the risk of wire breakage and bending has undermined the full potential of the process drastically reducing the efficiency and accuracy of the WEDM operation. A significant amount of research has explored the different methodologies of achieving the ultimate WEDM goals of optimising the numerous process parameters analytically with the total elimination of the wire breakages thereby also improving the overall machining reliability. This paper reviews the vast array of research work carried out from the spin-off from the EDM process to the development of the WEDM. It reports on the WEDM research involving the optimisation of the process parameters surveying the influence of the various factors affecting the machining performance and productivity. The paper also highlights the adaptive monitoring and control of the process investigating the feasibility of the different control strategies of obtaining the optimal machining conditions. A wide range of WEDM industrial applications are reported together with the development of the hybrid machining processes. The final part of the paper discusses these developments and outlines the possible trends for future WEDM research.

State of the art in wire electrical discharge machining (wedm)

Assisting Electrode Method for Machining Insulating Ceramics

A driving method suitable for a micro mechanism is introduced. It utilizes friction and inertial force caused by rapid deformations of piezoelectric elements. A one-dimensional linear positioner using this mechanism consists of one main object put on a guiding surface, a piezo, and a weight. The weight is connected to one end of the main object via the piezo. By controlling rapid extension or contraction of the piezo, it can make step-like movements of several nanometers up to ten micrometers bidirectionally against friction. By repeating this step movement, it can move for a long distance. Using this mechanism, two types of joints for micro robot arm are developed. One is a simple rotating joint with an arm of 5 cm, and the other is a three-degree-of-freedom (DOF) joint with an 8 cm arm. Minimum step movements of the two joints were smaller than 0.1 mu m and maximum velocities were larger than 2 mm/sec at the end of the arm. Combining two joints, a four-DOF micro robot arm was developed. >

Precise positioning mechanism utilizing rapid deformations of piezoelectric elements

This paper deals with a displacement control method of a piezoelectric actuator (piezo). When voltage is applied to conductive plates which are attached on both ends of a piezo, charges are induced on the conductive plates. This induced charge indicates the deformation of the piezo. Since the relationship between the deformation of the piezo and the induced charge has less hysteresis, the displacement of the piezo can be measured by observing the induced charge. In the case of step response, the displacement of the piezo can be controlled by the feedback of the induced charge as well as by a feedback of the displacement with other measuring instruments. This method can be used at a high driving frequency as the piezo is driven with a voltage source which has a low output impedance.

https://iopscience.iop.org/article/10.1088/0957-4484/9/2/009/pdf

Displacement control of piezoelectric element by feedback of induced charge

This paper describes the influence of the discharge current and the pulse duration on the titanium carbide (TiC) deposition process by electrical discharge machining (EDM) with titanium (Ti) powder suspended in working oil. Although the influence of the electrical conditions for removal EDM has been investigated, the criteria for deposition have not been discussed. In the experiments, a 1-mm copper rod was used for an electrode to prevent the flushing of working oil from the gap between the electrode and a workpiece. Ti powder reacted with the cracked carbon from the working oil, then depositing a TiC layer on a workpiece surface. A major criterion of the deposition or removal was the discharge energy over a pulse duration of 10 μs. A thickness of the TiC layer became the maximum at a certain discharge current and pulse duration. Larger discharge energy and power promoted the removal by heat and pressure caused by the discharge. The removal was classified further into two patterns; cracks were observed on the Ti-rich surface in removal pattern 1 and a workpiece was simply removed in removal pattern 2. The maximum hardness of the deposition was 2000 Hv. The workpiece about 10 μm beneath its surface was also hardened because of the dispersion of TiC. The machining conditions for the hardest deposition did not coincide with those for the highest one. Therefore, the discharge current and pulse duration should be optimized for the deposition.

Influence of electrical conditions on performance of electrical discharge machining with powder suspended in working oil for titanium carbide deposition process

Katsushi Furutani

Papers

Assisting Electrode Method for Machining Insulating Ceramics

Precise positioning mechanism utilizing rapid deformations of piezoelectric elements

Displacement control of piezoelectric element by feedback of induced charge

Influence of electrical conditions on performance of electrical discharge machining with powder suspended in working oil for titanium carbide deposition process

A New Process of Additive and Removal Machining by EDM with a Thin Electrode