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.

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State of the art electrical discharge machining (EDM)

State of the Art of Micromachining

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)

New Developments in Electro-Chemical Machining

A Combined Electrical Machining Process for Micronozzle Fabrication

A novel process for fabricating a micropipe has been developed This process is based on electrochemical deposition of metal onto a core or a microelectrode which is prepared by WEDG (wire electrodischarge grinding) This procedure is simple and the entire process can be carried out automatically Using this method, one can produce a high-accuracy micropipe with a length 100 times its inner diameter A 3-mm-long micropipe of 23- mu m ID and 186- mu m OD with extremely high precision of straightness, roundness, and concentricity was successfully manufactured Owing to the advantages of WEDG, the inner and outer shapes of the micropipe can be controlled independently, and produceable shapes include various irregular sections, such as triangular, rectangular, and polygonal sections >

A micropipe fabrication process

A process for fabricating a high-precision micronozzle with irregular inner shapes (at its end) and high aspect ratio (at its main part) was developed. Micronozzles 3 mm long with slit-type openings of 100*10 mu m, triangular openings of 50 mu m, and circular openings of 6 mu m were successfully obtained. By using a WEDG (wire electrodischarge grinding) polishing technology, a core with a smooth mirrorlike surface was prepared, improving the precision and inner surface quality of the micronozzles produced. The core preparation process with WEDG and WECG can be carried out using common low-conductivity water. This makes the fabricating process simple and effective. Stainless steel was suitable as the core material for WECG operation. A micropipe with an inner diameter of 50 mu m and aspect ratio of 40 was successfully manufactured without using parting film. >

C.-L. Kuo

Papers

A Combined Electrical Machining Process for Micronozzle Fabrication

A micropipe fabrication process

High-precision micronozzle fabrication