Electrochemical discharge machining (ECDM) is a hybrid non-conventional machining process, used to machine electrically conductive and non-conductive materials. It is a preferred process to fabricate micro scale features like micro holes, micro channels, microgrooves and 3-dimensional intricate shapes on variety of materials. In order to improve the efficacy of ECDM process, certain technical augmentations are provided with basic configuration of ECDM. These augmentations result in developments of ECDM process variants. Further, research community has developed ECDM based triplex hybrid methods for further process enrichment. This review article presents a comprehensive review of these recent developments in ECDM process, its variants and their triplex hybrid methods. The future research possibilities are identified and presented as research potentials.

Developments in electrochemical discharge machining: A review on electrochemical discharge machining, process variants and their hybrid methods

Electrochemical discharge machining has been proved to be efficient micro-machining process and significantly used for the machining of non-conductive materials. The miniaturized products have gain...

Electrochemical discharge machining: A review on preceding and perspective research:

Fabrication of micro holes in CFRP laminates using EDM

In the current scenario, biocompatible or biomedical materials are rising in demand for specific application requirements and its machining is one of the fundamental challenges. Many researchers fo...

Critical review on the impact of EDM process on biomedical materials

The present research deals with the evaluation of surface integrity of micro-holes machined in stainless steel (SS304) sheet, using ultrasonic vibration-assisted micro-EDM process. Experimental results showed that pulse duration, gap voltage, and the application of ultrasonic vibration significantly affected the surface integrity in terms of the changes in recast layer thickness, micro-hardness, and the chemical composition of the machined surface. It is observed that the thickness of the recast layer is in the range of 6–23 µm, but the recast layer thickness was less with application of the ultrasonic vibration of the work piece. The heat-affected zone (HAZ) could not be observed both in FESEM and optical images. The micro-hardness in the HAZ was found in the range of 146–238 HV. The lower values of the micro-hardness were obtained with the application of vibration to the work piece. The changes in the chemical composition of the edge of the fabricated micro-holes were analyzed through EDS test, and it was found that lower amounts of carbon, oxygen, and tungsten were present in the machined surfaces.

Influence of process parameters on the surface integrity of micro-holes of SS304 obtained by micro-EDM

Understanding the effect of processing parameters on the tool electrode wear during micro-electrical discharge machining (micro-EDM) is helpful to predict and compensate the electrode wear, so as to improve the machining precision. In this paper, experiments are carried out and the influences of tool electrode diameter on the micro-EDM process are discussed based on the skin effect and area effect. It is demonstrated that the machining speed, tool wear, and taper rate are different with the increase of tool electrode diameter. Due to the skin effect and area effect, larger electrode diameter results in higher material removal rate along with higher tool wear rate. The electrode material removal increment is more than the workpiece material removal increment with the increase of tool electrode diameter, which leads to the increase of relative tool wear ratio. Discharge energy is concentrated on the tool surface which enhances the possibility of discharge on the side face and the corner of the tool electrod...

Effect of Electrode Size on the Performances of Micro-EDM

A new piezoelectric self-adaptive micro electrical discharge machining (PSA micro-EDM), based on inverse piezoelectric effect, was developed in this paper. The working mechanism and working process were illustrated, and characteristics of the new system were analyzed. The self-adaptive regulation of discharge gap according to discharge conditions is achieved during the machining process. And the system has some specific merits, such as in favor of removing the debris, reducing the occurrence of arcing and shorting circuits, realizing self-elimination of short circuits, and so on. All these advantages can improve the discharge stability of the working process, and then the machining efficiency can be increased and the electrode wear can be reduced. Besides, the servo control system of this new technique is easy to implement and micro-EDM with micro-energy at low open voltage can be achieved. Based on this new concept, a piezoelectric self-adaptive micro-EDM device was set up. To validate the processability of the new micro-EDM device, some micro holes and structures were machined.

A novel micro-EDM—piezoelectric self-adaptive micro-EDM

Electrical discharge machining(EDM) is a promising non-traditional micro machining technology that offers a vast array of applications in the manufacturing industry. However, scale effects occur when machining at the micro-scale, which can make it difficult to predict and optimize the machining performances of micro EDM. A new concept of “scale effects” in micro EDM is proposed, the scale effects can reveal the difference in machining performances between micro EDM and conventional macro EDM. Similarity theory is presented to evaluate the scale effects in micro EDM. Single factor experiments are conducted and the experimental results are analyzed by discussing the similarity difference and similarity precision. The results show that the output results of scale effects in micro EDM do not change linearly with discharge parameters. The values of similarity precision of machining time significantly increase when scaling-down the capacitance or open-circuit voltage. It is indicated that the lower the scale of the discharge parameter, the greater the deviation of non-geometrical similarity degree over geometrical similarity degree, which means that the micro EDM system with lower discharge energy experiences more scale effects. The largest similarity difference is 5.34 while the largest similarity precision can be as high as 114.03. It is suggested that the similarity precision is more effective in reflecting the scale effects and their fluctuation than similarity difference. Consequently, similarity theory is suitable for evaluating the scale effects in micro EDM. This proposed research offers engineering values for optimizing the machining parameters and improving the machining performances of micro EDM.

Kan Wang

Papers

Effect of Electrode Size on the Performances of Micro-EDM

A novel micro-EDM—piezoelectric self-adaptive micro-EDM

Scale effects and a method for similarity evaluation in micro electrical discharge machining