Papers by Author: Yuan Gang Wang

Abstract: The concept and the primary preparation method of functional gradient materials are described in this paper. Functional gradient material is prepared as a tool electrode by electrochemical method and its performance is further tested in the micro electrical discharge machining (micro-EDM) experiments. Compared with the homogeneous material electrode, the functional gradient material electrode can effectively inhibit the wearing of the tool electrode and improve the distribution trend of current density during the micro-EDM process. The results disclose the prospects for functional gradient material to be used as tool electrode in the micro-EDM process.

Abstract: Electrode wear has a great adverse effect on the accuracy of Micro Electrical Discharge Machining (Micro-EDM) and impedes the improvement of Micro-EDM. In this study the distribution of electric field and current density was analyzed exhaustively in order to explore the generating mechanisms of rod electrode wear by finite element analysis and experiment. Experimental results indicated that corner wear occurred first, followed by side wear resulted from skin effect and debris in Micro-EDM, which was significant in enhancing the accuracy of machining.

Abstract: The numerical simulation of flow field and pressure field in the micro-region with different power ultrasonic were performed by FLUENT6.3 simulation software. Ultrasonic power on mass transfer effect was analyzed through the simulation results combined with surface morphology of micro casting. The results illustrated that micro electroforming assisted with appropriate power ultrasonic can significantly enhance mass transfer process and improve surface morphology of micro casting. And it was confirmed that Fluent was reliable in simulating the effect of ultrasonic on mass transfer and helpful to optimize and design deposition experiments with ultrasonic.

Abstract: Lateral and edge wear of electrodes in micro-EDM affects workpiece shape accuracy. A method that change materials property of lateral side of electrode was put forward, based on discharge performance difference of different materials, and it was demonstrated with experiments. Results show that the method proposed is more effective and improves the precision of deep holes, compared with traditional sampling methods. The technology can provide reference to practicality of micro-EDM for 3D structure cavity and deep holes.

Abstract: Wear course was experimental analyzed and mechanism of electrode wear was discussed based on finite element analysis and electromagnetic theory. Cu–TiN nano composite electrode was prepared on Cu electrode by electro deposition and effects of the electrode on discharging were studied. It is shown that electric field distortion and skin effect are two of the basic reasons on electrode wear. Cu–TiN nano composite electrode is one of the the effective ways for uniform wear of electrode in EDM.

Abstract: In micro electrical discharge machining (micro-EDM) of deep holes, the debris dispersed in gap may increase the possibility of secondary discharge, resulting in electrode shape changing and low accuracy of machined hole. In this paper, the debris movement caused by flow fluid in the machining gap is analyzed to understand the mechanism of debris transport by using software, FLUENT. Comparison of debris movement calculated by the modified N-S equation and N-S equation is conducted. Debris movement calculated by the modified N-S equation is demonstrated to be correct by experiment. The simulation results can explain the phenomena such as subulate electrode and hole, unstable machining process and low machining speed in micro-EDM of deep holes. It is helpful to improve the process of micro-EDM.

Abstract: Effects of additive powders on the machining mechanism of powder mixed EDM were researched. The whole discharging process was discussed based on theory of plasma and dielectric. Experiments, oscillograms and energy spectrum analysis gotten in experiments were performed in order to examine the changes of discharge between EDM and powder mixed EDM.

Abstract: Powder mixed EDM can effectively improve the surface quality of a machined workpiece. In order to study the mechanism of powder mixed EDM process, particles’ activities in working conditions are simulated and corresponding experiments are done. A 3D electric fields model described by finite element method of the particles suspended in working fluid in the electric field is built, the generated field is computed and presented, and the activities of particles in the breakdown process are analyzed. The results show that this method can serve as a good way to learn the activities of particles in the breakdown of discharge.