Unlike traditional machining processes, electrochemical machining has proved efficient for enhancing machining performance, producing high surface quality and reducing tool wear due to limited thermal effects. As such, it has been adopted in numerous industrial applications to fabricate hard materials with complicated geometries. However, the problems of poor machining accuracy and possible environmental impacts have hindered its further development and deployment. Restricting the electrolyte flow area through electrochemical jet machining and electrochemical machining with suction tool have been proposed to address the aforementioned challenges. This requires knowledge on the factors influencing machining characteristics with suction tool including the effects of hydrogen and oxygen generated during electrochemical machining processes.
Dr. Guixian Liu and Dr. Yongjun Zhang from the Guangdong University of Technology together with Professor Wataru Natsu from Tokyo University of Agriculture and Technology investigated the characteristics of the electrochemical machining process with suction tool under different patterns of flow modes. Also, they experimentally and theoretically studied the influence of the gaseous impurities sucked from the surrounding into the electrolyte due to suction pressure. The work is currently published in International Journal of Machine Tools and Manufacture.
In brief, the authors first developed a multi-physics model coupled with an electrical field and two-phase flow field to study the effects of the surrounding air particles on the electrochemical machining with a suction tool. For further verification of the simulation results and study of the flow field characteristics, observation and machining experiments were designed. This was performed under a high-speed camera to improve the quality of the results.
The authors observed that poor machining characteristics associated with the inward flow mode. This was attributed to sucking of the surrounding air into the machining area which further led to the formation of relatively stable gas-liquid zone. On the other hand, for the outward flow mode, the electrolyte was confined in a small area. This resulted in a significant improvement in the surface quality and machining accuracy of the electrochemical machining process. Nonetheless, suction pressure may trigger the collapse of the bubble inducing rapid entry of the surrounding liquid into the machining area.
From the experiments, a two-phase gas-liquid flow was formed along the direction of the electrode center, especially under the inward flow mode. Thus, the electrolyte conductivity was affected by the gas distribution resulting in a bulging machining surface and all points to the center of the electrode. Furthermore, machined structures under suction pressure exhibited even edges with no corrosion stray under outward flow mode.
In summary, the research team successfully investigated the influence of electrolyte flow mode on the electrochemical machining characteristics with a suction tool. Simulation results showed that the electrochemical machining with suction tool under outward flow mode produced better machining accuracy as compared to inward flow mode owing to its ability to achieve a stable constrained flow field. Therefore, electrochemical machining with a suction tool is a promising approach for improving the machining accuracy and quality under outward flow mode.
Liu, G., Zhang, Y., & Natsu, W. (2019). Influence of electrolyte flow mode on characteristics of electrochemical machining with electrolyte suction tool. International Journal of Machine Tools and Manufacture, 142, 66-75.Go To International Journal of Machine Tools and Manufacture