Fundamental Behavior of Bubbles in the Single Discharge of Micro-EDM

WU Zhaoyun; LI Guodong; YU Zuyuan; LIU Yu

doi:10.3969/j.issn.1674-6457.2026.08.023

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (8) : 255-264. DOI: 10.3969/j.issn.1674-6457.2026.08.023

Advanced Manufacturing Technology and Equipment

Fundamental Behavior of Bubbles in the Single Discharge of Micro-EDM

WU Zhaoyun¹, LI Guodong^1,2,*, YU Zuyuan³, LIU Yu^1,2

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Abstract

The work aims to reveal the fundamental behavior of bubbles including generation, deformation and motion of bubbles under coupled thermal-flow physical fields through in-situ observation with a high-speed camera and multi-physical- field simulation methods, thus providing a theoretical basis for clarifying the debris-removal mechanism in micro-electrical discharge machining. A pair of needle electrodes with a diameter of 39 μm was used for the single discharge experiment, and a high-speed camera was employed to capture the bubble evolution process after discharge breakdown. Based on the Gaussian heat source model, combined with the gas-liquid phase change and ideal gas models, the bubble behavioral characteristics and multi-physical-field evolution in free-flow and gap flow fields were investigated. The inter-electrode gap environment under actual machining conditions was simulated, and the effects of bubbles on medium exchange in the entire machining environment were analyzed. The consistency between in-situ observation and simulation results indicated the reliability of the simulation model. With the release and cooling of discharge energy, bubbles exhibited obvious oscillatory (expansion and contraction) behaviors, which could periodically expel and suck in the machining fluid. Moreover, bubbles possessed a stronger capacity to expel and draw liquid within the narrow machining gap, effectively facilitating the renewal of machining fluid in the bottom gap. Bubble oscillation is a direct reflection of the conversion of discharge energy into the pressure field. The vibration induced by bubbles acts not only on the bottom gap but also over the entire machining gap. With remarkable effects and no external force required, it possesses the potential to serve as a self-debris-removal method.

Key words

micro-EDM / single discharge / bubble behavior / high-speed camera / fluid simulation

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WU Zhaoyun, LI Guodong, YU Zuyuan, LIU Yu. Fundamental Behavior of Bubbles in the Single Discharge of Micro-EDM[J]. Journal of Netshape Forming Engineering. 2026, 18(8): 255-264 https://doi.org/10.3969/j.issn.1674-6457.2026.08.023

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Funding

National Natural Science Foundation of China (52405482, 52275408); Fundamental Research Funds for the Central Universities (JUSRP123025); Wuxi Science and Technology Development Fund Project (K20221012, G20232045); Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology (FMZ202303); Jiangsu Provincial Key Research and Development Program (BE2022069-2)