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The development and application of wire electrochemical micromachining (WECMM) technology have become a research hotspot of non-traditional machining. However, a series of problems cannot be eliminated due to the machining products of micromachining gap, which leads to poor machining performance. This paper proposed a new method named ultrasonic vibration–added wire electrochemical micromachining (UA-WECMM) technology, which can solve the mass transfer problem in WECMM with extremely narrow gap. Firstly, the flow field of machining gap was simulated. The results showed that the pressure range of machining gap was larger and was more conducive to the renewal of electrolyte when ultrasonic vibration was added. Secondly, the effects of ultrasonic amplitude and ultrasonic vibration object on machining accuracy and surface quality were compared by experiments, which illustrated that the machining performance was greatly improved with the increase of ultrasonic amplitude of the workpiece. The slit width can be reduced from 196.2 to 151.2 μm, and the surface roughness can be reduced from Ra 0.863 to Ra 0.259 μm. Finally, the micro-gear structure with surface roughness of Ra 0.263 μm and depth-to-width ratio of 6.7:1 was fabricated, which proved that UA-WECMM technology is an effective technology for fabricating metal microstructures with high aspect ratio and good machining quality.

Metal micro-holes structures have been widely used in aerospace and biomedical fields, such as aero engine, medical vaporizer, and so on. In this paper, a micro rotating ultrasonic-assisted electrochemical drilling (UA-ECD) method was proposed to improve the machining localization, efficiency, and stability. Firstly, a numerical simulation of the flow field in the machining gap is carried out, the simulation results show that the rotating electrode with ultrasonic vibration can renew the electrolyte in the machining gap and homogenize the flow field. Secondly, a mathematical model is established to study the effect of ultrasonic vibration and key machining parameters on machining results, which illustrate that the rotating ultrasonic-assisted electrochemical drilling method can improve the machining quality, machining efficiency, and stability sufficiently. Finally, after optimization of several groups of contrast experiments, a micro holes array with good quality is fabricated successfully on a 510-μm-thick 304 stainless steel workpiece. It is proved that the proposed rotating ultrasonic-assisted micro electrochemical drilling method has considerable potential and broad application prospects.

The microstructures with spherical end have been widely applied in micromachining and measurement. In this paper, a microelectrode with spherical end was fabricated combining electrochemical etching with spark discharge machining. Firstly, the formation mechanism of micro spherical electrode was simulated by molecular dynamics LAMMPS, and the energy model of the spherical end was established to guide machining micro spherical electrode. Secondly, on the basis of cylindrical microelectrode, the electrode tip was melted by spark discharge. Simultaneously, the molten electrode formed a spherical end due to surface tension in deionized water. Finally, sets of experiments were carried out to discuss the influence of polarity, applied voltage, and pulse width on the diameter ratio of spherical end to electrode tip. By using optimal machining parameters, the micro spherical electrode with a diameter of 21.25 μm and a coaxial error of 0.9 μm can be obtained, and the diameter ratio is almost 2.