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Jet Electrochemical Machining (Jet-ECM) is a manufacturing technology which is based upon anodic dissolution. This method enables a fast production of complex micro structures and therefore it has been widely used in many fields such as aerospace, medicine and electronic. However, there are also some drawbacks needing further improvement. The problem is that with the increase of the machining depth, the current density will gradually decrease, the material removal rate will decrease as well. Moreover, the lateral size of the feature will slowly increase with the increase of time. Therefore, there is a limitation for high aspect ratio structure machining in Jet-ECM. In addition, the current density distribution of the electrolyte jet flow is not concentrated enough, which also affects the shape accuracy. Hence, a wire-preposed Jet-ECM (WPJet-ECM) method is proposed, in which a wire electrode is put in the high-speed jet and passes through the nozzle. The electrode can feed into the structure to follow the dissolution of workpiece so that a high aspect ratio will be ensured. The current density is confined to the end face of the electrode to improve the shape accuracy by insulating the side wall of the electrode. An electric field simulation model is established to simulate the distribution of current density. The simulation results indicate that wire-preposed method can concentrate the current density effectively. Concave processing experiments by wire-preposed method are also performed to verify the effectiveness. The nozzle is kept feeding downward at a constant speed. The results demonstrate that the diameter of the concave is decreased and the depth is increased compared with the condition in which the nozzle stays still. Furthermore, the inner surface quality and edge quality of the concave are also significantly improved.

Single electrical discharge pulse is the base unit of electrical discharge machining(EDM). Research on the erosion feature of single electrical discharge pulse is of great significance on understanding the process of electrical discharge machining. With the continuous decrease of energy which is output by pulse power, EDM is widely applied in the meso scale manufacturing, the feature size of components is close to the grain size of crystal materials. However, the properties in the grains are different from the grain boundary which will have significant effect on the manufacturing process. In this paper, thermal-properties difference between the grain and grain boundary is analyzed briefly. An experiment of single electrical discharge pulse is carried out on two kinds of stainless steel(1Cr18Ni9) which has the different grain size. The theory analysis and experimental results both indicate that the smaller the grain size, the larger diameter and depth of the electrical pits.

During the process of three-dimensional scanning milling of micro-electrical discharge, both positive and negative poles usually present as arc shape. This phenomena is called “arc shape phenomena” in this paper. This paper is to introduce erosion mechanism of electrical pulse discharged on both. Typically, the hollow electrode is applied to modeling and simulation. And then real experiments will be conducted. There are two conditions for the electrode in the analysis and tests: rotating at 300 rpm and 0 rpm. Finally, the profiles of tool electrode and workpiece are provided. Results show that there are different erosion effects on both poles. It shows that the process parameters have a significant influence on the final machining results.

Micro-EDM discharge state is usually monitored by measuring the gap average voltage, because it's very simple. Yet according to its principle, the monitoring effectiveness, resolution and threshold voltage would vary with the pulse parameters, i.e. cycle time, pulse width and amplitude. Thus, the gap average voltage measurement (GAVM) method is lacking in adaptability. Aiming at this, a new monitoring method based on impedance-measuring is presented, in which the gap impedance is monitored to identify the discharge states. By this means, when the circuit is settled, the monitoring effectiveness, resolution and threshold voltage would not vary with the pulse parameters. Consequently, the impedance-measuring method could show good adaptability in realistic machining situation where lots of different groups of pulse parameters are needed for different processing requirements. Experimental results show that different discharge states are distinguished by the impedance-measuring circuit and the effectiveness of the impedance-measuring method is proved.