Micro rotating-structure manufacture has been largely carried out using a variety of processing methods. However, it is difficult to achieve the high-precise machining of the micro rotating structure due to the material constraints and the geometrical limitation of the free-form profile. This paper discusses the fabrication of micro-rotating structure using micro reciprocated wire electrical discharge machining (wire-EDM). To ensure machining accuracy, a gravity takeup for maintaining constant wire tension and a unit for suppressing the wire vibration are designed and fabricated, respectively. Besides, the effects of processing parameters on rotating groove width are investigated by conducting preliminary experiments, showing that high open voltage, discharge capacitance and revolving speed, and low discharge resistance and wire tension cause larger rotating groove width. Nevertheless, the rotating groove width firstly decreases with the reference voltage and feed rate increase in the initial stage and then increases when applying higher values. Based on the preliminary experiments, the proper processing parameters are determined and are used for machining micro bellows core-mould. Ultimately, the micro bellows core-mould is successfully machined by micro reciprocated wire-EDM, exhibiting high machining accuracy, excellent geometric shape and uniformity. Specifically, the machining errors along the axial direction and the radial direction of the micro bellows core-mould are less than 1.4 µm and 2.3 µm, respectively.

This paper develops an array micro-grooves manufacturing method using micro electrochemical machining (ECM) with disk electrode, which is prepared by in-situ micro wire electrical discharge machining (WEDM). This technology focuses on the difficulty of array structure manufacture in micro-electro-mechanical systems (MEMS). A micro-ECM system is built based on the micro-WEDM machine to achieve high precision processing of the array micro-grooves. Since micro-WEDM has good performance in high precision machining of the rotating structure, single and multi-edge disk electrodes can be fabricated in-situ using graphite. The as-prepared disk tool electrode is directly used for micro-electrochemical milling of the array micro-grooves without disassembling away from the device, which avoids the positioning error caused by the re-clamping of the disk electrode. With the advantages of high surface quality and no electrode loss, micro-ECM improves the manufacture performance of the micro-parts. Through wire path optimization, the shape accuracy of the disk edge is improved. After the research of the micro-ECM parameters, the process is improved, and finally, the high precision array micro-grooves are obtained. This method combines the advantages of micro-WEDM and disk electrode micro-ECM milling, and it is convenient for large-scale manufacture of array micro-structures on micro-parts and MEMS.

To improve the thermal management level of power battery packs for new energy vehicles, a novel cooling plate with vein flow channels was proposed. The vein flow channel structure includes bilaterally symmetrical vein-shaped branches, a dovetail-shaped outlet branch, and a side collecting branch. This study conducted a comparative analysis on the hydrodynamic characteristics, heat transfer performance, and pumping power consumption of the novel cold plate, while investigating the influence of flow channel structure on the working fluid distribution and cooling performance of the liquid cold plate (LCP). The results indicate that the dovetail-shaped outlet branch can significantly enhance the flow distribution capacity of the tail branch channels of the LCP, the side collecting channel can improve the overall flow distribution capacity of the branch channels by reducing flow resistance, and the converging main channel can effectively compensate for the insufficient flow distribution capacity at the front part of the LCP by mitigating the uneven distribution at the tail. Additionally, the results demonstrate that the optimized design achieves a 9.5 °C (21%) reduction in the maximum temperature and a 6.3 °C (32%) reduction in the temperature difference.