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The development of microtextures has had a transformative impact on surface design in engineering, leading to substantial advancements in the performance, efficiency, and functionality of components and tools. This study presents an innovative methodology for fabricating SEDM electrodes. The methodology combines additive manufacturing by mask stereolithography with an optimized electroforming process to obtain high-precision copper shells. A key aspect of the study involved redesigning the electroforming equipment, enabling the independent examination of critical variables such as anode–cathode distance and electrolyte recirculation. This approach allowed precise analysis of their impact on metal deposition. This redesign enabled the assessment of the impact of electrolyte recirculation on the quality of the shells obtained. The findings indicate that continuous recirculation at 60% power effectively reduced thickness deviation by up to 32.5% compared to the worst-case scenario, achieving average thicknesses within the functional zone of approximately 110 µm. In contrast, the absence of flow or excessive turbulence did not generate defects such as unfilled zones or non-uniform thicknesses. The shells obtained were validated as functional tools in SEDM, demonstrating their viability for the generation of textures with high geometric fidelity. This approach optimizes the manufacturing of textured electrodes and opens new opportunities for their application in advanced industrial processes, providing a more efficient and sustainable alternative to conventional methods.

The thickness nonuniformity of an electroformed layer is a bottleneck problem for electroformed micro metal devices. In this paper, a new fabrication method is proposed to improve the thickness uniformity of micro gear, which is the key element of various microdevices. The effect of the thickness of the photoresist on the uniformity was studied by simulation analysis, which showed that as the thickness of the photoresist increased, the thickness nonuniformity of the electroformed gear should decrease due to the reduced edge effect of the current density. Differently from the traditional method performed by one-step front lithography and electroforming, multi-step, self-aligned lithography and electroforming are used to fabricate micro gear structures in proposed method, which intermittently keeps the thickness of photoresist from decreasing during processes of alternate lithography and electroforming. The experimental results show that the thickness uniformity of micro gear fabricated by the proposed method was improved by 45.7% compared with that fabricated by the traditional method. Meanwhile, the roughness of the middle region of the gear structure was reduced by 17.4%.

Surface texturing has brought significant improvements in the functional properties of parts and components. Sinker electro discharge machining (SEDM) is one of the processes which generates great texturing results at different scale. An electrode is needed to reproduce the geometry to be textured. Some geometries are difficult or impossible to achieve on an electrode using conventional and even unconventional machining methods. This work sets out the advances made in the manufacturing of copper electrodes for electro erosion by additive manufacturing, and their subsequent application to the functional texturing of Al-Cu UNS A92024-T3 alloy. A combined procedure of digital light processing (DLP) additive manufacturing, sputtering and micro-electroforming (AMSME), has been used to produce electrodes. Also, a specific laboratory equipment has been developed to reproduce details on a microscopic scale. Shells with outgoing spherical geometries pattern have been manufactured. AMSME process has shown ability to copper electrodes manufacturing. A highly detailed surface on a micrometric scale have been achieved. Copper shells with minimum thickness close to 300 µm have been tested in sinker electro discharge machining (SEDM) and have been shown very good performance in surface finishing operations. The method has shown great potential for use in surfaces texturing.

Thickness nonuniformity is a bottleneck in the micro electroforming process of micro-metal devices. In this paper, a new method of fabricating a layered auxiliary cathode is proposed to improve the thickness uniformity of a micro-electroforming layer. In order to analyze the general applicability of the proposed method, four basic microstructures, namely circular, square, regular triangular, and regular hexagonal were used to study the effect of a layered auxiliary cathode on thickness uniformity through simulation and experimentation. The simulation results showed that with the help of the proposed auxiliary cathode, the thickness nonuniformity of four microstructures should decrease due to the reduced edge effect of the current density. The experimental results showed that the thickness uniformity of four microstructures fabricated via the proposed method was improved by 190.63%, 116.74%, 80.43%, and 164.30% compared to that fabricated via the traditional method, respectively. Meanwhile, the micro-gear was fabricated and the nonuniformity was reduced by 101.15% using the proposed method.

One of the manufacturing processes applications on a microscopic scale, consists in modifying parts or components´ surfaces to improve their properties. Unconventional machining processes are needed to generate complex geometries, high details reproduction, and excellent finished surfaces at that scale. Micro sinker electrical discharge manufacturing (μ-SEDM) process could be one good option. The electrode manufacturing is one of the main drawbacks. It supposes a big resources waste before starting to manufacture. In this way, working on a microscopic scale becomes a challenge to obtain different shapes and textures on functional surfaces. In this work, combined use of micro-electroforming and digital light processing (DLP) additive manufacturing is presented. These two additive techniques are completely different and unrelated in their applications, materials, and technological fundamentals. However, their combination is a low-cost option to obtain good results in the manufacture of μ-SEDM electrodes. Therefore, it was necessary to develop a micro-electroforming equipment to meet the challenge. Furthermore, device had to have the ability to adapt the process parameters to the needs of the parts. As a result of this experimental application, we got high-quality parts, which could have an industrial application.

The application requirements of terahertz hollow-core metal rectangular waveguides with a high-working frequency have become increasingly urgent with the rapid development of terahertz technology. Integral fabrication of terahertz hollow-core metal rectangular waveguides can improve considerably the transmission performance of terahertz signals. However, with current manufacturing techniques, the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides is difficult owing to their characteristically small end face size and the need for strict dimensional accuracy and high internal surface quality. In this paper, an innovative combined process of wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution is proposed firstly to overcome this puzzle. Taking the fabrication of an integral 1-THz hollow-core metal rectangular waveguide as an example, the manufacturing methods involved in each step are described particularly, together with the corresponding experimental investigations. With the end face size of 127 μm × 254 μm, edge radius less than 5 μm, and internal surface roughness less than 0.08 μm, the experimental results satisfy the design requirements for a 1-THz hollow-core metal rectangular waveguide. This study demonstrates that the proposed combined process is flexible, controllable, and suitable for the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides.

Micro electroforming technology is widely used in fabrication of multilayer or moveable metal micro devices. The fabrication of these devices is usually suffered from high internal stress in micro-electroformed layers which seriously restricts the application and development of micro electroforming technology. Therefore, to control the internal stress is very important for improving the quality and performance of micro-electroformed layer. However, published studies on internal stress in the electroforming layer were mostly based on additive-free solution. According to additive solution, the effect of ultrasonic and current density on compressive stress occurring in the electroforming layer is investigated in this paper. The results indicate that the compressive stress keeps increasing with current density within range from 0.2 to 2 A/dm2. Meanwhile, the compressive stress in ultrasonic solution decreases by 73.4 MPa averagely comparing to that in ultrasonic-free solution, and the compressive stress also keeps decreasing with the ultrasonic power which gets the lowest value at 200W. Moreover, the mechanisms of additive-induced compressive stress and ultrasonic relieving compressive stress are discussed. This research work will complement the ultrasonic-stress reduction theory and may contribute to the development of micro electroforming technology.

Electroformed microfluidic chip mold faces the problem of uneven thickness, which decreases the dimensional accuracy of the mold, and increases the production cost. To fabricate a mold with uniform thickness, two methods are investigated. Firstly, experiments are carried out to study how the ultrasonic agitation affects the thickness uniformity of the mold. It is found that the thickness uniformity is maximally improved by about 30% after 2 h electroforming under 200 kHz and 500 W ultrasonic agitation. Secondly, adding a second cathode, a method suitable for long-time electroforming is studied by numerical simulation. The simulation results show that with a 4 mm width second cathode used, the thickness uniformity is improved by about 30% after 2 h of electroforming, and that with electroforming time extended, the thickness uniformity is improved more obviously. After 22 h electroforming, the thickness uniformity is increased by about 45%. Finally, by comparing two methods, the method of adding a second cathode is chosen, and a microfluidic chip mold is made with the help of a specially designed second cathode. The result shows that the thickness uniformity of the mold is increased by about 50%, which is in good agreement with the simulation results.

This research integrates the Taguchi method, analysis of variables (ANOVA), back-propagation neural networks (BPNN), and hybrid PSO-GA to develop an intelligent optimization system of micro electroforming process for the mesh filter. From the outset of discussions with engineers in terms of past related literature survey of the micro electroforming process, the quality characteristics of product and control variables can be well ascertained, then transforming the problem of multiple quality characteristics into a single quality characteristic via the Taguchi method and ANOVA. However, the optimal parameter settings (solution) through the Taguchi experimental planning is still belong to a discrete optimal solution which is impossible to meet the process stability and quality goals. Therefore, this study first identifies the initial weight of BPNN，using hybrid PSO-GA with multilayer perceptron (MLP)，in order to improve training efficiency and precision of BPNN. Furthermore, the study constructs the signal-to-noise (S/N) ratios (BPNNS/N) and quality predictors (BPNNQ) based on hybrid PSO-GA and BPNN with the experimental data. The optimal parameter settings are obtained through a combination of BPNNS/N and BPNNQ with modified PSO-GA. Finally, confirmation experiments are performed to assess the effectiveness of the proposed system. The results show that the proposed system can create the best performance, and the optimal parameters not only enhance the stability in the micro electro forming process but also effectively improve the product quality.