Electrochemical jet milling (EJM) offers significant benefits for producing workpieces, showcasing various advantages in terms of quality and design flexibility. However, macro-scale EJM currently encounters limitations regarding machining efficiency and surface precision. A critical determinant of these aspects is the inter-electrode gap (IEG), with its optimization presenting an opportunity to enhance both precision and efficiency. Reducing the IEG is particularly desirable as it promises considerable improvements in machining efficiency and surface quality. Nonetheless, achieving a narrower IEG is challenging due to the risk of sparking from excessively high current densities at the cathode tool tips. To address this issue, this study introduces an innovative cathode tool design tailored to exploit the characteristics of electric in EJM. This design strategically removes the energy concentration area. As a result, this advancement allows for an ultra-narrow IEG of 0.05 mm, setting a new benchmark for the narrowest IEG achievable in macro EJM. Employing this novel cathode tool leads to a substantial leap in machining performance at an IEG of 0.05mm. When compared with the conventional machining gap of 0.2mm, the refined 0.05mm IEG not only boosts the material removal rate by an impressive 107% but also enhances surface quality. Specifically, the experimental results showed that the minimum surface roughness produced by the RD cathode tool was reduced by nearly 86.2% than that of the surface produced by the standard cathode tool. Moreover, the overcut area was reduced by nearly 60.1%, and stray corrosion was eliminated.

Electrochemical milling has broad application prospects for machining large aeronautical thin-walled components. This is because this technique has no cutting force, has no heat-affected zones, and is considerably flexible. In contrast to the non-rotating tool cathode of traditional electrochemical milling, the rotating cathode used in electrochemical milling has more promising prospects because it has the same motion mode as the milling cutter employed in mechanical milling. However, because of the uneven electric quantity supply from the cylindrical rotating cathode, the machined surface typically has a curved profile with inadequate surface flatness; this is the main drawback of rotating-cathode electrochemical milling. To improve the flatness of surfaces processed by rotating-cathode electrochemical milling, a novel multichannel cathode with the outlet hole arrangement that can improve the uniformity of electric quantity supply is proposed. Numerous large outlet holes are bored at the bottom center of multichannel rotating cathode. Numerical simulation results indicate that these holes cause a decrease in the electric quantity supply from the inner area at the bottom of the cathode from the perspectives of electric and flow fields, minimizing the unevenness of the electric quantity supply distribution. Validation experiments prove that compared with previously reported rotating cathodes, the straightness index and depth error of the surface machined by novel multichannel cathode are reduced by 80.9 % and 69.4 %, respectively. After obtaining grooves with flat surfaces, the step-over distance required to machine a plane using a multichannel rotating cathode increases; meanwhile, the flatness of the machined plane significantly improves. With the applied voltage of 25 V, electrolyte pressure of 0.2 MPa, initial inter-electrode gap of 0.2 mm, and cathode rotational speed of 500 rpm, a 42 x 40 mm plane is finally machined, whose planeness index (Delta hp) is only 0.047.

Macro electromechanical milling has recently attracted increasing attention because numerous large thin-walled structures composed of difficult-to-cut materials are employed in the aerospace field. This paper reviews recent developments in state-of-the-art macro electromechanical milling. The fundamental aspects of material removal mechanisms, such as the generation and breakdown behaviors of passive oxide films of typical difficult-to-cut materials, were discussed. Rapid methods for breaking down passive films are summarized, and simulation methods for the machining process coupling multiple physical fields are introduced. Specific electrochemical milling methods, including fly mode electrochemical milling and sink electrochemical milling, are classified. Efforts made to improve process performance, such as the material removal rate, surface quality, and machining accuracy, are discussed. In addition, the main hybrid electrochemical milling methods, including electrochemical discharge milling, mechano-electrochemical milling, and electrochemical mill grinding, are also presented.

Electrochemical Milling is an important non-contact machining method which can produce a complex surface with high precision by using a simple cathode. At present, most of electrochemical milling focus on tube electrode machining. In order to further improve the efficiency and applicability of electrochemical milling, this paper presents rectangular electrode structure is applied to electrochemical milling and three different cathode structures with internal flow channels were designed, and their effects on machined surface roughness were studied. Numerical simulations were applied to investigate the influence of these structures on the machining flow field distribution. The simulation results revealed that corner rectangular cathode is beneficial to obtain a stable flow field distribution. Electrochemical milling experiments on 316 stainless steel were also conducted to verify these results, which the smallest machined surface roughness was obtained by corner rectangular cathode, due to the stable flow field distribution.

Electrochemical jet milling (EJM), an important non-traditional machining technique, has been identified as a promising method for fabricating components on a wide range of conductive materials. However, EJM faces great challenges in fabricating uniform surfaces because the optimal step-over between two adjacent trajectories is difficult to ascertain. In the past, the optimal step-over has been determined roughly through a large number of experiments, which was inaccurate, time-consuming, and expensive. In this study, a mathematical model was innovatively proposed to predict the relationship between uniformity and step-over prior to the experiment. This method can predict features with good accuracy and low computational costs. A large cathode tool was used in the EJM to fabricate a large flat surface. The optimal step-over of different parameters for realizing flat surface was firstly proposed and the unique processing mark at optimal step-over was firstly revealed. The results indicate that the optimal step-over between two adjacent trajectories is the same as the width of the nozzle orifice. The processing mark of the flat surface at the optimal step-over exhibits a “valley–peak” shape. Moreover, the uniformity of the machined surface can be improved by utilising a higher cathode travel rate. The experimental results are in good agreement with the analytical model. In addition, a large flat surface with dimensions of 90 × 90 mm was successfully fabricated.

In electrochemical jet milling (EJM), enhancing the current density at the trail edge of a workpiece can improve the surface quality. In this study, a novel rectangular cathode tool structure insulated at one side was designed to reinforce the current density at the trail edge of a workpiece to improve the machined surface quality. Numerical simulation was performed to analyse the current density distribution with respect to various parameters, and experiments were conducted to verify the simulation results. The simulation results showed that the current density could be strengthened by utilising the tool with an insulated frontal nozzle tip, which can improve the surface quality during the machining process. Meanwhile, the experimental results revealed that a mirror-like surface could be obtained when utilising the tool under favourable conditions. Compared to other tools, the surface machined by the tool with an insulated frontal nozzle tip had minimum roughness, defects, and overcut.

In the macro electrochemical jet milling, the surface quality produced by the standard cathode tool is unsatisfactory owing to the inevitable effects of low current density and inefficient mass transfer. This paper proposes a novel cathode tool with an insulated nozzle tip and inclination angle to confine the low current density area and enhance the mass transfer. The theoretical analysis and numerical simulation results reveal that the designed tool with an inclined angle helps to increase the flow velocity of electrolyte in the machining gap and reduces the effect of the low current density during the machining process. Experimental results show that the surface roughness produced by the proposed tool (tool C) is reduced by approximately 6 times compared with the standard tool. Furthermore, the material removal rate of tool C is approximately 1.6 times equal to that of the vertical mode. Besides, a mirror-like surface with a clear reflection and surface roughness (Ra) of 0.12 mu m was successfully fabricated.

电解铣削加工技术具有加工柔性好、工具电极无损耗及与待加工材料力学性能无关等特点,在高效、精密加工难切削加工材料制作的复杂结构方面具有重要的应用前景,成为电解加工技术研究的热点.详细介绍了国内外研究者在电解铣削的材料去除机制、加工过程建模及加工工艺等方面的研究进展,发现目前距离该技术的规模化工程应用仍有加工精度、表面质量及加工效率等方面的诸多挑战,需在加工过程中就精确建模、提高加工效率、创新复杂型面加工工艺及复合加工方法等取得突破性进展,从而为规模化工程应用奠定技术基础.