Search Results (6)

GH4169 alloy/Inconel 718 is extensively utilized in aerospace manufacturing due to its excellent high temperature mechanical properties. Micro-structuring on the workpiece surface can enhance its properties further. Through-mask electrochemical micromachining (TMEMM) is a promising and potential processing method for nickel-based superalloys. It can effectively solve the problem that traditional processing methods are difficult to achieve large-scale, high-precision and efficiency processing of surface micro-structure. This study explores the feasibility of electrochemical machining (ECM) for GH4169 using roll-print mask electrochemical machining with a linear cathode. Electrochemical dissolution characteristics of GH4169 alloy were analyzed in various electrolyte solutions and concentrations. Key parameters including cathode sizes, applied voltage and corrosion time were studied in the roll-print mask electrochemical machining. A qualitative model for micro-pit formation on GH4169 was established. Optimal parameters were determined through experiments: 300 μm mask hole and cathode size, 10 wt% NaNO₃ electrolyte, 12 V voltage, 6 s corrosion time. The results demonstrate that the micro-pits with a diameter of 402.3 μm, depth of 92.8 μm and etch factor (EF) of 1.81 show an excellent profile and localization. Full article

To solve the problem of the nonuniform distribution of temperature and electrolytic products in the electrolyte flow field during through-mask electrochemical micromachining, the use of a rotating cathode with surface structures is proposed. The rotation of the cathode increases the efficiency of heat and mass transfer by the electrolyte flow. Simulations are performed to analyze the influence of the type of surface structure, the number of surface structures, and the rotational speed of the cathode on the electrolyte flow field. The results show that the use of a rotating cathode with surface structures significantly improves the mass transfer efficiency of the electrolyte flow field in comparison with a conventional cathode structure, and, in particular, a grooved rotating cathode can increase the outlet flow velocity by about 23%. An experimental demonstration of micropit array processing shows that the use of a grooved rotating cathode increases the mass transfer efficiency by 34% and the processing efficiency by nearly 40% compared with a smooth-surfaced rotating cathode. The grooved rotating cathode also gives the highest machining accuracy. Using this cathode, a uniform micropit array with an average micropit diameter of 201.83 μm, a diameter standard deviation of 3.49 μm, and a depth standard deviation of 0.87 μm is processed. Full article

Through-mask electrochemical micromachining (TMEMM) is a promising method to prepare micro dimples on the surface of metallic parts. However, the workpiece is machined one by one in traditional TMEMM. This paper introduced bidirectional pulse to TMEMM to improve the machining efficiency. Two masked workpieces were placed face to face, and connected to the ends of the bidirectional pulse power supply. Along with the change of the pulse direction, the polarities of the two workpieces were interchanged periodically, and micro dimples could be prepared on both workpieces at one time. The simulation and experiment results indicated that with bidirectional pulse mode, micro dimples with same the profile can be prepared on two workpieces at one time, and the dimension of micro dimple was smaller than that with unidirectional pulse mode. In bidirectional pulse current, the pulse frequency and pulse duty cycle played an important role on the preparation of micro dimple. With high pulse frequency and low pulse duty cycle, it is useful to reduce the undercut of micro dimple and improve the machining localization. With the pulse duty cycle of 20% and pulse frequency of 10 kHz, micro dimples with etch factor (EF) of 3 were well prepared on both workpieces surface. Full article

Micro-hole arrays have found wide applications in aerospace, precision instruments, and biomedicine. Among various methods of their production, including mechanical, laser, and electrical discharge, electrochemical machining (ECM) is considered the most lucrative due to its wide processing range, high surface quality, and excellent productivity. In particular, ultrasound-assisted through-mask ECM exhibits an enhanced machining precision due to ultrasonic cavitation, which promotes the removal of the electrolytic products and bubbles. In this study, the equation of cavitation bubble oscillation was derived and numerically solved to study the influence of six different parameters on the ultrasonic cavitation and electrolysis process, and their optimal values were determined. The feasibility of the proposed ultrasound-assisted through-mask ECM technology with the optimized parameters was experimentally corroborated by the fabrication of a high-quality hole array in an oxide dispersion strengthened (ODS) MA956 superalloy. Full article

Surface structures with micro-grooves have been reported to be an effective way for improving the performance of metallic components. Through-mask electrochemical micromachining (TMEMM) is a promising process for fabricating micro-grooves. Due to the isotropic nature of metal dissolution, the dissolution of a workpiece occurs both along the width and depth. Overcut is generated inevitably with increasing depth, which makes it difficult to enhance machining localization. In this paper, a method of electrochemical machining using a conductive masked porous cathode and jet electrolyte supply is proposed to generate micro-grooves with high machining localization. In this configuration, the conductive mask is directly attached to the workpiece, thereby replacing the traditional insulated mask. This helps in achieving a reduction in overcut and an improvement in machining localization. Moreover, a metallic nozzle is introduced to supply a jetted electrolyte in the machining region with enhanced mass transfer via a porous cathode. The simulation and experimental results indicate that as compared with an insulated mask, the use of a conductive mask weakens the electric field intensity on both sides of machining region, which is helpful to reduce overcut and enhance machining localization. The effect of electrolyte pressure is investigated for this process configuration, and it has been observed that high electrolyte pressure enhances the mass transfer and improves the machining quality. In addition, as the pulse duty cycle is decreased, the dimensional standard deviation and roughness of the fabricated micro-groove are improved. The results suggest the feasibility and reliability of the proposed method. Full article

A through-mask electrochemical micromachining process with a foamed cathode (foamed-cathode through-mask electrochemical micromachining (TMEMM)) has recently been proposed involving micro-scale surface microstructures with a high geometric consistency that are fabricated on the curved-surface workpiece. In this paper, to make the foamed-cathode TMEMM process more cost-efficient in the applications, significant modifications are made to this process and an upgraded version of the foamed-cathode TMEMM process is developed. In this modified process, the sandwich-like unit (including the foamed cathode, mask, and workpiece) is closely assembled by the magnetic field force instead of the conventionally-used mechanical force and is kept moving up-and-down inside the electrolyte, avoiding the use of the traditional pump-driven circulation for the electrode process. Experiments are carried out to evaluate the machining effect of this modified TMEMM for fabricating micro-dimples. The research results verify that this modified TMEMM process can produce highly uniform micro-dimples whose minimum CV (coefficient of variation) values in depth and in diameter are 5.4% and 1.9%, respectively, with smooth surfaces of the minimum Ra being 0.21–0.35 µm. These values are smaller than those previously reported. This results in the positive effects on the mass transfer driven by magnetohydrodynamic convection induced by the magnetic field within the interelectrode and the foamed electrode. Full article