Abstract Micro dimples as a typical surface texture has been used in many fields for enhancing the functionality and performance. Electrochemical machining (ECM) is a promising approach for generating micro dimple. However, due to the isotropy of metal dissolution, the lateral undercutting of micro dimple is inevitable in ECM, which reduces the machining localization. This paper proposed a method of conductive mask jet electrochemical machining to reduce the undercutting of micro dimple and improve the machining localization. In this method, a conductive patterned mask instead of insulated patterned mask was covered on the workpiece directly during machining, which could decrease the undercutting of micro dimple by reducing the electric field intensity at the edge of micro dimple. In addition, a metallic nozzle (inner diameter of 2 mm) was employed to provide a stable columnar jet flow for enhancing the attachment between the mask and workpiece as well as the renewal of electrolyte in machining area, which was useful for generating deep micro dimple. Simulated results showed that the conductive mask could reduce the electric field identity at the edge of micro dimple effectively, and the undercutting of the profile was evidently reduced compared to that generated with insulated mask. Experimental results indicated that with conductive mask JEM, the undercutting of micro dimple was just 9 μm when the depth increased to 55 μm, the etch factor (EF) reached to 6.11, and it was four times greater than that with insulated mask. With the depth increased from 45 μm to 85 μm, the undercutting of micro dimple enlarged from 7 μm to 15 μm. The material removal rate in depth was evidently faster than that in diameter, which showed a low undercutting and high machining localization. In addition, compared with pulse current, direct current was more appropriate for generating deep micro dimple in conductive mask JEM.

中文翻译：

---

带有导电掩模的微凹坑的喷射电化学加工

摘要 微凹坑作为一种典型的表面纹理已被用于许多领域以增强功能和性能。电化学加工 (ECM) 是一种很有前途的产生微凹坑的方法。然而，由于金属溶解的各向同性，微凹坑的横向底切在 ECM 中是不可避免的，这降低了加工局部化。本文提出了一种导电掩模喷射电化学加工方法，以减少微凹坑的咬边，提高加工定位。该方法在加工过程中直接在工件上覆盖导电图形掩膜代替绝缘图形掩膜，通过降低微凹坑边缘的电场强度来减少微凹坑的咬边。此外，采用金属喷嘴（内径为2 mm）提供稳定的柱状射流，以增强掩模与工件之间的附着力以及加工区电解液的更新，这有助于产生深微凹坑。仿真结果表明，导电掩模能有效降低微凹坑边缘的电场同一性，与绝缘掩模相比，轮廓的咬边明显减少。实验结果表明，使用导电掩模JEM，当深度增加到55μm时，微凹坑的咬边仅为9μm，蚀刻因子（EF）达到6.11，是绝缘掩模的4倍。随着深度从 45 μm 增加到 85 μm，微凹坑的底切从 7 μm 扩大到 15 μm。深度上的材料去除率明显快于直径上的材料去除率，表现出低咬边和高加工局部化。此外，与脉冲电流相比，直流电更适合在导电掩模JEM中产生深微凹坑。