Zou Zhixiang, Guo Zhongning, Huang Qinming, Yue Taiman, Liu Jiangwen, Chen Xiaolei
State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment, Guangdong University of Technology, Guangzhou 510006, China.
Guangzhou Key Laboratory of Nontraditional Machining and Equipment, Guangdong University of Technology, Guangzhou 510006, China.
Micromachines (Basel). 2020 Dec 26;12(1):17. doi: 10.3390/mi12010017.
Micro-electrical discharge machining (micro-EDM) is a good candidate for processing micro-hole arrays, which are critical features of micro-electro-mechanical systems (MEMS), diesel injector nozzles, inkjet printheads and turbine blades, etc. In this study, the wire vibration of the wire electro-discharge grinding (WEDG) system has been analyzed theoretically, and, accordingly, an improved WEDG method was developed to fabricate micron-scale diameter and high-aspect-ratio microelectrodes for the in-process micro-EDM of hole array with hole diameter smaller than 20 μm. The improved method has a new feature of a positioning device to address the wire vibration problem, and thus to enhance microelectrodes fabrication precision. Using this method, 14 μm diameter microelectrodes with less than 0.4 μm deviation and an aspect ratio of 142, which is the largest aspect ratio ever reported in the literature, were successfully fabricated. These microelectrodes were then used to in-process micro-EDM of hole array in stainless steel. The effects of applied voltage, current and pulse frequency on hole dimensional accuracy and microelectrode wear were investigated. The optimal processing parameters were selected using response-surface experiments. To improve machining accuracy, an in-process touch-measurement compensation strategy was applied to reduce the cumulative compensation error of the micro-EDM process. Using such a system, micro-hole array (2 × 80) with average entrance diameter 18.91 μm and average exit diameter 17.65 μm were produced in 50 μm thickness stainless steel sheets, and standard deviations of hole entrance and exit sides of 0.44 and 0.38 μm, respectively, were achieved.
微电火花加工（micro-EDM）是加工微孔阵列的理想方法，微孔阵列是微机电系统（MEMS）、柴油喷油嘴、喷墨打印头和涡轮叶片等的关键特征。在本研究中，对电火花线切割磨削（WEDG）系统的电极丝振动进行了理论分析，并据此开发了一种改进的WEDG方法，用于制造直径为微米级且高径比大的微电极，以用于孔径小于20μm的孔阵列的在线微电火花加工。改进后的方法具有一种定位装置的新特性，可解决电极丝振动问题，从而提高微电极制造精度。使用该方法成功制造出了直径为14μm、偏差小于0.4μm且高径比为142的微电极，这是文献中报道的最大高径比。然后将这些微电极用于不锈钢孔阵列的在线微电火花加工。研究了施加电压、电流和脉冲频率对孔尺寸精度和微电极磨损的影响。使用响应面实验选择了最佳加工参数。为了提高加工精度，应用了在线接触测量补偿策略来减少微电火花加工过程中的累积补偿误差。使用这样的系统，在50μm厚的不锈钢板上加工出了平均入口直径为18.91μm、平均出口直径为17.65μm的微孔阵列（2×80），孔入口和出口侧的标准偏差分别为0.44μm和0.38μm。
