Influence of various flow methods during fabrication of micro ellipse pattern by maskless electrochemical micromachining

Abstract

Electrochemical micromachining is extensively exploited to fabricate various surface textures, which have been used in many applications such as biomedical, defense, aerospace, tribology, etc. Maskless electrochemical micromachining (EMM) is a promising method for fabricating micro ellipse patterns with controlled shape, size and surface quality, which is based on electrochemical etching. In this paper, the effect of hydrostatic and three electrolyte flow methods is investigated during generation of micro ellipse patterns utilizing developed maskless EMM setup and SU-8 2150 masked tool. The developed setup consists of EMM cell, electrode holding devices, electrolyte circulation system and electrical connections. A patterned tool using SU-8 2150 mask can generate many high quality machined samples. The influences of major process parameters such as machining voltage, inter electrode gap, duty ratio, pulse frequency and electrolyte flow rate are explored on major and minor axis overcuts, machining depth and surface roughness (Ra) using hydrostatic and three different electrolyte flow methods during micro ellipse pattern generation. A mathematical model of the current efficiency is also developed to estimate the effectiveness of hydrostatic and different flow methods. An attempt has also been done to analysis the effects of hydrostatic and different flow methods during fabrication of micro ellipse patterns. From the experimental analysis, only upward vertical cross flow electrolyte method is recommended for the fabrication of uniform micro ellipse pattern with major axis overcut of 24.02 μm, minor axis overcut of 20.35 μm, controlled depth of 15.50 μm and surface roughness (Ra) of 0.0208 μm.