Electrochemical micro-machining of high aspect ratio micro-tools with a reverse conical shape tip using electrolyte liquid membrane

Abstract

With the outbreak of product miniaturization, the demand of micro-tools fabrication is increasing. Tungsten is a widely used material when fabricating micro-tools. However, tungsten is difficult to machine due to its high hardness. Electrochemical micro-machining (EMM) has many advantages over conventional machining processes, which makes it a potential method to manufacture tungsten micro-tools. This paper proposes a novel EMM fabrication method of high aspect ratio micro-tools with a reverse conical shape tip. During the machining process, a tungsten rod is passed through the electrolyte liquid membrane and makes a linear reciprocating motion. The anodic dissolution occurs only in the region where the rod and electrolyte are in contact. Comparing to the conventional method, this proposed method can improve the shape accuracy of micro-tools. A mathematical model is developed to predict the final diameter of the tool. Furthermore, the effects of main parameters, including electrolyte concentration, feeding rate, the thickness of electrolyte, and the position of the micro-tools, are investigated experimentally. Finally, optimum parameters are selected, and a high aspect ratio micro-tools with a reverse conical shape tip are successfully fabricated using these parameters.