DOI 10.1007/s00170-004-2270-9 ORIGINAL ARTICLE Int J Adv Manuf Technol (2006) 27: 939–944 M. Azizur Rahman · M. Rahman · A. Senthil Kumar · H.S. Lim · A.B.M.A. Asad Development of micropin fabrication process using tool based micromachining Received: 11 February 2004 / Accepted: 26 May 2004 / Published online: 23 February 2005  Springer-Verlag London Limited 2005 Abstract A micropin fabrication process has been developed based on micromachining technology. One group of microma- chining technology is microturning. It has the capability to pro- duce three dimensional features on the micro scale. This paper deals with the CNC microturning process. Basically two types of microturning processes are used: straight microturning and taper microturning. Experiments were performed using a pro- grammable multi-purpose miniature machine tool developed for tool based micromachining. NC codes were generated using Bor- land C++ Builder 6.0. Brass bars of 6 mm diameter have been machined to fabricate the micropin with carbide cutting tools. Work materials were clamped on the spindle which has the facil- ity of three-axis movements. Unlike the conventional processes, the cutting tool has no movement. A step cutting process was ap- plied to eliminate workpiece deflection in the microturning pro- cess. Finally a micropin was fabricated with 2 mm length. The larger and smaller diameter of the pin are 475 μ m and 276 μ m, respectively. Keywords CNC microturning · Fabrication · Micromachining · Micropin · NC codes 1 Introduction The accelerating trend of miniaturization is increasing day by day due to the recent advancement in MEMS technology and micro- machining technology contributes to this trend. Micromachining bridges the gap between MEMS manufacturing and the capabili- ties of conventional machining. It is the most basic technology for the production of miniaturized parts and components [1]. Without M.A. Rahman · M. Rahman (✉) · A.S. Kumar · H.S. Lim · A.B.M.A. Asad Advanced Manufacturing Laboratory, Department of Mechanical Engineering, National University of Singapore, Singapore 119260 E-mail: mpemusta@nus.edu.sg Tel.: +65-68742168 Fax: +65-67791459 micromachining technology, fabrication of miniature components is not possible on micron range dimensions. The term “micromachining” is self defining. It is generally used to define the machining process for parts having dimen- sions that lie between 1 and 999 μ m, although an upper limit of 500 μ m has recently been considered to set the border between micro and macromachining [2]. There are two basic groups of micromachining process: mask based and tool based microma- chining. The mask based technology has the limitations of fab- ricating 3D structures as it is applied to only two dimensional shapes. Examples of these processes are etching and electro- forming. On the other hand, the processes using tools, especially those using solid tools, can specify the outlines of various three dimensional structures owing to the easily defined tool path and the clear border at the tool – workpiece surface [3]. A cylindrical micropin can be made by grinding, wire electro- discharge grinding (WEDG), electrical discharge machining (EDM), electrochemical etching and microturning. Each process has its own advantages and disadvantages. Grinding has the prob- lem of the grinding force and the wear of the grinding wheel. In EDM, pin shape is limited to straight or stepped [3]. In electro- chemical etching, the bottle-neck is in controlling the shape and the diameter. Although WEDG is a powerful method to produce the micropin, it has the limitation of low productivity [4]. Depending on the abrasion behaviour of metals, brass is con- sidered to be the most appropriate material for micromachining and the most suitable material to fabricate microparts [5]. Be- cause microturning uses a solid cutting tool, it can clearly define and produce 3D shapes following various cutting path. Consid- ering all these, the CNC microturning method was conceived to fabricate the micropin of compound shape with brass (∼ 60% Cu, ∼ 40% Zn) material as shown in Fig. 1. Fig. 1. Proposed shape of the micropin