ORIGINAL ARTICLE Investigation on shape, size, surface quality and elemental characterization of high-aspect-ratio blind micro holes in die sinking micro EDM S. Barman & Naga Hanumaiah & A. B. Puri Received: 25 March 2013 /Accepted: 31 July 2013 # Springer-Verlag London 2013 Abstract Tool wear adversely affects the micro features ma- chined in micro electric discharge machining (micro EDM). Deformations of tool electrode and micro feature are the results of stochastic behaviour of discharge processes during machining. It is difficult to study the shape, size and surface quality of high-aspect-ratio blind micro holes without destructing the micro holes due to their miniature size. In this communication, an attempt was taken to study the geometry, surface texture characteristics and elemental characteristics of high-aspect-ratio blind micro holes machined in die sinking micro EDM by adopting a destructive method. Deformation of electrodes and tool profile on the workpiece were also studied. Keywords Micro EDM . Electrode wear . Surface quality . Energy dispersive spectroscopy . Elemental analysis 1 Introduction In micro electric discharge machining (micro EDM), material removal takes place through melting and evap- oration by discharge pulses when the thermoelectric energy is generated in the spark gap between a tool electrode and a workpiece usually submerged in a di- electric fluid. Advancement in pulse generators and development of CNC systems has helped micro EDM process to focus on the production of complicated and high-aspect-ratio micro features with improved surface quality and good repeatability of the process [1]. It is a widespread technique used in industry for high-precision machining of all types of conductive materials such as metals, metallic alloys and graphite and some ceramic materials regardless of their hardness [2]. Due to this advantage, micro EDM has become one of the most reliable methods used extensively in micro mould mak- ing and in the production of dies, cavities and many complex 3D structures [3]. Micro holes are the most basic machined features of micro manufacturing sectors used for various applications like circuit board of inte- grated circuit packages, fuel injection nozzles, spinneret holes, biomedical filters and others [4]. But for the miniature size of the micro holes, it is very difficult to study their geometry and surface quality irrespective of using high-precision equipment and techniques in a non- destructive method. Micro features with characteristic dimensions in the order of 100 μm or less are measured by a contact process using micro coordinate measuring machine (micro CMM) [5]. In CMM, errors associated with misalignment and non-orthogonality of the probe This paper is a revised and extended version of the paper entitled ‘Investigation on Shape, Size and Surface Quality of High Aspect Ratio Blind Micro Holes in Die Sinking Micro EDM’ presented at the 4th International & 25th All India Manufacturing Technology Design and Research (AIMTDR-2012) Conference, held in the Department of Production Engineering, Jadavpur University, Kolkata, India during 14– 16 December 2012. S. Barman (*) : N. Hanumaiah CSIR—Central Mechanical Engineering Research Institute, M.G. Avenue, Durgapur 713209, India e-mail: sbarman@cmeri.res.in A. B. Puri Mechanical Engineering Department, National Institute of Technology (NIT), M.G. Avenue, Durgapur 713209, India Int J Adv Manuf Technol DOI 10.1007/s00170-013-5243-z