The analysis of EDM electrodes wear in corners and edges
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(2020) 20:130
ORIGINAL ARTICLE
The analysis of EDM electrodes wear in corners and edges K. Mouralova1 · J. Bednar1 · L. Benes2 · P. Hrabec1 · M. Kalivoda1 · J. Fries3 Received: 11 June 2020 / Revised: 1 September 2020 / Accepted: 5 October 2020 © Wroclaw University of Science and Technology 2020
Abstract Die-sinking electrical discharge machining is an unconventional technology that allows to machine all at least minimally electrically conductive materials regardless of their physical and mechanical properties. Despite the fact that it is not a conventional technology, the tool gets also worn out, which is a tool electrode. The wear of the electrode does not only mean its loss but also the degradation of the shapes that are transferred to the resulting workpiece. For this reason, a design of experiments was conducted with 6 input factors, 2 were categorical: the electrode material (copper, graphite) and workpiece material (steel 1.2363 and steel 1.2343ESR) and 4 were numerical: Open-voltage, Pulse current, Pulse on-time, and Pulse off-time. In the framework of this design of experiments, the wear of the used graphite and copper electrodes at their corners and edges was evaluated, which was made possible by the use of electron microscopy and the use of approximation circles. Furthermore, the eroding speed, the topography of the machined samples, and the morphology of the surfaces of the used electrodes were investigated. It has been recognized that the use of a graphite electrode will allow for more accurate workpiece shapes and less wear. Keywords EDM · Electrical discharge machining · Wear · Design of experiment · Electrode · Corners
1 Introduction Die-sinking electrical discharge machining (EDM) is a technology operation that is indispensable in many industries, such as the automotive, aerospace, military, and medical industries. Machining is carried out without the contact of the tool (electrode) with the workpiece; therefore, there are no conventional cutting forces and the resulting workpiece is not stressed by them. This allows producing thin-walled profiles from soft materials which are conventionally very difficult to manufacture [1]. It is possible to machine all at least minimally electrically conductive materials regardless of their toughness, hardness, or mechanical properties. Workpieces can, therefore, be machined to final dimensions only after heat treatment. This avoids dimensional * K. Mouralova [email protected] 1
Faculty of Mechanical Engineering, Brno University of Technology, Brno, Czech Republic
2
Faculty of Mechanical Engineering, Czech Technical University in Prague, Prague, Czech Republic
3
Department of Production Machines and Design, Technical University of Ostrava, Ostrava, Czech Republic
and volume changes in the part. A wide range of materials can be machined using EDM, from polycrystalline diamond (PCD) coated tools, ceramics, composite materials, silicon, to soft aluminum alloys used in the aerospace industry [2, 3]. However, during the erosion process, the
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