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The analysis of EDM electrodes wear in corners and edges

Mouralova K., Bednar J., Benes L., Hrabec P., Kalivoda M., Fries J.

Archives of Civil and Mechanical Engineering

2020

Vol. 20, no. 4

484--497

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.

Influence of the cut direction through the semi-finished product on the occurrence of cracks for X210Cr12 steel using WEDM

Mouralova K., Klakurkova L., Matousek R., Prokes T., Hrdy R., Kana V.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 4

1318--1331

Wire electrical discharge machining (WEDM) is a key technological process for the production of parts from semi-finished products to the final heat treatment as it also enables the machining of very hard material. The quality of an electro-erosive machined surface is a very important factor with regard to the consequent functionality and life cycle of the manufactured part. The occurrence of cracks or burned cavities is therefore an acceptable defect of the sub-surface area, which along with residual stress may lead to the destruction of the machining. This study deals with the influence of the cut direction through a semi-finished product on the occurrence of defects (cracks, burned cavities) regarding the influence of setting up the parameters of the machine (gap voltage, pulse on and off time, wire feed and discharge current) and the type of heat treatment of the material. In order to study the surface and sub-surface area of the machined samples, electron microscopy was used, including the use of the local EDX chemical analysis.