Study of Machining Non-Conducting Materials using EDM
|International Journal of Engineering Trends and Technology (IJETT)||
|© 2016 by IJETT Journal|
|Year of Publication : 2016|
|Authors : Mayank Srivastava
|DOI : 10.14445/22315381/IJETT-V34P219|
Mayank Srivastava "Study of Machining Non-Conducting Materials using EDM", International Journal of Engineering Trends and Technology (IJETT), V34(2),88-92 April 2016. ISSN:2231-5381. www.ijettjournal.org. published by seventh sense research group
Electro Discharge Machining (EDM) is an electro-thermal non-traditional machining process, where electrical spark is generated using electrical energy and material removal occurs mainly due to thermal energy of the spark. There is no direct contact between the tool electrode and the workpiece. Therefore, the process works very efficiently, particularly in the machining of difficult-to-cut materials. Work material to be machined by EDM has to be electrically conductive. However, research and development of non-conductive (ex. ceramic materials), especially suited for electrical discharge machining (EDM), is still limited. Ceramic materials, (e.g. zirconia, silicon nitride or silicon carbide) exhibit excellent mechanical properties but are mostly electrically non-conductive. This can be compensated by an applied, electrically conductive assisting electrode. With this modification, the electrical discharge machining of non-conductive ceramic material is enabled. To initiate the sparks, a conductive layer of adhesive copper is applied on the workpiece surface. Kerosene is used as dielectric medium for creation of conductive pyrolytic carbon layer on the machined surface. Parameters like voltage (V), capacitance (C) and rotational speed (N) are varied to observe the pattern. During the machining of ceramics, unstable discharges occur. The formation mechanism of the electrical conductive layer on the EDMed surface is much different as compared to other ceramics. In addition to this, the electrically conductive layers are not formed sufficiently to adhere to the EDMed workpiece surface and keep a stable and continuous discharge generation on the ceramics. Graphite is widely used as electrode material in EDM. It is expected that carbon from graphite electrode implant and generate a conductive layer. The aim of this study is to explore the feasibility and development of an applicable process for processing non-conductive ceramics through EDM, which is specifically used for machining of conducting materials. Also, the effect of various tool electrodes were investigated with graphite, copper and brass tool electrodes on the MRR and surface characteristics of a non-conducting ceramics workpiece.
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Conducting materials, Non-Conducting Materials, Ceramics, Tool Electrode