Abstract
Advanced ceramic materials possess superior mechanical characteristics in terms of hardness, wear resistance, fracture toughness and flexural strength. However, these materials experience machining limitations due to their hardness. Machining process of such materials requires high cutting forces and results in high tool wear. Electro- discharge machining (EDM) can be considered as an alternative machining process for advanced ceramics, since this technique is a non-contact machining process, it does not involve high cutting forces but experiences moderate tool wear. However, EDM requires materials to have certain level of electrical conductivity, therefore, non-conductive and semi-conductive ceramic materials experience challenges during machining process. Assisting Electrode Method was suggested as a solution for machining of non-conductive ceramics by EDM. In this method, conductive layer is applied on top of non-conductive ceramics and thus workpiece can be machined by EDM process using residual conductive layer. In this study, coating consisting of three layers, where silver nanoparticles were sandwiched between two layers of silver and copper on top, was used as assisting electrode to machine Aluminium Nitride (AlN) ceramics by silver nanoparticles mixed micro-EDM. Successful machining of AlN was demonstrated and blind micro hole with higher than three aspect ratio was achieved.
Highlights
The electro-discharge machining (EDM) is a process where material removal occurs through evaporation and melting of workpiece
Conductive coating consisting of three layers, where silver nanoparticles were sandwiched between two layers of silver and copper on top, was proposed as assisting electrode to machine Aluminium Nitride (AlN) ceramics by Silver nanopowder mixed micro-EDM
Depth of hole was measured by optical microscope which is 996 μm measuring from coating surface
Summary
The electro-discharge machining (EDM) is a process where material removal occurs through evaporation and melting of workpiece. Development of this technology created an alternative way of machining special materials with particular requirements. For the traditional cutting technologies, machining of those materials are found to be problematic because of their high brittleness and toughness. High cutting forces that are applied in traditional cutting technologies result in surface and sub-surface cracks when applied to brittle materials. EDM is considered as a non-traditional machining process that is force-free and can be considered as an alternative machining technology which allows machining of ceramics irrespective of their hardness [2]
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