Powder Mixed Micro Electro Discharge Machining of Aluminium Nitride Ceramic

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