Micro-EDM machining behaviour of ZrO2-TiN ceramic composites

This work deals with the investigation of the micro Electrical Discharge Machining (micro-EDM) behaviour of a commercially available ZrO2-TiN ceramic composite. The study is performed on a dedicated micro-EDM milling centre; WC rods are used as tool electrodes. Taguchi orthogonal array and one factor variation design are employed as investigation methodology for the understanding of the influence of the electrical parameters on the micromachining performance and its optimisation, respectively. The response is evaluated in terms of volumetric Material Removal Rate (MRR), Relative Tool Wear (RTW) and surface quality. Due to the importance that surface integrity has on the mechanical behaviour of ceramics during service, the study focuses on the semi-finishing/finishing regime. The material investigated displays a MRR up to 0.22 mm3/min and RTW in the range of ~ 5-15 %. Surface roughness lower than 0.2 m are achievable. Due to the ideal flexural strength and fracture toughness of ZrO2-TiN composites, a micro-aerodynamic thrust bearing surface is realized as an application example.status: publishe