Investigation on Wire-EDM Finishing of Titanium Nitride Doped Silicon Nitride in CH-based Dielectrics

Abstract

Silicon nitride (Si 3 N 4 ) is a non-oxide ceramic with good thermal and mechanical properties, therefore it can be used for example as cutting edges in high performance turning processes. Because conventional machining is restricted due to hardness and brittleness, the force-free EDM is increasingly used for these ceramics. Due to the decomposition of silicon nitride during Electrical Discharge Machining (EDM) in water-based dielectric, a porous and foamy structure on the surface occurs. This has a negative impact on the workpiece behavior under mechanical load, reducing the usability in high performance processes. Therefore, improving the surface quality is crucial. So far, there are only a few published investigations focusing on wire-EDM finishing of silicon nitrides. Hence, in this paper a combination of main and trim cut technologies in CH-based dielectric for titanium nitride doped silicon nitride are examined. For these investigations, geometrical variations are used to identify the restrictions of the machinability with trim cuts. To determine the improvements, material analyses of the rim zone are applied. Based on literature, investigations regarding wire-EDM finishing of silicon nitrides are carried out.