Investigation of Ablation Behaviour in Micro-EDM of Nonconductive Ceramic Composites ATZ and Si3N4-TiN

Abstract

Micro-EDM is a well-known process for precision micro machining of difficult to cut materials. It is especially beneficial for machining of complex micro structures such as deep bores, grooves or undercuts in highly wear resistant materials.In the last years, research has successfully applied the assisting electrode method as a suitable process for machining non-conducting ceramics by micro-EDM. There, the EDM process is initiated after applying an electrically conductive starting layer onto the surface of the ceramic. Due to the great variety of ceramics like oxide ceramics, non-oxide ceramics or ceramic composites, different mechanisms for material removal can be observed depending on the raw material and its composition. Particularly for production oriented reasons it is necessary to determine the specific ablation behaviour of each ceramic with regard to the used process parameters. In this study two different ceramic composites, ATZ (Alumina Toughened Zirconia, ZrO2-Al2O3) and Si3N4-TiN (Titanium Nitride toughened Silicon Nitride), were investigated considering their ablation behaviour. Experiments were carried out to determine the maximum achievable aspect ratios of micro bores, the resulting surface quality and the possibility for machining complex 3D-structures by EDM-milling.