Fundamental material based investigations to understand electric discharge machinability of electrically conductive ceramics with oxide matrix

• Applicants: Professor Dr.-Ing. Thomas Bergs; Professor Dr. Frank Kern
• Subject Area: Glass, Ceramics and Derived Composites ; Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 283180766

Structural ceramics are used in applications in e.g. Engineering and Medical technology requiring good mechanical properties such as hardness and wear resistance. These properties restrict the machinability of the materials in terms of component complexity and material removal rate. In manufacturing technology of ceramics, net-shape strategies have therefore been developed to mass produce complex components while customized parts are typically produced by green machining of blanks. However for high precision a final machining of these components after sintering is necessary. Electric discharge machining allows for precision machining of customized ceramic components provided that the material is electrically conductive. Yet the EDM process which has become a standard process in machining of metals is not sufficiently understood in case of ceramics. In the project proposed, two material systems of ceramics with oxide matrix and carbide dispersion are investigated. The aim of the study is to elucidate in how far the ED machinability, surface properties and bulk properties of the ceramics can be deduced from their composition and microstructural architecture. Compositions of materials are systematically varied and their interaction with ED machining parameters is studied. For this purpose materials are characterized in depth before and after the machining process with a clear focus on the process zones created by the interaction of the ED process with the material surface. Complementary the machining data are recorded. The correlations found in this multidimensional parameter space are used as input data for a model. The aim is to understand the material removal mechanisms and to enunciate a model-based description of the ED-process which not only allows to quantitatively predict ED-machinability but also to devise a set of design and machining guidelines for the materials investigated. The acquired broad basic knowledge is provided to the industry, ceramics and tooling machine manufacturers as well as end users, for the development of ceramic materials tailored for specific applications as well as for a systematic design of ED machining technologies. It represents a milestone for the Implementation of standardized ceramic-specific technology databases in the tooling machines and will be the key to a widespread application of ED machinable ceramic materials. For this purpose the proposal consolidates the knowledge and experience of both project partners in the field of ED machinable ceramics and in ED machining.

• DFG Programme: Research Grants