Investigations to obtain fundamental insights into the formation of melt splashes using gaseous, dispersed and liquid dielectrics in electro-discharge contouring

• Applicant: Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 530862942

The main objective of the research project is to provide and extend basic knowledge on the formation of the melt pattern in the electro-discharge contouring with gaseous, dispersed and liquid dielectrics during the machining of metallic materials. Avoiding melt splashes and understanding how they are generated is of considerable relevance in various industrial applications, e.g. to ensure the form closure of injection moulds. For the processes of dry electrical discharge machining and near-dry electrical discharge machining, up to now no methodically and comprehensively obtained insights into the formation of the melt pattern exist. From the state of research, the generator parameters emerge as essential influencing variables on the characteristics of the melt pattern. However, the own preliminary experiments underline the assumption that, in addition, flow-mechanical influencing variables, such as the rotational speed, the flushing pressure or the flushing volume flows of the dielectrics, have a significant influence. The basis for a profound and systematic investigation of the phenomena in the working gap is the use of a specially developed IsoPulse-resistance capacitance (RC) pulse generator. It combines the variability and controllability of static pulse generators with the short discharge duration and low discharge energy of RC pulse generators. Using the scientific method of design of experiments a detailed analysis and systematic investigation of the formation and characteristics of the melt pattern is carried out. In addition to definitive screening designs, central composite response surface designs (CCD-RSM) are used to systematically investigate the influence of different variables on the geometric properties of the melt pattern by means of regression models. These variables are the generator parameters, the time-resolved process signal characteristics, the flushing with different dielectrics and the gravity. As a result, a process-reliable design of the electro-discharge contouring with gaseous, dispersed and liquid dielectrics is realized. After completion of the research project, basic knowledge about the formation of the melt pattern during the machining of metallic materials will be available. The overall result is a derivation of strategies for the avoidance of melt splashes in the mould and tool making industry.

• DFG Programme: Research Grants