Fundamental investigation on the application of an inverted pressure flushing method for electrical-discharge drilling with waterbased dielectrics

• Applicant: Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541367366

The main objective of the research project is to derive basic knowledge on the use of a new flushing method, the inverted pressure flushing, in electrical discharge drilling with water-based dielectrics in the first funding period and with hydrocarbon dielectrics in the second funding period. Electrical discharge machining is an industrially established manufacturing process based on thermal ablation by means of electrical spark discharges. Electrical discharge drilling is subordinate to electrical discharge machining. Its fields of application range from start hole drilling for wire erosion to drilling for colourant, textile and synthetic fibre drawing jets, optical apertures and sprue drilling in mould making. With increasing drilling depth, the process conditions in the working gap deteriorate during electrical discharge drilling. Material particles are accumulated between the tool and workpiece electrodes which cannot be efficiently removed. This leads to arc discharges and short circuits, resulting in a considerable increase of the erosion duration. Within the own preliminary work, it could be shown that fluid-mechanical influencing variables, such as the flushing direction, the flushing pressure and the flushing volume flows have a significant influence on the process results in electrical discharge drilling. These findings lead to the approach to counteract limited drilling depths by using an inverted pressure flushing method. In this method, the dielectric fluid and the removed material particles are pushed out through the central bore of the tool electrode with a flushing pressure p ≥ 1 bar. However, the complete investigation of a solution such as inverse pressure flushing, in which the dielectric is pushed out through the central bore of the tool electrode with a flushing pressure p ≥ 1 bar applied to the lateral working gap sL, has yet to be carried out and therefore forms the objective of this research project. On the basis of the preliminary work, the project is expected to reduce the erosion duration by ≥ 50 % and the length wear of the tool electrode by ≥ 10 %. Furthermore, the overall result of this research project provides detailed knowledge about a possible influence on the flushing conditions in the working gap and the necessary technological and strategic knowledge for the reliable use of inverted pressure flushing on an industrial scale.

• DFG Programme: Research Grants