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Ultrasonic assistance and nonconductive materials: Shifting the boundaries of micro-EDM

: Schubert, Andreas; Zeidler, Henning; Hackert-Oschätzchen, Matthias; Schneider, Jörg

Preprint urn:nbn:de:0011-n-1902084 (4.0 MByte PDF)
MD5 Fingerprint: 0a139f0b025febf24ea7db479e830404
Created on: 15.12.2011

Slabe, E. ; TECOS Slovenian Tool and Die Development Centre, Celje:
Industrial Tools and Material Processing Technologies : Proccedings of the 8th International Conference on Industrial Tools and Material Processing Technologies, October 2nd-5th 2011, Ljubljana; ICIT & MPT 2011
Ljubljana, 2011
ISBN: 978-961-6692-02-1
International Conference on Industrial Tools and Material Processing Technologies (ICIT&MPT) <8, 2011, Ljubljana>
Conference Paper, Electronic Publication
Fraunhofer IWU ()
Electro Discharge Machining; micromachining; ultrasonic; ceramics

Micro EDM is a known nonconventional process for the machining of hard to cut materials. Due to its ablating nature based on melting and evaporation through heat induced by electrical discharges it is independent of hardness, toughness or brittleness of the workpiece. Because of these benefits, EDM is widely used in tool- and mouldmaking; micro-EDM with its much lower discharge energies has been successfully applied to micromachining of high-accuracy parts. The precision manufacturing of high aspect ratio micro geometries such as deep micro bores relies on stable process conditions in the discharge gap. Its minimisation – precondition for minimal feature size and highest accuracy – limits the effectiveness of conventional flushing techniques, leading to a higher fraction of unwanted discharge states (open and short circuit), lower process speed and geometrical errors. New hybrid technology approaches such as ultrasonic or low frequency superposition significantly raise process stability and speed. Another restriction to EDM, the exclusive machinability of electrically conductive materials, is overcome by the application of the assisting electrode method that enables a micro-ED-machining of nonconductive zirconium oxide ceramics. This paper presents the current status of investigation into the micro-EDM process with ultrasonic vibration assistance – directly applied to the workpiece and indirectly applied high-intensity ultrasonic to the dielectric – in metallic materials as well as into the machining of electrically nonconductive ceramic materials. Using ultrasonically aided micro-EDM, the process speed can be raised by up to 40%, enabling bores of less than 90/m in diameter with aspect ratios >40 for metallic materials. The modified setup using the assisting electrode principle allows for machining of aspect ratio >5 for nonconductive ceramic materials, leading to new possibilities for the design and manufacture of complex, high-accuracy micro parts in high-performance engineering materials.