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Proceedings Paper

Melt expulsion by a coaxial gas jet in trepanning of CMSX-4 with microsecond Nd:YAG laser radiation
Author(s): Jens Willach; Ernst Wolfgang Kreutz; Jan Michel; Markus Niessen; Wolfgang Schulz; Reinhart Poprawe
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Paper Abstract

Trepanning of 200 μm holes in 2-5mm thick CMSX-4 sheets is done by laser radiation provided by a lamp-pumped Nd:YAG slab laser with pulse durations of 100 - 500 μs. Pulse energies <1J determine the material removal mainly by melt expulsion assisted by a processing gas jet coaxial to the laser beam. Stagnation and deflection of the gas jet at the entrance of the kerf, friction in the molten material, and friction at the liquid/solid interface hinder an efficient melt expulsion. A simulation tool for supersonic gas flow solving Euler equations by the Finite Volume Method is developed in order to investigate the gas flow through the trepanning kerf. Gas pressures above and within the kerfs while trepanning at different inclination angles, geometries and arrangements of nozzles as well nozzle reservoir pressures are presented. The computed gas flow is compared to melt expulsion investigated metallographically by the determination of kerf widths and the thickness of the resolidified melt.

Paper Details

Date Published: 18 November 2003
PDF: 6 pages
Proc. SPIE 5063, Fourth International Symposium on Laser Precision Microfabrication, (18 November 2003); doi: 10.1117/12.540753
Show Author Affiliations
Jens Willach, RWTH-Aachen (Germany)
Ernst Wolfgang Kreutz, RWTH-Aachen (Germany)
Jan Michel, RWTH-Aachen (Germany)
Markus Niessen, RWTH-Aachen (Germany)
Wolfgang Schulz, Fraunhofer-Institut fuer Lasertechnik (Germany)
Reinhart Poprawe, RWTH-Aachen (Germany)
Fraunhofer-Institut fuer Lasertechnik (Germany)

Published in SPIE Proceedings Vol. 5063:
Fourth International Symposium on Laser Precision Microfabrication
Isamu Miyamoto; Andreas Ostendorf; Koji Sugioka; Henry Helvajian, Editor(s)

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