Melt expulsion by a coaxial gas jet in trepanning of CMSX-4 with microsecond Nd:YAG laser radiation

Jens Willach; Ernst Wolfgang Kreutz; Jan Michel; Markus Niessen; Wolfgang Schulz; Reinhart Poprawe

doi:10.1117/12.540753

18 November 2003 Melt expulsion by a coaxial gas jet in trepanning of CMSX-4 with microsecond Nd:YAG laser radiation

Jens Willach, Ernst Wolfgang Kreutz, Jan Michel, Markus Niessen, Wolfgang Schulz, Reinhart Poprawe

Proceedings Volume 5063, Fourth International Symposium on Laser Precision Microfabrication; (2003) https://doi.org/10.1117/12.540753
Event: Fourth International Symposium on Laser Precision Microfabrication, 2003, Munich, Germany

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.

Citation Download Citation

Jens Willach, Ernst Wolfgang Kreutz, Jan Michel, Markus Niessen, Wolfgang Schulz, and Reinhart Poprawe "Melt expulsion by a coaxial gas jet in trepanning of CMSX-4 with microsecond Nd:YAG laser radiation", Proc. SPIE 5063, Fourth International Symposium on Laser Precision Microfabrication, (18 November 2003); https://doi.org/10.1117/12.540753

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