Product Code: ICAL05_P559

Gas Investigation in Percussionnal Laser Drilling
Authors:
Matthieu Schneider, GIP/GERAILP; Arcueil France
Laurent Berthe, GIP/LALP (CNRS); Arcueil France
Maryse Muller, GIP/LALP (CNRS); Arcueil France
Remy Fabbro, GIP/LALP (CNRS); Arcueil France
Mariette Nivard, GIP/LALP (CNRS); Arcueil France
Presented at ICALEO 2005

This paper concerns the study of the laser drilling in percussion regime which is used extensively in aeronautical industries. In this case, the drilling is dominated by melt ejection induced by recoil pressure. Experimental understanding study of such process is complicated due to the number of parameters and the laser sources which is unsettled pulse by pulse. In this paper, we present experimental and numerical investigations concerning assistant gas influence. The role of the assist gas is misunderstood. For some models, the assist gas is useful during laser-matter interaction, this pressure is reflected on the bottom non-breaking through hole. But recoil pressure is in the range of several hundreds bars which is higher than the assistant gas pressure applied. Experimental results show that gas pressure influences hole quality : the presence of droplets on surface and around the exit hole, the recast layer thickness and the hole geometry.
Numerical (using multi-physics code RADIOSS from MECALOG) approaches have been also coupled to determine ?a priori? the hole geometry from the laser parameters irradiation and assistant gas. Results are compared with experimental holes geometry drilled with a laser spatial profile ?top hat? delivered by the HL201P source (Trumpf) dedicated for this drilling regime.