Product Code: ICA12_203

Comparison of Keyhole Characteristics Obtained by Two Experimental Methods: The “Direct Observation of Drilled Hole” Method and the “Sandwich” Method
Authors:
Simone Matteï, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS / Univ. de Bourgogne; Le Creusot France
Jean-Marie Jouvard, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS / Univ. de Bourgogne; Le Creusot France
Massaud Mostafa, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS / Univ. de Bourgogne; Le Creusot France
Iryna Tomashchuk, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS / Univ. de Bourgogne; 71200 Lez Creusot France
Henri Andrzejewski, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS / Univ. de Bourgogne; Le Creusot France
Presented at ICALEO 2012

The present study is dedicated to examining the evolution of the keyhole obtained during the drilling of samples of Zinc by YAG laser beam. Two experimental methods are used to observe the shape of the keyhole. The first one is the direct observation of drilled hole, that let to obtain the shape of the keyhole for different laser powers and different pulse duration times. The observations are carried out after drilling. The second one needs to clamp the zinc sheet with a quartz glass. This glass is chosen because of its excellent thermal shock resistance and its high light transmittance. The observation of the keyhole shape is then realized through the quartz during the drilling with a high-speed CCD camera. The evolution of the shapes of the keyhole, obtained by both methods, led to highlight the role of the multiple reflections on the shape of the keyhole. Actually, in the first method, the multiple reflection of the laser beam on the wall of the keyhole occurs, whereas, for the second experimental set-up, it can be considered that there is only one impact of the laser beam on the keyhole walls.