Product Code: ICAL05_802

Effects of Laser Beam Scattering on Through-Transmission Welding of Polymers
Authors:
Jean-Christophe Kneip, LTm Laboratory - Univ. of Burgandy; Chalon sur Saone France
Alexandru Nichici, University Politechnic of Timisoara; Timisoara Romania
Mariana Ilie, LTm - IUT Le Creusot; Chalon sur Saone France
Simone Mattei, LTm; Le Creusot France
Presented at ICALEO 2005

Laser technology development in the field of plastics processing is now rapidly expanding and opens up a wide range of applications in various industrial fields that could not have been conceived of only a few years ago (automotive, plastic objects, packaging, ?). Among these processes, through-transmission laser welding of thermoplastic materials is more and more frequently used for industrial applications.
In this process, the laser beam energy may be deposited directly into the structure, at the interface between the semi-transparent and opaque slabs. Thereby the polymer compositions (presence of additives, pigments, reinforcements, ? ) may have a great influence on this deposition.
We present here a study of the scattering phenomena in semi-transparent polymers induced by their compositions in the through-transmission laser welding processes. In a 1st part the scattering of a laser beam into a polymer is explained as well as the mathematical modellings currently used. In a 2nd part a numerical study of the scattering is realized and compared with some experimental results obtained on PMMA polymers. We show here that the scattering of the laser beam is of prime importance for this process and that the simulation allows a good estimation of it. In the 3rd part, results are used into a finite elements program, specially developed to determine the thermal field and the structure behavior under laser excitation, in order to simulate a through-transmission laser welding process on PMMA polymers and compared with experimental data. We show here the interest of a good understanding of the scattering phenomena and the possibilities to simulate it.