Product Code: ICA12_M507

Laser Transmission Welding with Part Adapted Temperature Fields
Authors:
Martin Devrient, blz Bayerisches Laserzentrum GmbH; Erlangen USA
Verena Wippo, LZH Laserzentrum Hannover e.V.; Hannover Germany
Peter Jaeschke, LZH Laserzentrum Hannover e.V.; Hannover Germany
Uwe Stute, LZH Laserzentrum Hannover e.V.; -
Thomas Frick, blz Bayerisches Laserzentrum GmbH; Erlangen Germany
Heinz Haferkamp, LZH Laserzentrum Hannover e.V.; Hannover Germany
Michael Schmidt, blz Bayerisches Lasersentrum GmbH, LPT Lehrstuhl Fuer Photonische Technologien der Friedrich-Alexander Univ. Erlangen-Nuernberg; Erlangen Germany
Presented at ICALEO 2012

Thermoplastics are present in a wide variety of industrial applications. Different techniques like vibration, resistance and laser welding are used to join these materials. Laser transmission welding is known for high flexibility and for the possibility of process automation. Today, the interest of joining large thermoplastic parts with a three dimensional formed weld seam is rising. Therefore, the parts have to be clamped gap free to avoid welding failures, poor achievable process speed or low weld seam strengths. To overcome these problems, new laser transmission welding techniques were developed to achieve part adapted temperature fields based on a combination of contour and quasi-simultaneous welding. In addition, the authors investigated the effectivity of these strategies with a thermal finite element model. This model focuses on the heat affected zone geometries, temperature gradients and the simulated melt pool geometries depending on the parameters creating nearly a quasi-simultaneous temperature field. These results were verified by experiments with a diode laser, providing a focus diameter of 500 microns. Furthermore, process control strategies were developed, which can later be used to ensure a constant part quality. The process control is carried out by a pyrometer, which allows a temperature detection in the weld seam.