Product Code: ICA13_603

Laser Transmission Welding of White Thermoplastics with Adapted Wavelengths
Authors:
Viktor Mamuschkin, Fraunhofer Institute for Laser Technology ILT; Aachen Germany
Mirko Aden, Fraunhofer Institute for Laser Technology; Aachen Germany
Christoph Engelmann, Fraunhofer Institute For Laser Technology; Aachen Germany
Alexander Olowinsky, Fraunhofer Institute for Laser Technology; Aachen Germany
Arnold Gillner, Fraunhofer Institute for Laser Technology; Aachen Germany
Sibylle Glaser, Treffert GmbH & Co. KG; Bingen-Sponsheim Germany
Presented at ICALEO 2013

Since its introduction transmission welding continuously gained importance and opened up a wide field of applications within the plastic industry. However, in some areas as in household appliances where mainly white polymers are used transmission welding could not be applied yet. The reason is titanium dioxide (TiO2) pigments which normally are added to the polymer in order to give it the demanded brilliant white tone. However, TiO2 causes strong scattering which is responsible for the colour brilliance of the material on the one side but complicates the energy deposition in the joining plane on the other side. Up to now only parts with low TiO2 content and thus low opacity could be welded. Since in household appliences white thermoplastics are often used for housing parts a high opacity is required to cover underlying parts.
The analysis of the optical properties reveals that outside the conventional wavelength range of polymer welding there are areas with more favorable properties. New diode lasers provide a broad variety of wavelengths which allows exploiting those areas by adapting the wavelength and thus enable welding of fully opaque white parts.