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Laser transmission welding of white thermoplastics with adapted wavelengths

: Mamuschkin, V.; Aden, M.; Glaser, S.; Engelmann, C.; Olowinsky, A.; Gillner, A.

Kaierle, S. (Congress General Chair) ; Laser Institute of America -LIA-:
ICALEO 2013, 32nd International Congress on Applications of Lasers & Electro-Optics. Congress proceedings. CD-ROM : October 6-10, 2013, Miami, FL, USA
Orlando, Fla.: LIA, 2013 (LIA publication 616)
ISBN: 978-0-912035-98-7
International Congress on Applications of Lasers & Electro Optics (ICALEO) <32, 2013, Miami/Fla.>
Fraunhofer ILT ()

Within the plastic industry, laser transmission welding ranks among the most important joining techniques for plastic parts. To obtain a specific look, plastic parts are normally coloured with dyes or pigments, which can have a major impact on the welding process. This can especially be observed with white polymers, which so far could not be welded by the means of transmission welding. In order to get a bright white tone polymers usually are added titanium dioxide (TiO2) pigments, which is one of the most used colorants. The content of TiO2 determines the opacity of the colour and also the scattering behaviour of the doped polymer. Until now only parts with low TiO2 content and thus low opacity could be welded with conventional laser beam sources. However, in applications where high opacity of the plastic parts is demanded (casings etc.) transmission welding could not be used yet. The analysis of the optical properties of TiO2 loaded polymers reveals that outside the co nventional wavelength range of polymer welding there are areas with more favourable optical 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.