Influence of Adapted Wavelengths on Temperature Fields and Melt Pool Geometry in Laser Transmission Welding

Abstract

Laser transmission welding is an established joining technology for the creation of strong, hermetic and aesthetic weld seams between thermoplastic parts. However, weld seam properties are strongly dependent on the optical properties of the materials involved. This paper investigates the wavelength-dependent absorption properties of polymeric materials and carbon black, their influence on temperature field generation and the resulting melt pool geometry in laser transmission welding. A FE simulation model is developed to examine the possibilities of influencing the temperature fields during contour and quasi-simultaneous laser transmission welding by adapting the wavelengths under consideration of the absorption and scattering properties. The application of laser wavelengths in the spectral range of 1400nm to 2000nm leads to modified temperature fields and melt pool geometries, which are expected to feature a better load-bearing capacity and a much improved gap-bridging capability.