New perspectives for the absorber free laser welding of thermoplastics

Polymeric products play an important role in almost every aspect of our lives and they can be found in a wide variety of products starting from everyday products up to high tech products in the automotive, electronics, medical and other sectors. The possibility to fabricate complex shapes in various sizes provides design flexibility and high performance at lower costs and allows designers to face today's complex demands. Starting as an unconventional joining technology for the manufacturing of polymeric products the laser beam welding earned over the last decade through an extensive research effort a respectable place among the other available joining methods. Currently one of the main process limitations is related to the requirement of having a laser transparent and a laser absorbing joining component. One possibility to overcome this limitation is to adapt the wavelength of the laser source to the absorption characteristic of the material and to select a suitable irr adiation strategy. Following this approach this paper presents the latest results and the future perspectives for the laser absorber free welding using adapted laser wavelengths and irradiation strategies. The welding results for Poly(methyl methacrylate) - PMMA transparent components with feed rates up to 100 mm/s and different laser wavelengths such as 1550 nm, 1700 nm or 1908 nm are presented and discussed.