Simultaneous laser beam welding of thermoplastics : innovations and challenges

The compact and modular set up of high power diode lasers permits simultaneous laser beam welding. The entire weld seam is irradiated as a whole and welded with one single laser pulse (sequence). Apart from short process times, which are of interest for big lot production, simultaneous welding allows a more moderate irradiation (inter-action). Additionally, it promises wider process windows, a marked gap bridging capability as well as an enhanced weld strength compared to contour welding. By means of appropriate beam forming and guiding a homogeneous intensity distribution fitting to the entire weld seam geometry has to be generated, which represents the challenge of the simultaneous process. There are different strategies possible to accomplish simultaneous welding. Some strategies will be illustrated in brief. Furthermore, results of systematic investigation concerning weldability, gap bridging capability, hermetic sealing as well as reachable burst pressure of sample boxes are presented. Finally, an op...