Extending the Limits of Laser Polymer Welding using Advanced Irradiation Strategies

After enjoying a significantly increased industrial acceptance, mainly due to the development of high power diode lasers, the laser polymer welding has faced extensive investigation over the last decade in order to become nowadays a strong competitor for the other polymer joining processes. The latest developments in the field of laser materials processing such as laser sources with excellent beam quality are bringing new opportunities and also challenges for the laser welding of polymers and lead to a further extension of the process limits. This paper presents the achieved results for the polymer welding using high brilliance laser sources together with advanced irradiation strategies based on the local und temporal modulation of the laser beam such as the recently developed method called TWIST -Transmission Welding by an Incremental Scanning Technique. This approach leads to an optimized thermal management within the welding zone, an exact control of the temperature field generated by the absorbed laser energy, and a significant increase of process robustness, welding quality, process flexibility and efficiency. Experimental results for welding of polymers with a weld seam width from 100 m up to 800 m and a processing speed up to 30 m/ min are presented and discussed.