The electronic and automobile industries have a growing interest on laser welding of polymers. Laser welding of polycarbonate has been widely studied in numerous different occasions. Novel ways for creating stronger and visually better welds are continuously studied. The need for short welding times and narrow welds gives a challenge for quasi-simultaneous laser welding: The welds have to be as strong as the base material when weld widths are from 0.2 mm and up but the welding times must be less than 1 second.
This paper examines the effect of clamping force during welding and the possibilities to use a ridge, typical for ultrasonic welding, on top of the absorbing part to improve the weld properties. Depending on the welded part there is a need for high clamping forces in order to close all air gaps caused by inaccuracies of and variation on injection molded parts. Results on weld widths on different clamping forces with and without the ridge are presented. Outcome of the research is discussed based on these results.