Laser transmission welding of optical transparent thermoplastics

Laser transmission welding is a well known joining technology for thermoplastics. As undoped thermoplastics have a low absorption for electro-magnetic radiation with wave lengths from 350 nm till 1,400 nm absorbers are used for laser transmission welding. One disadvantage may be the unmeant colouration which occurs when thermoplastics are doped with absorbers. Therefore an approach to weld transparent thermoplastics by the use of common diode lasers but without absorbers is presented. The developed system technology is introduced and results of welding experiments as well as results achieved by process simulation with a finite element model are shown.