Laser Transmission Welding of Thermoplastics: Analysis of the Heating Phase

In laser transmission welding, the parts to be joined are brought into contact prior to welding, and the heating and joining phase take place simultaneously. The laser beam of the Nd:YAG laser penetrates the transparent part being joined and is converted into heat by the absorbing part. The transparent part is similarly heated and plasticised by means of heat conduction, thereby ensuring that the parts are welded together. When the heating phase was analysed, it was seen that if the part that absorbs the laser beam has a high adsorption constant, this process phase can be readily described by a physico-mathematical model by analogy to single-sided heat impulse welding. A comparison of calculated and measured melt layer thicknesses showed that, by introducing a correction factor, it is possible for this model to be successfully used for the case of a low absorption constant as well.