A step towards understanding the heating phase of laser transmission welding in polymers

Abstract

In recent years, laser transmission welding has gained in significance by displaying its specific advantages among the established welding processes for thermoplastics. However, a deep understanding of the developed process variants is so far missing. Useful results for temperature development were obtained in cases of high absorption constants by setting up an analytical model by analogy to single‐sided heat impulse welding. Yet there is no physico‐mathematical model considering the different energy conditions for joining parts with various absorption properties. This investigation is a first step towards a deep and detailed insight into the heating phase of the laser transmission welding process. Experimental data for temperature progression was collected for polypropylene. In addition, an analysis of the heat transfer problem using the finite element method showed a good level of agreement with the experimental results.

Weld line transverse energy density distribution measurement in laser transmission welding of thermoplastics

“…Becker and Potente (2002) describe measurement of the power flux distribution at the weld interface after passing through a 5-mm thick sample of unreinforced polypropylene (a light-scattering semi-crystalline thermoplastic). A 1-mm diameter pinhole is placed directly below the laser-transparent part and a power meter is placed below.…”

Diode laser welding of ABS: Experiments and process modeling

“…In computing the temperature field within the materials and at the interface, the heat conduction equation is used [3][4][5][6][7] taking in account a perfect contact between the two components subjected to welding. An estimation of the temperature at the interface is required for establishing the welding process parameters like laser power and welding speed.…”

Fusion Bonding/Welding of Thermoplastic Composites

“…To control the conversion of laser radiation to heat, pigments or additives can be used. For example, in laser transmission welding, the joining parts are fixed and pressed tightly together [45,46]. The laser beam transmits through one of the joining part, which is usually a transparent material, and is absorbed at the top surface of the second joining part which is usually a non-transparent material or is pigmented with special ingredients, such as carbon or absorbing dies.…”