Executing Organisation: German Federation of Industrial Research Associations (AiF) | Federal Ministry of Economic Affairs and Energy (BMWi)
Due to the increasing complexity of products made of plastics, individual components are often manufactured by injection molding and then combined by joining to form larger assemblies. This research project considers the long-term properties of laser-welded plastic seams. The focus of the investigations is on the dynamic fatigue strength and the resistance of the welds to alternating climatic loads.
Design plans for contour welding or quasi-simultaneous welding of ABS and PA6.6 were set up, in which the main process parameters such as power and feed rate of the laser beam varied. Subsequently, the manufactured welded joints were tested by the research partner SKZ with respect to their short-term, fatigue and climate change resistance and correlations between the strengths were analyzed. In the following, a demonstrator component was fabricated to examine the extent to which the knowledge gained from test specimens can be transferred to more complex components.
The failure of the assembled demonstrator components (see left picture) was generally carried out exclusively in the joint seam, whereby the break (see right picture), especially for ABS in the short-term test, was preceded by a significant overstretching of the component deck. The strength of the ABS demonstrator components remains unaffected in the climate change test within the scope of the measuring accuracy. In contrast, the strength of the PA6.6 demonstrator components is reduced by climatic changes. Since the reduction in the strength of the demonstrator components is more pronounced than in the typical sample geometries, the cause is probably due to the geometry-induced formation of stresses in the component.