Project Details
Projekt
Stress-related process know-how and process optimasiton of plastic welding unsing the example of laser transmission welding
Subject Area
Plastics Engineering
Production Automation and Assembly Technology
Production Automation and Assembly Technology
Term
from 2014 to 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 239632851
On the plastic weld quality evaluation, the focus is now on the consideration of the short term strength determined in a quasi static, tensile shear test. Different operating conditions of real components, however, lead to various stresses and strains, e. g. within laser transmission weld seams. Thus, the connection responses in reality differs from that observed in laboratory conditions. In use complementary to quasi static loading dynamic, multi axis and possibly loads acting for a long time may occur. It is unknown whether welds bearing maximum short term tensile shear strength withstand also other loads optimally. Also unknown is whether determined under different load types weld factors correlate with each other and thus can be possibly suggested from one to the other. Regarding laser transmission welding, a correlation of the short and long term weld factors are jet presented. It turned out that the short and long term tensile shear strength weld seam factors are linearly related. Further it was shown, that in the welding process prevailing conditions influence the morphology and the weld seam strength considerably. A correlation apparently valid for various plastic welding processes, as has been documented similar to the extrusion and hot plate welding. A part of the project is therefore to investigate how laser transmission weld seams behave depending on different types of stress and the welding process prevailing temperature fields. Moreover it should be clarified what causes possible deviations. Are findings on the relationship between the welding process, the effected material properties and the weld seam strength for different stresses attributed to the temperature field determining the welding process, it is possible to take the laser transmission welding as a precedent for other plastic welding process and to gain transferable knowledge. Since the temperature field effected by laser transmission welding can be formed extremely flexible, the exemplary study of laser transmission welding offers very well requirements to gain transferable findings. Therefore laser transmission welding should be chosen for the proposed investigation. It is expected that temperature fields leading to optimal strength for different stresses will be different. The reasons for this have to be examined and understood fundamentally. Furthermore, by laser transmission welding resulting spatially and temporally varying temperature fields shall be affected to achieve optimal rather stress customized weld seam strengths. The approach of optimization will be the use of two beam paths with two discrete laser wavelengths, both guided by a highly dynamic beam delivery component.
DFG Programme
Research Grants
