P 909 - Complementary concept for bubble-free seam sealing of seam bonding

In order to avoid the costs for the repair work, the increased expenses in quality assurance and a potential loss of image in the event of a serious corrosion problem, the mechanisms of the formation of defects and measures to reduce them as well as the development of a bubble-free seam seal are the subject of research. The aim of the research project was to develop the technological basis for the industrial production of bubble-free seam seals on seam bonding. The project is based on two complementary approaches: The reduction of cavities within the seam bonding on the process path (minimising the damage potential), as well as the substitution of the PVC plastisol, which is prone to defects, with a bubble-free seam sealing material on the material path (increasing the damage tolerance). Comparative tests of alternative NAD materials were carried out on the material path, which led to the qualification of an MS polymer as a potential PVC substitute. As part of the process path, the formation of cavities and the influence of process and individual part tolerances on the filling level were investigated. Based on these findings, detailed recommendations for optimising the seam bonding process and seam sealing were developed. The seam bonding process investigated is used both in large-scale production and in the production of small batches and individual parts. The integration of the recommendations for action developed in the project into the series processes will increase process reliability when joining steel components using seam bonding. The prevention of bubbles in the seam seal means a considerable economic benefit for the automotive industry and its suppliers, as the additional work involved in reworking and the risk of corrosion are prevented.