Transition between flow-drill screwing systems considering joining process and joint characteristics

Abstract

Flow-drill screwing is one of the key joining technologies for car body structures in multi-material lightweight design. In the course of technological developments and subsequent volume production of a product, different assets are used to obtain the same joints, assuming that similar processes yield the same joint characteristics. Since a simple transfer of the process parameters for joining the same materials is usually not possible, a remarkable experimental effort is required to meet manufacturing requirements. In this study the transition to an enhanced flow-drill screwing system and its effects on the joint is investigated. For this purpose, two flow-drill screwing systems typically used in the automotive industry are considered. An application-oriented approach for determining the joining parameters is shown. First, the optimal joining parameters for the target system were determined based on the process curves and parameters of the initial system by fulfilling the requirements for the joint. The joints were evaluated by using cross sections and single-lap shear tests. On this basis, the results of both flow-drill screwing systems were compared. Due to the further development of the flow-drill screwing system the process times can be significantly shortened while achieving the same mechanical properties and better process control at the same time.