Joining process for fiber-reinforced thermoplastics and sheetmetal without additional adhesion promoter

Abstract. Thanks to their excellent mechanical properties and low structural weight, multi-material structures offer a promising solution for lightweight design, body construction, and functionalisation in the automotive industry. A common approach is combining metal and plastic to enhance the performance of the final component compared to single-material structures. This paper presents the development of a manufacturing cell for joint forming and heat-assisted press joining of steel and continuous fiber-reinforced thermoplastics, specifically using unidirectional carbon-fiber tapes. To achieve shorter cycle times and ensure cost-effective production, the manufacturing cell was equipped with two robots for automated handling and utilised an isothermal two-stage forming tool concept. The produced composite components were evaluated regarding their mechanical performance, confirming the feasibility of the process. All composite parts demonstrated higher specific load capacity compared to pure steel components. Cycle times of less than 60 s were consistently achieved, marking a significant reduction in process time compared to variothermal tool concepts.