Process Design for the Combination of Tube Hydroforming and Compression Molding

Abstract The combination of forming and joining metal and plastic parts in a single process step enables a shorter process chain for manufacturing lightweight and functionally integrated hybrid components. Traditionally, tube-based metal–plastic hybrid parts are produced via a complex and cost-intensive process combination of hydroforming and injection molding. As an alternative novel approach, combined hydroforming and compression molding using metal and fiber-reinforced plastic tubes as semi-finished products is presented. The compression molding of the plastic component is realized by the metal tube, which is deformed by internal pressure. Preliminary experimental results indicate the feasibility of this process combination even for complex geometries. Furthermore, the process enables the integration of additional functional elements like thread inserts. Important parameters for producing good quality component are the internal pressure and temperatures of tubes and tools. To enable process design in industrial applications, finite element (FE) simulations were carried out using Simufact Forming. Although the FE model remains computationally intensive and does not account for initial defects in the semi-finished products, the preliminary work shows sufficient agreement between the simulated and experimental final part geometries. The relationships between process parameters and component quality are also presented. This hybrid process provides industry with a manufacturing process for producing tube-based metal–plastic hybrid components, which sets significantly lower demands on equipment technology and process control than comparable manufacturing processes.