Engbert, T.; Biermann, D.; Zabel, A.; Pietzka, D.; Tekkaya, A. E.; Ben Khalifa, N.:
In: European Aluminium Congress: Aluminium Automotive Applications - Material for Lightweight Construction and Design, Session 6 - Paper 3, 23.-24.11.2009, Düsseldorf


Composite extrusion is an innovative process for the manufacture of reinforced profiles for lightweight structural applications. During extrusion of a regular aluminium billet, reinforcing elements are fed into the welding chamber of a modified die, where they are embedded in the extruded material. In this paper, the manufacturing of composite profiles with different complexity is presented. Stainless steel wires were used as reinforcement. Different strategies to improve the material properties of the structure by increasing the reinforcing volume were determined. Furthermore, the influence of reinforcing elements on the material flow has been analyzed. The processing of composite extrusions is challenging due to the different mechanical properties of the materials used. The reinforcement is discrete and its location within the profile is determined. So the influence of the position of the reinforcing elements, relative to the tools used in the following machining processes, is of special interest for process design. The paper describes influences of the reinforcement on the flow-drilling pro¬cess and subsequent threading operations, which are necessary to join different extrusions to form a complete frame structure or to assemble parts via screw-coupling. Threads are produced by thread forming, tapping and thread milling. The cross-sections were evaluated qualitatively and pull-out tests were conducted to quantify the strength of the threads.