Development of an additive manufacturing process based on the extrusion of semi-solid metal filaments

• Applicant: Dr.-Ing. Kim Rouven Riedmüller
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 572738510

Additive manufacturing processes may offer a more material- and energy-efficient solution compared to casting, forming and subtractive manufacturing processes, particularly when small and complex components as well as spare parts are produced in small quantities. Here, the question of whether components can be additively manufactured more efficiently depends not only on the required quantities, but also on the process itself. For processing metallic materials, for example, powder bed technologies are usually applied in the industrial practice. However, these processes are associated with high production costs, as expensive beam sources and metal powders are used. In addition, powder bed-based processes are subject to inherent physical impairments such as a relatively low building rate and pronounced thermal gradients. Here, wire-based extrusion of semi-solid materials offers an innovative alternative for additively processing aluminum alloys with potentially higher production rates and moderate process costs. However, the inductively heated print heads currently used for these processes cause uncontrollable thermal interactions with the workpiece and the system peripherals due to the applied magnetic field. Furthermore, the print heads do not feature extrusion shoulders, leading to macrostructural component defects due to the lack of extrusion pressure. Therefore, the objective of this project is to further develop extrusion-based additive manufacturing with semi-solid aluminum wires for the production of flawless workpieces. To this end, a fundamental understanding of the process is first obtained by means of thermal transient simulations and CFD simulations. Based on this, an optimized print head structure with conductive heating and extrusion shoulder is designed with numerical support and subsequently tested experimentally. Afterwards, simulatively predetermined system parameters are evaluated and, if necessary, iteratively optimized by experiments. In addition, a specific deposition strategy, enabling the break-up of oxide layers, is developed and experimentally validated. The suitability of the determined parameters is evaluated by microstructural and mechanical investigations on test specimens produced with them. Finally, a complex demonstrator component designed as a compressor wheel for turbochargers is additively manufactured in order to finally validate the developed process principle.

• DFG Programme: Research Grants