In the field of monolithic materials, IFU research projects are concerned with the development of new process routes and innovative tool concepts for shaping in a semi-liquid state. Among other things, the determination of optimum heating and shaping parameters for difficult-to-form, high-strength materials and the associated adjustment of a defined, homogeneous solid/liquid phase proportion are being addressed. Overall, the aim is to increase process reliability through simplified process technology in conjunction with early simulative design. Furthermore, the possibilities of the process to reduce material loss, to reduce process steps and to recycle secondary materials are to be highlighted in order to increase its acceptance by potential industrial users.
Left: Preparatory tensioning of the fibers; right: CT image of the "lever" force deflection element with integrated sensory element
This research project is currently in its second funding period and is concerned with the generation of intelligent hybrid force deflection and force transmission elements (HIKE), which consist of a defined combination of different materials or material classes in the sense of reinforced light metal matrices. It is anticipated that the research results will contribute to the development of design and process engineering guidelines for the integration of characterisation and reinforcement components into a light metal matrix by shaping them in a semi-liquid material state. During the initial funding period, a carbon fibre-reinforced lever with integrated sensor and structural elements was produced. The second funding phase will focus on integrating inherent, actuator-initiated elements (e.g. adaptive bearing points), which will enable a reversible modification of the component's properties to a significant extent. Moreover, additional high-strength reinforcement components are to be examined with respect to their viability for integration into HIKE.
Duration: 01.2014 - 12.2017
Current metal-based additive manufacturing processes have inherent shortcomings in terms of limited production speed and high machine and system costs. Processes from the material extrusion process group, which use a partially liquid material state, offer a completely new option for additive processing of aluminium alloys. The associated schematic process methodology, based on a wire-shaped feedstock, involves heating the material to a semi-liquid state within a print head and subsequent layer-by-layer deposition onto a print bed. This enables the direct processing of metallic alloys by controlling the microstructure of the material and the resulting rheological behaviour. In this context, the specific thixotropic flow behaviour of semi-liquid metallic melts with a globular microstructure enables the production of three-dimensional structures through low viscosity during the actual extrusion as well as high dimensional stability of the already deposited material. While material extrusion, and more specifically the Fused Deposition Modelling (FDM) process for polymers, has been widely commercialised, the adaptation of semi-liquid metallic materials has only just begun.
The research project currently being pursued at the Institute of Forming Technology (IFU) is concerned with the final application of the semi-liquid material state to the extrusion-based additive processing of aluminium wire, due to the potential shown in this specialist area. The objective is to achieve a transfer of the process-specific advantages of the FDM process to metallic materials. In order to evaluate the experimental process, a dedicated system concept, developed at the IFU (see Figure 2), is being used for the semi-liquid extrusion and deposition of aluminium welding wire. Previous studies have already demonstrated the proof of concept and feasibility of the desired process by producing a simple workpiece from several layers. The iterative design adjustments to the print head were conducted in parallel with the experimental testing, taking into account the specific characteristics of semi-liquid additive manufacturing.
Duration: Seit 03.2022