Hybrid and compound casting

The field of "hybrid casting" deals with novel joining technologies using cast components. Directly integrated metallic structures or also plastics or fiber structures are used to realize a multi-material design. Directly during the casting process of the metal component, the possibility of material joining is given. This allows innovative components to be realized with savings in production steps, bringing with them various advantages.

Advantages of hybrid and compound casting technology

These advantages of hybrid castings produced using casting processes are primarily in the shortening of the process route compared to sequential manufacturing processes. In the latter, a sequence of many process steps is necessary to produce hybrid components. This means that hybrid cast components are not only perfectly designed to meet their requirements, but are also more cost-effective than differential hybrid assemblies.

Compound casting from aluminum castings in combination with aluminum semifinished products currently occupies a particularly important position. In addition to the above-mentioned advantages, there are additional benefits here due to the use of the same material system; e.g. similar coefficients of thermal expansion or later recycling by type in the sense of a circular economy.

The advantages at a glance:

• Optimized for lightweight construction
• Short process route
• Small installation space
• Various material combinations possible
• Reduction of machine and tool sizes possible compared to pure cast design

By combining this with existing expertise in the field of simulation, simulation models and interface modeling can be built directly for these novel multi-material systems at the same time as they are being developed. This enables a comprehensive consideration of this novel and future-oriented construction method.

Metal-to-metal compound casting for innovative cast components

Cutting-edge composite material systems are increasingly being used in lightweight construction. Classic metals retain a very high status in lightweight construction suitable for large-scale production; the motivation of using materials in a way that is appropriate to the load remains unchanged. Thus, different metals with their individual properties can make a major contribution to lightweight construction as well as to functional integration.

Whereas classic metal-to-metal joining concepts involve a subsequent joining process by welding, adhesive bonding or mechanical joining, the metal-to-metal composite casting concepts for various applications can be implemented directly in the casting process of an aluminum component. In this way, highly integrated, complex multi-material components can be implemented while saving production steps.

Current challenges on the market relate, for example, to the integration of cooling channels in cast components, which are realized by hollow bodies made of aluminum or copper, for example, integrated in the cast component. Different casting processes have different challenges in terms of positioning, connection or stability during the casting process.

The integration of metallic profile or sheet metal structures on cast node elements can also be seen as a current trend in order to realize an alternative production route for highly integrated large cast structures (cf. "Giga casting") in vehicle construction.

The experts at Fraunhofer IFAM have extensive experience in this field and the appropriate plant technology to implement development projects with you close to series production.

CFRP-aluminum hybrid casting for lightweight construction

Fiber-reinforced plastics (FRP) still have very high lightweight construction potential due to their high strength and stiffness properties. However, large-scale use is often not economically feasible due to the cost structure of the material. Therefore, joints of FRP and metals represent an interesting alternative - here, too, hybrid casting can be the appropriate solution, combining the advantages of metallic components with those of fiber-reinforced plastics. Fraunhofer IFAM is able to join both individual fiber structures and fiber composite components in the casting process and thus realize a multi-material design.

Integration of additively manufactured metal structures in cast components

A current field of research at Fraunhofer IFAM is concerned with the local integration of additively manufactured metal structures into cast components. The focus is on multilayer functionalized SLM metal structures which are locally integrated into the cast component during the casting process. On the one hand, the aim of the technology development is to combine the advantages of metal additive manufacturing with a high degree of complexity and the economic metal casting process. On the other hand, this combination makes it possible to eliminate process-related limitations such as geometric degrees of freedom or mappable component sizes.

Infiltration of porous materials: metal-graphite composites

In plain bearing applications, higher operating and emergency temperatures have to be ensured due to required increases in performance and efficiency e.g. in the form of increasing speeds, higher operating and emergency running temperatures must be guaranteed. Plain bearings are currently made of polyimide, among other materials, which is a polymeric material that can be used at high temperatures but degrades during its service life and therefore does not offer sufficient reliability.

In order to extend the service life of plain bearings, such as those used in aircraft engines, new types of temperature-stable materials will therefore be required in the future. These can be realized, for example, by casting metal-graphite composites in which a graphite semi-finished product is infiltrated with liquid metal, thus providing a high-temperature-stable and wear-resistant starting material for further processing into plain bearings.