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Metal foams in research and development - new approaches in industrial aluminum foam production

Presentation held at MatCel 2017 & DynMatCel 2017, Cellular Materials: Structural Behaviour, Modelling and Characterisation, 25-27 September 2017, Aveiro, Portugal
Metallschäume in Forschung und Entwicklung - neue Ansätze in der industriellen Aluminiumschaumfertigung
: Hipke, Thomas; Vogel, René; Hohlfeld, Jörg; Schuller, Friedrich

presentation urn:nbn:de:0011-n-4810723 (3.8 MByte PDF)
MD5 Fingerprint: f6ebe66dae4a584c70555b4ccb01e0bb
Created on: 24.1.2018

2017, 21 Folien
National Conference on Cellular Materials (MatCel) <2, 2017, Aveiro>
International Conference of Dynamic Behaviour of Cellular Materials (DynMatCel) <2017, Aveiro>
Presentation, Electronic Publication
Fraunhofer IWU ()
aluminum foam; sandwich structure; lightweight design

In the last years metal foams were used in different applications like core material in light weight constructions, crash absorbers or damping elements in machine tools [1]. Sandwiches with aluminum foam core have been established as lightweight construction material. These semi-finished products are used particularly in the fields of engineering, construction, shipbuilding and commercial vehicle design [2]. The core operates as a shear resistant element and keeps the cover layers at a constant distance ensuring the functionality of the sandwich. Because of the high strength and stiffness commonly steel cover sheets are used for the sandwich manufacturing. In the manufacturing process the two cover sheets are placed and fixed in a foaming mold. A foamable precursor based upon aluminum and a foaming agent is inserted between these cover sheets. This is followed by a heat treatment at the melting range of the aluminum base alloy. During the foaming process a metallurgical bonding is created resulting in a rigid sandwich called SAS (steel – aluminum foam – steel) [3].For the manufacturing process of aluminum foam sandwiches with aluminum cover sheets another production route was standard the last years. The foamable material is placed in between two aluminum sheets. Afterwards the loose bond is rolled to a single composite with metallurgical bonding. During the foaming process the heat transfer into the rolled composite especially the core precursor is very good. By choosing alloys having different melting ranges it is possible to expand the core layer without melting the cover sheets. For this technological process the term AFS® (Aluminum Foam Sandwich) has been established [4]. Beside the final foaming process the most important step for the production of these foamable composite is the rolling. The process is complex and expensive. Therefor alternative production methods needed to be considered as well. A new and cheaper achievement is the manufacturing of aluminum foam sandwiches with aluminum cover sheets by using the already mentioned SAS-method. In this case the use of aluminum cover sheets it is rather more difficult, because core and cover sheets are made of nearly the same material. Furthermore there is no metallurgical bonding between the sheets and the core before the foaming process. Therefore it is necessary to achieve a stable heat is transferred through the cover sheets into the placed precursor material. The already successfully tested approach of the SAS production was revisited. By the construction of new foaming devices and a well-regulated heat transfer it was possible to manufacture small and large scale sandwiches with aluminum cover sheets according to the SAS process. First serial parts were produced in early 2017.References[1] Hipke T. Applications and design guidelines for metal foams constructions in machine tools. CELLMET 2008; Dresden, Germany; 8-10 October 2008; conference proceedings: 81-85 [2]Hipke T., Lies C., Vogel R., Meltke R. Applications of metal foams in shipbuilding and mining. CELLMAT 2012; Dresden, Germany; 7-9 November 2012; conference proceedings: 45 pages[3] Neugebauer R., Hipke T., Hohlfeld J., Lies C. Adhesion in sandwiches with aluminum foam core. Production Engineering. Research and development 1, 2007; 3: 271-278[4] Banhart J., Seeliger H.-W. Recent Trends in Aluminium Foam Sandwich Technology. Advanced Engineering Materials 14(12), Euromat Montpellier 2011.