Sandwiches are very rigid and lightweight composites that can be used to meet extremely effective lightweight design requirements. The load-bearing, rigid cover layers of the sandwich are combined with a light, shear-resistant core, such as Aluminum foam. Sandwiches with an Aluminum foam core show the special feature that the core is foamed in a heat treatment process and connects to the metallic Aluminum cover layers in a material-locking manner. No adhesive is required.
The so-called AFS process (AFS... Aluminum Foam Sandwich) from Pohltec metalfoam GmbH has proven itself for the sandwiches production with a foam core and cover plates made of Aluminum. A foamable compound, is required as pre-product for the sandwiches, is produced by rolling. Rolling is a key step in the manufacturing process and represents a technical and economic challenge due to the complex process technology and process control. From an economic point of view, the rolling process is only suitable for the production of very large quantities of metal sheets. This procedure is extremely unprofitable for small quantities such as a few square meters. Moreover, free rolling capacities are rarely available.
For that reason a new EMS-Process (Expandable Material for Sandwiches) has been developed that is characterized by the following process steps: A loose composite consisting of two solid Aluminum tube halves and an extruded foamable Aluminum core is extruded into a rectangular, foamable compound. The core of the composite is foamed in a subsequent heat treatment process. As result a sandwich is created showing a substance-to-substance bonding between the cover layer and the foam core. To prove the feasibility of the new approach it was examined in random tests and finally patented.
In the article, the new and unconventional process variant "Extrusion of foamable composites for the production of sandwiches" is explained. The new approach avoids the rolling process step and replaces it with a more flexible process that is going along with higher system availability. The process-related new, elongated semi-finished product shape opens up new design and production possibilities.