Modern machine tools have to be stiff but also light, they should work quickly and precisely. So, development engineers are in a field of conflict. The conflict cannot be solved with conventional methods and materials. To match these conditions the compound material HoverLIGHT was created. It consists of a metal matrix material (aluminium foam) and small particle filled hollow spheres with a diameter of 3-5 millimetres. The HoverLIGHT material is used for the core in sandwiches. It combines the lightweight on one side and good damping properties on the other side.

The presentation reports about a research project conducted in a collaboration of Fraunhofer-IFAM and Fraunhofer-IWU. Aspects of the project were first to bring the material into an industrial scale and second to show the benefit for machine tool industry. For that reason, it was decided to create a demonstrator in the form of a gantry from a milling machine.

The demonstrator was designed to replace a conventional assembly in an existing machine, so it has to meet all the functional requirements. First, all interfaces to joining parts have to be realised, that means the outer shape could not really be modified. In the next step the static stiffness of the original part must be achieved with the new material and of course, preferably, with less weight. Therefore, a lot of simulation work was done with FEM-software ANSYS. As a result, the demonstrator has nearly the stiffness of the massive steel assembly, but a reduction of weight by 20 %.

But static stiffness is only the first step to meet the requirements of machine tool industry, also the dynamic behaviour must be in focus. In general, the demonstrator has the same natural frequencies in comparison to the massive steel design. But there, appear in higher frequencies some wall-vibrations. These can be prevented by the sandwich-design.

Furthermore, in diagram, which shows flexibility over frequency-range, simulation shows how the HoverLIGHT-material damps amplitudes efficiently.