Manufacturing of polygon fiber reinforced plastic profiles by rotational molding and intrinsic hybridization

The manufacturing of lightweight shafts, pipes and profiles often uses hollow structures made from fiber reinforced plastics (FRP) due to their better density related properties. For applications with locally high tribological stresses, the use of FRP is not yielding proper results. In terms of lightweight construction, a hybrid design with a hollow FRP basic structure and local metallic elements in areas of high tribological stress is ideal for these applications. A promising approach for the production of these parts is rotational molding. Rotational molding for FRP–metal profiles is understood as a manufacturing process where machined, metallic elements and dry continuous fiber structures will be assembled and laid in a closed mold. Afterwards, the liquid matrix will be casted and the mold is then rotated at high speed until the fiber structure is fully impregnated and the matrix is cured. As there are short flow paths, this process is offering the potential to realize short cycle times of only a few minutes. Within this paper, the manufacturing of polygon profiles via rotational molding is described. These profiles can be produced by using centrifugal cores which were developed at the wbk Institute of Production Science. These cores are made of an elastomer composite material and they expand during the rotational molding process. The modeling of these cores and their impact on the impregnation pressure is shown here as well as their contribution in achieving higher fiber volume fractions.