One of the main areas of focus for KraussMaffei at JEC Composites Show in Paris (March 24 to 26) will manufacturing large parts made of fibre-reinforced PUR, with a high-gloss surface finish produced in the mould. The injection molding machine maker will exhibit two alternative processes for this purpose namely LFI (Long Fiber Injection Moulding) and Fiber Composite Spraying (FCS) at the event. Apart from this, KraussMaffei will demonstrate innovative composites moulding processes including Reinforced Reaction Injection Moulding (RRIM), Structural Reaction Injection Moulding (SRIM), Structural Component Spraying (SCS) und Resin Transfer Moulding (RTM).
In the LFI process, the long glass reinforcing fibres are chopped from an endless roving and wetted in the mixing head with the PUR mix. Fillers in the PUR prevent the glass fibres spoiling the quality of the surface finish. The part is then pressed and compression moulded into shape, ensuring that no air bubbles form in the material. In fibre composite spraying (FCS) the glass fibres and the PUR mix come into contact only after the PUR has been discharged from the mixing head. As in LFI, the glass fibres are chopped from an endless roving, but they are wetted with the PUR mix in the spray cone. The PUR/fibre mix is sprayed in thin layers. The first layer is a barrier layer consisting of PUR without glass fibres. This barrier layer produces an optically flawless surface, ready for in-mould or post-mould painting. Subsequent layers, containing reinforcing fibres, are applied in thin layers until the specified wall thickness is reached. Different layers - compact, foamed or reinforced - can be combined to comply with product specifications.