Bladder molding with RRTM

Different materials can be used for bladders, giving larger, equal, or smaller diameter than the largest diameter of the hollow component. These can be fixed (polyolefins) or flexible (silicones) and an auxiliary core can be used to pre-drape the reinforcement. It is possible to match the possible variations to each specific molding project. IKV tested a number of options in transparent (polymethyl methacrylate) molds, looking also at lost core systems, in which the bladder or core remains in the hollow molding, and possibilities of automation. 

As opposed to the relatively thick silicone bladders that have to be removed from the component, thinner bladders may remain inside without negative effect on mechanical properties. Thin unstretched tubular polyamide films appear to offer best drapability and, at an air pressure of 0.5 MPa, they could expand into the edges of the component. Good results were obtained with these with braided glass fiber textile tubes, with the following process parameters  

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