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Syllabus Dot Point
thermosetting polymers
– structure/property relationships and their application
– manufacturing processes
– compression moulding
– hand lay-up
– vacuum lay-up
– modifying materials for aircraft applications
Compression Molding
Compression molding is a closed-mold composite manufacturing process that uses matched metal molds with the application of external pressure. In the compression molding process, an engineered composite layup is placed in the open mold cavity, the mold is closed, and consolidating force is applied.
Hand Lay-Up
Hand lay-up is a molding process where manually placed chopped strand or woven fiberglass mat is combined with various resin formulations and applied to an open mold. Manual rolling of the open mold is then used to ensure even distribution of resin and to eliminate trapped air pockets.
Vacuum Bag Molding
Vacuum bag molding is a process in which the layup is cured under pressure generated by drawing a vacuum in the space between the layup and a flexible sheet placed over it and sealed at the edges. In the vacuum bag molding process, the plies are generally placed in the mold by hand layup using prepreg or wet layup.
Pre-preg Laminating
Pre-preg laminating is a highly specialised method of composite manufacture mainly used in aviation. The laminate comes in the form of a cold sheet, and is moulded to the shape of the mould using specialist tooling. A prepreg consists of a reinforcement material – such as fibreglass – preimpregnated with a resin matrix. The resin is partially cured and is then used to lay up the finished part before leaving it to cure completely. The heat and pressure required for curing will vary with the resin system and the intended application.
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