Multiple tool pieces are used with increasing production numbers and the requirement for better part tolerances and improved surface finish. For low production rates single sided moulds are often employed, in conjunction with resin infusion under a flexible bag (i.e., VARTM, SCRIMP). Required mould construction and supporting clamping equipment depend on the composition of the part (i.e., type of fibre reinforcements, desired fibre volume fraction), and intended scale of production. Some form of mould is used to conform the fibre reinforcement to the intended shape of the part, and to withstand local forces due to resin pressures generated internally, and the resistance to deformation offered by the preform. The preform can be composed of short discontinuous, or long continuous fibres. The term liquid composite moulding (LCM) denotes those processes that involve infiltration of a dry fibrous preform with a liquid polymeric resin. Kelly, in Manufacturing Techniques for Polymer Matrix Composites (PMCs), 2012 11.1 IntroductionĬlosed mould processes for the manufacture of fibre reinforced plastics continue to grow in popularity, being applied within an increasing range of industries. Hence, good support from the resin or column vendor is crucial when defining packing methods and/or setting up a pressure-flow measurement.Ĭompression resin transfer moulding (CRTM) in polymer matrix composites The flow pack parameters will depend on liquid viscosity, temperature, bed height, resin type and column diameter. In its final position, the adapter will prevent the bed from decompressing when the flow is stopped. Finally, the adapter is moved down to the compressed bed at the same time as the flow is stopped. The bed is then compressed by application of a high fluid velocity to achieve the correct compression factor, which may be readily available from the resin vendor or is to be defined from a pressure flow experiment, see Fig. 26.11) to create a consolidated homogenous bed. The best approach is a two-step method, where the resin is first settled at a lower fluid velocity (e.g., 30 percent of the maximum fluid velocity as determined in Fig. In a constant flow or pressure method, the slurry inside the column is settled and packed using a flow of liquid from the top to the bottom.
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