The RTM process utilizes reinforcing fibres such as continuous strand mats, woven fabrics, or specifically developed fabric geometries. A wide variety of different fibre types, such as glass, aramid, carbon, natural fibres, and many others can be employed as reinforcement during RTM process. Core materials such as polyurethane foam, PVC foam, balsa wood, and other materials can be used for sandwich constructions. A multitude of resin systems, such as polyester, vinyl ester, epoxy, or phenol resins are also available.
In a typical process the reinforcement and if required sandwich materials are placed in the mould. The mould is then closed and the resin/hardener mixture is injected via one or more injection ports. The mould may also first be placed under vacuum in order to improve the resin flow and impregnation. The cure process is often accelerated by using suitable mould temperature.
Intense promotion of RTM in the USA in the mid 1970’s resulted in hundreds of companies switching from open casting processes to RTM process without having necessary know-how about the technical requirements. As a result, by the mid-1980s, the RTM process was once again disappeared from the market.
Today, the RTM process is once again gaining its popularity due to advances in production equipment and process technology. Modern RTM has proven itself as a highly effective method of producing fibre-reinforced plastic components.