It is a production method with using of very hard closed moulds. First the gel coat is applied (it is possible to produce a version without gel coat). In the next stage the carrying layers (glass mats, synthetic mats, „sandwich” mats, coremata, roving, etc.), as well as possible reinforcements and adaptations, are applied on the mould. An appropriate pressure and closing force should be ensured when closing with the second part of the mould. Compressed air, special clamps, servo motors or presses are used in this order. Due to the occurence of big closing forces and during the generation of pressure for the resin injection, the moulds used in this method must have an adequate resistance. In this order the special pastes, composite materials, metal frame constructions and suitable reinforcements are used.
The resin is injected after closing of the mould through a special opening (openings) made in the mould.

Strengths of The Method

• method cost-effectiveness in case of big production series,
• low emission of volatile substances to the environment,
• very high and uniform quality of the products,
• very good mechanical properties allowing for additional wall thickness reduction,
• high glass contents and the highest product resistance,
• esthetic and smooth surface on both sides (even without application of the geal coat),
• the highest process efficiency,
• wall thickness tolerance up to ±0.25 mm,
• small amount of wastes and lower consumption of the materials,
• very low unit cost of element production – at relatively high cost of the tooling.

Method Limitations

There are the technological limitations (for instance the technological radii, wall inclinations and others), as well as the other limitations regarding the shapes, dimensions and the level of complicatedness. RTM method can be applied for less complicated elements. A relatively high cost of the tooling limits the possibility of this method application for the production of large-size elements. Others:

• high cost of the tooling,
• high cost of the production start-up (tooling and equipment),
• limited possibility to introduce the changes on the mould,
• a relatively long time of production preparation.