Resin Transfer Molding (RTM) is a particular useful manufacturing process processes that use liquid resin to impregnate the stationary fibrous preform. During the RTM Process, the preform is placed into the mold cavity, the mold is closed and the resin is injected into the cavity under pressure. The mold with the preform is often put under vacuum so that the vacuum removes all the entrapped air in the preform and speeds up the RTM process. Once the liquid resin fills the mold cavity, it cures, during which the resin hardens due to the formation of polymeric network forming the matrix of the composite, allowing the part to be de-molded. Typically thermoset polymers of Epoxy, Vinyl Ester, Methyl Methacrylate, Polyester or Phenolic are used with fiberglass, carbon fiber Arimid and synthetic fibers reinforcements either individually or in combination with each other.
This technique is well known and has been traditionally applied to moderately large parts in various application. It allows one to obtain even very complex neat-shape parts with good surface finish, in many cases at reasonable production rates.The fiber architecture, permeability of the preform and the fabric crimps, resin viscosity, temperature of operation, have an influence on the wetting of the fabric. Careful process design is needed to obtain a repeatable high quality product.

Images from Suresh Advani:

Recommended Book