RTM (Resin Transfer Mouding) is a closed mould and low pressure process used to produce composite parts.

A thermoset resin is injected under low pressure into a closed mould. Depending on the production rates, the cure can be made at either ambient temperature or via a heating system.

"Classic" RTM

RTM is a closed moulding process. Resin is injected on a dry prefrom or fabrics laid up onto the tool cavity.
The injection pressure is from 1.5 to 20 bars.
It is recommended for high-volume production.


  • Production cost reduction
  • Investment reduction
  • Quality and Repeatability
  • Some post-processing steps are eliminated
  • High fibre volume
  • 3D interlock


  • Structural aircraft parts
  • Class A surface finish automotive part


Light RTM

There is no need of a press with the light RTM process. Vaccum is enough to ensure that the tool is properly closed during the injection stage. This technology is suitable for low-volume production.



  • Preforms or fabrics plies are laid up dry in he tool cavity
  • Vacuum bagged
  • Resin injection


  • Low cost tooling
  • Suitable for medium volume production (5,000 parts/year)
  • Large parts can be manufactured
  • The upper part of the tool can be made of composites


  • More complex parting line
  • Difficult to perform this process well