Resin Transfer Molding (RTM) is a liquid composite molding process.
Unlike materials used in RIM or SRIM processes, where the chemical reaction is activated by mixing the reactants, the chemical reaction for resins used in RTM are thermally activated by heat from the mold wall and fiber mat (preform). The reaction rate in RTM processes is typically much slower than that in SRIM, allowing a longer fill time at lower injection pressure.