Light Resin Transfer Molding (LRTM)

Light Resin Transfer Molding (LRTM)

Suitable for medium volume production of components up to 150 sq ft., light resin transfer molding is an intermediate process between the slower open mold processes with lower tooling costs and the faster compression molding methods with higher tooling costs.

LRTM is a vacuum-assisted, resin transfer process with a flexible solid counter tool for the B-side surface compression. This process yields increased laminate compression, a high glass-to-resin ratio, and outstanding strength-to-weight characteristics. RTM parts have two finished surfaces.

Reinforcement mat or woven roving is placed in the mold, which is then closed and clamped. Catalyzed, low-viscosity resin is pumped in under pressure, displacing the air and venting it at the edges, until the mold is filled.

With RTM Light, resin is introduced via a pumping mechanism under 2psi. Flexibility in types of resins and fillers is possible, and an intermediate range of fiber contents. Benefits include good cosmetic finishes and consistent part thickness. Fast cycle times mean a lower manufacturing cost. Tools can be aluminum, steel or composite.

  • Recommended for products with high strength-to-weight require- ments, or with slight design returns, edge overhangs, or high draft angles that would cause die-locks on rigid B-side mold surfaces.
  • Best suited for mid-volume production in the range of 200 to 5,000 parts per year*
  • Pre-placed of reinforcement can be employed to achieve optimum strength-weight ratios
  • In-mold gel coat finishes can be employed for desired cosmetic finishes
  • Environmentally-friendly – this closed mold process involves no resin exposure

*Volume recommendations are averages and provided only as a general guideline. Actual volume efficiencies are a more complex matter requiring detailed statstics about the part to manufactured.

Center of Excellence for Low Pressure Molding