VARTM – Vacuum Assisted Resin Transfer Molding

Also known as RTM Lite, VARTM is a closed mold process where the primary mold is similar to the mold used in open molding and the second or “counter” mold is a semi rigid, lightweight mold used to compress the resin and fiber matrix that comprises the part.

In VARTM, the reinforcements are placed in the mold dry, often combined with cores or other special inserts. Vacuum is then applied to compact the reinforcement and eliminate air. Resin is pumped in at under 2psi and the vacuum draws it through the reinforcement.

VARTM allows more flexibility in types of resins and fillers than in Vacuum Bagging and also a wider range of fiber contents. Benefits are better cosmetic finishes and variation in part thickness, and faster cycle times for lower cost.

The VARTM process is suited to medium volume part production in the 200 to 5,000 parts per year range. It allows for the application of gel coat finishes for desired part finish and is considered to be environmentally friendly because the resin in the bulk laminate cures in a closed mold, minimizing the release of VOC’s.