Abstract: A resin transfer molding preform is disclosed comprising a formation of fiber reinforcement material and a web in direct contact with the formation and encapsulating at least a portion thereof, i.e., the web secured or fixed to the fiber reinforcement material mechanically or by adhesion, etc. A method of making certain of the resin transfer molding preforms of the invention comprises spraying random chopped fiber reinforcement material onto a forming member while drawing a vacuum through the forming member, applying a web over at least a portion of the fiber formation while it remains on the forming member, and compressing the fiber reinforcement material under the web to reduce the loft thereof. Also disclosed is a resin transfer molding process employing a preform according to the invention.

Abstract: The invention provides a preform for a resin transfer molding process and a preform core for same. The invention further provides a resin transfer molding process employing such preform. A surface portion of the core having a concavity therein, the core comprises a flexible web secured to its surface forming a convexity over such concavity. The convexity formed by the web is deformable into the concavity during the resin transfer molding operation, but prior to the molding operation is sufficiently firm to support, without substantial deformation, oriented continuous fibers applied under tension onto the surface of the core.