AX100 Resin Transfer Molding, resin transfer molding

Orenco Composites uses a closed-molding process called Resin Transfer Molding (RTM) to produce high-volume, high-quality composite parts made of fiber-reinforced plastic (“fiberglass”). RTM uses a matched mold set to create a fixed cavity from which a part is made. The diagram below describes how the RTM process works. In simple terms, fiberglass mat or fabric is laid into the mold cavity, the mold is closed, and resin is then injected into the mold cavity, impregnating the fiberglass. After the resin hardens, the mold is opened and the part is removed. Vacuum is often used to aid in the RTM process, and this molding variant is called Vacuum-Assisted Resin Transfer Molding (VARTM). The vacuum assist helps provide mold clamping force, as well as improved resin flow and part quality.

Resin transfer molding process diagram, resin transfer molding

Common materials used to build RTM molds, also known as “tooling,” include fiberglass, aluminum, and steel. The material chosen to build a particular mold is based on a variety of factors, such as part quantity, part size, finish quality, part complexity, and required cycle time. For high-volume production, molds are usually heated and incorporate computerized control systems to automate the entire molding process. Orenco Composites has an in-house tooling shop to build most molds, as well as a sophisticated controls shop to design and build all molding control systems. We’ve also developed our own robotic preforming process to automate the process of loading fiberglass reinforcements into molds.

AX100 Mold, resin transfer molding

Parts built with the RTM process are typically superior to conventional “spray-up” fiberglass in terms of structural properties, watertightness, and aesthetics. Since parts are made within a closed mold, part consistency is excellent. Parts have two smooth surfaces, and RTM allows the use of high strength fabrics, encapsulation of core materials (which create strong, stiff “sandwich” laminates), and production of complicated part geometry.

Resin Transfer Molding, resin transfer molding form

Closed-molding processes, such as RTM and vacuum infusion, allow for a nicer, cleaner working environment and are far more environmentally friendly than manual spray-up, which often produces ten times more emissions than closed-molding. In fact, closed-molding is considered by the EPA to be such an environmentally friendly process that the MACT (Maximum Achievable Control Technology) standard for reinforced plastics does not require the additional emissions controls or material limitations that are required for “open-molded” processes such as spray-up.

AX20 Mold, resin transfer molding

Need assistance with your project? Orenco Composites has the services and expertise you need! We’ll work closely with you and your team from start to finish. We design the product to meet your specific application needs and we deliver on time, so you can finish your project on time. Give one of our technical sales reps a call today.

Leaders in Our Industry

Orenco Composites

Orenco Composites is a leader in fiberglass manufacturing. Each of our divisions utilizes the unique processes we’ve developed over more than 30 years to create cutting-edge products.

Orenco Systems®, Inc.  designs and sells economical, sustainable wastewater treatment products for properties not served by conventional sewers. These include fiberglass septic tanks and septic systems, advanced treatment systems, effluent sewers, and electrical control panels. Our award-winning technologies are cited in water treatment and wastewater texts and have been installed all over the world.

FiberGraphic™ Custom Furnishings has taken fiberglass technology one step further by embedding photos and logos inside its products. Now, anyone can design and order their own custom-branded products: ping-pong (table tennis) tables, conference tables, end tables, benches, and more.

To learn more about the processes used by Orenco Composites, visit: