Composites Manufacturing Processes

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. 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.

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.

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.

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.

Orenco Composites uses a process called "filament winding" to produce cylindrical-shaped fiberglass parts, such as tanks, scrubbers, basins, and pipes. Filament winding is accomplished by wrapping (winding) continuous fiberglass roving onto a rotating mandrel. The roving is typically “wet-out” through a resin bath just prior to being wound onto the mandrel. The roving is then wrapped in precise — typically helical — patterns. After the roving has been wound on the mandrel to the desired thickness, the resin is allowed to cure, and the part is pulled off of the mandrel. Filament winding is used in many different industries for a wide variety of components, from rocket engine cases to sewer pipes to soy sauce tanks.

Orenco Composites uses a closed-molding process called "vacuum infusion" to produce very large parts (often over 10,000 pounds), as well as relatively low-volume parts that cannot be economically produced using the RTM process. Vacuum infusion is also useful for producing extremely strong parts that require very high reinforcement content and parts requiring sophisticated coring, negative drafts, or other complicated laminate structures. Vacuum infusion has been widely adopted by manufacturers in the aerospace and yacht industries because the process lends itself to these types of large, complicated, low-volume structures.

Vacuum infusion molds can be relatively inexpensive since they are typically single-sided and do not require matched male/female mold sets. In fact, standard spray-up molds can sometimes be adapted to the vacuum infusion process.