Case Study: Closed Mold Process Used on Innovative Combine Grain Extension Covers

The closed mold process is a method of working with resin that delivers many benefits. These include reduced waste and emissions, lower material and disposal costs, a more consistent, repeatable process, and reduced cycle times for higher productivity and lower labor costs. When dealing with composites, closed mold processes like light resin transfer molding (RTM), vacuum infusion and reusable bag molding can be attractive alternatives to open mold processes.

Plastics Unlimited innovates combine grain extension covers with closed mold process

For Plastics Unlimited, a Midwest manufacturer of thermoformed plastics, advanced composites, fiber reinforced plastics, polyurethane molding and carbon fiber, the closed mold process has allowed the company to innovate. One specific application of their closed mold approach was a grain extension cover for a combine. The watertight cover both decreased overall combine weight and increased grain storage capacity by 38 percent, in addition to protecting harvested grain during inclement weather, for possible cost savings due to a reduced risk of lost harvest.

The monolithic panels are created when a thermoformed acrylic skin shell is co-extruded with a second layer of ABS. The acrylic offers UV protection, while the process provides improved impact resistance, durability and toughness. Fiberglass is bonded to the thermoformed shell, with closed cell foam structural ribs and metal brackets encapsulated within. The ribs create localized stiffeners, and the metal brackets help bolt the extension covers to the hydraulic lifters, canvas connectors and the combine itself. The glass fiber is held in place by thermosetting resin injected under vacuum into the fiber and cured. This resin/fiber combination also encloses the stiffeners and brackets, allowing the bond with the thermoplastic shell. The result is a lightweight extension cover that serves as a lower-maintenance alternative to the steel covers previously used in these instances.

Composites One is the leading supplier in North America of high-quality composite materials

Composites One is the leading distributor of composites and advanced composite material throughout North America. We work with many industries supplying composite materials for a wide variety of projects and to improve and innovate with approaches like closed mold processes. To learn more about the materials we distribute, contact our technical specialists today.