SPE Thermoforming Division highlights construction equipment composite hood innovation

The Society of Plastics Engineers (SPE, Danbury, Conn., U.S.) Thermoforming Division highlights an entry from Plastics Unlimited (Preston, Iowa, U.S.) for its biennial parts competition that improved the composite hood of a customer’s horizontal directional drills, construction equipment that is used to install underground utilities like pipes and cables without disturbing the ground surface. 

The rear hood developed for the OEM’s directional drills faced a major issue: the existing orange gelcoated fiberglass hoods, exposed constantly to UV rays, would fade over time — turning a dull, chalky white. The customer approached Plastics Unlimited for a solution, resulting in replacing the original gelcoated fiberglass with a co-extruded ABS with acrylic cap to maintain vibrant appearances and performance even under harsh environmental conditions. 

According to Plastics Unlimited, the new hood uses a process that bonds two materials into a single, high-performance structure. The outer layer is a 0.350-inch-thick, color-matched, co-extruded ABS with an acrylic cap, providing a Class A finish. This passes stringent accelerated weathering and corrosion tests, ensuring the orange color stays bright and fade-resistant. The structural backing, however, is still fiberglass, to ensure the delivery of high strength and to endure extreme temperatures — ideal for engine enclosures. Combined, the plastics and composites material systems offers durability, impact resistance and weight savings.

The production part uses tooling consisting of a single-cavity, temperature-controlled aluminum mold, optimized for consistent quality and cycle time.

Plastics Unlimited notes that no attachment points are visible from the Class A side, preserving a clean, professional appearance. Mounting brackets and screens are adhered to the B-side using structural adhesive. Moreover, assembly fixtures were designed and manufactured in-house to ensure tight customer tolerance requirements were met.