Fort Worth, Texas — Greg McCunn, a veteran John Deere composites and materials engineer, walked an audience of thermoformers through the advance of plastic body panels that have given a sleek look to farm combines and hay balers.
Speaking at the Society of Plastics Engineers' Thermoforming Conference, McCunn presented a rapid-fire slide show of photos taken at farm equipment shows around world as if it was a slideshow from vacations. Except instead of pictures of the Grand Canyon, it was the Farm Products Show and the Agritechnica in Hanover, Germany.
Many of the combines and balers combined metal body panels and thermoformed plastic panels. That makes it a challenge because of surface matching and the different expansion rates, McCunn said.
Thermoformed parts, mounted to a steel frame underneath, can give low-cost styling, he said. In some cases, thermoforming has replaced other plastic processes, such as resin transfer molding and sheet molding compound.
Twin-sheet thermoforming is gaining ground in agricultural equipment, McCunn said. For example, Deere's large baler sold in North America that turns out square hay bales had used RTM body panels, but twin-sheet thermoforming replaced that process. One factor: Twin-sheet formed parts needed fewer fasteners than the RTM parts.