Engineers turn soy resins into light-weight, 
long-life farm equipment

—by Richard Mandel

Engineers at John Deere, Lenexa, KS, a company long-connected with agricultural equipment, have been working with Bayer Corporation, Pittsburgh, PA to develop recycled materials that add value to their agricultural equipment. They’ve succeeded not only in creating new materials that improve performance over what they replace, but also in creating plastic materials that incorporate resins derived from the very crops that are to be farmed by that equipment. 

The first commercial application was introduced last August as the rear panel on John Deere STS combines. The panels were made using HarvestForm composite, a hybrid of Bayer’s Baydur polyurethane reaction injection molding (RIM) system with soy-based resin displacing a portion of the polyol typically used in the plastic. The part measures 6 x 6 ft., with molded-in ribs for strength, and weighs in at just 75 lbs. — 25 percent less than than a comparable part made with steel. Weight is a critical issue in agricultural machines, as the lower the mass of the equipment, the less the soil compacts beneath the vehicle. And soil compaction is what the farmers counteract each time they turn the soil over for new crops. The lighter weight also eases the task of removing the panel to gain access to the internal components of the combine.

Under development for several years, early versions of the material were tried on a baling machine. A formulation that preceded HarvestForm was first tested on 30 combine machines two years ago and subjected to the normal daily rigors of exposure to weather, dusts, and the vibration inherent to a machine designed to operate way off the highway. After months of (literally) field tests, the Bayer engineers found no difference in the performance of the new material as opposed to standard-production Baydur. End-of-life issues are no different either — HarvestForm parts use the same recycling technologies as standard polyurethanes.

Cooking with soy

Also participating in the development of HarvestForm was the molder, GI Plastek of Newburyport, MA. According to Charlie Beck, GI Plastek’s technical director of R & D, the company found that HarvestForm required no changes in process. “It’s a true drop-in replacement,” says Beck. 

Strengthening ribs are molded into the panels during the RIM process. The material also responded well to the company’s In-Mold Coating System, which provides molded plastics a durable alternative to after-process painting. The process involves directly spraying urethane paint into the tool cavity before clamping, which causes the paint to become incorporated into the surface of the plastic as it enters the mold. This was appealing to John Deere engineers, who desired a long-lasting appearance without altering the distinctive shade of green that has become a company hallmark. GI Plastek also notes that their In-Mold process is especially cost-saving during large-part, small-run production, and can also apply top and pigment coats.

Soy futures

Beginning with the 2002 model year, the entire line of combines from John Deere Harvester Works will include panels made from HarvestForm. But this is not the only step the company has taken towards sustainable industry. While the formulation for RIM processing includes the soy resin, another formulation, in the form of a sheet molding compound, will add corn polymers as well. Not only does this create an association of material and product for the customers, it illustrates John Deere’s involvement with commodity checkoff organizations such as the United Soybean Board and the National Corn Growers Association. These groups, and others like them, invest in research and development of new applications of their products.

The role of soy in John Deere farm equipment has, incidentally, gone beyond use in body panels. Last December, the company approved the use of soy-based Biodiesel fuel in all of its diesel-powered products. The company has worked for 35 years to aid development of alternative fuels that ultimately support commodity producers. The use of biodiesel fuels also reduces engine emissions.

For more information:

Circle 345—John Deere, or connect directly to their website via the Online Reader Service Program at www.rsleads.com/202df-345

Circle 346—Bayer Corp., Specialty RIM Group, or connect directly at www.rsleads.com/202df-346

Circle 347—GI Plastek, or connect directly at www.rsleads.com/202df-347