THERE IS AN element missing in today's farm equipment. It's called ferric oxide, also known as corrosion. Simply stated — rust. In the last 10 to 15 years, ag equipment manufacturers have focused on this problem, which a study by CCTechnologies and the National Association of Corrosion Engineers (NACE) International says costs the ag industry about $1.1 billion a year.
“In our industry there has been a tremendous turn in product improvement and appearance in the last 10 years,” says Imants (Nick) Ekis, materials engineer for paints with New Holland. Ekis says the industry's efforts are in response to consumer demand. “Buyers expect more from a piece of equipment than they did 40 or 50 years ago as far as appearance and aesthetics,” he says.
Their rising expectations are driven by the automotive industry. Cars built today do not rust nearly as fast as cars made in the '60s and '70s did because of the advancements in corrosion protection. The equipment industry is adopting many of the same technologies to improve the appearance of tractors and combines.
“The coating technologies and application methods have improved significantly over the past 15 to 20 years, providing protection for iron for a much longer time than they used to,” says Bob Butikofer, materials engineer with paint processes at Deere. “Additionally, more of our tractors today are made of plastic materials that will not rust.”
So just how much longer will machinery last without rusting? Mark Stewart, corporate manager for product finishing at Case IH, says, “Based on my knowledge of improved processes and materials, the main panels and components of tractors and combines should last at least five to 10 times as long before corrosion occurs than they did even a decade ago.”
Here's a rundown of the new materials equipment makers are using and the new technologies they are adopting to prevent rust.
- higher-grade steels
Most farm equipment is made out of steel. Steel rusts because it contains iron. “Rust cannot occur without iron,” says New Holland's Ekis. “Iron is the magic to that word.”
However, certain grades of steel rust faster than others. Because of this difference, major machinery companies are investing in higher grades of steel to inhibit corrosion. These higher grades include stainless steel or cor-ten structural steel, which contains alloying elements such as nickel or chromium. Stainless steel can be found in parts such as metering components on planters or fertilizer applicators and high-abrasion parts such as troughs on corn heads.
- better degreasing
When metal comes from the steel mill, grease and oil are removed before the metal is primed and painted. According to Case IH's Stewart, the chemical process of cleaning hasn't changed much in recent years, but the equipment used for cleaning has gotten better, making the process more efficient. “The kinds of spray nozzles and attachments have improved so that you can readily adjust and clean them frequently,” Stewart says. “They used to be made of metal with threaded connections that had to be screwed into place, so you couldn't remove — or even adjust — them easily.”
- more durable coatings
Once cleaned, the metal is coated with a protective layer to further prevent corrosion. Oftentimes the metal receives what is called a “conversion coating,” in which a thin layer of zinc or iron phosphate is applied on top. This conversion coating creates a bumpy surface for better adhesion of the paint, according to Kevin Wilkening, engineering design supervisor with Claas. He says the cost of coatings may be 20 to 40% of a part's total cost. Sealers are then applied to further increase corrosion resistance prior to painting.
- better paints
Paint provides yet another layer of protection to prevent iron from mixing with oxygen and moisture. How well paint adheres to the metal determines its level of corrosion protection.
“Farm machinery used to be painted with alkyd paint, the kind you'd find in a spray can at your local hardware store,” Ekis says. Today the industry has switched to higher-performance coatings that adhere to metal longer and offer better shine retention and rust prevention than the old alkyd paints did. These include epoxy primers, acrylic and urethane liquid topcoats, and polyester powder paints.
- better application methods
Not only have the paints improved but so have the processes for applying them. In the past, paints were predominately sprayed on. Now, in addition to spray coating, the major equipment companies are using powder coating and electrocoating for a more even, automotive finish that is shiny and more durable.
With powder coating, each part is pretreated and then electrically charged so that dry paint particles are attracted to the metal. The paint is then baked into the metal at high temperatures. Electrocoating, or e-coating, is another application process where the part is dipped in a bath of electro-charged chemicals that make the paint adhere to the metal. E-coating covers not only the outside surfaces but also cracks, crevices and channels that would be difficult to reach with spraying.
- more stringent specifications
Driving the improvement in coatings, paints and processes have been higher standards. “Fifteen or 20 years ago, the requirements for equipment were lower than what they are today because consumer expectations were lower,” says Ekis, who writes standards dictating what the company expects from its materials suppliers.
Ekis says products are put through a battery of accelerated tests to ensure coatings will provide the required level of corrosion protection. These tests include:Salt spray
Salt is sprayed on panels of painted steel and left outside on a rack. The paint is scratched and the surface is then scraped to measure corrosion.Cyclic corrosion testing
Metal is exposed to a salt spray followed by high humidity and is allowed to sit for a period of time before corrosion is measured.Ultraviolet light exposure
Formerly called the Florida sun test, it measures color and gloss retention, fading and degrading.
- use of plastics
Finally, to bypass corrosion altogether, the major machinery makers are using plastics and composites; molded-in color; painted, in-mold films; and gel coats in more applications, such as hoods, fenders, side panels, light housing, grille frames, corn snouts and cab interiors.
“Fifteen years ago, there was not near the amount of nonmetallic parts or plastic substrates used as today in our industry because of the advancements in molding technology,” Stewart says. Molding technologies include a compression molding process called Sheet Molding Compound (SMC) and Reinforced Injection Molding (RIM).
One of John Deere's molders, the largest co-injection machine in the world, molds thermoplastic hood enclosures for Deere's 7020 and 8020 series tractors, according to Gene Ream, materials engineer and plastics consultant for Deere. “Now we can mold large parts that we couldn't in the past,” Ream says, adding that the injection-molded plastic has a more automotive finish.
Deere also is using a soy- and corn-based SMC formulation for use in its 9000 series 4-wd tractors introduced last year. “We recognize the adoption of plastics has given us a huge step forward in the corrosion protection of the tractor itself because parts that are made of iron, given enough time and wear and tear, are going to rust,” Ream says. “But the plastic part has good durability and it will not rust even if you scratch it.”
a look at future rust-fighting technologies
WHAT WILL be the next breakthrough in corrosion prevention technology? One will be the adoption of more durable finishes on hardware, such as dacroment-coated hardware in place of zinc-plated hardware, according to Bob Butikofer, materials engineer with paint processes at Deere. The major equipment companies already use dacroment-coated hardware, an organic-based type coating, in some applications.
Customers also will see increased use of noncorrodible coatings and substrates like plastic, according to Gene Ream, materials engineer and plastics consultant for Deere. “These are not new technologies, but I believe their adoption will accelerate,” he says.
Currently most of the plastic used in farm equipment must be coated to achieve the required durability, scratch resistance, mar resistance and gloss retention. However, future plastics will have those qualities built in, along with molded-in color, according to Ream.
“At this point we still need to paint many of the plastic parts,” Ream says. “But we are starting to see encouraging things in plastic development that are equal to or better than paint as far as gloss, color and durability. However, the technology is not to the point where we are willing to jump in and pay the cost for it yet.”