By: Paul Mills
Corrosion is a fleet-eating problem on commercial trucks that costs the industry $4 billion annually. When the American Trucking Association called for improved corrosion protection in 2005, Accuride accepted the challenge and responded with the trucking industry's first powder coated steel wheel to come with a corrosion warranty.
It's where the rubber meets the road," Mike Waller says playfully. Waller, the director of operations for Accuride's steel wheel plant in Henderson, Ky., explains, "No metal part of a commercial truck sits closer to the ground than our wheels." Six inches from the road means closer to the rocks, dirt, snow, rain and chemicals that wreak havoc on metal parts.
"Take something as simple as the road salt used to melt snow and ice," explains Dennis Winn, director of technology and business development at Accuride. "More and more states and municipalities are switching to magnesium chloride to improve safety," says Winn. "But magnesium chloride stays moist and is much tougher to wash off than sodium chloride. It's more tenacious; creeping into any pinhole or crack in the finish, making it more corrosive to wheels and all steel parts on cars and trucks."
To be sure, corrosion is more than just a minor annoyance. Left unchecked, corrosion can attack the wheel and jeopardize safety. The American Trucking Association (ATA) estimates that corrosion is a $4 billion annual problem for commercial truck fleets. A 2005 ATA study called for improving corrosion protection. "To our knowledge, Accuride is the first wheel supplier to respond to the challenge," says Winn.
"Corrosion eats fleets," says Rafael Gonzalez, director of product management for wheels. "On average, owners have had to refinish their steel wheels every two to three years. Our Steel Armor™ powder coated wheels introduced in 2014 can double that lifetime, and we expect our new EverSteel™ powder coated wheels to last eight to 10 years before they need to be refinished," says Gonzalez.
"You could say we've reinvented the wheel," says Timothy Weir, director of public affairs, communications and marketing for Accuride. "With a 5-year limited warranty against corrosion, Accuride's latest EverSteel wheel is the industry's first and only steel wheel that comes with a corrosion warranty."
The majority of Accuride's steel wheels are sold to large OEM truck and trailer manufacturers. Many of these vehicles are re-sold during that five-year time period, so buying an EverSteel wheel could save owners the cost of refinishing wheels before they sell the truck, amounting to hundreds of dollars in savings per vehicle. "For a fleet of a thousand 18-wheelers, at $35 a wheel for refinishing, that adds up to a savings of $630,000," says Weir. According to Accuride, one fleet running in the United States Midwest was spending $3.5 million a year refurbishing steel wheels. "Besides, after a factory finished wheel is refinished in the aftermarket, it's typically an even shorter period of time until it has to be refinished again. Typically in the 18- to 24-month range," explains Gonzalez.
Corroded wheels also have other, more subtle consequences. "If a driver pulls into an inspection station with a truck that looks bad, they're likely to face more scrutiny than the driver who pulls in with a well-maintained vehicle," Weir comments. "Corrosion sends a signal that screams, ‘look more closely at me' to inspectors. More citations means more fines, downtime, and lost productivity."
"Drivers also take a lot of pride in their vehicles," says Winn. "While an average passenger vehicle may be driven 15,000 or 20,000 miles a year, a commercial vehicle will see 120,000 miles on average and up to 240,000 miles a year with two drivers," observes Winn. "And drivers usually don't want to drive a bad-looking rig."
Accuride Corporation, the largest supplier of commercial vehicle steel wheels in North America with revenues around $700 million, began to invest heavily in its operations and new technology in 2011 when Rick Dauch joined the company as president and CEO. Dauch, along with Scott Hazlett, president of the Accuride wheels division, who also joined Accuride in 2011, laid out a vision that included a transition to lean manufacturing and innovation that provides value to Accuride customers. At 365,000 square feet sitting on 118 acres, Accuride's Henderson facility produces more steel wheels than any other plant. Currently it powder coats about 1.5 million wheels per year, and has a capacity of over 3 million wheels a year.
Lean manufacturing has produced impressive results. In Henderson, the initiative reduced work in process by over $1 million. The plant has seen a 61 percent improvement in lead times, a 42 percent improvement in productivity and a 19 percent reduction in its controllable costs per wheel. "The Lean process also opened up over 13,000 square feet of floor space," says Waller. "That allowed us to install the new powder coat line without having to expand the building, and avoiding $2 million in additional capital investment."
The Lean work at Henderson earned the plant a 2014 award from the Association of Manufacturing Excellence. The AME Excellence Award recognizes North American manufacturing plants that have demonstrated continuous improvement, best practices, creativity and innovation. "We are really proud of the award," says Waller. "Only two plants in the U.S. and four in all of North America received the award that year."
The second prong of Dauch's vision, a commitment to value-added innovation in their products, prompted Accuride's $6.5 million investment in the Henderson, Kentucky and Monterrey, Mexico, plants' paint systems. The development of Accuride's new powder coating process was led by Mario Facione, an engineer and the company's ‘resident paint guru' based at Accuride's London, Ont., plant, and Craig Kessler, vice president of engineering for the company's wheel division. "Our commitment to powder R&D led first to the Steel Armor- coated wheel in 2014, and to the new EverSteel wheel this year," says Winn.
"Before Steel Armor, our wheels were pretty typical of industry performance," says Gonzalez. "We were getting about 1,200 hours of ASTM B117 salt spray resistance, and about 20-30 cycles of cyclic corrosion performance. Steel Armor's improvement in performance means a fleet gets two to three or more years of service before a wheel would need to be refinished."
"We've gone the extra mile to document the breakthrough performance and durability of our Steel Armor coating process," says Gonzalez. "While the industry norm is to test salt spray and chip resistance, we have added over a dozen tests, including exposing coated parts to Xenon Arc Exposure testing, South Florida exposure, chemical resistance/wheel cleaner, abrasion and cyclical corrosion testing."
Steel Armor is a fully automated, three-step process for attaining better performance. First, the wheels are loaded two-high onto a heavy-duty continuous monorail conveyor and pretreated using a high performance tri-metal zinc phosphate formulation. "Zinc phosphate provides excellent adhesion for the subsequent e-coating step," explains Winn. The zinc phosphate stage is part of a seven-stage chemical pretreatment process that begins with an alkaline cleaner, followed by a city water rinse and a conditioner. The zinc phosphate coating is applied in the fourth stage and is followed by another water rinse, sealer, and final reverse-osmosis water rinse. Next, the pretreated wheels undergo a cathodic epoxy electrocoat. Developed with Valspar, the e-coat has been optimized to retain maximum paint coverage on the wheel's sharp edges, lug holes and hand holds.
After e-coat, the wheels are robotically transferred to the chain-on-edge powder coating line. "Painting the wheels horizontally helps to provide more uniform film build and gives us better flow and leveling of the powder," says Waller. The powder coated wheels are again robotically transferred from the powder coating conveyor to the curing line, where they are also cured horizontally in a gas-fired convection oven for 40 minutes at 400°F.
"The Steel Armor proprietary blended resin powder coating was developed in cooperation with Valspar to have a number of properties that are optimized for the large steel wheel service environment," says Gonzalez. It is formulated to inhibit the initiation and growth of corrosion in several ways, and it is designed to inhibit the spread of corrosion at points of initiations such as gouges, chips and scratches that could expose metal. Proprietary additives are included to minimize the drawing away from sharp edges when cured. This is important for giving extra protection at the hand holes, bolt holes and the rim edge. Special attention was also given during formulation to ensure good coverage in recesses and in Faraday areas. "Any exposed area allows rust to move in, expand and destroy steel. The combination of pretreatment,
e-coat and powder coating significantly reduces the growth of corrosion from expanding across the wheel's metal surface." says Winn.
Now, in 2016, Accuride has once again raised the bar on corrosion protection. The EverSteel wheel improves corrosion protection by treating the wheel's steel prior to chemical pretreatment using a proprietary plating process.
What makes the EverSteel wheel more corrosion-resistant is a finishing process that combines a proprietary method of treating the bare metal prior to the Steel Armor process of zinc phosphate, e-coat and powder coating. "In simple terms, it can best be described as a zinc-nickel plating process," says Winn. "The wheel first goes through a traditional cleaning process and then is preconditioned for plating." The wheel is electrolytically plated using a ZnNi-based material that does not substantively change the metallurgy of the wheel. "The ZnNi is a noble, sacrificial plating, which provides a superior plating technology compared to zinc," says Winn. "Part of our technology is a proprietary technique that places a microscopically-thin ceramic layer on the wheel that encases the wheel and blocks corrosion," explains Winn. "Part of the proprietary process ensures the EverSteel technology achieves a highly uniform plating capable of delivering maximum protection for the subsequent layers."
"Our competition typically meets 20 cycles of corrosion testing," says Weir. "With the Steel Armor process, we can double or even triple that to 50 to 60 cycles. Now, with EverSteel, our powder coated wheels exceed 125 cycles. Wheel refinishing can be delayed by up to eight years, saving customers real money. We estimate that could be $140 a wheel, or over $2,500 a vehicle."
"We have worked for years with Henkel and Valspar, our pretreatment and coating partners to develop a superior process," says Winn. "In total, EverSteel involves 36 discrete steps that encompass plating, pretreatment, e-coat, and powder coating to ensure the highest level of performance. Along the way, we were continually refining the system to maximize performance and process robustness."
The steel wheels, weighing anywhere from 68 to 112 pounds, are formed on two separate assembly lines at the Henderson plant. These lines come together at the plant's central wheel finishing system, which coats up to 540 wheels per hour. "We don't use any masking because we want to get 100 percent powder coverage," explains Waller. "We can do this because we keep such tight tolerances over the powder coating process." To accomplish this, Accuride uses a Nordson Excel Series Cartridge side draft powder coating booth outfitted with 36 automatic Encore® spray guns. These guns are positioned to provide 100 percent coverage to all surfaces of the wheel, including the deep recesses.
The entire EverSteel process, which results in an overall combined coating thickness of about 3.0 mils, is controlled to a small fraction of a mil. “Too much paint can cause problems with mounting the wheel, and too little powder can result in reduced corrosion protection,” says Winn. To help maintain these tight tolerances, Accuride installed a powerful, Nordson iControl® integrated control system uses closed-loop digital flow, to provide consistent, repeatable coating performance on the powder line. The graphic touchscreen interface provides complete monitoring and control of critical powder system parameters such as atomizing and air flow rates, charging characteristics, and gun triggering for each of the 36 guns in the booth. “The iControl System provides automatic feedback current control that leads to more consistent coverage and penetration of recessed areas,” says Winn, “and the guns perform well on these wheels where tight recesses and deep, small-diameter holes required good Faraday-cage penetration for more uniform coverage.”
Waller says that nearly 80 percent of Accuride’s wheels are powder coated white on the dedicated line, but gray and black are other standard Steel Armor colors. “And we can also powder coat wheels in any custom color in our secondary powder coating system.” Each powder coated wheel is inspected visually by one of four quality inspectors, and wheels are sampled for a wide range of performance tests including cure, adhesion, film build, color and gloss. “Each wheel is arked to indicate which of the four spray stations it was processed in,” says Peter Anderson, manager of quality assurance at Henderson. This allows traceability back to the correct spray station during inspection. This attention to detail is part of the plant’s TS16949 ISO quality management system that provides for continual improvement and emphasizes defect prevention and the reduction of variation and waste in the process. “The paint line runs 24 hours a day from Monday through Friday with 99 percent throughput and never stops,” says Waller.
“Customers may choose steel wheels over aluminum because they cost less, but that doesn’t mean lower performance,” says Weir. As North America’s second largest aluminum wheel supplier for commercial vehicles, Accuride can offer a wide range of both steel and aluminum wheels to their customers. “Now that they have been used on the road for several years, the performance of Steel Armor wheels has been proven under real driving conditions, and the market is beginning to see the benefits for themselves. We are starting to see more fleets specifying Steel Armor wheels, even though they may cost slightly more than competing wheels. Their ability to help customers avoid expensive refinishes makes it worth it to them,” says Weir. “In a few years, the EverSteel wheel should have the same effect; making the case for purchasing a higher quality powder coated wheel even stronger.”
Paul Mills is a marketing and business development consultant to industry chemistry and equipment suppliers. He has been a writer for the powder coating industry since 1994. Paul can be reached at 440-570-5228 or via email at firstname.lastname@example.org