Winter highlights the impact of corrosion on wheels

The winter of 2013/2014 was one for the record books. Fortunately, it is over.

For fleets, it was brutal. Their operating costs and frustration levels escalated right along with the traffic congestion. Shipments were delayed. Deadlines were missed.

The resulting breakdowns, accidents and unexpected vehicle maintenance demands cost fleets plenty.

On the nation’s highways, the weather conditions were so persistent and pervasive that many counties, and in some cases entire states, exhausted their budgeted supplies of road salt and chemical de-icers used to keep the roadways clear of ice and snow. The severity of this winter meant that the nation’s commercial vehicle fleet was exposed to a higher, more damaging dose of salt and chemicals than in recent years.

Unfortunately, the properties that make these chemicals effective at clearing the roads of snow and ice also make them more corrosive. To control maintenance costs, it is critical for fleets to use every tool available to prevent or minimize corrosion.

Corrosion in the commercial vehicle industry remains a key topic for the American Trucking Associations’ Technology and Maintenance Council. New CSA regulations magnify the need for solutions to this problem for fleets, including the wheels on their trucks and trailers.

Long-Term Solutions Sought

Most metals oxidize when exposed to moisture and oxygen. Finding long-term solutions to corrosion is not easy, and is quite often expensive, and this is an expense that many end users do not want to bear.

For this reason, only a few companies remain on the front lines of the fight for reliable corrosion solutions for medium and heavy duty commercial vehicles. We are one of them.

These days, fleets are keeping their trucks and trailers longer to maximize their ROI. This magnifies the need to reduce corrosion-related maintenance costs.

Not all undercarriage components, however, can be easily removed and refinished after medium or severe corrosion shows up. Wheels are an example of components that are costly to refinish.

Aluminum Wheels

Steel and even aluminum wheels eventually oxidize. Some aluminum wheels are offered with a unique pretreatment process that prevents oxidation.

This aluminum pretreatment process comes with a clearcoat finish that protects the aluminum substrate. This reduces maintenance and provides for easy cleaning.

Aluminum wheels that are offered without this protection will eventually oxidize. Oxidized aluminum wheels will have to be re-polished to restore their original luster.

Aluminum wheels are increasingly popular on Class 8 vehicles. However they cost significantly more than steel wheels. Often, it is hard for fleets to justify this additional expense on trailers, especially without a compelling ROI.

Steel Wheels

Steel wheels that need to go through a refinishing process get exposed to a range of variables. Most refinishers in today’s marketplace cannot match the paint properties that the original wheel manufacturer can provide, and typically end up applying a coat of paint over bare, untreated steel.

Refinished wheels will need to be refinished again in a short period of time.

The leading powdercoated OEM steel wheels today come with three layers of protection:

A pretreatment stage, where the metal is prepared to bind with the first coat of paint.

An epoxy e-coat layer.

A final powdercoat layer.

Powdercoating

The U.S. steel wheel industry has now standardized on powdercoat for its superior performance characteristics. In other international markets, manufacturers are still offering wheels with a liquid top-coat.

U.S. steel wheel manufacturers recommend that wheel paint not exceed 3.5 mils thickness. Paint in excess of this thickness can lead to nuts loosening, which could result in loose wheels or premature wheel failure.

Few wheel refinishers have the equipment necessary to correctly remove the original paint by chemically stripping the wheel. Instead, most refinishers shot-blast the wheel to remove the paint. With this procedure, it is hard to completely remove 100 percent of the paint.

This harsh practice, when done multiples times over the life of the wheel, could compromise the integrity of the steel.

Special Attention Items

Special attention should be paid to wheel mounting surfaces to prevent any new paint from building up over the old paint. It is easy to build up paint thicknesses above the industry recommended maximum of 3.5 mils when paint is applied manually.

To prevent this from occurring, wheel refinishers should use paint thickness gauges to ensure that paint applied is within the recommended tolerance on the mating surfaces. Wheels that are returned to service with excess paint on the mating surface could cause false torque readings.

The extra-thick paint layer will compress under the nut or between disc areas. The thicker paint may eventually pulverize or disintegrate during the normal fretting process, which may cause the nut to lose its original torque level, leading the other nuts to also lose torque. This could potentially create a loose wheel situation.

After refinished wheels are installed, it is imperative for truck drivers and fleet maintenance personnel to follow up with periodic torque rechecks after conducting a wheel rotation.

The Evolution Continues

Wheel coating and corrosion-protection technology continues to evolve. Fleets’ willingness to adopt cost-saving solutions in the fight against corrosion is increasingly evident.

With tractors and trailers lasting longer and fuel consumption per mile improving, longer-lasting undercarriage components resistant to corrosion will continue to emerge in the marketplace.

Rafael Gonzalez is the director of wheel product management at Accuride Corporation (www.accuridecorp.com), a leading supplier of components to the North American commercial vehicle industry.

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