January 2014, TruckingInfo.com - Department
Back in 1984, the Occupational Safety and Health Administration issued a regulation requiring that truck wheels be stripped of rust and debris before mounting a tire. Easier said than done, the industry moaned at the time. Labor was less costly then, but wire brushes and elbow grease weren’t going to cut it.
Pictures are worth a thousand words, they say. What sort of a
message do the wheels on this trailer convey about its owner?
Two years later, International Marketing Inc. brought to market its Series 2010 Wheel/Rim Refinishing System, a fast and cost-effective technology that allowed fleets and tire dealers to meet the OSHA requirements more efficiently. IMI installed its first system at a Goodyear Truck Tire center in Brunswick, Ohio, and invited representatives from the three biggest LTL fleets in the country at the time, Yellow Freight, Consolidated Freightways and Roadway, to drop by.
“It was unique at the time, and it really opened up some service opportunities for the tire dealers and service centers,” says Jeff Redding, National Equipment and Coatings manager at IMI. “Safety is what drove it. Today, with CSA and all the added scrutiny from the DOT, fleets want to avoid throwing up any red flags during an inspection – and bad wheels really draw a lot of attention.”
Wheel refinishing has become a commodity of sorts over the years, and fleets often complain about the quality of the work from various vendors, even though the process costs a fraction of the price of a new wheel.
Cost ranges with volume, account bundling and a host of other factors, but fleets can pay anywhere from $20 to $35 per wheel for shot blasting, inspection and new powder coat. Compare that to somewhere between $85 and $100 for a brand new steel wheel.
Chris Folweiler, the tire shop foreman at Wilson Trucking of Fisherville, Va., looks after the tires and wheels on a fleet of 900 trucks and 1,900 trailers. He has his own wheel refinishing installation at the terminal. He says he can do a wheel for about $23, and a wheel could be refinished three to five times over its service life.
An operator visually inspects a wheel prior to the blast cleaning process.
“That wheel would look pretty sad over that length of time in service without refinishing, and it’s much less expensive for us to refinish them rather than replace them. I believe refinishing has cut our wheel consumption by about 70%,” he says.
After dismounting the tire, the wheel should be cleaned and degreased, and then inspected for obvious defects such as cracks or distortions. If the DOT stamp and/or manufacturer’s marks are illegible, or the wheel is damaged it should be scrapped.
The previous coating is usually removed inside a blasting cabinet, where the wheel is blast cleaned using media such as steel shot, sand or glass beads of varying sizes. IMI President and CEO Robert Fogal says the size and type of media makes a difference.
“The media should be chosen for coating removal and paint preparation,” he says. “You can short-cut the process by using larger, more aggressive media, but you run the risk of pitting the wheel or possibly peening thin cracks closed. Use too fine a media, and the process takes longer.”
IMI’s 20/20 blaster can strip a wheel to the bare metal in about three minutes in most cases with coating thicknesses up to 15 mils. Previously powder-coated or e-coated wheels with very durable finishes can take longer.
Swabbing the wheel with acetone or methyl-ethyl-ketone will reveal if the paint was properly cured.
All the previous coating has to be removed, and the surface of the wheel should be rendered reasonably smooth and free of shot pitting. Pitting deeper than 3 to 3.5 mils could result in excessive coating thickness on critical areas of the wheel.
Once the old coating and all the corrosion has been removed, the wheel is inspected once again for damage that may have been obscured by the paint.
Mark Fonte, marketing and sales manager for OE Truck Wheels at Maxion Wheel, says corrosion pitting is metal from the wheel that has been eaten away. He advises caution when working with deeply pitted wheels.
“When you take off layers of corrosion, you’re taking some base metal away from the wheel,” he says. “If you go too far you can weaken the wheel.”
With the wheel stripped clean of previous coating material and rust, it should be handled with gloves, not bare hands, to prevent oils from contaminating the surface. The bare metal should be promptly recoated to minimize contact with moisture.
Some processes apply a primer coat, while others paint directly or use an electro-static coating. Pricing can vary with the type of coating used and the quality.
Application of the final coating is critical, Redding says. “The coating cannot be any more than 3 - 3.5 mils thick, especially on the mounting surfaces and between the bolt holes,” he warns. “Excessive coating thickness can lead to a loss of clamping force and eventually loose nuts and possibly a wheel loss.”
A typical wheel prior to blast-cleaning. After the blast cleaning, defects will be visible. If the DOT stamping is not clearly visible, scrap the wheel.
Depending on the coating, curing can produce better results than air drying. It’s just another part of the process than can add cost.
There are gauges for measuring coating thickness, and Fogal recommends fleets audit their suppliers from time to time.
“This is a hot topic for fleets,” he notes. “They want to be sure that the vendor is using a coating designed for a harsh environment that meets certain corrosion-resistance thresholds, not just an off-the-shelf paint you’d use on a filing cabinet, and that it’s properly applied and cured.”
Swabbing the wheel with acetone or methyl-ethyl-ketone can ensure it was properly cured. Uncured paint will come off on the swab. A properly cured coating will not.
Folweiler says Wilson trucking began refinishing its own wheels in 1993. Once a wheel has been shot blasted that many times, it would be wise to mic the wheel just to be sure it’s still structurally sound, he advises.
“I’m not sure how many, but I know we still have some wheels in service that date back to 1993 when we started doing out own refinishing,” he says. “That has been a tremendous savings for us.”
Information sources for wheel inspection and refinishing
• TMC Recommended Practice RP 240 gives a comprehensive overview of the proper refinishing procedures.
• TMC Recommended Practice RP 222C contains wheel inspection criteria and procedures.
• Accuride Service Guide W4.000 “Wheel Out-of-Service Guide” helps identify common wheel defects with illustrations.
• OSHA regulation 3086, “Servicing Single Piece and Multi-Piece Rim Wheels” outlines wheel inspection criteria and out-of-service conditions.
Irregularities on the mounting face of this wheel were likely caused by loose fasteners. The damaged surface will prevent proper clamp load from being applied evenly around the wheel. This wheel should be scrapped.
Not fit for service
A bright and freshly painted wheel isn’t necessarily a safe wheel. Damaged or worn out wheels should not be put back into service, but sometimes it’s hard to discern the actual physical condition of a wheel when it covered in rust, peeling paint, etc. Close inspections of the wheel while it’s stripped of coating can reveal damage you might miss otherwise. Take the wheel out of service and look for possible causes.
Cracks can appear in several locations around the wheel for different reasons, and may appear as cracked paint at first. When the paint is removed during refinishing, the cracks become obvious. Any visible cracking on any part of the wheel is not repairable. Take the wheel out of service.
• Cracks running from bolt-hole to bolt-hole indicate loose cap nuts. Review wheel torquing procedures.
• Cracks running from hand-hole to hand-hole, hand-hole to bolt-hole or hand-hole to rim indicate overloading.
• Circumferential cracks at the back flange radius, bead seat or in the middle of the rim indicate overloading or overinflation.
Bent or distorted wheels should not be repaired and returned to service. Even minor distortions can cause problems such as air seepage, leading to low-pressure conditions and irregular tread wear. A complete inspection should include checking for excessive run-out using a dial indicator.
• Rim base or flange distortion, or chorded or bent rim gutters, can indicate excessive or improper torque, mounting to the wrong type of hub or a previous run-flat condition.
• Wheels with worn or distorted bolt-holes indicate loose cap nuts and improper torquing procedures.
Corrosion and wear
Wheels or rims with heavy rust, corrosion or severe pitting cannot be repaired. Remove them from service.
• Burrs or raised metal edges or protrusions around the bolt-holes on some wheels may be filed off using a flat file. These can be considered for refinishing if the bolt-holes are not distorted.
As truck parts go, wheels are among the less expensive. Does it make sense to invest technician time trying to repair a damaged wheel?
“At less than $100 in many cases, you can quickly find yourself wasting money trying to put damaged wheels back in service,” says Mark Fonte, marketing and sales manager for OE Truck Wheels at Maxion Wheel. “Repairing wheels raises safety concerns. TMC lists a series of out-of-service conditions for steel wheels. Fleets can cost-effectively refinish a wheel and restore its appearance, but it won’t fix damaged wheels. Repairing wheels usually isn’t worth the trouble.”
— Sources: Technology & Maintenance Council PR 222C, Accuride’s W4.000 Wheel Out-of-Service Guide