Keeping with the Volvo Group’s strong tradition of high-performance and environmental excellence, personnel at the company’s Motor Grader Assembly Line recently sought out ways to improve its masking operations...
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Shercon’s custom mask installs quickly, protecting the sizable hub surface area from their finishing process while meeting Volvo's environmental standards.
The Volvo name has always been synonymous with high-quality performance vehicles. But what some people don’t know is that the Volvo Group’s product offerings extends well beyond its automotive industry roots and now reaches into aerospace, commercial trucking and construction equipment to name a few. For instance, the company’s Motor Grader division, part of Volvo Construction Equipment, is one of the largest and oldest (130 years) producers of motor graders worldwide. As with its sister divisions, quality, safety and environmental care are the three core values that form the foundation of the Construction Equipment Group.
The task of ensuring quality and performance falls to the 700 employees at Volvo Motor Grader’s Ontario, Canada assembly plant. Because the motor graders must be able to withstand the demands of everyday use in a variety of climates, a quality finish is imperative.
In the facility’s paint shop, Volvo employs a multi-step finishing process designed to meet the company’s quality standards while still conforming to its strict environmental policies.
As parts enter the paint shop, they are washed and sent through a dry-off oven. After being dried, they are subjected to a “wet-on-wet” coating process in which the parts are first painted with a primer coat. Before the primer dries, the topcoat is applied. As Volvo uses a true paint-before-assembly process, masking plays a critical role. A single part may contain dozens of machined areas or threaded surfaces that need to be protected from the paint. After the topcoat has been applied, the parts are sent through an IR oven, where temperatures reach 200°F.
A strong environmental ethic is part of Volvo’s corporate philosophy, so the ongoing disposal of thousands of single-use masks conflicted with their values.
“We were discarding literally barrels of plastic plugs per year,” said Mike Gilbert, manufacturing services supervisor at Volvo Motor Graders. “We knew that every one of those plastic plugs ended up in a landfill. We didn’t like that, as it is contrary to our ISO 14001 Environmental ideals.”
Another concern revolved around Volvo’s use of heavy, 20-pound steel masks to protect the machined hub surfaces of their large, built-to-order motor graders. Cumbersome to fit and remove, each steel mask had to be shipped off-site for “burning”—a process which literally burned the built-up paint off the steel masks.
Using the Internet, Gilbert began exploring potential solutions for his masking dilemma. He discovered Shercon, Inc, a California-based custom molded rubber products manufacturer and made contact with the company. A short time later, he replaced his disposable plastic caps and plugs with Shercon’s off-the-shelf “high-temperature” molded caps and plugs.
“The caps are holding up great” said Gilbert. “Our IR oven heats our just-painted parts to more than 200°F, and we needed long-lasting, easy-to-install masks that would excel in that kind of application. The new parts are doing just that.”
“The longevity is at least 40:1 compared to plastic plugs,” said Gilbert. “And while we’re happy with the environmental results, we also see reusable plugs as providing an overall cost savings.”
After replacing their one-use caps and plugs with Shercon caps and plugs, Gilbert inquired about possible alternatives to the 20-pound steel masks used to protect the six hub surfaces on every motor grader from paint.
“Each steel mask had to be shipped over 60 miles to get the paint buildup burned off,” explains Gilbert, who also pointed out that the heavy steel masks were difficult to remove off the just-painted assemblies.
Because the heavy steel masks had to be shipped out for cleaning, Gilbert needed to maintain multiple sets of masks to be sure he always had enough for the motor graders that moved down the assembly line each day.
In addition, the high temperatures involved in the paint removal process sometimes caused the steel masks to warp, which limited their life and forced an added inspection step to ensure the warped masks were not used.
Gilbert explored a variety of replacement masking products, but many of them were unable to withstand Volvo’s demanding wash/prime/paint/bake finishing cycle or were simply too time consuming to install.
Designing a custom replacement for Volvo’s steel masks fell to Ruben Dominguez, a production engineer at Shercon. “Designing a mask to protect a large hub surface and the 10 threaded holes surrounding it wasn’t simple—the outside diameter of the mask ended up at 13.5 inches, which is a big mask.”
Shercon produced prototypes from Gilbert’s mechanical drawings and shipped them to Gilbert for testing. After these prototypes were tested on Volvo’s assembly line, Gilbert requested a few changes, hoping to improve clearances around some of the plugs and easing worker access for insertion and removal. The masks went into production a week after Shercon received feedback from Gilbert. Later, one more minor modification was made to improve mask fit.
The resulting mask was complex, yet effective—the result of some deft engineering touches by Dominguez. For instance, Dominguez wanted to reduce the amount of material used in mask fabrication (to reduce mask costs) while keeping mask strength at a maximum (for the sake of longevity). As a result, he engineered the masks using extensive ribs and gussets.
“This helped reduce cost, yet maintained mask performance and longevity,” said Dominguez. His sentiments were echoed by Gilbert, who anticipates getting years out of the masks.
“Because we wanted to completely seal a large opening from the wash/prime/paint process, I also designed the mask with a bit of undercut, which promoted a much stronger seal across the large open area,” says Dominguez, who incorporated plugs for the 10 threaded holes surrounding the hub right into the mask, so workers installed one mask instead of eleven.
Shercon’s custom solutions have performed beyond Gilbert’s expectations, whose line workers have fully embraced the benefits of the considerably lighter and more flexible masks.
The new masks don’t require Volvo to ship the used masks to an outside paint removal vendor. In fact, according to Gilbert, workers can easily remove paint buildup from the masks. Volvo’s non-toxic paint simply comes off the flexible mask and can be disposed of in the everyday garbage. The masks are simply dropped in a box until they are needed again.
While costs savings weren’t the primary goal of Volvo’s mask upgrade program, Gilbert figures his costs will ultimately prove to be lower, with full payback in about two years.