MRO Magazine

Harmony: Water & Bearings Can Get Along

It's a well-known fact that water and bearings don't get along. Or is it?


It’s a well-known fact that water and bearings don’t get along. Or is it?

If you ask the folks at George’s Further Processing Inc., a chicken deboning operation, you’ll discover the rules have changed. “We just took it for granted, when our 800-psi pressure washes knocked the grease out of our conveyor bearings, that frequent bearing failure was part of the cost of keeping our conveyors clean,” says Don Carter, maintenance manager.

“Our crews would regrease the bearings at least twice a week, and then the sanitation people would come along, pressure wash the conveyor and flush out the bearing grease. That’s the way our cycle went for years.”

However, a composite mounted bearing unit with a double-protection seal and high quality insert bearing has changed all that.

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Lube Loss

The Springfield, Ark., chicken processing plant was replacing as many as six bearings a month due to excessive wear, a direct result of inadequate lubrication. “We process 16 hours a day, so there’s not a lot of time to take care of regreasing. And when we did, we greased until the grease pushed past the seal. That was the only way to be certain the bearing had enough lubricant, but that very process pushed out the seal and made the bearing vulnerable to water,” says Carter.

George’s Further Processing maintenance team also typically regreased bearings after production hours so consistent overtime pay had to be factored into operating/maintenance costs.

Rusty housings

Replacing bearings due to rust on the housings was another ongoing cost for the firm. “The constant moisture in the air due to our pressure washes created an ideal environment for rust. You can’t have rusting bearing housings near exposed meat on a conveyor belt because it presents a contamination risk,” reports Carter. “Our old bearings had either steel or nickel housings, and had to be replaced when rust became obvious regardless of how well the unit might be functioning internally.”

Composite mounted bearing unit

Such was the situation at George’s Further Processing, until an SKF bearing specialist showed up with a big promise: “We can provide you with a corrosion-resistant bearing unit that needs no regreasing, so you won’t have to worry about failed seals and grease wash-out,” he told Carter.

“I didn’t believe that was possible,” Carter recalls, “yet we had nothing to lose by trying this option.”

The bearing units, called Marathon Series, are from SKF. Designed explicitly for food and beverage processing equipment, the maintenance-free units have a composite housing, an extra-duty sealing arrangement, and are permanently lubricated. George’s Further Processing employs Marathon Series with a composite pillow block housing configuration and an insert bearing equipped with MRC Bearing Services’ proprietary ZMaRC corrosion-resistant coating.

Marathon Series units are also available as two- or four-bolt flange units, tapped-base units, narrow- and wide-slot take-up units, or three-bolt bracket flange units. The insert bearings are also offered in stainless steel. Bore sizes range from 3/4 in. to 1-15/16 in. and 20 mm to 40 mm.

The bearing unit’s double-protection stainless steel flinger (ANSI 304) and sealing arrangement uses two low-friction nitrile rubber lips to provide a double barrier against contaminants and high-pressure washdowns. The space between the seals is filled with food-grade grease for even greater sealing integrity.

Carter says his firm installed only a few of the new units initially, but came to see their advantages very quickly. “I’m from the old school that says you have to grease bearings and grease them often, so this new bearing concept was hard to accept. I almost wanted to see them fail just to prove that there is no such thing as a bearing that doesn’t need regreasing, so I watched these units like a hawk. I’m glad I was stubborn enough to investigate, though, because you don’t have to regrease bearings that don’t lose grease.”

Problem solving

The Marathon Series bearing units solved two problems for Carter at once. First, there was no grease loss due to pressure washouts because the seals remained in place; and second, there was no rust possibility on the housings, since they are made of a polyamide composite, a polymer known for its durability and heat resistance.

They even look nice. “They are white pillow blocks,” Carter notes, “so they convey a sense of cleanliness, and that’s important in a food processing environment. We have the public through here from time to time, and these bearings look as though they were created specifically with food handling in mind.”

Since installing MRC Marathon bearing units over two years ago, the plant has tripled its processing volume and now has approximately 100 conveyor lines. “If we were still using our former bearings, we’d probably be replacing them at a rate of 15 to 20 a month, and we’d be logging a lot of overtime hours for regreasing, but that’s all history now.

“The greatest part of our switchover to the composite bearing units is that we haven’t had a single operational bearing failure in two years. The grease stays in, and water stays out. Our story proves that water and bearings can get along.”

Carter estimates that Marathon bearing units save his company up to $1,000 monthly in bearing replacement costs. They save an additional $300 per month in lubrication and related labour costs.

The firm also has avoided the cost of additional maintenance resources despite the growing size of the operation, a fact Carter partly credits to his firm’s switchover to the new bearing units. “We still have a few of the old (nickel-plated) units around, but our intention is to convert 100 per cent to the composite mounted bearing units. They are approximately the same cost as our previous bearings, so we don’t have to spend more money to save money.”

For more information on SKF’s Marathon Series, send an e-mail to marketing@skf.ca, call 1-866-832-6753, or use the reply number below