Differential motion conveyor from Food Engineering Corp. moves food to the packaging area through slow-advance, quick-return cyclic motion. Spherical roller bearings that support drive shafts require H1 grease where food is exposed. For conveyors in dusty environments, bearings are double-sealed and may use H2 grease.
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Lubricants used in machines that handle food and beverages must be nontoxic. To achieve this result, they’re prohibited from containing ingredients used in other lubricants to enhance performance characteristics such as wear resistance and corrosion resistance. This restriction applies especially to H1 lubricants, which are used where they may contact the food or beverage (see box, “Primer on food-grade lubricants”). H2 lubricants have fewer limitations because they don’t contact the food.

These ingredient restrictions limit the effectiveness of lubricants used on bearings, gears, chain, and other machine components, especially in severe operating environments that are common to food processing and packaging. In canning operations, for example, the principle environmental factors are water washdown and high temperatures.

As a result, those who manufacture food packaging machines must find ways to either compensate for the lubricant shortcomings or boost lubricant performance. Here are some of the ways in which they handle this performance issue.

Water washdown

Machines in food and beverage plants are frequently cleaned with water or steam, which washes away or dilutes the lubricant in machine components. You can do two things to prevent this problem, according to Ricardo Hein, area manager for international business, Castrol Industrial North America, Downers Grove, Ill:

• Install protective guards around the machine components or seal them to prevent the lubricant from washing away.

Or, you can teach maintenance personnel to avoid washing the lubricated areas when cleaning.

• Select either a mineral-based (petroleum) or synthetic lubricant with good water resistance. Synthetics are required for extreme temperatures (over 180 F, and under O F).

Be sure that the lubricant also has good wear resistance, shear stability, corrosion resistance, and oxidation stability (for long life) by consulting the manufacturer’s selection guide. These guides generally list the main performance attributes of each lubricant. They may also include pertinent data from ASTM or other tests used to evaluate lubricant characteristics.

Hot and dusty ride

The conveyors that transport food from processing to packaging operations contain drive components such as bearings, geared speed reducers, conveyor chain and sprockets, and belt sheaves. In most cases, H2 lubricants suffice for these components. But if the food is exposed to the lubricant, H1 is required.

High-speed can seamer (1,800 cans/min) from Angelus Sanitary Can Machine Co. features a multiple-spindle turret with seaming rolls supported by ceramic ball bearings that require little lubrication.
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A differential motion conveyor, for example, moves food products to the packaging area by cycling slowly forward and quickly backward. The X-Force conveyor, manufactured by the Food Engineering Corp. (FEC), Minneapolis, uses grease-lubricated spherical roller bearings to support the conveyor drive shafts. The bearings operate at 200 to 800 rpm, which generates enough heat to soften some greases and cause them to drip. Because the conveyor is typically in an exposed food area, H1 lubricant must be used.

“Some of the H1 greases that we tried in these bearings overheated,” says FEC project leader Tim Batman, “causing the bearings to fail.” Eventually, the company found an H1 grease that inhibits heat buildup, and it has prevented further bearing failures.

“Dusty environments are also a problem,” continues Tim Batman. “For example, dust from sugar gets into conventional bearings and prevents the lubricant from maintaining sufficient film thickness.” This causes overheating, which breaks down the lubricant, in turn causing more overheating, until the bearings become pitted and eventually seize.

FEC tried to find bearings with seals that keep the lubricant in and dust out, but these were unavailable. Therefore, for dusty applications, the company seals the bearings inhouse, applying a labyrinth seal inside and a lip seal outside, with a cap and O-ring over the entire assembly.

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