David Como
U.S. Lubricants Expertise Group

Gordon Elfstrom
Dow Corning Molykote
Midland, Mich.

Complicated gear systems require exacting performance of highquality lubricants. Today's synthetic technologies have been employed to provide maximum protection of critical components.

Complicated gear systems require exacting performance of highquality lubricants. Today's synthetic technologies have been employed to provide maximum protection of critical components.

Keeping packaging lines operational for a long service life is a key driver behind most packagingequipment designs. To maximize equipment uptime designers are specifying synthetic hydrocarbon

PAO ( polyalphaolefin) lubricating oils. Synthetic lubes last longer and perform at wider temperature ranges and heavier loads than their mineral-oilbasedcounterparts. They also can provide cleaner operating environments, help equipment consume less energy, and boost equipment service life.

Synthetic lubricants are also an attractive high-performance alternative in food-product packaging where containers must be filled and wrapped without product contamination. Because it's not always possible to use nonlubricated or selflubricating drive components, manufacturers are relying on synthetics to minimize contamination and extend service life while using less oil.

LUBE-FOR-LIFE GEARBOXES
Synthetic lubricants have also fueled a growing design concept to use bearings and gearbox drives that are prefilled with synthetic lubricants at the factory. These lube-for-life bearings and gearboxes can lower costs to equipment suppliers by reducing component failures under warranty, and to equipment owners by lowering the total cost of ownership.

The improvements of lube-for-life products have made them standard fare in packaging-machinery design, especially in the food-processing arena. Gearbox and bearing designers, for example, specify the coatings to fight corrosion initiated during equipment washdowns. The coatings have improved sealing properties at the points of contamination entrance, (i.e., shaft seals and cover gaskets), giving components extended life without the need for routine maintenance.

The most popular gearbox product available has been the single-reduction, right-angle worm speed reducers. The recommended interval to change the mineral oil of a typical single-reduction speed reducer is 2,500 hr. Even if only 15 min is required for a gearbox, annual oil changes could cost $40 to $60/ gearbox in labor alone, without prolonging the life of the equipment. The labor costs of oil changes for the use of a normally maintained gearbox could easily exceed the replacement cost of an expired lubefor-life gearbox.

The wide temperature range of synthetic PAO oils lets gearboxes be filled at the factory with one lubricant for almost all applications, except the most-severe temperature extremes. For example, the ISO 460 PAO oils used in worm-gear drives typically have a service temperature range from 30°F or lower to 300°F. The low-temperature performance of PAO oils is a natural property due to their negligible wax content. This eliminates the need for using lower-viscosity oils in most cold conditions, including most foodfreezer applications.

Thanks to high lubricity, PAOs also lower equipment energy consumption. Because a worm-gear drive is inherently inefficient, its operation cost may be higher than the initial cost of the drive, relative to other gearbox designs. Synthetic PAO oils can lower power consumption 10 to 17%, depending on drive input-tooutput ratios. The higher the ratio, the greater the efficiency gain. This results in significant cost savings when hundreds of worm-gear drives operate in a typical packaging plant.

Equally important is the synthetic PAO oil's resistance to oxidation compared to mineral oils as well as its 5 to 10 longer service life. Both properties boost equipment operating temperature capacity and lower horsepower consumption. And over time, the PAOs won't become more viscous, as happens with mineral oils, so horsepower consumption won't increase as they age.

The use of synthetic PAO oils means the useful life of the mechanical components and the lubricant will end at approximately the same time. Then the replacement of the entire unit is the most economical and logical choice.

CHAIN DRIVES
Packaging machines outfitted with roller chains that act as the prime mover in a drive system are also troublesome for traditional lubrication. That's particularly true for internal or intermediate drives that power transfer functions during packaging. The chains are often difficult to access for routine lubrication, and when common oils are used, excess oil tends to buildup. These buildups subsequently contaminate the packaging process by either dripping on to the finished products, attracting dirt and holding it in the oil, or slinging off due to the speed of the chain.

Many designers of packaging machines make use of automatic gravity-feed oilers. These single-point lubrication systems maintain a supply of oil in a polycarbonate reservoir. This design is often desirable in applications such as food-processing plants where there would be dangers of broken glass from older-style glass oilers. These units also serve as oil-level indicators, reserve reservoirs, or provide back-pressure relief on machine start-up. It's important to note that these applications are typically drip type and many don't have flow controls that regulate low enough to keep the amount of oil dispensed at satisfactory levels to control contamination from excess oil.

Use of PAO-based chain oils can contribute to much cleaner chain lubrication. These oils have a much longer life than mineral oils and therefore a much lower amount of PAO oil can adequately lubricate the chains. Simply using less lubricant alleviates the contamination of excess oil, without losing lubrication. Immediate cost savings are gleaned through reduced lubricant inventory, reduced energy consumption, and extended equipment life.

BEARINGS
The availability of synthetic PAO greases in either standard or H-1 food-grade formulations ( incidental food contact) provides improved life and performance for packaging-machinery designers. Many bearing manufacturers now provide bearings that are factory-filled with synthetic H-1 grease. When used in dry-foods applications it can extend the interval between relubrication by a factor of 5 to 10. This is a big benefit for machinery performance and contamination issues from excessive greasing practices.

Although the use of PAO as standard factory-fill grease for nonfood-grade bearings is not common, most manufacturers are familiar with PAO greases. The inherent properties of synthetic greases lets lubricant manufacturers boost lubricity without the use of solid lubricant additives such as molybdenum disulfide, graphite, and others. This makes for cleaner grease, further reducing contamination control issues.

BASE OIL COMPARISON
Type

Temperature
range (C)

Additive
acceptance
Viscosity
index
Plastic/rubber
compatibility
Ballpark
pricing ($/lb)
Mineral
-35 to 150
Excellent
Fair
Fair
< 5
Polyalkyline glyco (PAG)
-45 to 175
Excellent
Good
Good
< 5
PAO
-60 to 200
Good
Good
Very Good
5 to 10
Ester
-45 to 200
Good
Good
Fair
10 to 20
Silicone
-75 to 200
Poor
Excellent
Very Good
10 to 20
Fluorosilicone
-40 to 250
Poor
Very Good
Excellent
50 to 75
PFPE
-60 to 300
Poor
Fair
Excellent
75 to ?
Temperature range and viscosity index (the material's tendency to thin or thickin with temperature) are typically the most critical differentiators of base oils along with cost. At the high end of the PFPE range, use of the ultrapure linear materials, needed for applications with high-temperature extremes, vacuum, or oxidizer exposure can quickly translate into hundreds of dollars per pound. Combined with PFPE's density of nearly twice that of the other materials, costs can be significant, i.e., hundreds of dollars/lb.

MAKE CONTACT:
Dow Corning Molykote, Midland, Mich.
(989) 496-6000
www.molykote.com