When using a filter cart with high-viscosity gear oil, it is helpful to completely drain the unit filter housing, hoses and replace the filter element. When filtering oils ISO VG 680 or higher, the temperature needs to be around 30C or warmer. At our cement plant the slowdown season is normally during the winter (Jan.-Mar.), making filtering of high-viscosity oils nearly impossible due to the temperature.

Because some oils can be extremely expensive, changing them is out of the question. I found that enclosing the work area with tarps and using a heater helps. If you are able to, completely shutdown and lockout the equipment, take the oil to the shop or another heated building and filter it there. Use a particle counter, and when you get the recommended ISO code, put it back in the machine. This helped my company; I hope it helps yours. (Jason Frankiewicz, Lube Tech, Holcim)

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I spend a considerable amount of time in plants helping companies develop a strategic plan to improve lubrication practices. I've visited almost every type of plant and industry, from pharmaceuticals to mining, steel to food processing, and while the challenges may be different, one question is a constant: How should we lubricate electric motors?

For those who believe that there's nothing exciting or controversial about lubrication, try initiating a discussion between a maintenance mechanic, an electrician and an operations manager about motor lubrication, then sit back and watch the sparks fly! For the operations manager, it's all about preventing downtime. Nothing is likely to invoke more passion than an issue that has caused a recent production outage.

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"What is a friction modifier? How do these modifiers help in industrial gear oil?"

Friction modifiers and mild antiwear agents are polar molecules added to lubricants for the purpose of minimizing light surface contacts (sliding and rolling) that may occur in a given machine design. These are also called boundary lubrication additives. Esters and natural and synthetic fatty acids, and some solid materials such as graphite and molybdenum disulfide, are used for these purposes.

These molecules have a polar end (head) and an oil-soluble end (tail). Once placed into service, the polar end of the molecule finds a metal surface and attaches itself. If one could see the orientation of the molecules on the surface, it would appear something like the fibers of a carpet, with each molecule stacked vertically beside the others.

As long at the frictional contact is light, these molecules provide a cushioning effect when one of the coated surfaces connects with another coated surface. If the contact is heavy, then the molecules are brushed off, eliminating any potential benefit of the additive.

When the machine designer anticipates more than light surface contact (from shock loading for instance) then the designer would select a stronger type of friction modifier characterized as an antiwear additive. Zinc dialkyldithiophosphate is a common antiwear agent. This type of additive literally reacts with the metal surface when the reaction energy (temperature) is high enough. The reaction layer provides sacrificial surface protection.

As the loading and metallic contact increase, the strength of additive and the strength of the reaction process increases. This leads to the use of sulphur-phosphorus based EP chemicals. The EP additives form organo-metallic salts on the loaded surfaces that serve as sacrificial films to protect against aggressive surface damage.

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