Are greased applications causing unexpected downtime in your operation?

by John Geyer

Improper greasing practices can translate into significant financial loss due to downtime coupled with unplanned and expensive maintenance and repair costs. Because of this, it is critical to understand the importance of proper grease-related lubrication and maintenance practices in aggregate operations.

To practice proper grease application and lubrication procedures for equipment reliability, companies should consider three key causes of grease-related problems: improper grease selection (wrong product choice for the application), under-greasing (lack of lubrication), and over-greasing (too much lubrication).

Grease selection
Choosing the right grease and oil viscosity combination is the most important factor in practicing proper grease maintenance. OEM specifications for lubricating oils normally include viscosity at ambient operating temperature, additive requirements, base oil type, and even considerations for different environmental conditions. Grease specifications, however, often lack the necessary details to make a proper selection, leaving it up to the lubrication engineer to make assumptions for the application involved.

Due to the lack of specificity in many of these applications, it is important to learn how to properly select the right grease or combination of greases for individual application in the plant. Consider the following factors when selecting the most effective grease product for your specific needs:

§  Is the application located in an indoor or outdoor environment?

§  Are there high levels of contaminants? If so, what are they?

§  Is water a factor? If so, is the water directly sprayed at the bearing surfaces or is the bearing submerged or subjected to cascading water? Does the water contain other fluids such as solvents or coolants?

§  Are there external temperature extremes the grease must operate within, i.e. extreme heat or cold?

§  What are the operating temperatures of the bearing under load?

§  Are the equipment revolutions per minute (rpm) running at a low or high speed?

§  Does the grease have to pump through a centralized system? If so, how far and under what conditions?

§  Can the application be greased easily or are there safety concerns to get to the application when the equipment is running?

§  Have there been previous failures believed to be related to the incumbent lubricant used?

Extreme heavy-duty, high-load applications usually require grease with a higher oil viscosity. Often, these applications have much lower rpms and the grease needs to be able to maintain proper film thickness between the metal-to-metal surface contact points to prevent premature wear. High loads often squeeze lighter-viscosity oils out of the bearing and leave contact points vulnerably exposed.