6. Grease Lubrication

To understand why greases are difficult to clean up once contaminated, first some background information on greases.

There are three components that form lubricating grease: oil, thickener and additives. The base oil and additive package are the major components in grease formulations, and as such, exert considerable influence on the behavior of the grease. The thickener is often referred to as a sponge that holds the lubricant.

Background information on grease

Function

The function of grease is to remain in contact with and lubricate moving surface without leaking out under the force of gravity, centrifugal action or being squeezed out under pressure.

Applications suitable for grease

Grease and oil are not interchangeable. Grease is used when it is not practical or convenient to use oil. Based on the properties of grease, the following list describes situations where grease is the lubricant of choice:

Where leakage and drippage is present
In hard-to-reach places where lubricant circulation is impractical
Where sealing is required in a high-contaminant environment (i.e. water and particles)
To protect metal surfaces from rust and corrosion
To lubricate machines that are operated intermittently
To suspend solid additives such as moly during slow-speed, high-load sliding conditions
For use in sealed-for-life applications such as electric motors
To lubricate under extreme or special operating conditions
To lubricate badly worn machines
Where noise reduction is important

As with oil, grease displays its own set of characteristics, that must be considered when being chosen for an application. Once the correct grease has been selected, it has to be applied properly with the right amount at the right frequency.

There are many different options for doing this. Ideally, a small amount should be applied more frequently. This is the advantage of using an automated system, such as single-point lubricators and centralised grease systems. The most common application system, though, is still the manual grease gun.

It is recommended to use techniques that avoid uncleanliness during storage and application: the lesser transfer of bulk grease the better. Use of cartridges or automatic lubrication systems are preferred.

While it may be one of the oldest lubricants known to man, grease continues to be a vital part of any lubrication program. That’s because the majority of bearings in a typical industrial plant are grease lubricated.

The importance of selecting the correct grease and applying it properly—both in amount and frequency—cannot be overstated. These activities are key factors in a world-class lubrication program. Getting them right is crucial in improving (and ensuring) the reliability of the equipment within your operations.