Bearing Failure: Lubrication


Lubrication is an integral part all machinery, in which anything that involve motion, such as bearings, need lubricant and lubrication activities. According to a variety of studies, improper lubrication tops the list for bearing failures where it accounts for 36%, followed by poor fitting at 16%, while 14% is led by contamination problems and reaching its natural lifespan constitutes 34%.

Image shows a table that features the different causes of bearing failures

It is safe to say that lubricant is the lifeblood of machineries. It is evident in the bar chart that lubrication plays a significant role in bearing systems. Industrial lubricants are substances used to reduce friction between two surfaces. Their most essential function is to prevent direct metal-to-metal contact between the rolling elements, raceways and cages of bearings, and also between other tools, finished parts, or industrial machinery. Lubricants also slow down wear and protect surfaces against corrosion through the removal of moisture. Despite the case, however, lubrication is often understated and many overlooked the importance that it has on equipment.

Improper lubrication practices and contamination are the main causes of premature bearing failures.

1. Contamination

Contamination happens when foreign particles such as dust and dirt enter into bearing lubricants or lubricant solutions, which can aggressively contaminate a bearing. It is especially harmful if a large amount of foreign materials enter into your equipment. As there is only little room for lubrication between a bearing, they can grid and scratch a machine's gears if lubrication is mishandled.There are several ways contaminants can enter the lubricant. Depending on how it is stored, transported, and filtered, foreign materials are likely to get in with improper handling practices. The most common factors are due to contaminated work areas, dirty work tools and hands in lubricants.

Illustration shows a contaminated bearing with a zoomed in image of irregular dents along the inner raceway of the bearings

     Symptoms of lubrication contamination

The simplest way to prevent this type of contamination is to make sure that the work areas are clean, as well as tools and hands could help to reduce contamination. Also, only open the original packaging of bearings when they are ready for installation. It is really important to check that they are sealed well as faulty seals can expose the bearings to contamination. Lastly, always remember to remove particles by filtering your lubricants  before applying them to bearings to reduce the risk of contamination.

2. Water Contamination/Corrosion

Water contamination is one of the largest factor in the reduction of bearing life and causes a lot of concern. As it can be a very costly problem,  it is essential that measures are taken to minimize this issue.

Illustration shows the corrosion of bearings with a zoomed in image of a bearing raceway with brown discoloration and three brown and rusty steel balls

     Symptoms of water contamination

Why does water cause corrosion to bearings?

Water molecule is made up of oxygen and hydrogen atoms, and here, the culprit is hydrogen. As a water molecule passes through the bearing load zone, the huge pressure frees the hydrogen ions. These ions then moves through the cracks into the metal below the raceway surface of the bearing through an amalgamation of force. This causes the surface to crack and result in premature failure.

In the case of water contamination, bearing failure does not happen instantaneously; instead, it may take a long time (up to several years) for bearing failure to even be noticeable. Regardless of the time it takes, the lifespan of the bearings is still being reduced greatly.

The easiest way to prevent water contamination is to keep water out, however, often times this can be overlooked as water is so common and the water levels are difficult to control that it is not easy to prevent water exposure. Another way is to apply additive chemicals which can help extend bearing life considerably as they have been found to have fatigue-prevention mechanisms.


3. Excessive or too little lubrication.

Moderation is the key to success, and this truly applies to lubrication. Excessive lubrication is another reason contributing to bearing failure.

Greasing bearings is necessary to maintain bearing life. However, the misuse of the grease gun can cause premature failure of the bearing and cancel out any benefits the grease had in protecting the bearing. One of the results caused by over greasing is heat buildup due to the fact that there is nowhere for heat to dissipate. The heat, along with the internal churning of the bearing will drive the grease to travel outside of the bearing. The grease will then break down and harden, preventing any grease to enter the surface.

Illustration shows a bruised bearing with a zoomed in image of a discolored brown and blue track along the raceway of the bearing

Symptoms of lubricant failure

As a result, the restricted lubricant flow and excessive temperature contribute to lubrication failure and  affect the ability of an asset to operate efficiently and this gives rise to higher operating cost. Ironically, an attempt to adequately lubricate a bearing by giving it a few extra pumps from a grease gun leads to its failure due to too little lubrication.

One of the easiest solution to this problem is to determine how much grease is expelled with every pump of the grease gun. A service technician can measure the number of ounces of grease that are discharged per pump with a scale.

Even the most miniscule contaminant can reduce a machine's performance and reliability, therefore, it is very important that proper lubrication methods are being implemented.

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SLS provides a range of lubricants and grease products, if you would like to know more information about these products or would like to know more about lubrication solutions, click below:

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At SLS, our SLSPRO technical and maintenance team are highly skilled on proper lubrication management. We provide technical support and service along with integrated solutions utilizing the latest lubrication management programs, for a proactive approach in prolonging your machine life and increasing productivity.

by SLS on February 27, 2017

categories: Bearing Maintenance, Product- Bearings

Written by SLS

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