MRO Magazine

Don't kill your bearings with 'kindness'


August 24, 2010
By PEM Magazine

Question: We spend a lot of preventive maintenance (PM) time performing manual lubrication tasks, yet we still experience an inordinate amount of bearing failures. Do we have to increase our lubrication regime?

The most likely cause of your excessive bearing failures is over lubrication. “Killing a bearing with kindness” is a common phenomenon due to the mistaken belief that if a little lubrication is good then a lot of lubrication must be better. (Other common causes are incorrect PM issue frequency and mixing incompatible lubricants.)

Ideally, a bearing cavity should contain between 40 to 50-percent grease. Filling the cavity completely creates “churning,” where the bearing requires considerably more input energy to move the lubricant out of the way so the bearing can operate as designed. As a result, the internal friction causes the lubricant and bearing temperature to spike, prematurely reducing the life of both the bearing and lubricant.

Fight over-lubrication with a lubrication program. To ensure the right lubricant is always used, enter into a lubricant consolidation program with the supplier in which all bearing points and lubricant requirements are identified. This often resulting in the reduction of known lubricants in the plant by two-thirds. Afterward, all grease guns in the plant must be standardized, ensuring the output delivery and pressure is uniform. Then every bearing requirement and application frequency must be calculated according to size, speed, load and usage, and then added to the PM job task. (Most companies will require professional assistance with this.) Once completed, all maintainers will require training.


Alternatively, companies may choose to automate their lubrication practices with the application of multi-point automatic grease delivery systems, delivering a small amount of lubricant to the bearing point on an almost continual basis, resulting in a 300-percent increase in bearing life.

And the best part? Doing this, maintainers will reduce their asset’s energy requirement and reduce their carbon footprint.

For more information on implementing asset maintenance and energy management programs, contact Ken Bannister at (519) 469-9173 or by email at