The Science Of Self-Lubricating Plain Bearings

Plain Bearings

Simplicity linear plain bearings exhibit real benefits, when compared to over other styles of linear bearings; such as the self-lubricating quality of the bearing’s Frelon liner, as well as the wiping action on the shaft which enables smooth linear motion. These capabilities allow a linear motion system to not only avoid catastrophic failure but to also lengthen the life of the system.

What Is Self-Lubrication?

Self-lubrication is characterized by the bearings ability to transfer microscopic amounts of material to the mating surface. This transfer process creates a film that provides lubrication and reduces friction over the length of the rail or shaft. Self-lubrication has several advantages over traditional lubricated bearings. Self-lubricating bearings save time and money on preventative maintenance, and require no hazardous waste from the lubricant, disposal, or cleanup to handle. Self-lubrication ensures frictional forces on the bearings and drive system remain consistent, and no added grease or oil is required that can attract contaminants that destroy conventional bearings.


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The Transfer Process

The transfer process is an ongoing dynamic function of the self-lubricating bearing that will continue throughout its operational life.

The first and most critical step in the process is the break-in period. This is when the initial transfer of material to the mating surface takes place. The amount of bearing material affected during the transfer is dependent upon multiple factors including the speed, load, and length of stroke, etc. for the application. Typically the initial transfer process will be accomplished in 50-100 strokes of continuous operation.

The secondary and ongoing phase of the transfer is where the self-lubrication is most effective.

What Makes A System Self-Lubricating?
  1. The lubrication is an integral component of the bearing material.
  2. The lubrication (typically oil or grease) is NOT added to the original bearing design.
  3. The lubrication will NOT breakdown and be ineffective over time (lubricant aging).
  4. The lubrication is consistently applied to the shaft surface.
  5. Additional components do not add cost to the overall system.

To truly be self-lubricating, a bearing system must do exactly what the name implies. It must provide its own lubrication throughout the life of the system and not have some external source facilitating lubrication for a period of time. It must be designed and manufactured into the bearing material from the beginning.