Online monitor rewrites bearing lubrication practices

Three German organisations have developed a sensing system that monitors the state of grease in rolling bearings as they are running, thus giving advance warning of any problems and allowing the grease to be replaced only when necessary.
The online condition monitoring system – developed by Schaeffler in conjunction with Freudenberg and the lubricants specialist Klüber – is said to be ideal for monitoring critical plant and machinery located in remote or difficult-to-access areas, such as wind turbines and automated assembly lines.
It will allow the replacement of rolling bearing grease to be planned precisely into maintenance schedules. It detects any changes in the condition of the grease long before the bearings suffer any damage, and before vibration-based monitors reveal any potential damage (as shown in the graph above).

In preventive maintenance, the operating life of the grease is critical, especially if it is shorter than the expected life of the bearing. In this case, the bearings are normally re-lubricated halfway through the grease operating life. The disadvantage of this approach is that the grease is replaced without knowing anything about its condition.

For example, it may have been possible to continue using the grease for longer without affecting the performance of the bearing. Conversely, if the bearing has been damaged by the ingress of water or high temperatures, the grease should have been replaced earlier.

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