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Choosing the Right Viscosity for High Speed Greases


Release time:

2021-03-31

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"What is the typical base oil viscosity for grease used in high-speed bearings?"
The base oil composition of the grease may provide substantial separation between two surfaces that may be in contact. Therefore, choosing the right viscosity is very important. A common way to determine the appropriate viscosity is to first determine the speed factor, which is calculated from the bearing speed (revolutions per minute) multiplied by the pitch circle diameter (if the NDm method is used). As the bearing speed increases, the speed factor also increases. If the bearing speed and speed coefficient increase, the corresponding viscosity of the application will need to decrease.
As shown in the figure below, when approaching a speed coefficient of 600,000, a base oil viscosity of less than 70 centibase (40 degrees Celsius) is ideal. Since high-speed applications tend to have higher temperatures and therefore shorter grease life, the overall grease characteristics should be designed to withstand these conditions.