What is the speed of precision crossed roller bearings and what are the factors affecting the speed?
Precision crossed roller bearings are designed for high rigidity, accuracy, and load-carrying capacity in a compact space, not for high speed. Their speed capability is generally considered low to moderate compared to other bearing types like deep groove or angular contact ball bearings.
A typical speed for a medium-sized (e.g., 100-200mm bore) crossed roller bearing under standard grease lubrication might be in the range of 500 to 2,000 RPM. However, this is a very rough estimate, and the actual permissible speed can be significantly higher or lower depending on numerous factors.
The most accurate way to define bearing speed is with a speed factor (dn or ndm value), which combines the bearing size and its rotational speed. For crossed roller bearings, this value is often limited to a range of 100,000 to 300,000, whereas high-speed ball bearings can exceed 1,000,000.
Precision Crossed Roller Bearings Speed
Instead of a simple RPM value, engineers use a speed factor to create a more universal metric that accounts for bearing size.
Speed Factor (dn Value)
n: Rotational Speed (in RPM)
d: Bearing Bore Diameter (in mm)
Sometimes dm (mean diameter) is used, which is (bore + outside diameter) / 2.
dn Value = d x n
Why is this used? For a given RPM, a larger bearing has rollers that travel at a much higher surface speed, generating more friction, heat, and centrifugal force. The dn value represents this peripheral velocity and is a better indicator of the bearing’s physical speed limit than RPM alone.
Typical dn Values for Crossed Roller Bearings:
Grease Lubrication: 70,000 to 150,000
Oil Lubrication (Oil Bath/Mist): 150,000 to 300,000+
Example:
A crossed roller bearing with a 100mm bore (d=100) is lubricated with grease.
Its maximum dn value from the catalog is 130,000.
Maximum allowable speed (n) = dn / d = 130,000 / 100 = 1,300 RPM.
If the same bearing were lubricated with circulating oil and had a dn limit of 250,000:
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More detailed information about precision crossed roller bearing speed can be found at:https://www.lynicebearings.com/a/blog/precision-crossed-roller-bearing-speed.html
