Balls or rollers are used for the rolling elements. Since the rolling elements are in point or line contact, the coefficient of friction is lower than in plain bearings with face contact. Since product dimensions are internationally standardized, there is compatibility between products made by different manufacturers. However, due to errors in the machining accuracy of the rolling elements, smooth rotation is not possible compared to plain bearings. Due to the large mounting outside diameter, it is difficult to select if the mounting space is limited. Depending on the shape of the rolling element, rolling bearings can be categorized into “ball bearings” and “roller bearings”. Sliding bearings have no rolling elements. Rolling bearings support the movement of the rotating shaft by means of the rolling elements, whereas plain bearings support the movement of the shaft by means of the sliding of the material. Compared with rolling bearings, they are less prone to damage because of their simpler structure. There are no international standards for plain bearings, and the diameter, length and thickness vary from manufacturer to manufacturer. The coefficient of friction is higher because there is face contact between the shaft and the bearing. In addition, the mounting space can be reduced because the mounting outside diameter is smaller than that of a rolling bearing with the same diameter.

1. Characteristics of ball bearings (ball bearings)
Ball bearings have the following 3 advantages.

Suitable for high speed rotation

Small loads on rotating power sources

Low cost for radial loads

The greatest advantage is that they are suitable for high speed rotation. Since the rolling element is a sphere, the contact area is small, and it is suitable for high-speed rotation.
Since the contact area is small, the load on the rotating power source can be reduced. In addition, ball bearings are cheaper than roller bearings for radial loads.

On the contrary, it has the following 2 disadvantages.

Not suitable for high loads

Expensive when used for axial loads

The disadvantage is that the rolling elements are in contact with each other at the apex of the balls, so they are not suitable for high loads. In addition, they are more expensive than roller bearings for thrust loads. When selecting for high loads, please choose roller bearings.

2. Characteristics of Roller Bearings (Roller Bearings)
Roller bearings have the following 2 advantages.

Suitable for high loads

Inexpensive when used for thrust loads

The greatest advantage is that they are suitable for high loads. Since the rolling elements are cylindrical, the contact area is larger. Therefore, it is suitable for high loads. In addition, they are cheaper than ball bearings for thrust loads.
On the contrary, its disadvantages are the following 3 points.

Not suitable for high speed rotation

High price for radial loads

High loads on rotating power sources

The biggest disadvantage is that it is not suitable for high-speed rotation because of the large contact area of the rolling elements. Moreover, the large contact area causes a large load on the rotating power source. In addition, they are more expensive than ball bearings for radial loads.
When selecting a bearing for high-speed rotating loads, choose ball bearings.
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