As an essential part of mechanical products, Bearing plays an important role in supporting the rotating shaft. According to the different friction properties of bearings, bearings are divided into rolling friction bearings (referred to as rolling bearings) and sliding friction bearings (referred to as sliding bearings). The two types of bearings have their own characteristics in structure and advantages and disadvantages in performance. When choosing bearings, they should be considered comprehensively according to the actual situation.

1. Comparison of structure and movement mode

The most obvious difference between rolling bearings and plain bearings is whether there is a rolling body.

Rolling bearings have rolling body (ball, cylindrical roller, tapered roller, needle), by its rotation to support the rotating shaft, so the contact part is a point, the more rolling body, the more contact points.

Plain bearings have no rolling body and rely on smooth surfaces to support the rotating shaft, so the contact part is a surface.

The difference between the two structures determines that the motion mode of rolling bearing is rolling, and the motion mode of sliding bearing is sliding, so the friction situation is completely different.

2. Comparison of carrying capacity

Generally speaking, due to the large bearing area of sliding bearing, its bearing capacity is generally higher than that of rolling bearing, and the ability of bearing impact load of rolling bearing is not high, but the fully liquid lubricated bearing can bear larger impact load due to the role of lubricating oil film in buffering and vibration absorption. When the speed is high, the centrifugal force of the rolling body in the rolling bearing increases, and its carrying capacity should be reduced (noise is easy to occur at high speed). For the dynamic pressure plain bearing, its bearing capacity increases with the increase of speed.

3. Comparison of friction coefficient and starting friction resistance

Under general working conditions, the friction coefficient of rolling bearing is lower than that of sliding bearing, and its value is relatively stable. However, the lubrication of sliding bearings is easily affected by external factors such as speed and vibration, and the friction coefficient varies widely.

At startup, the resistance of the sliding bearing is greater than that of the rolling bearing because the sliding bearing has not formed a stable oil film, but the starting friction resistance and working friction coefficient of the hydrostatic sliding bearing are very small.

4, applicable to the comparison of working speed

Rolling bearings are limited by the centrifugal force of the rolling body and the temperature rise of the bearing, the speed can not be too high, generally suitable for medium and low speed working state. Incomplete liquid lubricated bearings because of bearing heating and wear, the working speed can not be too high. The high-speed performance of fully liquid lubricated bearings is very good, especially when the hydrostatic sliding bearings use air as lubricant, its speed can reach 100000r/min

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