The friction between the rotating shaft and the bearing seat in mechanical operation is referred to as rolling friction bearings, namely rolling bearings.
Bearings operating under sliding friction are known as sliding bearings.
Rolling Bearings: Rolling bearings use rolling elements (such as balls or rollers) to roll between the inner and outer rings, reducing friction. This design allows rolling bearings to withstand higher axial and radial loads while maintaining relatively low friction.
Sliding Bearings: Sliding bearings support and guide the shaft through direct sliding contact between surfaces. Typically, lubricating oil or grease is used to reduce friction and prevent premature wear of bearing components.
Below is a detailed explanation of the differences between rolling bearings and sliding bearings:
1. Structural Differences
Rolling bearings have a clear and structured design, consisting of four parts: inner ring, outer ring, rolling elements, and a cage. The inner ring, which cooperates with the central shaft and rotates together, is matched with the outer ring, which supports the entire bearing on the bearing base. The role of the rolling elements is facilitated by the cage, which evenly distributes them between the inner and outer rings. The performance and lifespan of rolling bearings are directly influenced by the shape, size, and quantity of the rolling elements. The cage's essential role includes evenly distributing the rolling elements and preventing them from falling off, while also facilitating lubrication during rotation. Rolling bearings are relatively easy to maintain, and the maintenance steps are convenient and quick. Therefore, medium working speeds are one of the conditions under which rolling bearings can work stably.
The structure of sliding bearings is less apparent. Compared to the structure of sliding bearings, the choice of materials is more critical for their production. Sliding bearings exhibit stability and low noise during rotation, thanks to the support of a sliding surface rather than a point, which increases the contact area and enhances stability. However, this contact surface also leads to some drawbacks, such as the need for additional power to overcome initial resistance when starting rotation.
Due to the larger contact area, sliding bearings require the application of lubricating oil during operation. The presence of lubricating oil forms a thin oil film between the sliding bearing and the sliding contact surface, effectively reducing friction and surface wear.
Sliding bearings can be applied in areas where applying lubricating oil is challenging or for routine maintenance. They are also more widely used in situations with heavy loads and low-speed operations.
2. Different Types of Movement
As the names suggest, sliding and rolling are the respective modes of operation for sliding bearings and rolling bearings, indicating different forms of friction during operation.
3. Different Friction Forces
Reducing friction between contact points is the main function of bearings. However, for rolling bearings, the size of the friction force is closely related to the structure and manufacturing level of sliding bearings. For sliding bearings, the influence of raw materials on the size of the friction force is more critical. In general, sliding bearings can be classified into metal and non-metal categories.
4. Different Advantages
High Speed Capability: Due to the design of rolling elements, rolling bearings can provide lower friction at high rotational speeds, making them suitable for applications requiring rapid rotation, such as mechanical transmission systems and motors.
High Load-Carrying Capacity: Roller bearings effectively distribute loads, making them suitable for high-load applications, such as automotive wheel hubs bearing the weight of vehicles.
Precision and Rigidity: Rolling bearings typically have high precision, offering good axial and radial rigidity. This makes them popular in applications that demand high accuracy and stability.
Maintainability: Roller bearings are generally relatively easy to maintain due to their design, allowing for easy replacement of rolling elements and extending bearing life.
Low Noise: Sliding bearings typically generate less noise due to lower sliding friction during operation. They are suitable for noise-sensitive applications, such as household appliances.
Simple Design: The design of sliding bearings is relatively simple, often composed of fewer components. This simplicity makes them suitable for special designs or applications with limited space.
Low Cost: Due to their simple structure, sliding bearings have relatively low manufacturing costs, making them suitable for applications with tight budgets.
Low-Speed and High Torque Applications: Sliding bearings are commonly used in low-speed rotation and high-torque applications, such as door hinges, skateboards, and hand-crank generators.