Basic Cognition and Daily Use Q&A of Bearings

1. What is the core function of a bearing? What are its main categories?
The core function of a bearing is to reduce friction between rotating or moving parts of machinery, minimize wear, accurately position components, and ensure stable and efficient mechanical operation. It can be divided into two categories based on friction properties: rolling bearings and sliding bearings. Rolling bearings transmit friction through rolling elements (steel balls, rollers, etc.) and are widely used, such as deep groove ball bearings and tapered roller bearings; sliding bearings reduce friction by forming an oil film between contact surfaces with a lubricating medium, suitable for heavy-load, low-speed scenarios, such as engine crankshaft bearings.

2. What are the main components of a rolling bearing and their respective functions?

A rolling bearing usually consists of four core components: inner ring, outer ring, rolling elements, and cage. The inner ring fits closely with the shaft and rotates with it; the outer ring fits with the bearing housing or shell and is generally fixed (can also rotate as needed); the rolling elements are core friction components that roll between the raceways of the inner and outer rings, converting sliding friction into rolling friction; the cage is used to separate rolling elements, avoid mutual collision and friction, ensure uniform distribution of rolling elements, and improve bearing operation stability.

3. What is the purpose of bearing lubrication? What are the common lubrication methods?

The core purpose of bearing lubrication is to reduce internal friction and wear, while playing roles in cooling, rust prevention, sealing, and vibration buffering to extend bearing service life. Common lubrication methods are divided into two types: grease lubrication and oil lubrication. Grease lubrication is suitable for low-speed, heavy-load, and well-sealed scenarios, such as motor bearings and household appliance bearings, with advantages of good sealing and no frequent replenishment; oil lubrication is suitable for high-speed, high-temperature scenarios, such as machine tool spindles and automotive transmission bearings, with stronger heat dissipation and effective reduction of friction loss at high temperatures.

4. What are the possible reasons for abnormal noise in bearings during use?

Abnormal noise in bearings is mostly an early warning of faults, with common reasons including: ① Insufficient lubrication: lack, deterioration, or mismatched type of grease/oil, leading to direct metal friction and noise; ② Improper installation: loose/tight fit between inner ring and shaft, outer ring and bearing housing, or inclination and collision during installation, resulting in uneven force during operation; ③ Bearing wear or damage: pitting, spalling, cracks on rolling elements or raceways, or deformed cage, causing irregular impact noise during operation; ④ Foreign matter intrusion: dust and metal debris entering the bearing, friction with rolling elements producing noise.

5. What is the difference between radial load and axial load on bearings? How to select corresponding bearings?

Radial load is the load perpendicular to the bearing axis, such as belt tension on the motor shaft and radial force in gear transmission; axial load is the load parallel to the bearing axis, such as thrust of centrifugal pump impellers and axial force generated by bevel gear transmission. When selecting bearings: deep groove ball bearings and cylindrical roller bearings can be used for radial load only; thrust ball bearings and thrust roller bearings for axial load only; angular contact ball bearings and tapered roller bearings for combined radial and axial loads.

6. What precautions should be taken when storing bearings?

Bearing storage requires moisture, dust, deformation, and corrosion prevention: ① Store in a dry, clean, and well-ventilated environment with temperature controlled at 5-25℃ and relative humidity not exceeding 65% to avoid rust caused by moisture; ② Place horizontally, avoid excessive stacking to prevent deformation of bottom bearings, and large bearings can be stored by hanging; ③ Keep the original packaging intact, no need to apply grease in advance for unopened bearings, and do a good job in sealing protection after opening to avoid foreign matter intrusion; ④ Keep away from acid-base, corrosive gases, and vibration sources to prevent surface corrosion or internal component displacement.