Analysis of professional terminology for bearings

Bearings are the "joints" of the mechanical world, and their technical field has a rich and precise system of professional terminology. Mastering these terms is the foundation for understanding bearing selection, application, maintenance, and fault analysis. This article will systematically sort out and explain the key professional terms of bearings.

1、 Infrastructure and Type Terminology
Rolling Elements

Explanation: Rolling elements that transfer loads between raceways.

Common types:

Ball: Point contact, good high-speed performance, but relatively low load-bearing capacity.

Roller: Line contact, high load-bearing capacity, but low ultimate speed. Divided into cylindrical rollers, tapered rollers, self-aligning rollers, and needle rollers.

Rings

Explanation: A component that includes a raceway and serves as a support.

Classification:

Inner Ring: Usually installed on a shaft and rotates together with the shaft.

Outer Ring: Usually installed inside the bearing seat to provide support.

Cage/Retainer

Explanation: A component used to isolate and guide rolling elements, preventing them from colliding and rubbing against each other. The materials can be stamped steel, engineering plastics, brass, etc., which have a significant impact on the speed and noise of the bearings.

bearing type

Deep Groove Ball Bearing: The most common type of bearing that can withstand radial and certain bi-directional axial loads.

Angular Contact Ball Bearing: It can withstand combined loads (radial and axial), and the contact angle determines its ability to bear axial loads.

Tapered roller bearing: capable of withstanding large combined radial and axial loads, usually used in pairs.

Spherical Roller Bearing: With self centering function, it can compensate for misalignment caused by installation errors or shaft bending.

Thrust Bearing: A bearing specifically designed to withstand axial loads.

Plain Bearing: A bearing that operates on sliding friction without rolling elements, such as shaft sleeves or bushings.

2、 Performance and parameter terminology
Clearance

Explanation: The clearance inside the bearing (in non installed state) usually refers to radial clearance or axial clearance. The clearance size directly affects the operational accuracy, vibration, noise, and lifespan of the bearing. Divided into groups C1, C2, CN (standard), C3, C4, C5, etc., the larger the value, the larger the clearance.

Precision/Tolerance

Explanation: Refers to the manufacturing deviation range of bearing size and rotational accuracy. The common grades from low to high are P0 (ordinary grade), P6, P5, P4, P2 (ultra precision grade). The higher the level, the higher the size and rotation accuracy, the better the speed and stability, and the higher the cost.

Rated Life

Explanation: Based on classical life theory, the life that 90% of the same batch of bearings can achieve or exceed (usually measured in revolutions or working hours). Commonly used L10 lifespan representation.

Basic Dynamic Load Rating (C)

Explanation: A constant representing the load capacity of a bearing at a rated life of 1 million revolutions per minute. It is the most critical parameter for measuring the bearing capacity. The larger the value, the stronger the carrying capacity.

Basic Static Load Rating (C0)

Explanation: The maximum load that a bearing can withstand without permanent deformation at rest or extremely low speeds. Used to verify the safety of bearings in a stationary state.

Limiting Speed

Explanation: The maximum allowable working speed that a bearing can achieve under specific conditions depends on the type, size, accuracy, cage structure, and lubrication method of the bearing.

Contact Angle

Explanation: The angle between the force direction at the contact point between the rolling element and the raceway in a bearing and the radial plane. This angle determines the bearing's ability to withstand axial loads, and the larger the angle, the stronger the bearing's ability to withstand axial loads.

3、 Lubrication and Sealing Terminology
Lubricant

Grease Lubrication: The most commonly used method, which is simple and has a certain degree of sealing.

Oil Lubrication: Suitable for high-speed, high-temperature, or heat dissipation situations, including oil bath lubrication, drip lubrication, spray lubrication, etc.

Seal

Explanation: Components that prevent lubricant leakage and external contamination from entering.

Type:

Contact Seal: such as rubber sealing ring (RS), has good sealing effect, but high friction and temperature rise.

Non contact seal: such as dust cover (ZZ), with low friction, suitable for high speed, but slightly inferior sealing effect.

4、 Fault and maintenance terminology
Fatigue Spalling

Explanation: The phenomenon of material flake peeling on the surface of bearing raceway or rolling element due to alternating stress is a typical form of bearing life termination.

Smearing

Explanation: Due to poor lubrication or overload, the surface metal undergoes local fusion welding and tearing.

Fretting Corrosion

Explanation: Oxidative wear caused by small vibrations between mating interfaces is common on the mating surfaces of bearings and shafts or bearing seats, which can lead to loose mating.

Brinelli indentation

Explanation: Permanent indentation on the raceway caused by impact load or improper installation. The bearing indentation caused by the rotor not being locked during equipment transportation is also known as "transportation rust".

summary
The professional terminology of bearings is the cornerstone of their technical language, and a precise understanding of these terms is crucial for correct selection, installation, maintenance, and fault diagnosis. Whether it is the precision control of "clearance" and "tolerance", or the performance potential represented by "rated dynamic load", each term is associated with profound engineering theory and practice. Mastering this language is essential for effective communication with these precise mechanical components, ensuring stable and efficient operation of the mechanical system.