Views: 0 Author: Site Editor Publish Time: 2025-04-15 Origin: Site
Bearing, known as the machine's "joint", plays a vital role in the mechanical system. It is to achieve the host performance, functionality, and efficiency of the important guarantee. When other machine parts in the axis of each other to produce relative motion, bearings can be used to maintain the center of the shaft, play a role in supporting the role of the rotating body; in addition, bearings can be used to reduce the friction, to ensure that mechanical equipment, rotating parts of the smooth operation. There are thousands of types of bearings in the world, such as deep groove ball bearings, thrust ball bearings, self-aligning ball bearings, tapered roller bearings, cylindrical roller bearings, needle roller bearings, and so on. Different types of bearings have their own advantages and disadvantages and are suitable for different working environments.
According to the rolling elements, bearings can be classified into ball bearings and roller bearings. And ball bearings are the most common bearings and they are widely used in various fields due to their low friction and high efficiency. To help users know more about ball bearings knowledge, LNB Bearing will systematically introduce the ball bearing meaning, types and applications in detail, hoping to bring some help to bearing users.
Ball bearing is a kind of rolling bearing, relative to roller bearing. It mainly consists of four basic components: element (ball), inner ring, outer ring, and cage. The balls are mounted in the middle of the inner and outer steel rings and are capable of withstanding large loads. Industrial ball bearings usually meet the standards of AISI 52100, rolling bodies, inner and outer rings and other materials are usually made of high chromium steel, Rockwell hardness of about 61-65; while the material of the keeper has a variety of options, such as brass, carbon steel, aluminum alloy, chrome steel and other metal materials, as well as Teflon, PTEF, polymers and other non-metallic materials. The design of ball bearing makes it has the advantages of low friction and high speed, which are widely used in various mechanical equipment in industry and life.
The biggest difference between ball bearings and roller bearings is the difference in rolling bodies (balls and rollers). However, ball bearings themselves can be categorized into a variety of types according to different designs, uses, structural features, etc., and each type has its own unique design and application areas. The following are common ball bearing types:
Deep groove ball bearings are the most common type of ball bearings used in industry and household appliances. They have deep raceways on both the inner ring and outer ring and are capable of withstanding large radial loads as well as certain axial loads. Deep groove ball bearings are characterized by compact structure, high rotational speed, cost-effective and easy maintenance, etc., they are widely used in motors, automobiles, home appliances and other general-purpose scenarios.
Angular contact ball bearings' key feature is that they are designed with a certain angle (usually 15°~40°) between the inner and outer rings. The larger the contact angle, the greater the axial load carrying capacity, but the lower the rotational speed. And the smaller the contact angle is favorable for high speed operation. In practice, a single angular contact ball bearing can only withstand one-way axial load, usually need to be used in pairs to meet the two-way axial loading requirements. Widely used in machine tool spindle, gear box and other scenes.
Self-aligning ball bearings usually use spherical type outer ring raceway, with automatic self-aligning function, allowing axial deviation due to mounting error or due to shaft skewing, but the relative tilt of its inner and outer rings shall not exceed 3 degrees. Self-aligning ball bearings are suitable for the assembly precision requirements are not high, but the working conditions are poor or subject to vibration, bias load situation is more occasions, such as motors, textile machinery, long shaft drive, agricultural machinery.
Thrust ball bearings are specially designed to withstand axial load (unidirectional or bidirectional) limit speed is low. Its structure is simple, easy to install, low cost; but they are not suitable for bearing large radial load at the same time. Thrust ball bearings are commonly used to withstand high-speed axial load conditions, such as machine tools, lifting devices, vertical pumps and other applications.
Ball bearings are mostly made of high-quality, high-carbon chromium bearing steel (such as GCr15), which has the characteristics of high hardness, abrasion resistance, fatigue resistance, dimensional stability, and so on. In addition, in order to meet the application requirements in wet, corrosive environments, part of the ball bearing using stainless steel (such as AISI440C, 316, 304, etc.), stainless steel has excellent rust resistance, corrosion resistance, and good fatigue resistance.
Ceramic ball bearings are divided into full ceramic ball bearings and hybrid ceramic bearings. Full ceramic ball bearings are usually made of silicon nitride or zirconium oxide, etc., with high-temperature resistance, corrosion resistance, lightweight, high speed, and so on. Hybrid ceramic bearings are usually made of ceramic balls, while the inner and outer rings and cages are still made of bearing steel or stainless steel. This combination combines the low friction of ceramic ball and steel toughness, cost-effective.
In some special occasions, ball bearings may be made of high-performance engineering plastics, such as nylon (PA), polyacetal (POM), PEEK (polyether ether ketone), polytetrafluoroethylene (PTFE) and so on. These materials have the advantages of lightweight, self-lubricating, corrosion resistance, low friction, but bearing capacity and temperature resistance is poor.
Open type ball bearings have no sealing or dustproof device, thus they have low friction and are suitable for high speed, clean environments or higher lubrication requirements, which need regular maintenance and replenishment of lubricating grease. Open ball bearings have simple structure, low cost, and high speed, but easy to be polluted, and need regular maintenance, only for a clean, dry environment.
Sealed ball bearings have rubber seals on one side or both sides to form a closed space, and the rear code is usually RS (single side), or 2RS (double side). Sealed ball bearings are strong, can effectively block dust, moisture, and other pollutants into the bearing inside, and help to keep the bearing internal lubricant, and prolong service life, but in very high temperatures or high-speed conditions may have some effect on heat dissipation and friction.
Shielded ball bearings are equipped with steel dust caps on one side or both sides, and usually, the rear code of the bearing model is Z (single side), or ZZ (double side). A shielded ball bearing dustproof ability is strong, can block large particles of pollutants; has high-temperature resistance and durability, friction is small, suitable for medium and high speed. However, the water resistance is weak and cannot be supplemented with lubrication (factory pre-filled grease).
According to the different ways of oil supply, Oil lubrication can be subdivided into oil bath lubrication, drip oil lubrication, circulating oil lubrication, jet lubrication, oil mist lubrication, and so on. Oil-lubricated ball bearings have good heat dissipation and are suitable for middle and high speeds, high temperatures or high loads and other different conditions, but oil lubricated ball bearings need complex seals to prevent leakage, with high maintenance cost and the oil is easy to be contaminated.
Grease lubrication bearings use semi-solid grease as a lubricating medium, the grease is composed of base oil, thickener, and additives. It usually accounts for 30%~50% of the internal space of the bearing (excessive amount can easily lead to temperature rise). Grease-lubricated ball bearings have good adhesion and sealing, and can form a stable lubrication film inside the bearing, simple maintenance, dust and leakage prevention. However, it is easy to dump oil at high speed, and the limiting speed is lower than oil lubrication; grease is easy to oxidize and fail under high temperature.
Single-row ball bearing usually consists of a row of steel ball compositions, suitable for bearing small load.
Double row ball bearing is composed of two rows of steel balls, can withstand greater loads, suitable for heavy loads and high-speed applications.
Multi-row ball bearing is usually used for special applications, providing higher load carrying capacity and stability.
Generally speaking, the ball bearing dimensions are mainly composed of three main parameters: inner diameter, outer diameter, and width. Bearing measurement is usually listed as: inner diameter x outer diameter x width.
(1) Inner diameter (d):Refers to the bore diameter of the inner ring of the bearing, and usually matches the diameter of the rotating shaft.
(2) Outer diameter (D):Refers to the diameter of the outer ring of the bearing, determines the mounting space of the bearing.
(3) Width (B):Refers to the thickness of the bearing, which affects its load-carrying capacity and stability.
Bearing dimensions are usually given in millimeters or inches, and the two can be converted. However, the fact is that the vast majority of bearing suppliers and manufacturers offer bearing measurements in both metric and inch systems. Different types of bearings are available in different models, and the models correspond to different bearing dimensions (inside diameter, outside diameter, width). When selecting ball bearings, a reasonable selection of dimensions is essential to ensure the proper operation of the equipment.
Deep groove ball bearing sizes including 6000 series, 6200 series, 6300 series, 6400 series, 16002 series, 61800 series, 61900 series, etc.
Miniature ball bearing sizes including 600 series, MR series, etc.
Angular contact ball bearing sizes including 7000 series, S 70000 series, SN 70000 series, 3200 series, 3300 series, etc.
Self aligning ball bearing sizes including 1200 series, 2200 series, 1300 series, 2300 series, 10000K (KTN1, KM) + H0000 series, etc.
Thrust ball bearing sizes including 51000 series, 52000 series, etc.
The reason why ball bearings have a variety of sizes is determined by their wide range of application scenarios, technical needs, standardized design, and the historical accumulation of the industry development together. The following are the main factors leading to the diversification of ball bearing sizes:
In mechanical design, the mounting space of bearings is usually pre-determined. The space requirements of different mechanical equipment vary greatly, such as compact and small equipment need miniature bearings or thin-section bearings, while large industrial equipment needs thick-walled and large-sized bearings.
Different mechanical equipments also have different demands on load and speed. For example, light equipments as well as high-speed scenarios need small-sized bearings to bear light loads, reduce centrifugal force and increase speed, while low-speed heavy machines need large-sized bearings to disperse stress, bear heavy loads and have lower demands on speed.
In order to meet the requirements of various applications, bearing manufacturers have developed different series and sizes of bearings according to international standards (e.g. ISO standards, DIN standards, JIS standards, etc.). Standardized sizes and series allow designers to select the most appropriate bearing type for specific needs.
With the development of technology and process, bearings have also seen new changes with more materials such as all-ceramic bearings, ceramic hybrid bearings, plastic bearings and so on. Material and technological advances have also enriched the size series of bearings.
Ball bearings are widely used in the field of mechanical engineering due to their unique design and performance, and their core advantages lie in their simple structure, adaptability, and reliable performance. The following is a detailed analysis of its core advantages:
The rolling body (ball) and inner and outer rings of ball bearings are in rolling friction, compared with the sliding friction of plain bearings, the coefficient of friction is extremely low (about 0.001~0.005), the resistance during startup and operation is small, so the energy loss can be significantly reduced, and the efficiency of a mechanical system can be improved.
Ball bearings rolling bodies (steel balls) are regular in shape and can be arranged densely, under the same load capacity, the volume and weight are smaller than that of plain bearings or roller bearings, which is convenient for the lightweight design of mechanical systems.
Some ball bearings are designed to withstand both radial and axial loads (e.g. angular contact ball bearings, etc.), adapting to multi-directional forces and meeting diversified engineering needs.
Ball bearings have relatively simple structure, low lubrication requirements, high degree of standardization, easy to install, replace and maintain, reducing the complexity and cost of equipment maintenance.
Ball bearings have mature production process, low mass production cost, high cost performance, widely used in a variety of scenarios from ordinary machinery to high-end equipment.
(1) Motors & generators: such as motor rotors, gearboxes, gearboxes, inverter motors, wind generators, etc.
(2) Pumps & compressors: such as centrifugal pumps, high-pressure compression pumps, chemical pumps, etc.
(3) Machine tools: such as machine tool spindles, machining centers, numerical control machines, etc.
(4) Conveying equipment: such as conveyor belts, roller conveyors, etc.
(5) Construction and Construction Machinery: such as excavators, cranes, etc.
(1) Automotive industry: such as automobile engines and transmissions, steering systems, wheel hub units, etc.
(2) Railway and rail transportation: such as bogie suspension systems, high-speed rail traction motors, etc.
(3) Aerospace: such as aircraft landing gears, jet engines, drones, motors, etc.
(1) Consumer Electronics: such as smart phones, laptop computers, etc.
(2) Household appliances: such as air conditioners, washing machines, refrigerators, vacuum cleaners, etc.
(1) Medical machinery: such as dental drills, CT scanners, surgical robots, etc.
(2) Precision instruments: such as rotary axes of coordinate measuring machines (CMM), optical instruments (telescopes, microscopes), etc.
(1) Bicycle hubs, head bowls, bicycle pedals, etc.
(2) Roller skates and skateboard wheels, etc.
(3) Finger gyros, fishing wheels, etc.
(1) Office equipment: such as printers, fax machines, hard disk drives, etc.
(2) Robotics: such as joints for industrial robots, collaborative robots, etc.
(3) New energy and high-tech equipment: such as the spindle for wind turbines, semiconductor equipment, etc.
