Introduction:

Deep groove ball bearings are components of modern industrial workshops and play a key role in many mechanical systems. From daily household appliances to advanced industrial equipment, deep groove ball bearings are used everywhere to provide equipment with smooth and reliable operation. Whether you’re an engineering professional or a hobbyist interested in mechanical principles, use this guide to learn about deep groove ball bearing construction, materials, and diverse applications and how to choose the right bearing product.

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What is a deep groove ball bearing?

Deep groove ball bearing is a kind of widely used rolling bearing, which is characterized by small frictional resistance, high speed, and ability to withstand radial load or radial and axial at the same time role of combined load. Deep groove ball bearings are usually used in small power motors, automobile and tractor gearboxes, machine tool gearboxes, general machines and tools.

Definitions and basic structure

Deep groove ball bearing composition is a widely used rolling bearing, and its basic structure consists of an outer ring, an inner ring, a group of steel balls and a group of cage compositions. Deep groove ball bearing is characterized by small frictional resistance and high speed, can withstand radial or radial-axial at the same time as the joint load, and can also be used to bear the axial load on the machine parts.

Working Principle

Deep groove ball bearings are mainly subjected to radial loads but can also be subjected to radial and axial loads. When deep groove ball bearings are subjected to radial loads only, the contact angle is zero. A deep groove ball bearing with a large radial clearance can withstand a large axial load. Deep groove ball bearings have a very low coefficient of friction and high limiting speeds, making them suitable for high or even very high-speed operation. They are very durable and do not require frequent maintenance.

Types of deep groove ball bearings

There are various types of deep groove ball bearings, mainly including the following:

Open deep groove ball bearings: These bearings are mainly used to withstand radial loads but can also withstand smaller axial loads. Their axial displacement is limited to the range of axial clearance, and the inner ring can be tilted relative to the outer ring.

Deep groove ball bearings with dust cover: including single-sided and double-sided bearings with dust cover, there is a gap between the dust cover and the inner ring retaining edge. The limiting rotational speed is the same as that of the open deep groove ball bearings, but the seal is better.

Deep groove ball bearings with seals: including single-sided bearings with seals and double-sided bearings with seals. Seals and the inner ring retaining edge are contact or non-contact. The contact sealing effect is good, but the friction resistance and speed limit are low.

Deep-groove ball bearings with stop grooves in the outer ring: This type of bearing can simplify the axial positioning of the bearing in the housing bore after the stop ring is fitted.

Common materials (steel, ceramics, etc.)

Commonly used materials for deep groove ball bearings include the following:

Chromium steel: Chromium steel is one of the most commonly used materials for deep groove ball bearings, which has excellent wear and high-temperature resistance and is suitable for high-speed rotation and high-load mechanical equipment.

STAINLESS STEEL: Stainless steel is highly resistant to corrosion and high temperatures and is commonly used in machinery and equipment in the food and medical industries, especially in wet and corrosive environments.

High-carbon chromium-molybdenum steel: This high-strength alloy steel, with high strength and toughness, is suitable for high loads and high-speed mechanical equipment, such as bearing components in automotive, aerospace and other fields.

Ceramics: Ceramic materials such as alumina ceramics and silicon nitride oxide ceramics are characterized by high strength, hardness, and low coefficient of friction, making them suitable for high-speed, high-temperature, and high-precision application scenarios.

Plastic: Plastic bearings such as PEEK, PI, and other engineering plastics are suitable for applications with special weight and cost requirements.

Properties and benefits of each material

Carbon and Bearing Steels: Carbon and bearing steels (e.g., GCR15 or AISI ) are commonly used to manufacture rings and balls for deep groove ball bearings. These materials are heat-treated to provide excellent strength and wear resistance and are suitable for high load and high-speed conditions.

Stainless Steel: Stainless steel materials have excellent corrosion resistance and are commonly used in wet or chemically corrosive environments. Stainless steel deep groove ball bearings can extend service life and reduce maintenance requirements.

Plastics and Ceramics: Plastic and ceramic materials such as alumina ceramics and silicon nitride ceramics are characterized by high strength, high hardness and low coefficient of friction, making them suitable for high-speed, high-temperature and high-precision application scenarios. Plastic materials are typically used in light-duty applications, while ceramic materials are suitable for extreme environments.

Accuracy class and tolerance class

Bearing precision refers to the size of the processing error in bearing manufacturing and is an important indicator of bearing performance. It reflects the degree of accuracy of the bearing in terms of geometry, size, rotational accuracy and so on. According to ISO standards, bearing accuracy can be divided into grade and tolerance systems.

Bearing tolerance refers to the bearing manufacturing size and design size of the difference between the range, which allows the bearing size, shape and position within a certain range of change. The tolerance size directly affects the rotational accuracy, load-carrying capacity and bearing service life. Bearing tolerance is usually divided into positive tolerance and negative tolerance; positive tolerance refers to the bearing manufacturing size being larger than the design size of the deviation, and negative tolerance refers to the manufacturing size being smaller than the design size of the deviation.

Explanation of different accuracy classes

• ISO accuracy classes (P0, P6, P5, P4, P2)

ISO accuracy classes (P0, P6, P5, P4, P2) are accuracy classification standards developed by the International Organization for Standardization (ISO) for bearings and other rotating machinery components. These grades reflect the degree of accuracy of bearings in terms of geometry, dimensions, rotational accuracy, etc., and are, in descending order, P0, P6, P5, P4, P2.

• ABEC rating system

The ABEC rating system is a set of standards developed by the American Bearing Manufacturers Association (ABMA) under the Association/Committee for Annular Bearing Engineering (ABEC) for evaluating bearing tolerance classes. This system is primarily geared toward precision bearings, including deep groove ball bearings. It differentiates between different accuracy classes using numerical numbers (1 to 9), with higher numbers indicating higher bearing accuracy.

• Comparison between ISO and ABEC systems

Both the ISO and ABEC systems are valid standards for evaluating the accuracy of bearings. Still, they differ regarding the organization that developed them, their application’s scope, their grades’ classification, and how they are numbered. Designated organization: The International Organization for Standardization formulated the ISO system, and the American Bearing Manufacturers Association formulated the ABEC system. I. Scope of application: ISO accuracy grades are widely used for various rolling bearings. Although initially designed for skateboard shoe bearings, the ABEC system has gradually been applied to evaluate other precision bearings, especially in the U.S. market. Second, the grade division and numbering method: ISO system, ISO precision grade is usually expressed in P level, such as P0, P6, P5, P4, P2, etc. The smaller the number, the narrower the tolerance band and the higher the precision. Third, the ABEC rating system uses digital numbering to indicate the accuracy level; the larger the number, the narrower the tolerance band, and the higher the accuracy. The opposite of the ISO system of numbering. Fourth, the accuracy characteristics: ISO system, ISO accuracy grade from P0 to P2 gradually improve, each grade corresponds to a certain tolerance band range. The ABEC rating system from ABEC-1 to ABEC-9 progressively improves the accuracy requirements.

Impact on performance and applications

• Running accuracy

Running accuracy refers to the stability and accuracy of bearings in rotary motion; it is affected by the joint influence of precision and tolerance; high precision and small tolerance bearings can ensure higher running accuracy.

• Noise and vibration levels

High-precision bearings usually have lower noise levels and can maintain lower vibration levels during operation. When the tolerance is too large, the precision of the fit between the rolling elements, inner and outer rings and other parts of the bearing is reduced, which can easily lead to uneven clearance and shock vibration, thus increasing the noise; too large or too small a tolerance may lead to unstable vibration of the bearing during operation.

• Heat generation

High-precision bearings usually require smaller tolerance ranges to ensure the stability of their performance; tolerances that are too small may increase the difficulty and cost of manufacturing or lead to excessive assembly stress and accelerate bearing wear and damage. Therefore, when selecting precision and tolerance, they must be considered to balance the bearing’s performance, cost, and service life, among other factors.

• Bearing life

High-precision bearings and proper tolerance ranges can extend bearing life.

Deep groove ball bearing applications

Deep groove ball bearings are characterized by simple structure, high speed, and small coefficient of friction, and can withstand radial load or radial and axial simultaneously. The role of joint load in the industrial field is mainly used in the automotive and power industries.

Common Uses in Vehicles

Deep groove ball bearings in the automobile industry are commonly used in automobile and motorcycle wheel bearings, transmission bearings, and other parts. They are used to bear the vehicle’s weight and the force of various road conditions to ensure the smooth running of the car. In the automobile, the engine, transmission, and other key components, at the same time, can provide normal operation and transmission to improve the car’s overall performance. Deep groove ball bearings in motors and generators can support not only rotating parts, reduce friction loss, and withstand load capacity but also have high precision, heat, high-speed resistance, easy installation and maintenance, etc. These advantages make them one of the indispensable key components in motors and generators. As a key component in heavy machinery, deep groove ball bearings can support rotating parts, reduce friction and wear, withstand heavy loads and high rotational speeds, improve the precision and reliability of machinery, and adapt to harsh working environments.

Specific requirements and challenges

• Size limitations: Deep groove ball bearings have limited mounting space, and their size selection is usually determined by mechanical design or design constraints. The main dimension table of the bearings is compiled according to the international scale bore size, so special attention needs to be paid to matching and selecting dimensions in practical applications.
• Speed and lubrication: The speed of deep groove ball bearings depends on factors such as their type, size, accuracy, type of cage, load, lubrication method and cooling method. The choice of lubrication method has an important influence on the speed and life of the bearing; usually, deep groove ball bearings are suitable for high-speed running occasions.
• Dimensional tolerances and rotational accuracy: The dimensional accuracy and rotational accuracy of deep groove ball bearings are according to ISO and JIS standards. For machinery requiring high precision and high-speed operation, it is recommended to use bearings with grade 5 or higher accuracy.
• Axial load: Deep groove ball bearings have certain limitations when bearing axial load. Usually, deep groove ball bearings can also withstand a certain amount of axial load after bearing a certain radial load, but the axial load is too large may shorten the service life of the bearings.

Deep groove ball bearing maintenance and troubleshooting

Deep groove ball bearings daily maintenance techniques can effectively maintain the performance and life of deep groove ball bearings mainly through regular inspection, cleaning and maintenance, selecting the right lubricant, adding the right amount of lubricant and paying attention to avoiding overload, shock and vibration.

Deep groove ball bearings can effectively reduce the failure rate of deep groove ball bearings by formulating a maintenance plan, including determining the maintenance cycle, specifying the maintenance content (cleaning, lubrication, inspection, recording), etc.; adopting condition monitoring technology, including vibration monitoring, temperature detection, sound detection, etc.; and implementing predictive maintenance methodology, including the collection of inspection data and the establishment of a life prediction model for bearings, and other methods.

Common failures of deep groove ball bearings include fatigue spalling, wear, rust, and cage damage. The noise and vibration problem can be solved by choosing bearings with high precision grade and low noise characteristics, adopting the correct lubrication method, etc. The causes of overheating of deep groove ball bearings include poor lubrication, seizing inner and outer rings, incorrect mounting, etc. They can be solved by timely refuelling or replacing lubricants, timely cleaning or replacing bearings and reasonably designing bearing loads.

Deep groove ball bearing mounting guide

Bearing mounting should be based on the bearing structure, size and bearing parts with the nature of the determination; the pressure should be added directly to the tightly fitted to the end of the ring surface and shall not be through the rolling body to pass the pressure. Installation methods mainly include press fit, heating fit and cold installation. Installation should pay attention to keeping clean, avoiding violent installation, choosing the right tool and so on.

Installation

Cold press installation method：

The deep groove ball bearing cold pressure mounting method can be understood as in the bearing or mating parts after cooling treatment, the use of pressure will be mounted in place of the process; this method is suitable for small and medium-sized deep groove ball bearings, when the bearing and the shaft or the bearing housing of the fit between the tighter, the use of cold pressure mounting method can reduce the difficulty of mounting, at the same time should pay attention to the need for strict control of the cooling temperature and time, in order to avoid the bearings to cause unnecessary damage.

Heat installation method：

The hot mounting method for deep groove ball bearings is suitable for bearings with larger dimensions or larger overload. The main steps are heating the bearing, rapid mounting, cooling and fastening. Attention should be paid to controlling the heating temperature during the mounting process, protecting the bearings during the mounting process, and checking whether the bearings are mounted in place after the mounting is completed.

Maintenance and care suggestions

1. Selection of suitable lubricant: Choose a suitable lubricant or grease according to the bearing’s environment and operating conditions, and check and replace the lubricant regularly.
2. Bearing cleaning: Bearings are susceptible to dust, moisture and other pollutants in the working environment, which can accelerate wear and corrosion and reduce their lifespan. Bearings should be cleaned with appropriate detergents and tools and then wiped dry with a clean cotton cloth or paper towel.
3. Avoid overloading: Check the bearings’ operation regularly to ensure that they are operating within the rated load. If any abnormal vibration, noise or temperature rise is found in the bearings, they should be stopped, inspected and dealt with in time.
4. Reasonable storage: The bearings should be cleaned and lubricated before storage and protected with a rust inhibitor. They should be stored in a dry, clean and non-corrosive gas environment, avoiding direct sunlight and high temperatures. Regularly check the storage conditions and status of the bearings to ensure they are in good condition.

How to choose a deep groove ball bearing manufacturer

There are many bearing manufacturers worldwide, and to choose the right deep groove ball supplier, you need to compare and select carefully. The following list some of the world’s more well-known bearing manufacturers.

Criteria for evaluating bearing manufacturers

1. Product quality and precision

Product quality and precision are key factors for evaluating deep groove ball-bearing manufacturers. Product quality mainly includes raw material quality, manufacturing process, quality control system and product certification and standards; precision mainly includes dimensional, rotational, and accuracy levels. By examining product quality and precision, we can specifically understand deep groove ball manufacturers’ production capacity and product quality level.

2. Technological innovation and R&D capabilities

Technological innovation and R&D capability are the key factors for assessing deep groove ball-bearing manufacturers. Technological innovation includes applying new materials, manufacturing process innovation, lubrication and sealing technology, etc.; R&D capability includes the R&D team and investment, R&D results and patents, customized R&D capabilities and industry-university-research cooperation. Through the assessment of technological innovation and R&D capability, the strength level of deep groove ball manufacturers can be fully understood.

3. Industry reputation and customer reviews

Industry reputation and customer evaluation are key to evaluating deep groove ball-bearing manufacturers. By assessing these two factors, it is possible to get a comprehensive picture of the manufacturer’s market position, product quality, service level and customer satisfaction.

Top brands and their specialities

1. SKF: SKF Group is a leading global supplier of a wide range of bearing products, including deep groove ball bearings, which are widely used in many industrial fields and also occupy an important position in the deep groove ball-bearing market.
2. Germany FAG/INA: FAG/INA, part of the Schaeffler Group, is a global leader in the production of rolling bearings and linear motion products with industry-leading quality and performance.
3. NSK: NSK is Japan’s earlier design and production of bearings manufacturers; the company has now expanded to automotive parts, precision machinery products, electronic applications, and other fields and is the world’s leading bearing manufacturer.
4. TIMKEN Timken: Founded in in the United States, TIMKEN Timken Company is the world’s leading supplier of high-quality anti-friction bearings, related products and services and alloy steel and steel components.
5. NTN: NTN is one of the world’s comprehensive precision machinery manufacturers, founded in Japan. Its products are widely used in orbit satellites, aviation, railway and automobile, office equipment and food machinery and other industrial sectors in various fields. It has an important position in the deep groove ball bearing market; the quality of its products and technical level are at the forefront of the industry.
6. KOYO bearings: KOYO bearings are the brand of Jettaigt (China) Investment Co., Ltd, which started in Japan in . The company enjoys an important position in the field of bearings, automobile power driving and mechanical equipment.
7. Wafangdian Bearing Group Co., Ltd (ZWZ Waxial): Wafangdian Bearing Group is the birthplace of China’s bearing industry; the company produces bearings for major technical equipment, rail transportation bearings, automotive bearings, military equipment bearings and other products.
8. Harbin Bearing Manufacturing Co., Ltd (HRB) is a well-known bearing manufacturer in China. The company is mainly engaged in the production of railroad bus speeding bearings, precision machine tool spindle bearings, and mining metallurgy bearings.
9. Renben Group Co., Ltd (C&U Renben) is one of the leading enterprises in China’s bearing industry; the company mainly produces bearings and, at the same time, is involved in commercial supermarkets, electromechanical trade and other sectors.
10. TFL Bearing Co., Ltd: Located in Jinan City, Shandong Province, China, the company is a bearing-based, research and development, production and sales as one of the precision bearing manufacturing enterprises to provide various customers with bearing products, covering a variety of industrial applications.

Frequently Asked Questions

1. How do single-row deep groove ball bearings differ from double-row bearings?

• Single-row deep groove ball bearings: These kinds of bearings only have deep grooves on one side of the rolling body and cage. The structure is relatively simple. This design makes single-row ball bearings have low friction and heat generation in high-speed operation, making them suitable for low-load and high-speed operation occasions. However, its bearing capacity is relatively weak and unsuitable for large radial loads.
• Double-row deep groove ball bearings: These bearings have deep grooves and rolling elements on both sides, which complicate the structure. Therefore, double-row ball bearings can withstand higher radial loads and are suitable for low—or medium-speed operation and high-load occasions. However, they may produce higher friction and heat generation at high-speed operation.

2. Is the durability of miniature bearings comparable to that of standard-sized bearings?

Miniature bearings are designed and manufactured with special applications in mind, so their durability can be comparable to that of standard-sized bearings when properly used and maintained. However, due to size constraints, they may be more susceptible to overloading or contamination and, therefore, may require more frequent inspection and maintenance in some applications.

3. What are the advantages of deep groove ball bearings in high-speed applications?

The advantages of deep groove ball bearings in high-speed applications are mainly due to their design construction to withstand radial and axial loads, low friction, and low resistance to motion. Deep groove ball bearings also offer durability and low maintenance requirements for high-speed operation.

4. What are common mistakes when installing deep groove ball bearings?

I. Improper installation method; II. Too tight or too loose fit; III. Damage caused by knocking installation; IV. Improper heating installation; V. Improper lubrication; VI. Improper storage and custody; VII. Wrong installation sequence and steps.

5. How do I choose the right accuracy class for my deep groove ball-bearing application?

Selecting the correct accuracy class requires comprehensive consideration of a number of factors, mainly including clarifying the requirements for use and the working environment, understanding the meaning of the accuracy class, selecting the appropriate accuracy class according to the needs, considering the economic benefits, and referring to professional advice.

Deep groove ball bearings

Deep groove ball bearings are available in single row and double row designs.

Single row bearings are particularly suitable where:

• high and very high speeds are required
• the bearing arrangement must be operated with very low friction
• very low running noise is required, without reducing the speed, load carrying capacity and operating life of the bearing (Generation C) ➤ link
• high demands are made on the sealing of the bearing, without increasing heat generation or limiting the speed (Generation C) ➤ section
• the bearing position is to be designed particularly economically

Double row bearings can be considered for bearing arrangements where:

• the load carrying capacity of single row deep groove ball bearings is no longer sufficient ➤ link
• axial loads in both directions and/or tilting moments must be supported in addition to radial loads ➤ link
• a high load carrying capacity is required and the design envelope available in a radial and axial direction is relatively small

Bearing design

Design variants

Single row deep groove ball bearings are available as:

• standard bearings ➤ Figure
• bearings of Generation C ➤ Figure and ➤ Figure
• matched bearing sets ➤ Figure
• corrosion-resistant bearings ➤ link

Double row deep groove ball bearings are available as:

• standard bearings ➤ Figure

Single row deep groove ball bearings are also available in many other designs and sizes, as well as for specific applications, by agreement. Corrosion-resistant bearings TPI 64, larger catalogue bearings GL 1.

Standard bearings

Proven and versatile bearings with high market shares

Single row deep groove ball bearings are self-retaining units, which are part of the group of radial ball bearings. The solid outer and inner rings have deep raceway grooves, with shoulders which are not generally interrupted by filling slots ➤ Figure. Solid cages made from polyamide PA66 or brass, and sheet metal cages made from steel or brass, are used as standard cages ➤ Table. The bearings are open or sealed. Due to the manufacturing processes used, open bearings, which are also available as sealed versions, can have turned recesses in the outer and inner ring for sealing washers or sealing shields.

Single row deep groove ball bearings are particularly versatile, robust in operation, easy to maintain and very economical. Due to their significant advantages, they are the most widely used rolling bearings worldwide. As a result, Schaeffler also manufactures these bearings in a large number of sizes and designs.

Deep groove ball bearings of Generation C

Gen. C = optimised design of standard bearings

Deep groove ball bearings of Generation C correspond in their structure to single row standard deep groove ball bearings, but are specially optimised in relation to:

• significantly quieter running
• even more effective sealing
• a further reduction in the already very low frictional torque

Measures to reduce noise

Schaeffler has analysed the causes of noise generation in deep groove ball bearings using the most advanced methods. On the basis of the findings obtained from these analyses:

• The surface of the raceways has been improved
• The ball quality has been increased
• Osculation has been optimised
• The production tolerances have been reduced
• Deep groove ball bearings have been fitted with new riveted cages made from steel

The result of this is a noise reduction in Generation C bearings over comparable standard deep groove ball bearings.

Gen. C = particularly high sealing effect due to new and improved seals

The quality of the seal, together with the rating life, has a considerable influence on the efficiency of a rolling bearing. As a result, the seal must not only protect the running system reliably against contamination, the ingress of moisture and the loss of grease, but also ensure that the total frictional torque and heat generation in the bearing remains low despite the high sealing action. The new sealing shields, non-contact seals and contact seals of Generation C deep groove ball bearings (suffixes Z, BRS, HRS, ELS), demonstrate the success of Schaeffler in performing this difficult technical step effectively ➤ Figure and ➤ Figure. Description of sealing shields and seals ➤ section.

Gen. C = technical and economical advantages of very low friction

Electric motors, electrical machinery, washing machines, ventilators and electric tools are the preferred application areas of single row deep groove ball bearings. However, in order to facilitate further increases in the efficiency of these motors, machines and tools, the power loss occurring in the bearing arrangements must be reduced. The above-mentioned measures for reducing noise also resulted, for example, in an approximate reduction in friction of 35%, giving the designer a range of application-specific advantages:

• lower heat generation
• a longer grease operating life
• higher possible speeds
• a longer bearing operating life
• a reduced energy consumption
• lower energy costs
• lower overall cost of the bearing position

Gen. C = a leading player among single row deep groove ball bearings

In summary, this means that, in addition to their technical advantages, bearing positions with deep groove ball bearings of Generation C are also considerably more economical than bearing arrangements with single row standard deep groove ball bearings. Generation C is available in series 60, 62 and 63.

Matched bearing sets

Bearing sets in O, X or tandem arrangements

If the load carrying capacity of a single bearing is not sufficient, or the shaft is to be guided axially in both directions with a defined clearance, single row standard deep groove ball bearings are also available as matched bearing sets ➤ Figure.

As the arrangement of the bearing pairs is specific to the application, Schaeffler supplies bearing sets by agreement.

Corrosion-resistant bearings

Wide product range

Corrosion-resistant bearings are suitable where particular requirements for anti-corrosion protection are present. Schaeffler supplies deep groove ball bearings of this type in open and sealed designs.

The load carrying capacity for bearings made from corrosion-resistant steel is slightly lower than for bearings made from rolling bearing steel.

The range of these bearings and housings is described in detail in Technical Product Information TPI 64.

Double row deep groove ball bearings

Double row deep groove ball bearings of series 42 and 43 correspond in their structure and function to single row deep groove ball bearings arranged in pairs ➤ Figure. They have deep raceway grooves in the outer ring and a narrow osculation between the raceway grooves and balls. However, they are slightly narrower than two single row deep groove ball bearings of the series 62 and 63 with the same bore and outside diameter.

Double row deep groove ball bearing,
open

Fr = radial load

Fa = axial load

Load carrying capacity

Single row deep groove ball bearings – radial load carrying capacity

Suitable for predominantly radial loads

The balls are in contact with the raceways at one point only. Under purely radial load, the contact points between the rolling elements and raceways lie at the centre of the raceway. As a result, the connection between the contact points passes through the radial plane, i.e. the optimum load direction is a pure radial load ➤ Figure.

Larger bearing cross-sections permit higher loads

The load carrying capacity is dependent on the bearing series. As a result, deep groove ball bearings of series 618 and 619, with their smaller bearing cross-sections, cannot support loads as high as series 60, 62 and 63 – with identical dimensions relative to bore diameter d – with their larger cross-sections ➤ Figure.

Single row deep groove ball bearings – axial load carrying capacity

Capable of supporting axial loads in both directions

Due to the deep raceway grooves in the bearing rings and the narrow osculation between the raceway grooves and balls, single row deep groove ball bearings can support axial loads in both directions ➤ Figure. The axial load carrying capacity is dependent, for example, on the bearing size, the internal construction and the operating clearance. If the axial load is too high, however, this can increase the running noise and considerably reduce the operating life of the bearings.

If there is any uncertainty regarding the axial load carrying capacity of the bearings, please consult Schaeffler.

Double row deep groove ball bearings

Considerably higher load carrying capacity than single row bearings

Due to the larger number of rolling elements, double row deep groove ball bearings can be subjected to greater loads than single row deep groove ball bearings. They can replace two single row deep groove ball bearings if a smaller design envelope width is required.

Also suitable for tilting moment loads

Double row deep groove ball bearings can also support tilting moment loads in addition to radial and axial loads ➤ Figure. They are therefore suitable for particularly short shafts that are supported by only one bearing.

Compensation of angular misalignments

Single row deep groove ball bearings – permissible adjustment angle

The adjustment angle is dependent on the magnitude of the load

Single row deep groove ball bearings are only suitable for compensating static angular misalignments to a very limited extent. As a result, the bearing positions must be well aligned. Misalignments shorten the operating life, as they place an additional strain on the bearing. In order to keep these loads at a low level, only small adjustment angles are permissible – dependent on the load – for deep groove ball bearings ➤ Table.

Permissible adjustment angles

Double row deep groove ball bearings

Due to their internal construction, double row deep groove ball bearings do not have an angular adjustment facility. When using these bearings, therefore, misalignments are not permissible.

Lubrication

Single row deep groove ball bearings

Greased bearings are maintenance-free

Deep groove ball bearings sealed on both sides are lubricated with a high quality lithium soap grease with a mineral oil base, which has good anti‑corrosion characteristics. The grease filling is measured so that it is sufficient for the entire life of the bearing. As a result, these bearings are generally maintenance-free.

Do not wash greased bearings out prior to mounting. If mounting is carried out using thermal tools, the bearings should not be heated to a tem­perature in excess of +80 °C, taking account of the grease filling and seal material. If higher heating temperatures are required, it must be ensured that the permissible upper temperature limits for grease and seals are not exceeded. Schaeffler recommends the use of induction heating devices for heating purposes ➤ link.

Oil or grease lubrication is possible

Open bearings and bearings with seals on one side are not greased as standard. They must be lubricated with oil or grease. Lubrication is carried out via the end faces of the bearings.

Compatibility with plastic cages

When using bearings with plastic cages, compatibility between the lubricant and the cage material must be ensured if synthetic oils, lubricating greases with a synthetic oil base or lubricants containing a high proportion of EP additives are used.

Contact us to discuss your requirements of Deep Groove Ball Bearing. Our experienced sales team can help you identify the options that best suit your needs.

Observe oil change intervals

Aged oil and additives in the oil can impair the operating life of plastics at high temperatures. As a result, stipulated oil change intervals must be strictly observed.

Double row deep groove ball bearings

Open bearings are greased

As standard, the bearings are lubricated with a high quality lithium soap grease with a mineral oil base and are maintenance-free for most applications.

Sealing

Single row deep groove ball bearings

The bearings are available in open and sealed designs

Single row deep groove ball bearings are available in open designs, as well as with seals on one or both sides ➤ Figure. In the case of sealed bearings, either non-contact or contact seals are used.

Provide additional seals in the adjacent construction

In the case of unsealed bearings, sealing of the bearing position must be carried out by the adjacent construction. The sealing system should reliably prevent:

• moisture and contaminants from entering the bearing
• the egress of lubricant from the bearing

Single row bearings with non-contact seals and sealing shields – standard bearings and Generation C

For bearing assemblies with high speeds and lower requirements for sealing

Non-contact seals are particularly suitable for applications with high speeds and high requirements for low heat generation ➤ Table. They are free from friction, except for a small amount of lubricant friction in the sealing gap. As a rule, non-contact seals do not undergo wear and therefore have an unlimited operating life. Deep groove ball bearings with non-contact seals on one or both sides have the suffixes RZ and 2RZ, or BRS and 2BRS; the suffixes Z and 2Z indicate seals on one or both sides with sealing shields.

Z sealing shields for standard bearings and for bearings of Gen. C

Z sealing shields are made from sheet steel. They sit securely in the outer ring and form a narrow, non-contact seal gap relative to the surface of the inner ring ➤ Table. This sealing arrangement is particularly suitable for applications with a rotating inner ring, high to very high speeds and low contamination impact.

RZ seals for standard bearings of series 618 and 619

RZ seals are rubberised sealing washers with a sheet steel reinforcement, which sit securely in the outer ring and form a narrow, non-contact seal gap relative to the surface of the inner ring ➤ Table.

BRS seals for bearings of Gen. C

BRS seals are rubberised sealing washers with a sheet steel reinforcement, which sit securely in the outer ring and form a narrow, non-contact seal gap relative to the surface of the inner ring ➤ Table. The seal is securely anchored in the outer ring. A recess incorporated in the inner ring forms a labyrinth in conjunction with the seal lip, which is filled with grease. The frictional behaviour of this seal is comparable with that of the Z sealing shield , however, the protection against ingress of dust and egress of lubricant is higher.

Single row bearings with non-contact seals – standard bearings and Generation C

For lower speeds and higher requirements for sealing action

As these seals are in contact with a defined contact pressure against their sliding surface, they provide very good sealing action against the egress of lubricant and ingress of moisture and dust. Attention must, however, be paid to the loss of energy resulting from friction at the sealing contact. Furthermore, in bearings with contact seals, the bearing speed is restricted by the permissible sliding velocity at the seal lip, i.e. the speed suitability of these bearings is lower than for open bearings or bearings with non-contact seals.

RSR seals, for standard bearings

RSR seals are elastomer lip seals with a sheet steel reinforcement ➤ Table. One seal lip is in radial contact with the inner ring.

HRS and ELS seals for bearings of Gen. C

HRS and ELS seals are securely anchored in a recess in the outer ring. The sealing material is vulcanised onto a sheet steel reinforcement ➤ Table. The sealing washer, together with the inner ring, forms an axial sealing system. In addition, the outer non-contact lip forms a protective labyrinth with the inner ring. An additional increase in the sealing action is also provided by the film of grease between the two seal lips. With this sealing arrangement, higher speeds can be achieved than with conventional RSR seals , as the frictional torque and thus the heat generation in the bearing is lower.

Generation C deep groove ball bearings with contact seals are supplied with HRS seals as standard. ELS seals are available for these bearings by agreement.

Seal characteristics – standard bearings and Generation C

Suffix

Type of seal

+++ = excellent
++ = very good
+ = good
o = satisfactory
– = unsatisfactory

Seal characteristic

low-friction running

high speeds

sealing integrity against ingress of water

sealing integrity against ingress of dust

sealing integrity against loss of grease

Double row deep groove ball bearings

The bearings are of an open design

Double row deep groove ball bearings are not sealed. As a result, sealing of the bearing position must be carried out by the adjacent construction ➤ section.

Speeds

Limiting speeds and reference speeds in the product tables

Two speeds are generally indicated in the product tables:

• the kinematic limiting speed nG
• the thermal speed rating nϑr

Limiting speeds

The limiting speed nG is the kinematically permissible speed of the bearing. Even under favourable mounting and operating conditions, this value should not be exceeded without prior consultation with Schaeffler ➤ link.

The values given in the product tables are valid for oil lubrication in the case of bearings without seals or shields and for grease lubrication where bearings are supplied greased and with seals or shields.

Values for grease lubrication

For grease lubrication, 85% of the value stated in the product tables is permissible in each case.

Reference speeds

nϑr is used to calculate nϑ

The thermal speed rating nϑr is not an application-oriented speed limit, but is a calculated ancillary value for determining the thermally safe operating speed nϑ ➤ link.

Bearings with contact seals

For bearings with contact seals, no speed ratings are defined in accordance with DIN ISO :. As a result, only the limiting speed nG is given in the product tables for these bearings.

Speeds for bearing sets

For matched bearing pairs in an O, X or tandem arrangement, the speed must be limited to approx. 80% of the individual bearings. More accurate speed data for a specific application can be requested from Schaeffler.

Noise

The Schaeffler Noise Index (SGI) has been developed as a new feature for comparing the noise level of different bearing types and series. As a result, a noise evaluation of rolling bearings can now be carried out for the first time.

Schaeffler Noise Index

The SGI value is based on the maximum permissible noise level of a bearing in accordance with internal standards, which is calculated on the basis of ISO . In order that different bearing types and series can be compared, the SGI value is plotted against the basic static load rating C0.

This permits direct comparisons between bearings with the same load carrying capacity. The upper limit value is given in each of the diagrams. This means that the average noise level of the bearings is lower than illustrated in the diagram.

The Schaeffler Noise Index is an additional performance characteristic in the selection of bearings for noise-sensitive applications. The specific suitability of a bearing for an application in terms of installation space, load carrying capacity or speed limit for example, must be checked independently of this.

Temperature range

Limiting values

The operating temperature of the bearings is limited by:

• the dimensional stability of the bearing rings and rolling elements
• the cage
• the lubricant
• the seals

Possible operating temperatures of single row deep groove ball bearings ➤ Table.

Permissible temperature ranges

Legend

C0r N

Basic static load rating ➤ link

f0 -

Factor

Fa N

Axial load

Equivalent static bearing load

F0a/F0r ≦ 0,8 or F0a/F0r ＞ 0,8

For deep groove ball bearings under static loading ➤ Equation and ➤ Equation. The calculation of P0 is dependent on the load ratio F0a/F0r and the factor 0,8.

Equivalent static load

Equivalent static load

Legend

P0 N

Equivalent static bearing load

F0r, F0a N

Largest radial or axial load present (maximum load)

Static load safety factor

S0 = C0/P0

In addition to the basic rating life L (L10h), it is also always necessary to check the static load safety factor S0 ➤ Equation.

Static load safety factor

Legend

S0 -

Static load safety factor

C0 N

Basic static load rating

P0 N

Equivalent static bearing load

Minimum load

In order to prevent damage due to slippage, a minimum radial load of P ＞ C0r/100 is required

In order that slippage does not occur between the contact partners, the deep groove ball bearings must be constantly subjected to a sufficiently high load. Based on experience, a minimum radial load of the order of P ＞ C0r/100 is necessary for this purpose. In most cases, however, the radial load is higher than the requisite minimum load due to the weight of the supported parts and the external forces.

If the minimum radial load is lower than indicated above, please consult Schaeffler.

Design of bearing arrangements

Support bearing rings over their entire circumference and width

In order to allow full utilisation of the load carrying capacity of the bearings and thus also achieve the requisite rating life, the bearing rings must be rigidly and uniformly supported by means of contact surfaces over their entire circumference and over the entire width of the raceway. The seating and contact surfaces should not be interrupted by grooves, holes or other recesses. The accuracy of mating parts must meet specific requirements ➤ Table to ➤ Table.

Radial location of bearings – fit recommendations

For secure radial location, tight fits are necessary

In addition to supporting the rings adequately, the bearings must also be securely located in a radial direction, to prevent creep of the bearing rings on the mating parts under load. This is generally achieved by means of tight fits between the bearing rings and the mating parts. If the rings are not secured adequately or correctly, this can cause severe damage to the bearings and adjacent machine parts. Influencing factors, such as the conditions of rotation, magnitude of the load, internal clearance, temperature conditions, design of the mating parts and the mounting and dismounting options must be taken into consideration in the selection of fits.

If shock type loads occur, tight fits (transition fit or interference fit) are required to prevent the rings from coming loose at any point. Clearance, transition or interference fits ➤ link.

The following information provided in Technical principles must be taken into consideration in the design of bearing arrangements:

• conditions of rotation ➤ link
• tolerance classes for cylindrical shaft seats (radial bearings) ➤ link
• shaft fits ➤ link
• tolerance classes for bearing seats in housings (radial bearings) ➤ link
• housing fits ➤ link

Axial location of bearings – location methods

The bearings must also be securely located in an axial direction

As a tight fit alone is not normally sufficient to also locate the bearing rings securely on the shaft and in the housing bore in an axial direction, this must usually be achieved by means of an additional axial location or retention method. The axial location of the bearing rings must be matched to the type of bearing arrangement. Shaft and housing shoulders, housing covers, nuts, spacer rings and retaining rings etc., are fundamentally suitable.

Axial adjustment by means of spring element to reduce noise

Example: single row deep groove ball bearing, bearing arrangement in an electric motor

If the bearing arrangement is to run particularly quietly, this can be achieved economically with commonly available spring elements ➤ Figure. The bearings in the figure must only support guidance forces in an axial direction. The inner rings have a tight fit on the shaft and are abutted on the shaft shoulders. The outer rings are mounted with a sliding seat. A spring washer is fitted between the outer ring of the right hand bearing and the cover collar. The bearings are thus axially adjusted by the tensioned springs. This achieves particularly smooth running.

Bearing arrangement axially adjusted with a spring washer

Deep groove ball bearing

Spring washer

Cover

Dimensional, geometrical and running accuracy of the bearing seats

For bearings with tolerance class Normal, a minimum of IT6 should be provided for the shaft seat and a minimum of IT7 for the housing seat

The accuracy of the cylindrical bearing seat on the shaft and in the housing should correspond to the accuracy of the bearing used. For deep groove ball bearings with the tolerance class Normal, the shaft seat should correspond to a minimum of standard tolerance grade IT6 and the housing seat to a minimum of IT7; with tolerance class 6, the shaft seat should correspond to a minimum of IT5 and the housing seat to a minimum of IT6. Guide values for the geometrical and positional tolerances of bearing seating surfaces ➤ Table, tolerances t1 to t3 in accordance with ➤ link. Numerical values for IT grades ➤ Table.

Guide values for the geometrical and positional tolerances of bearing seating surfaces

The mounting dimensions of the shaft and housing shoulders, and spacer rings etc., must ensure that the contact surfaces for the bearing rings are of sufficient height. However, they must also reliably prevent rotating parts of the bearing from grazing stationary parts. Proven mounting dimensions for the radii and diameters of the abutment shoulders are indicated in the product tables. These dimensions are limiting dimensions (maximum or minimum dimensions); the actual values should not be higher or lower than specified.

Mounting and dismounting

The mounting and dismounting options for deep groove ball bearings, by thermal, hydraulic or mechanical methods, must also be taken into consideration in the design of the bearing position.

Ensure that the bearings are not damaged during fitting.

Deep groove ball bearings are not separable. In the mounting of non‑separable bearings, the mounting forces must always be applied to the bearing ring with a tight fit.

Schaeffler Mounting Handbook

Rolling bearings must be handled with great care

Rolling bearings are well-proven precision machine elements for the design of economical and reliable bearing arrangements, which offer high operational security. In order that these products can function correctly and achieve the envisaged operating life without detrimental effect, they must be handled with care.

The Schaeffler Mounting Handbook MH 1 gives comprehensive information about the correct storage, mounting, dismounting and maintenance of rotary rolling bearings http://www.schaeffler.de/std/1B68. It also provides information which should be observed by the designer, in relation to the mounting, dismounting and maintenance of bearings, in the original design of the bearing position. This book is available from Schaeffler on request.

Legal notice regarding data freshness

The further development of products may also result in technical changes to catalogue products

Of central interest to Schaeffler is the further development and optimisation of its products and the satisfaction of its customers. In order that you, as the customer, can keep yourself optimally informed about the progress that is being made here and with regard to the current technical status of the products, we publish any product changes which differ from the printed version in our electronic product catalogue.

We therefore reserve the right to make changes to the data and illus­trations in this catalogue. This catalogue reflects the status at the time of printing. More recent publications released by us (as printed or digital media) will automatically precede this catalogue if they involve the same subject. Therefore, please always use our electronic product catalogue to check whether more up-to-date information or modification notices exist for your desired product.

Further information

In addition to the data in this chapter, the following chapters in Technical principles must also be observed in the design of bearing arrangements:

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• Determining the bearing size ➤ link
• Rigidity ➤ link
• Friction and increases in temperature ➤ link
• Speeds ➤ link
• Bearing data ➤ link
• Lubrication ➤ link
• Sealing ➤ link
• Design of bearing arrangements ➤ link
• Mounting and dismounting ➤ link