Deep groove ball bearings are the most commonly used type of bearings in motors.
In the field of industrial motors, the usage of deep groove ball bearings constitutes over seventy percent of the total bearing usage. If we consider the number of bearings used, its proportion is even greater.
Therefore, if a motor engineer has a thorough understanding of deep groove ball bearings, they can have a significant grasp of the application of motor bearings.
Deep groove ball bearings were formerly known in domestic standards as radial ball bearings. As the name suggests, this type of bearing is designed to handle radial loads, and they are a type of rolling bearing with spherical rolling elements.
The radial load mentioned here is also known as the centripetal load. Therefore, the main load-bearing capacity of deep groove ball bearings lies radially.
Meanwhile, due to the structural characteristics of their grooves, these bearings can handle a certain amount of axial load. The axial load-bearing capacity of deep groove ball bearings is significantly weaker than their radial load-bearing capacity.
Therefore, under conditions with axial load, it is necessary to verify the life expectancy of deep groove ball bearings to ensure that the bearings can achieve the expected operational effects under this load.
The image below shows a typical deep groove ball bearing.
Compared to roller bearings, deep groove ball bearings have point contact between the internal rolling elements and the raceway. Let’s briefly analyze the characteristics and limitations of deep groove ball bearings.
I. Characteristics of Deep Groove Ball Bearings
1. Lesser radial load capacity compared to roller bearings
Deep groove ball bearings possess a lower load capacity than their roller bearing counterparts, however, they are suitable for general industrial motors.
For conditions with additional radial loads like externally connected pulley wheels, the load capacity might not meet the requirements, in such cases, cylindrical roller bearings can be used.
2. Reduced internal friction and heat generation
The point contact between the rolling element and the raceway results in relatively less heat generation within the bearing. For bearings with seals, the frictional heat from the seal during operation should be taken into account.
3. High rotational speed capability
The rolling elements in deep groove ball bearings are spheres, which have relatively less mass compared to roller bearings. This results in lower centrifugal forces during high-speed rotations.
Commonly used stamping steel cages and nylon cages also possess good strength, hence, deep groove ball bearings have relatively high mechanical limit speed.
Correspondingly, due to less heat generation, their thermal reference speed is also relatively high.
4. Simple bearing arrangement
Deep groove ball bearings can accommodate both axial and radial loads, making these bearings suitable for both locating bearing and non-locating bearing arrangements.
5. Simple usage and convenient storage and transportation
Deep groove ball bearings typically have an integrated bearing structure, making their installation, storage, and transportation simpler compared to split bearings.
6. Easy maintenance
Deep groove ball bearings generally come in open type, with dust cover, and with sealed types, greatly simplifying the task of replenishing the lubricant, which makes them easy to operate and maintain.
II. Limitations of Deep Groove Ball Bearings
Deep groove ball bearings, due to their structural characteristics, have inherent limitations:
1. Eccentricity Resistance
Standard deep groove ball bearings have very limited ability to adjust eccentricity, usually within less than 10 minutes of arc. This eccentricity capability is a result of the structure and clearance, not intended for operational use.
Therefore, it is not recommended for motor engineers to utilize this eccentricity tolerance.
2. Damage During Bearing Installation
Deep groove ball bearings have point contact internally, making them highly susceptible to damage during installation.
Hence, during motor bearing installation, it is crucial to prevent installation forces from damaging the raceway via the rolling elements.
3. Temperature Limitations
Without specific clarification, the heat treatment dimensional stability of standard deep groove ball bearings is 120 degrees Celsius.
Consequently, deep groove ball bearings are not suitable for operations above this temperature.
Moreover, when choosing deep groove ball bearings for high-temperature applications, considerations for the temperature limits of the lubricant, cage, and seals are necessary. (Please refer to related articles in our public account.)
4. Application under Vibrational Conditions
Deep groove ball bearings are prone to raceway and rolling element damage under vibrational conditions, thus posing significant challenges in such operational environments.
In summary, deep groove ball bearings are excellent for motor use. Of course, slight differences exist between various brands, and this article shares only the common characteristics of such bearings.