Application and selection of ball bearings in industrial equipment

The Importance of Ball Bearings

In various industrial machines, the ball bearing is a vital component. Its role extends beyond simple support and rotation. It acts as a critical "bridge" connecting moving and stationary parts, significantly reducing friction during operation, thereby enhancing power transmission efficiency.

Impact on Equipment Performance, Efficiency, and Reliability

A well-designed and properly installed ball bearing can:

• Increase Equipment Efficiency: By reducing frictional forces, it effectively lowers energy consumption, making the equipment more economical to run.
• Ensure Running Precision: It provides stable support for rotating components, ensuring machines maintain a precise trajectory, even at high speeds or under heavy loads.
• Extend Equipment Lifespan: A good bearing can absorb and dissipate impact loads, reducing wear on components and thereby prolonging the life of the entire piece of equipment.

A failed ball bearing, on the other hand, can lead to decreased equipment performance, abnormal noise and vibration, or even severe mechanical failure, causing production stoppages and economic losses. Therefore, the correct selection, installation, and maintenance of ball bearings are key to ensuring stable and efficient industrial equipment operation.

Ball Bearing: Structure, Classification, Key Performance, and Maintenance

Structure

The basic structure of a ball bearing consists of four main parts that work together to enable smooth rotation and support loads.

• Inner Ring: Mounted on the shaft, it rotates with the shaft.
• Outer Ring: Mounted in the bearing seat or housing, it is typically stationary.
• Rolling Elements: Steel balls located between the inner and outer rings that reduce friction through rolling.
• Cage: Keeps the steel balls evenly spaced, preventing them from colliding during rotation.

Some ball bearings also include seals or shields to prevent contaminants from entering and lubricant from escaping.

Classification

Ball bearings can be classified into several types based on their structure and application. Here are some common classifications:

• Deep Groove Ball Bearing: The most common type, capable of handling both radial and moderate axial loads.
• Angular Contact Ball Bearing: The raceways of the inner and outer rings can be relatively displaced, allowing them to handle large radial and unidirectional axial loads simultaneously.
• Self-aligning Ball Bearing: The outer ring raceway is spherical, which automatically compensates for angular misalignment caused by shaft or housing deformation.
• Thrust Ball Bearing: Primarily used to handle pure axial loads and typically cannot withstand radial loads.

Key Performance

When selecting a ball bearing, the following performance parameters should be a key focus:

• Load Capacity: Divided into static load capacity and dynamic load capacity. Static load capacity refers to the maximum load a bearing can withstand without permanent deformation while stationary or at low speeds. Dynamic load capacity refers to the load a bearing can withstand for a specific lifespan while rotating.
• Speed Limit: The maximum safe rotational speed at which a bearing can operate without generating excessive heat and wear.
• Stiffness: The bearing's ability to resist deformation under load. High stiffness bearings ensure the operating precision of precision machinery.
• Friction Torque: The internal friction generated by the bearing during rotation. Lower friction torque means higher operating efficiency and lower energy consumption.

Maintenance

Proper maintenance is crucial for extending the life of a ball bearing and includes the following key aspects:

• Lubrication: The most critical part of bearing maintenance. The lubricant (grease or oil) reduces friction and wear, prevents corrosion, and helps dissipate heat.
• Sealing: Choosing the right sealing method effectively prevents external contaminants (such as dust and moisture) from entering the bearing and stops lubricant from leaking out.
• Installation: Correct installation methods prevent bearings from being damaged during the process. Dedicated tools should be used to ensure a tight fit between the bearing's inner and outer rings, and brute force or hammering should be avoided.
• Monitoring: Regular monitoring of bearing vibration, temperature, and noise can help detect potential faults early, preventing unexpected equipment downtime.

Ball Bearing Selection Strategies

Choosing the right ball bearing is crucial for ensuring the long-term stable operation of equipment. This process requires a comprehensive consideration of various factors to find the bearing type best suited for specific operating conditions.

Operating Condition Analysis

In this section, we will delve into the analysis of operating conditions and how they influence the selection of ball bearings.

• Load: This is one of the most important factors.
• Radial Load: Force perpendicular to the shaft. For example, tension in a belt drive.
• Axial Load: Force parallel to the shaft. For example, the thrust in a gear drive.
• Combined Load: A situation where both radial and axial loads are present simultaneously.
• Rotational Speed: Can be high-speed, low-speed, or variable-speed operation. High speeds generate more heat, requiring consideration of heat dissipation and lubrication issues.
• Working Environment:
• Temperature: High temperatures can affect the performance of lubricants and the strength of bearing materials.
• Humidity and Contamination: Environments that are damp, dusty, or contain corrosive substances require bearings with good sealing or special materials.

Selection Key Points

Based on the results of the operating condition analysis, the following key points should be followed when selecting a bearing:

• Select the Appropriate Ball Bearing Type Based on Load Type
• Deep Groove Ball Bearing: Suitable for conditions with moderate radial loads and small bidirectional axial loads.
• Angular Contact Ball Bearing: Suitable for conditions that must withstand large radial loads and unidirectional or bidirectional axial loads, especially in applications with high stiffness requirements.
• Thrust Ball Bearing: Specifically designed to withstand pure axial loads.
• Consider Expected Lifespan and Reliability Requirements
• For critical equipment components or applications that are difficult to maintain, bearings with a higher rated life and reliability should be chosen.
• For general equipment, a more cost-effective bearing can be selected as long as it meets basic requirements.
• Balance Installation Space and Cost
• In space-constrained equipment, a more compact bearing series should be selected.
• In satisfying the performance requirements, cost is also an important factor to consider during selection.

Application Cases of Ball Bearings in Typical Industrial Equipment

Motors and Pumps

• Application Characteristics: Motors and pumps typically require bearings to operate stably at high speeds while maintaining low noise and vibration.
• Selection Preference: Deep groove ball bearings are the most common choice in this field. Their simple structure, ease of installation, and ability to handle moderate radial loads and small axial loads make them ideal. For equipment with extremely high noise requirements, higher precision grade and low friction torque deep groove ball bearings are selected.

Fans and Blowers

• Application Characteristics: This equipment usually operates at high speeds, but the load is relatively light. In some cases, it may also need to withstand some axial thrust.
• Selection Preference: Deep groove ball bearings or angular contact ball bearings.
• Deep Groove Ball Bearings: Suitable for most fan applications, effectively balancing speed and load.
• Angular Contact Ball Bearings: In applications that require handling larger axial thrust or have higher stiffness requirements, a paired installation of angular contact ball bearings is often used to provide stronger axial load capacity and higher rotational precision.

Transmission Equipment (Belt Conveyors, Gearboxes)

• Application Characteristics: This equipment typically operates for extended periods under high or heavy loads, with extremely high requirements for the bearing's load capacity and reliability.
• Selection Preference: Depending on the specific load conditions, a combination of different bearing types is chosen.
• Deep Groove Ball Bearings: Used in idler rollers of belt conveyors where loads are relatively light.
• Angular Contact Ball Bearings: In applications like gearboxes that need to withstand large radial and axial loads, they are often used to support the gear shaft to ensure transmission precision and stability.

Precision Machine Tools

• Application Characteristics: The main spindle of a precision machine tool has extremely strict requirements for the bearing's precision, stiffness, and speed. Any minute vibration or displacement can affect the processing quality.
• Selection Preference: Paired or multiple precision angular contact ball bearings.
• Parameter Comparison: Compared to ordinary deep groove ball bearings, precision angular contact ball bearings have a higher speed, higher stiffness, and smaller runout.
• Installation Method: They are usually installed in a preloaded "face-to-face" (DF) or "back-to-back" (DB) arrangement. The preload force is adjusted to increase the stiffness of the entire spindle system and reduce deformation during operation.

Ball Bearing Installation and Common Failure Troubleshooting

Correct Installation

Proper installation is the first step to ensuring the long-term stable operation of a ball bearing. Improper installation can lead to premature bearing failure, shortening its service life.

• Use Specialized Tools: When installing a bearing, specialized tools (hydraulic, heating, or mechanical) should be used to apply force evenly to the bearing ring that has the tight fit. It is strictly forbidden to use hammers or other tools to directly strike the bearing, as this can cause damage.
• Control Fit Clearance: During installation, the fit clearance between the bearing's inner ring and the shaft, and the outer ring and the bearing seat, must meet design requirements. An excessively tight fit can generate unnecessary preload, leading to premature bearing failure, while a loose fit can cause relative sliding and wear during operation.

Common Failures

Even with correct installation, ball bearings may still fail after prolonged operation. Here are some common failures and their causes:

• Abnormal Noise and Vibration:
• Causes: Poor lubrication, improper installation, excessive preload, contaminants inside the bearing, or the bearing itself being damaged.
• Troubleshooting: First, check the lubrication status, then check if the installation is correct, and finally, replace the bearing.
• Overheating:
• Causes: Insufficient or excessive lubrication, incorrect lubricant type, load or speed exceeding the bearing's design limits, or a too-tight installation.
• Troubleshooting: Check and adjust the amount and type of lubricant, confirm that the bearing selection matches the operating conditions, and check the installation fit.
• Failure Modes:
• Pitting: Usually caused by fatigue from high loads and prolonged operation, appearing as small pits on the raceway or rolling element surface.
• Flaking: A further development of pitting and the ultimate manifestation of material fatigue.
• Wear: Caused by poor lubrication, contaminant ingress, or improper fitting, appearing as the removal of material from the raceway and rolling element surfaces.

Shanghai Yinin Bearing & Transmission Company, as an industry and trade integrated enterprise that combines design, production, sales, and service, deeply understands every aspect of a ball bearing's journey from design to maintenance. We have a professional technical team that provides high-quality bearing products and offers expert selection and technical support. Our product range covers various types of ball bearings, including standard ball bearings for motors and customized non-standard high-end bearings for special requirements. We consistently adhere to the philosophy of “quality as the basis, service as the first, and technology as the foundation” to continuously provide the highest quality bearings to our customers.