Did you know that a staggering 51 percent of all motor failures can be traced back to bearing issues? Understanding electric motor bearings, their types, common problems, and proper maintenance can significantly extend the life of your equipment and prevent costly downtime.
What Are Electric Motor Bearings?
Electric motor bearings are crucial components that support the rotation of the motor’s shaft. They facilitate power transmission and maintain precise shaft alignment. To function optimally, bearings must minimize friction and heat generation.
High-quality electric motor bearings are essential for motors to operate smoothly and efficiently. These specialized components, often referred to as EMQ bearings, adhere to stricter standards than general-purpose bearings. It’s important to note that EMQ standards can vary between manufacturers.
Bearing Characteristics and Load Types
Bearings differ in design based on factors like speed, friction, wear tolerance, heat generation, and their ability to handle axial and radial loads.
Load types:
- Radial Load: A force applied perpendicular to the shaft, pushing the bearing outward.
- Axial Load: A force applied parallel to the shaft, pushing the bearing toward or away from the motor housing.
Types of Electric Motor Bearings
The specific motor design, load conditions, operating environment, and other factors will determine which bearings are used in an electric motor. Engineers must carefully consider these factors to ensure optimal performance and efficiency for that particular application.
Electric motors typically utilize two main types of bearings: ball bearings and roller bearings.
Ball Bearings
Ball bearings are one of the most common electric motor bearings. They feature steel balls that rotate within inner and outer rings. Ball bearings are used due to their high-speed capabilities, low friction, and relatively low cost.
There are many sub-types of ball bearings for different applications. Here are a few of the most common:
- Deep Groove Ball Bearings: These are the most common type of ball bearing. Deep groove ball bearings have more contact area between the balls and the raceways, which makes them suitable for high speeds. They are often found in small appliances and fans. They are capable of handling predominantly moderate radial and axial loads. They are widely used in various applications due to their versatility and affordability.
- Angular Contact Ball Bearings: Designed primarily for axial loads, these bearings can be used in pairs to accommodate radial loads as well. They are common in high-speed applications where radial and axial loads are present. Angular contact ball bearings are used in applications such as electric motors, machine tools, robotics, gearboxes, pumps, and compressors.
- Self-Aligning Ball Bearings: These bearings can accommodate misalignment between the shaft and the housing, reducing stress on the bearing. They are recommended for applications with potential shaft misalignment, such as agricultural equipment and construction machinery.
Roller Bearings
Electric motor roller bearings support the shaft using cylindrical rollers inside a racetrack. They are ideal for applications with heavy loads and high torque requirements.
- Cylindrical Roller Bearings: These bearings are designed to handle primarily radial loads and are often used in high-speed applications with heavy loads, such as fans, blowers, and pumps.
- Needle Roller Bearings: These bearings have small-diameter rollers characterized by their high length-to-diameter ratio, allowing for compact designs and high-load capacities. They are commonly used in applications with limited space, such as in small appliances, power tools, automotive starter motors, gearboxes, and other compact electrical motors.
- Tapered Roller Bearings: Capable of handling both radial and axial loads, tapered roller bearings are suitable for combined load applications such as industrial gearboxes, automotive wheel hubs, and machine tools.
Sealed, Shielded, & Open Motor Bearings
To protect bearings from contaminants, manufacturers often employ sealing methods:
- Sealed Bearings: These bearings are packed with grease and have seals on both sides to prevent contaminants like dust, dirt, and moisture from entering. They are maintenance-free but will have a limited grease life and will need to be wholly replaced.
- Shielded Bearings: Similar to sealed bearings, shielded bearings have a single metal shield on one side to provide some protection while still allowing the maintenance crew to lubricate the bearings. New grease increases their lifespan.
- Open Bearings: These bearings have no seals and run cooler with less friction. They are easy to lubricate but require more frequent maintenance to prevent contamination.
Common Electric Motor Bearing Failure Indicators
Recognizing the signs of motor bearing failure can help prevent costly equipment damage. Common indicators include:
- Excessive Vibration: Increased vibration can indicate bearing wear or damage.
- Noise: Unusual noises, such as grinding or squealing, often signal bearing issues.
- Overheating: Bearings that overheat can be a sign of improper lubrication, misalignment, or impending failure.
- Stiffness or Roughness: Resistance to rotation or rough operation indicates bearing wear or damage.
Bearing Maintenance & Lubrication
Proper maintenance is essential for extending bearing life. Key practices include:
- Regular Inspection: Visually inspect bearings for signs of wear, damage, or contamination.
- Bearing Lubrication: Adhere to the manufacturer’s recommended lubrication schedule and type. Over-lubrication can be as harmful as under-lubrication.
- Temperature Monitoring: Keep track of bearing temperatures to identify potential overheating issues.
- Alignment: Ensure proper shaft and housing alignment to prevent premature bearing wear.
- Contamination Control: Protect bearings from contaminants by maintaining a clean operating environment.
IBT Pro Tip: Always purge as much of the old grease as possible, use the recommended lubrication, and do not mix different types of grease thickeners. It’s best practice to avoid mixing different types of grease and to always use a grease gun to ensure accurate measurement. If mixing grease is unavoidable, perform a grease compatibility test. If the grease is incompatible, greases will soften or become fluid.
By understanding the different types of electric motor bearings, recognizing failure indicators, and following proper maintenance practices, you can significantly extend the life of your equipment and reduce downtime.
Learn more about what to expect during an industrial bearing replacement installation.
IBT Industrial Solutions: Your Experts in Electric Motor Bearings
Do you need help with your electric motor bearings? IBT Industrial Solutions can assist you with all aspects of your electric motor, including its bearings and maintenance.
We offer off- and on-site industrial maintenance services and online or in-person training for your maintenance crew.
Purchase electric motors, components, lubrication, and bearings on ShopIBT.
If you need help finding the right motor, bearing, or lubrication, our experts are standing by, ready to help. We even offer engineering services to ensure your process is as efficient and long-lasting as possible. Contact us today for expert advice, maintenance, engineering, and service for your electric motor bearings.
