Electric motors and gearmotors are the backbone of modern industry. From pumps and conveyors to fans, mixers, and heavy-duty machinery, these motors keep facilities running smoothly. But did you know that more than half of electric motor failures can be traced back to bearing issues?
Bearings are small components with a big responsibility. They minimize friction, support loads, and ensure smooth motor operation. Yet, when they fail, the consequences can be severe: unplanned downtime, costly repairs, and in some cases, catastrophic equipment damage.
At Square One Electric Motors & Pumps, we understand the challenges maintenance teams face when it comes to keeping equipment running. By recognizing common failure modes and adopting preventive strategies, facilities can extend the life of their motors and bearings, saving time and money.
👉 Need help now? Contact our expert service team for troubleshooting, maintenance, and repairs.
Bearing Life Expectancy and the L10 Formula
The bearing industry uses a standardized calculation called the L10 formula to estimate bearing life. This calculation predicts the number of operating hours at which 90% of a group of identical bearings will still be operational.
The formula takes into account:
-
RPM (rotational speed)
-
Dynamic load
-
Lubricant quality
-
Bearing size and type (ball vs. roller)
While helpful for selection and planning, the L10 calculation assumes ideal conditions. Real-world factors such as contamination, overheating, and poor lubrication often cause bearings to fail well before their predicted lifespan. This is why proper installation and maintenance are just as critical as initial bearing choice.
Read our Blog: Extend Bearing Life
How Bearings Fail: The Fatigue Process
Bearings rarely go from “healthy” to “broken” overnight. Failure is typically a progressive process with identifiable stages:
-
Microscopic fractures (spalling) develop under surface stress.
-
Flaking and material separation appear on raceways or rollers.
-
Noise and vibration begin to increase noticeably.
-
Critical dimension changes occur, causing misalignment and increased stress.
-
Excess friction and heat accelerate wear.
-
Final failure results, often damaging shafts, housings, and other components.
Understanding these stages helps maintenance teams take corrective action early—before a small defect turns into an expensive motor rebuild.
1. Thermal Stress on Bearings
One of the most common causes of bearing failure is excessive heat. Bearings are designed to operate below 100°C (212°F) under normal conditions. Beyond this point, thermal expansion, lubricant breakdown, and metal-to-metal contact can occur.
To simplify monitoring, remember the “80-90-100 Rule”:
-
80°C – Normal, safe operation
-
90°C – Warning; check for lubrication or load issues
-
100°C and above – Shutdown required to prevent catastrophic failure
Monitoring Options:
-
Thermocouples & RTDs for continuous monitoring
-
Infrared thermography for fast visual checks
-
Color inspection – overheated bearings may turn purple, blue, or black
👉 Read ABB Baldor’s Whitepaper: How to Extend the Life of Your Motor Bearings
Industry Example: In HVAC blower motors, high ambient temperatures combined with poor ventilation often push bearings above safe levels. Monitoring and timely lubrication can extend service life dramatically.
2. Loading Stress: Radial vs. Axial
Bearings are designed to handle two main types of load:
-
Radial loads – perpendicular to the shaft
-
Axial (thrust) loads – parallel to the shaft
Problems arise when motors are installed incorrectly or operated outside their design parameters. For example:
-
Roller bearings should not be run without radial load for long periods. Running “unloaded” can cause rollers to skid instead of roll, leading to heat damage.
-
Vertical pump motors require thrust bearings to handle axial loads. Installing a standard horizontal motor in a vertical application may lead to rapid failure due to lubrication and load mismanagement.
Pro Tip: Always confirm motor orientation and load direction before installation to ensure the correct bearing type is used.
3. Vibration & Shock Stress
Vibration is another silent killer of motor bearings. Sources include:
-
Rotor imbalance
-
Loose motor mounts
-
Shaft misalignment
-
External vibration from nearby machinery
Even motors in storage are at risk. False brinelling—a form of wear caused by vibration in stationary bearings—creates characteristic patterns on raceways:
-
Ball bearings → spherical indentations
-
Roller bearings → lined or “fluted” wear
Industry Example: Conveyor systems often create vibration that transfers through housings to motor bearings. Without dampening or alignment checks, vibration damage accumulates quickly.
4. Environmental Stress
Industrial environments are rarely ideal. Dust, moisture, and chemical contaminants can compromise bearings quickly.
-
Condensation → Rust on raceways and rollers
-
Dust & particles → Abrasive wear inside housings
-
Chemical exposure → Grease incompatibility and corrosion
-
Poor ventilation → Reheating of ambient air, raising motor temps
Prevention:
-
Select the right lubricant for environmental conditions
-
Use desiccant bags in stored motors
-
Ensure housings and seals remain intact
5. Mechanical Stress
Mechanical missteps during installation or operation frequently shorten bearing life. Issues include:
-
Misalignment between motor and driven load
-
Improper shaft or housing fits
-
Reduced clearance from corrosion or contamination
-
Use of undersized or incorrect bearings
Red Flag: If bearings are difficult to install or remove, it may be due to shaft or housing tolerances being out of spec. Machining may be required for proper fit.
6. Electrical Stress: VFDs and Bearing Currents
With the rise of variable frequency drives (VFDs), electrical stress has become a leading cause of bearing failure.
When shaft voltages discharge through bearings, they create:
-
Pitting – small craters visible to the naked eye
-
Fluting – lined wear patterns on raceways
-
Micro-cratering – microscopic pits reducing surface smoothness
Common Causes:
-
Magnetic dissymmetry in laminations
-
Static electricity from driven equipment
-
Capacitive coupling from VFD switching frequencies
Prevention:
-
Install insulated bearings
-
Use shaft grounding brushes
-
Apply filters to VFD systems
Best Maintenance Practices to Prevent Bearing Failure
Preventive maintenance is the key to extending motor and bearing life. A small investment in time and attention can save thousands in repair and downtime costs.
🔧 Best Practices Include:
-
Lubrication: Use correct grease, follow manufacturer intervals, avoid over/under-lubrication.
-
Temperature Tracking: Regularly monitor with IR cameras or permanently installed RTDs.
-
Vibration Analysis: Detect early signs of imbalance or misalignment.
-
Alignment Checks: Use laser alignment tools to ensure shaft accuracy.
-
Seal Integrity: Inspect regularly to keep contaminants out.
-
Storage Practices: Protect idle motors with desiccants and vibration control.
👉 Square One’s expert technicians can assist with preventive maintenance programs, bearing diagnostics, and motor repair. Schedule a service today.
Related Blogs
For deeper insights, explore our related articles:
Why Choose Square One Electric Motors & Pumps?
When it comes to motors, gearmotors, and pumps, choosing the right partner makes all the difference.
With Square One, you get:
✅ Brand-new motors with manufacturer’s warranty
✅ Fast shipping from the nearest warehouse
✅ Expert technical support & repair services
✅ Competitive pricing and reliable solutions
Whether you need a replacement motor, a preventive maintenance plan, or troubleshooting for complex bearing issues, our team is here to help.
👉 Request a quote today and keep your equipment running smoothly.