Angular contact ball bearings are precision components widely used in high-speed, high-precision applications such as electric motors, gearboxes, machine tools, and pumps. Understanding how to judge the complete failure of these bearings is essential not only for preventing catastrophic breakdowns but also for improving maintenance schedules and extending equipment life.

As a bearing application engineer, I will explain in detail how to accurately identify complete bearing failure, the root causes behind it, and the professional practices to apply for diagnosis and prevention.

What is “Complete Failure” in Angular Contact Ball Bearings?

Complete failure refers to the point at which the bearing can no longer perform its intended function due to severe damage or degradation. At this stage, the bearing’s structural integrity is compromised, and continued operation may lead to equipment failure, safety hazards, and costly downtime.

1. Audible and Vibrational Symptoms

One of the earliest and most accessible indicators of failure is unusual noise or excessive vibration. When an angular contact bearing fails completely, you’ll typically notice:

• Loud rumbling, grinding, or knocking sounds during rotation
• A sudden increase in vibration amplitude, especially in the axial or radial directions
• Spikes in envelope spectrum analysis (if using condition monitoring tools)

These symptoms indicate the presence of broken rolling elements, raceway spalling, or internal clearance loss.

2. Sudden Increase in Operating Temperature

Angular contact ball bearings rely heavily on correct preload and lubrication. Failure often presents as:

• A rapid temperature spike, often beyond 90–100°C, even under normal load
• Uneven temperature distribution across the housing or shaft
• Temperature rise that doesn’t stabilize, even after load reduction

Such heat generation usually results from internal friction due to cage damage, lubricant failure, or excessive preload caused by axial misalignment or shaft deflection.

3. Irregular Shaft Movement or Seizure

Once a bearing has failed, axial and radial control is lost. Symptoms include:

• Shaft wobble or axial play
• Complete seizure, where the shaft can no longer rotate
• Locking or jamming during speed variation

This stage often corresponds to catastrophic inner/outer ring fracture, cage collapse, or rolling element deformation.

4. Lubricant Contamination and Leakage

Angular contact ball bearings often run at high speeds with tight tolerances. When failure occurs:

• Grease or oil leaks from the seal or bearing housing
• Presence of metallic particles in the lubricant
• Discoloration of lubricant due to burning or contamination

These signs typically indicate cage wear, material fatigue, or debris ingress—all common failure accelerators.

5. Visual Inspection After Disassembly

If a suspected failure occurs, disassemble and inspect the bearing:

• Look for spalling or flaking on the raceways
• Check for cracks or fractures in the inner or outer rings
• Examine the cage for deformation or breakage
• Assess rolling elements for pitting, wear, or flattening

Complete failure usually leaves permanent deformation, broken components, and material transfer between elements.

6. Electrical Damage (in Motor Applications)

For angular contact bearings in electric motors:

• EDM (Electrical Discharge Machining) effects appear as micro-pits
• Raceways show frosted or fluted patterns
• Bearings often seize due to arcing damage from stray currents

This is a less obvious but critical form of failure in high-speed or VFD-controlled motors.

Root Causes of Complete Failure

To prevent recurrence, always identify the root cause:

• Improper preload or misalignment
• Poor lubrication (wrong type, contamination, over/under-lubrication)
• Over-speed or over-load conditions
• Incorrect installation or handling
• Use of non-genuine or low-quality bearings

Conclusion: Professional Judgment Prevents Downtime

Identifying the complete failure of angular contact ball bearings requires a combination of sound technical judgment, field monitoring, and failure analysis. For bearing users, wholesalers, and distributors, the ability to judge such failure not only enhances reliability but also positions you as a knowledgeable and trusted resource in the supply chain.

Professional recommendation: Regular condition monitoring (vibration, temperature, and lubricant analysis), combined with proper installation practices and high-quality bearing sourcing, is your best defense against total bearing failure.