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Bearing Failure Symptom Triage - Diagnostic Decision Helper

Identify likely bearing failure causes from observed symptoms, noise patterns, and visual inspection findings

Free bearing failure diagnostic tool that helps maintenance teams identify the most likely cause of bearing problems from observed symptoms. Select the symptoms you are seeing - noise type (rumble, squeal, clicking, grinding), vibration characteristics (overall high, periodic, random), temperature behavior (running hot, sudden increase, fluctuating), and visual inspection findings (spalling, discoloration, cage damage, contamination, corrosion). The diagnostic engine cross-references your symptoms against common bearing failure modes: fatigue spalling, inadequate lubrication, contamination, misalignment, overload, electrical damage (fluting), corrosion, and improper mounting. Each diagnosed cause includes a confidence level, explanation of the failure mechanism, and recommended corrective actions to prevent recurrence. This is not a vibration analyzer - it is a structured diagnostic aid for maintenance teams who need to quickly narrow down the cause of a bearing failure and take the right corrective action rather than just replacing the bearing and hoping the problem does not come back.

Pro Tip: The single most valuable piece of diagnostic evidence is the failed bearing itself. Never throw away a failed bearing until someone has examined it. The damage pattern tells the story: spalling on the inner ring raceway at one spot indicates a static overload. Spalling that goes all the way around indicates fatigue from normal operation. Fluting (parallel lines on the raceway) indicates electrical damage. Discoloration (straw to blue) indicates overheating from inadequate lubrication.

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Bearing Failure Symptom Triage

How It Works

  1. Describe the Noise

    Select the type of noise observed: rumbling or growling (suggests spalling or contamination), high-pitched squeal (suggests lubrication starvation), rhythmic clicking (suggests rolling element or cage damage), grinding (suggests severe wear or contamination), or no abnormal noise.

  2. Describe Vibration

    Select vibration characteristics: overall vibration increase (general degradation), periodic vibration at shaft speed or harmonics (misalignment or unbalance), random vibration spikes (contamination or cage damage), or vibration at bearing frequencies (BPFO, BPFI, BSF).

  3. Describe Temperature

    Select temperature behavior: running hotter than normal (lubrication or preload), sudden temperature spike (lubrication failure or seizure), temperature fluctuations (intermittent contact or lubricant issues), or normal temperature.

  4. Describe Visual Findings

    Select what you see on the bearing and shaft: spalling or flaking, discoloration, cage damage, contamination (particles, water), corrosion or rust, fretting marks on the shaft, electrical fluting marks, or no visible damage.

  5. Review Diagnosis

    Get a ranked list of likely failure causes with confidence levels, failure mechanism explanations, and specific corrective actions. The most likely causes appear first based on symptom matching.

Built For

  • Maintenance mechanics diagnosing bearing failures during equipment repair
  • Reliability engineers conducting root cause failure analysis on recurring bearing problems
  • Maintenance supervisors training staff on bearing failure recognition and diagnosis
  • Predictive maintenance teams correlating vibration data with bearing condition
  • Plant engineers investigating chronic bearing failures on specific equipment

Frequently Asked Questions

Inadequate lubrication causes approximately 40-50% of premature bearing failures in industrial applications. This includes insufficient grease quantity, wrong grease type, contaminated grease, and exceeding the regreasing interval. The second most common cause is contamination (dirt, water, process material entering the bearing), responsible for about 20-25% of failures. True fatigue failure (the bearing reaching its calculated L10 life) accounts for less than 10% of replacements.
Spalling is flaking or pitting of the raceway surface. It starts as a small rough area that you can feel with a fingernail and progresses to visible craters and flakes of bearing steel. Early spalling looks like a rough or frosted patch. Advanced spalling shows obvious pits and missing material. The location and pattern of spalling indicates the cause: localized spalling suggests a point load or mounting problem, while spalling that extends around the full raceway suggests fatigue.
Electrical fluting appears as a pattern of closely spaced parallel lines etched into the raceway surface, like a washboard. It is caused by electrical current passing through the bearing, typically from VFD-driven motors without shaft grounding. The current arcs across the oil film at the contact point, melting tiny craters in the surface. Over time, the craters connect to form visible fluting lines. The bearing runs rough and noisy long before its mechanical fatigue life is reached.
Address the root cause, not just the symptom. If the bearing failed from lubrication starvation, fix the lubrication program, do not just install a new bearing. Key prevention strategies: (1) proper lubrication type and interval, (2) effective sealing against contamination, (3) correct shaft fit and alignment, (4) shaft grounding on VFD-driven motors, and (5) proper installation using correct tools and methods.
Disclaimer: This diagnostic tool provides guidance based on common failure mode patterns. Actual root cause analysis may require detailed vibration analysis, oil/grease analysis, metallurgical examination, and review of operating history. For critical equipment, consult a bearing application engineer or vibration analyst. This tool does not replace professional failure analysis for safety-critical or high-value equipment.

Learn More

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Bearing Life Calculations: What L10 Actually Means

Why calculated bearing life and actual bearing life are often very different numbers, what L10 predicts, what it misses, and how to use it for maintenance planning.

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Bearing Grease: Choosing the Right One and Knowing When to Apply It

Base oil viscosity, NLGI grade, thickener type, regreasing intervals, and why over-greasing causes as many failures as under-greasing.

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Bearing Failure Modes: Reading the Evidence

How to tell what killed a bearing by looking at the damage pattern. Fatigue spalling, lubrication failure, contamination, electrical fluting, and corrective actions.

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Bearing Loads: How to Calculate What Your Bearing Actually Sees

Radial loads, axial loads, X and Y factors, belt tension, gear mesh forces, and the loads people commonly forget in bearing life calculations.

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