Management

What is Failure Rate and How does They Impact Machine Reliability

• 29 Jan. 2025
• 05 min read

Let's Dive into the World of 1/MTBF – Understanding Failure Rate

1. Introduction – The Reality Behind 1/MTBF

Failure is not a sudden event—it is an accumulation of unnoticed changes over time.

The inverse of MTBF (1/MTBF) defines failure rate (λ), the probability of failure per unit time.

While failures demand immediate attention, their root causes are often ignored until it’s too late.

To master reliability, we must shift our focus from failure events to failure rate itself.

Example: Aircraft Engine Reliability

Consider a fleet of aircraft engines with an MTBF of 5,000 hours. This means:

• The failure rate is 1/5000 = 0.0002 failures per hour.
• For a fleet of 100 engines running continuously, we expect one failure every 50 hours across the fleet.
• A single engine may not fail soon, but collectively, failure is a statistical certainty.
• This is why airlines prioritize condition monitoring and predictive maintenance to lower failure rates instead of waiting for failures to occur.

2. Defining Failure Rate – The Unseen Probability of Breakdown

Failure rate (λ) = 1/MTBF is a statistical representation of how often a system or component is expected to fail.

Unlike MTBF, which gives a false sense of "average lifetime," failure rate shows the likelihood of failure at any given moment.

Example: Industrial Pump Failures

A chemical plant operates 100 pumps, each with an MTBF of 8,000 hours. That means:

• Failure rate = 1/8000 = 0.000125 failures per hour per pump.
• The plant experiences one pump failure approximately every 80 hours.
• If failures cause production loss, reducing the failure rate through better lubrication, alignment, and predictive monitoring can save millions.

3. The Silent Progression Toward Failure

A. Degradation and Wear

Mechanical fatigue, erosion, and corrosion gradually reduce structural integrity.

Example: Bearing Failures in Motors

A motor bearing may have an MTBF of 20,000 hours. If lubrication is inadequate, contaminants accelerate wear, shortening MTBF to 10,000 hours.

B. Environmental and Operational Stresses

Temperature fluctuations, vibration, and humidity accelerate failure mechanisms.

Example: HVAC Compressors in Extreme Climates

Compressors operating in hot, dusty environments fail 30% faster than those in controlled conditions.

C. Maintenance and Human Factors

Improper maintenance—both over-maintenance and under-maintenance—affect failure rate.

Example: Wind Turbine Gearbox Failures

A misalignment during maintenance can increase stress on the gearbox, leading to premature failure.

4. Failure Rate vs. Failure Event – A Shift in Perspective

The failure event is simply the final outcome of a rising failure rate.

Managing failure rate is more valuable than reacting to failures.

Example: Power Grid Transformer Failures

A power transformer has an MTBF of 30 years, but insulation degradation increases its failure rate over time.

5. Turning Failure Rate Awareness Into Action

Modern CMMS and AI-driven analytics allow us to track failure rate trends in real time.

Example: Automotive Fleet Maintenance

A fleet of 500 trucks faces frequent fuel injector failures. By implementing better fuel filtration and scheduled injector replacements, breakdowns drop by 40%, improving uptime.

6. Conclusion – The Takeaway

Failure is not the problem— failure rate is.

By internalizing failure rate, we shift from reactive firefighting to proactive reliability.

"The best way to prevent failure is to see it long before it happens."

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