What Is Mean Time to Failure (MTTF)?
Discover how MTTF (mean time to failure) can enhance your facility management strategy by minimizing downtime and costs.
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Mean time to failure (MTTF) measures the average time a non-repairable asset will function correctly before it fails. This metric is critical in understanding equipment failure rates because it provides fundamental insights into how long different systems typically last based on historical failure rates.
Facility managers can use MTTF data to make more informed decisions about asset lifecycle costs and maintenance schedules. Instead of relying on guesswork, you can use MTTF to plan replacements and scheduled maintenance work based on actual performance data. This approach lowers costs, reduces downtime, and promotes better service.
What Is The Difference Between MTTF and MTBF?
The key difference between mean time to failure (MTTF) and mean time between failures (MTBF) is that MTTF applies to non-repairable components while MTBF applies to repairable components. For example, MTTF would make sense for disposable light bulbs designed for one use, while MTBF would make sense for manufacturing machinery designed for periodic repairs.
This difference is why clarifying equipment downtime metrics for each asset matters. Using the wrong metric for the wrong asset may give you false insights.
If you apply MTTF to a repairable item, you ignore the fact that it can return to service after failure. This practice skews your data by treating each failure as the end of the asset’s life. If you apply MTBF to a non-repairable item, you treat it like it can be fixed and reused, which may lead to an inadequate inventory of replacement parts.
How to Calculate MTTF Data
MTTF calculations are determined using the following formula.
MTTF = Total hours of operation ÷ Total assets in use
To determine these numbers, follow these steps:
Step 1
Determine the identical assets in your group. Different types of assets may have varying lifespans for unrelated reasons, which can skew your data. So, it’s best to calculate MTTF based on smaller groups of identical assets instead of based on a larger group of all assets you want to track.
Step 2
Record how many hours each asset ran. Combine all of those hours into one total. This total must reflect all usage time across all assets you want to track. Make sure you base your total hour calculations on the smaller subgroups you determined in Step 1 instead of one large group of all assets. Also, do not limit the calculation to only failed units. MTTF uses the total hours from all assets, whether they have failed or not.
Step 3
Now, you can use the formula presented above. Simply divide the total number of hours from Step 2 by the number of assets in your group from Step 1.
For example, if 100 identical machines run for a total of 50,000 hours, that total time reflects the entire group’s combined lifespan. When you divide 50,000 by 100, you get 500 hours. That tells you that, on average, each machine lasts approximately 500 hours before failure occurs.
When used alongside any insights on common causes of equipment failure, MTTF helps you identify patterns across similar units. For example, if multiple fans fail due to motor wear, and you consistently see a drop in MTTF, the issue may lie in how the motor handles temperature or vibration.
Guidelines for Precise Data Collection
Consistently Log Maintenance Activities
Record the date, time, asset ID, type of work performed, and technician every time you perform maintenance work (planned or unplanned). This information will help you trace the potential root cause of failure patterns. Comparing preventive and reactive maintenance strategies may also help you identify patterns.
Implement Software That Captures Real-Time Operational Data
Use software and monitoring tools to track total operating time, performance metrics, and downtime. These tools remove guesswork and prevent errors that can come with manual entry. Accurate information allows you to calculate MTTF based on what actually happened, not on estimates.
Define Clear Failure Criteria
Decide what counts as a failure before you start collecting data. If you leave it open to interpretation, some team members may record minor issues while others only log full breakdowns. That inconsistency will skew your results.
Conduct Regular Data Audits
Schedule reviews of your data. These audits help you catch missing entries, repeated values, or outdated records. Such misses may affect your results when you calculate MTTF.
How to Integrate MTTF Into Your Maintenance Strategy
Although it’s easy to find resources that explain how to calculate MTTF, there are fewer that connect it to real-world applications. MTTF gives asset managers a clear view of how long equipment performs before it fails.
These insights support preventive maintenance scheduling, budgeting, and compliance documentation. When appropriately used, MTTF is a powerful metric that helps your facility avoid compliance penalties tied to unexpected failures.
Add MTTF to performance reports to improve capital planning. Start by collecting accurate failure data across asset types. Then, calculate the MTTF for each category and include the result in dashboards used for maintenance planning and budget reviews. Leadership can identify equipment near failure, plan replacements earlier, and allocate capital before downtime disrupts operations.
MTTF Integration: Dos and Don’ts
Do Use MTTF to Guide Preventive Maintenance Planning
MTTF can help you truly discover the benefits of preventive maintenance. You can use the insights you gain from your MTTF calculations to plan scheduled maintenance based on expected wear. The result will be a longer average lifespan for each asset.
Don’t Rely on MTTF Alone
Combine MTTF with other reliability metrics. Single-metric planning can lead to missed information that may affect how you service your equipment.
Do Use MTTF to Improve Inventory Forecasting
Use MTTF data to better plan for replacements. If you know when components are likely to fail, you can stock what you need before you need it. Having replacements on hand when system failures occur decreases the average time you will be left without that system.
Don’t Ignore Variability
Do not treat MTTF values as one-size-fits-all numbers. MTTF reflects averages, and real-world performance can differ across equipment types or different models of the same kind of equipment. Adjust your strategy based on operating conditions, usage levels, and past failure records.
Do Connect MTTF to Cost Savings
Make the financial value of MTTF-driven planning clear. Communicating the return on investment for data-rich maintenance can be a challenge. Help managers understand that using MTTF helps avoid unnecessary downtime and costly repairs.
For example, CorePower Yoga used this data-driven approach to cut facility spending per studio by nearly 50% and reduce invoice amounts by 15% per work order.
Don’t Overestimate Your Historical Data
While assessing your historical maintenance records is valuable, do not over-rely on them. Equipment upgrades, changes in usage patterns, or increased workloads can make older information less reliable. Keep your records up to date to maintain an accurate view of asset performance.
Enhance Your Maintenance Strategies with ServiceChannel
Adopting MTTF-driven decisions can elevate your maintenance strategy to a new level. It can also make asset management much easier, as you will be better able to stock your inventory correctly. While most companies can benefit from this approach, not all have the resources to make it happen.
Choose ServiceChannel’s platform to prepare your team to react before any systems fail. Our tools help you quickly see your average failure rate so that you can make key maintenance decisions sooner and faster.
Take control of your maintenance!
Request a demo from ServiceChannel to enhance your system reliability in the long run.
