Maintenance professionals are constantly on the hook for finding ways to prevent or avoid equipment failure. And for good reason. By avoiding failures, companies can minimize downtime and enhance efficiency. A helpful tool is a metric known as Mean Time Between Failures or MTBF.
MTBF is a helpful way of estimating how long your equipment can operate before experiencing failure. It helps maintenance teams make informed decisions about maintenance practices, and equipment lifecycle management. In this article, we will explore how to use this metric to help machinery function better than ever and positively impact your bottom line.
What is MTBF?
Mean Time Between Failures or MTBF is the average time that passes from the end of one repair to the next failure. MTBF is widely used in reliability engineering to measure the average time between failures over a specific period of time during a system’s regular operation.
MTBF is a helpful tool for maintenance teams working to predict breakdowns and improve reliability. In the field of reliability engineering, MTBF can help you:
- Predict the frequency of repairs
- Manage workload for maintenance technicians and ensure sufficient labor resources
- Ensure repairs are effective across team members and asset types, keeping systems operational
- Plan preventive maintenance inspections and maintenance activities that may help avoid breakdowns
While MTBF is helpful, it can provide even more value when combined with other failure metrics such as Mean Time To Failure (MTTF) and Mean Time To Repair (MTTR) which can help provide important context and insights into maintenance planning.
How is MTBF calculated?
With all that MTBF promises, it might sound complicated to calculate. However, it only takes a few key pieces of information on your maintenance and operations to get there. Let’s break down the process and explore how to calculate MTBF.
The MTBF formula
MTBF is calculated by dividing the total operating time over a specific period, by the number of failures that occurred in that same period. Operating time is the amount of time the system or machine was operational or was planned to be operational. Operating time should not include planned downtimes or previously planned or scheduled non-operating time (such as evenings or weekends).
MTBF = Total Operating Time in Hours / Number of Failures
Step-by-step MTBF calculation
- Define the timeframe you want to examine in number of hours
- Record total operating hours within this period
- Count the number of breakdowns (failures) that occurred
- Divide total operating hours by the number of failures
For example, if a piece of equipment that operates for 1000 hours in a 4-month period and experiences 5 failures, its MTBF for that 4-month period is 200 hours.
Applying MTBF
When looking at an MTBF calculation on its own, it may not mean much other than when you can expect your next breakdown (which is still valuable). Here are a few questions to ask about an MTBF that can help you gain more from the calculation:
- Does my team have enough resources (labor, parts, etc.) to continue performing repairs at the current MTBF rate?
- What changes to our preventive maintenance activity could extend the time between failures?
- Are there significant differences in MTBF for different time periods, locations, or production lines?
- Has MTBF changed significantly over time?
Advanced considerations
The basic MTBF formula is used by a wide variety of industries in many different ways. The more data you track on your maintenance program, the more options you have to dissect and analyze MTBF from different angles. Your organization may choose to:
- Calculate MTBF for specific types or durations of failures
- Include planned downtime or maintenance activities to understand the impact of a broader category of stoppages
- Calculate MTBF for assets of a certain age separately to understand how asset lifecycle impacts the frequency of failures
Advanced documentation and reporting capabilities in solutions such as a Computerized Maintenance Management System (CMMS) automatically track many of the data points that can be used to analyze MTBF in different scenarios. Not only can they provide supplementary data to contextualize these calculations, but they can also automatically calculate them for you and share the data within dashboards and other easily accessible platforms.
Why you should use MTBF
Calculating MTBF isn’t just about predicting your next breakdown. It has the potential to influence much of your preventive maintenance strategy as you try to make improvements. By leveraging MTBF, your teams can:
- Single out assets that need more attention than others
- Distribute resources more effectively
- Recommend equipment upgrades or replacements
- Compare company performance with others in the industry
- Better forecast spare parts inventory needs
Impacts on preventive maintenance and asset lifespan
MTBF helps organizations shift away from a reactive approach to asset maintenance to a more proactive approach that can reduce unplanned downtime and the costs that come with it. When maintenance teams are familiar with the frequency of failures, they can schedule preventive maintenance activities at the right times, making sure equipment runs optimally while avoiding too much wear and tear.
How to improve MTBF
It is important that MTBF is not just a metric that gets tracked regularly. To get the most out of it, it is important to explore actionable tactics for extending it. After all, a higher MTBF means that your equipment and systems are experiencing fewer failures which is great for your business overall.
Implement effective preventive maintenance
Develop a preventive maintenance program tailored to each asset’s specific needs. To prevent minor issues from escalating into major ones, schedule regular inspections, lubrication, and part replacements, extending the time between breakdowns.
Conduct thorough root cause analysis, especially for outliers
If failure happens, don’t just perform a repair and move on. Do a deep dive into the underlying causes of the failure using techniques like the 5 Whys or Ishikawa diagrams. These approaches help you identify and deal with the root cause of the failure, better ensuring they won’t happen again.
Improve equipment reliability through design and upgrades
Retrofit older equipment with more reliable components or upgrade to newer models with improved reliability features. These investments will pay off through lower maintenance costs and fewer failures overall.
Train teams well and develop SOPs
When your operators are trained to operate equipment properly, machines are less likely to fail. Offer comprehensive training programs and clear standard operating procedures (SOPs) based on OEM guidelines. These will show team members how to use equipment safely and detect problems early.
Continuously improve maintenance processes and schedules
It is important to always look for ways to improve maintenance processes. Use MTBF and other data to adjust your schedule for maintaining equipment, balancing the need for uptime with preventive care. Consider condition-based maintenance strategies that save money but also improve the precision of maintenance plans.
Ensure high-quality replacement parts
Don’t skimp on spare parts. The quality of the parts used in maintenance activities has a direct effect on asset reliability. Use MTBF to uncover spare parts that are of insufficient quality or that may be faulting at an unacceptable rate.
Use CMMS and other maintenance software
You’re missing out if you don’t use technology to report on MTBF consistently or manage maintenance activities more efficiently. Learn about the 10 benefits of using CMMS software that positively impact productivity and reliability.
Build the best proactive maintenance strategy possible
By pairing MTBF with other metrics and emerging technologies like AI and machine learning, maintenance teams can unlock new levels of predictive accuracy. It is a simple metric that can provide endless insights to benefit your maintenance practice and your business’s productivity.
