Tips for Using MTBF Effectively: Get the Most out of Your Equipment's Lifetime

Mean Time Between Failures (MTBF) is a commonly used metric in reliability engineering that measures the average time between failures of a system.

Despite its widespread use, there are widespread misconceptions about MTBF, including:

MTBF tells you how long a piece of equipment will last.
No, it only tells you how long a piece of equipment is expected to work before it fails again. It does not tell you how long the equipment will last overall.

MTBF is the only metric you need to evaluate equipment reliability.
MTBF is just one metric that can be used to evaluate equipment reliability. Other metrics, such as Mean Time To Repair (MTTR), are also important.

MTBF is not a perfect metric and has limitations, but is a useful tool to evaluate and understand how reliable your equipment are.

In this guide, we talk about MTBF, its pros and cons, steps to calculate it, and tips to use MTBF effectively to help you make the most of MTBF for your reliability initiatives.  

What is MTBF?

MTBF is defined as the average time between failures of a system, measured in hours. It is calculated by dividing the total operational time of a system by the number of failures that occurred during that time.

MTBF is often used as a reliability indicator for complex systems, such as electronic equipment, where failures can be costly and dangerous.

Why is MTBF important?

Well, MTBF helps you plan and schedule maintenance activities effectively. If you know the MTBF of a piece of equipment, you can predict when it's likely to fail and plan maintenance activities using a predictive maintenance approach.

By monitoring the MTBF continuously, over time, you can detect patterns and trends that may indicate a problem and upgrade to more advanced maintenance strategies like prescriptive maintenance.

How to calculate the mean time between failures?

Calculating MTBF requires accurate data on both the total operating time and the number of failures. You can collect this data manually or through automated systems.

Step 1: Define what constitutes a failure

First, you need to define what constitutes a failure. This can vary depending on the machine or equipment. For example, a failure might be a machine that stops working completely or a printer that produces smudged or unreadable prints.

Step 2: Determine the total operating time

Next, you need to determine the total operating time. This is the amount of time the machine or equipment has been in use.

Step 3: Count the number of failures

Count the number of failures that have occurred during the operating time.

Step 4: Calculate MTBF

Finally, you can calculate MTBF by dividing the total operating time by the number of failures. The result is the average time between failures.

The result is a measure of how long the equipment or system can operate on average before experiencing a failure. The higher the MTBF, the more reliable the equipment or system.

Automated systems like CMMS can simplify the process by collecting data automatically and calculating MTBF in real-time, saving you time and reducing the risk of errors.

Benefits of measuring MTBF

Measuring MTBF brings many benefits, including:

1. Helps prevent unexpected downtime and repairs by predicting when equipment or systems are likely to fail.
2. It identifies systems with low reliability that pose threats to operations, enabling you to plan ahead and save unnecessary replacement costs.
3. Provides data-driven insights into equipment or system performance to help you make better decisions around maintenance scheduling, equipment replacement, and budget allocation.
4. It indicates the quality of parts used, comparable brands, and OEE.
5. It can be telling of the preventive maintenance & repairs effectiveness.

Downsides to relying on MTBF

While MTBF can be a useful metric for determining reliability, there are some limitations to keep in mind:

• MTBF does not take into account the severity of failures. A minor failure that is easily fixed is treated the same as a catastrophic failure that causes extensive damage.
• MTBF assumes that the time between failures follows a statistical distribution, such as the exponential distribution. This is not always the case in practice, especially for complex systems.
• MTBF does not account for repairs or maintenance that may prevent a failure from occurring.

Ultimately, while MTBF can provide valuable insights into equipment or system performance, it should be used alongside other metrics and considerations to get a complete picture of maintenance performance.

Using MTBF to improve maintenance and repairs

Now that you know how to calculate MTBF, how can you use it to improve maintenance and repairs?

Identifying trends and predicting failures

By measuring MTBF over time, you can identify trends and predict when a machine is likely to fail. This allows you to take action before a breakdown occurs.

Scheduling maintenance and repairs

Using MTBF, you can plan maintenance and repairs based on the expected lifespan of the machine. If a machine has a low MTBF, you may want to schedule more frequent maintenance to prevent breakdowns.

Comparing equipment reliability

MTBF can also be used to compare the reliability of different machines or equipment. By comparing MTBF values, you can determine which machines are more reliable and which ones may need more maintenance and repairs.

There is a lot that goes into keeping equipment and infrastructure performing optimally and safely, and measuring MTBF is a step in the right direction toward keeping your assets reliable and improving operational efficiency for your facilities.

Facilio's Connected CMMS unifies assets from across your portfolio to create a centralized control and command center for all things O&M.

It integrates seamlessly with your existing BMS/BAS systems, uses IoT sensors to gather real-time performance data from your assets, and enables bi-directional communication so you can control and command your assets remotely.  

With powerful workflow automation, it can also execute self-set-point corrections for deviations from the optimal working conditions or dispatch work orders to an available technician with details about the root cause of the failure, recommendations and checks to conduct, and an overview of the inventory available.  

Facilio's simple interface and powerful platform enable your maintenance team with the right tools to keep your assets reliable and productive and extend their life cycles.

FAQs for MTBF

1. What is the difference between MTBF and MTTR?
   MTBF measures how often a machine fails, while MTTR measures how long it takes to fix a machine after it has failed.
2. What is the difference between MTBF and MTTF?
   MTBF measures how long a machine will work before it fails, while MTTF measures the average time a machine will work before it fails.
3. Can MTBF be used for all types of equipment?
   MTBF can be used for any type of equipment as long as you have data on how often it fails and how long it operates between failures.
4. Is a higher MTBF always better?
   A higher MTBF is generally better, but it's important to consider other factors like cost and downtime when evaluating equipment reliability.
5. Can MTBF be used to predict future failures?
   MTBF is not a perfect predictor of future failures, but it can give you a general idea of how reliable your equipment is and help you plan maintenance activities accordingly.
6. Can MTBF be used for non-repairable items?
   MTBF is typically used for repairable items that can be restored to working conditions after a failure. For non-repairable items, you may want to use a different reliability metric like Mean Time to Failure (MTTF).
7. How often should I calculate MTBF?
   The frequency of MTBF calculations depends on the equipment and the level of detail you need. For critical equipment, you may want to calculate MTBF on a monthly or even weekly basis, while for less critical equipment, an annual calculation may be sufficient.