Mean Time Between Failures (MTBF)

Equipment failure is common in many businesses and is regarded as a root cause of unplanned downtime in manufacturing processes. System failures and the resulting unplanned downtime can have a significant impact on businesses. Asset failure can result in lost production, missed deadlines, dissatisfied customers, and, ultimately, a dip in profits. All this is before calculating the cost of the repair process.

Unplanned downtime is expensive and estimated to cost up to $50 million each year. So, how can businesses effectively reduce downtime and ensure their company runs at full capacity throughout their operating hours?

Here, we will discuss mean time between failures and describe what MTBF is, how to calculate MTBF, and how this can help your business to minimize downtime. Read on to learn everything you need to know about mean time between failure and how to calculate MTBF.


What is Mean Time Between Failures?

Mean time between failures is often referred to by the acronym MTBF. Mean time to failure is a calculation in reliability metrics to assess a system’s reliability.

An MTBF calculation acts as a maintenance metric to measure the average time between failures and the total uptime of the equipment.

The MTBF is measured in hours, providing useful data on asset reliability.

Mean Time Between Failures being examined by two male staff members


How to calculate MTBF

Mean time between failures is calculated using the MTBF formula. To accurately calculate MTBF, you need to carry out some data collection to obtain the following figures:

  • The total number of operating hours that the asset was working correctly.
  • The number of times failures occur.
  • The total number of hours that the repair took to complete.

When gathering your repair data, it is essential that you do not include scheduled maintenance activities of each asset in your calculations, as this will impact the accuracy of your MTBF calculation and deliver inconsistent results.


MTBF formula

To calculate mean time between failure, you need to take the total uptime the equipment operates and divide this by the number of times the asset fails during this same period.

Your MTBF calculation will look like this:

Total hours of uptime/number of breakdowns = MTBF


MTBF formula example

After gathering your data, you will be ready to calculate MTBF using the formula.

Your machine runs for 24 hours before a component fails, and each failure takes two hours to repair.

An example of time between failures MTBF calculation for this data would look as follows:

24 hours of uptime with two failures – four hours of repair = 20 hours

20 hours/two failures = 10

This data shows the average time between failures for this piece of equipment is just 10 hours.


Why is calculating MTBF important?

Calculating time between failures MTBF is essential for assessing the reliability of critical assets. MTBF plays a crucial role in informing your company’s failure metrics and can be used to inform inventory control and reduce the failure rate of equipment while improving reliability.


Understanding your MTBF results

Once you have gathered your data and used the MTBF formula to calculate the results, it is time to get a better sense of what the data is telling you. Based on your results, you can determine how to reduce your mean time between failures and identify where equipment improvements need to be made to increase reliability.

Low MTBF – A lower MTBF rate means that your equipment is prone to frequent failures and that the reliability of your assets is at a low level.

High MTBF – A higher MTBF rate shows that you are achieving an asset’s reliability rating that is high, meaning that equipment failure is a rare occurrence.

System failures are a situation that no business wants, especially when assets fail to work on a regular basis. So, if your MTBF rate shows that system failures occur regularly in your business, it is crucial to work toward achieving a high MTBF rate.


What are the benefits of MTBF calculation?

Now that you have completed calculating MTBF, you will have a clearer idea of your asset performance and how frequent equipment failure is in your operation. But you may now be wondering what to do with these results and how they will benefit your company.

Understanding your asset performance delivers many benefits for your organization. Here are just some of the benefits that MTBF provides:


Reduce unplanned downtime

MTBF data provides your maintenance team with a clearer understanding of when equipment failure occurs and how frequently this takes place. This information helps the team determine when best to carry out preventive maintenance tasks to minimize the risks of downtime.


Improve operational efficiency

Maintenance metrics are essential when making informed decisions on how to manage assets. Understanding whether each piece of equipment is helping to improve efficiency or reducing it will determine whether the asset needs to be replaced and whether it is worth further repair and maintenance.


Measure an asset’s reliability

Reliability engineering is central to any manufacturing business. All assets need to be chosen and used based on their ability to perform without failure. The MTBF calculation identifies pieces of equipment that fail frequently and helps to predict their reliability in the long term and the impact this may have on uptime and system downtime.

Enhance equipment buying decision making process

Investing in reliable equipment is an excellent way to make informed asset purchase decisions and source the best equipment for your business. Buying high-quality, reliable equipment will help to lower costs by ensuring that system failure is rare and the MTBF score is low.


Inform preventive maintenance schedules

Root cause analysis is essential when deciding on the next steps that your maintenance teams need to take. Planning maintenance programs and where best to direct resources are decisions that need to be made based on reliable data, which can be provided using the MTBF formula.

If a machine breaks down frequently, preventive maintenance may no longer be a cost-effective option that is worth pursuing. However, if a machine tends to fail after the same number of hours and frequently has the same fault, a preventive maintenance schedule informed by the MTBF calculation can be a significant help.

Two heavy industry engineers calculatin MTBF in manufacturing


What is the difference between MTTF, MTBF and MTTR?

MTBF is not the only measure of equipment time and failures. Another mean time measure used for equipment failure is MTTF, which stands for mean time to failure. MTTR is another mean time measure commonly used and refers to mean time to recovery. MTTR, MTTF, and MTBF are each important measures for achieving optimum efficiency, as they perform different roles and are used in different circumstances.

While MTBF is used to measure the mean time between failures of assets, MTTF is used to measure the mean time a piece of equipment is used before it completely fails. So, the MTBF measure is used to inform businesses of the mean time before their equipment requires repair; MTTR measures the average time taken from when an asset fails until it becomes operational once again. In contrast, MTTF measures the mean time before an asset reaches the end of its lifecycle and suffers complete failure requiring unscheduled removal.


Issues when capturing MTBF data

Understanding the potential limitations and issues that can occur when calculating your MTBF data is essential. Here are some of the potential issues that can impact the accuracy of your data:

Potential inconsistencies

While everyone in your business may use the same MTBF formula to perform their calculations, there is still room for inconsistencies. Differences in the classification of a failure may occur and lead to inconsistencies in your MTBF data.

Some of your team may only record critical failures, while others may include system aborts and partial failures in their downtime calculations. These reporting inconsistencies can significantly impact the accuracy of your MTBF data calculations.

Incomplete reporting

Incomplete reporting of repairs and failing to update maintenance records can impact the reliability of your MTBF data. Without complete maintenance and repair records, calculating your MTBF figures accurately will be impossible.

MTBF results being examined by operations manager of manufacturing plant

How to improve MTBF

Using the MTBF formula can be extremely helpful in determining the reliability of assets, how often proactive maintenance is required, and their cost-effectiveness. In turn, this data can inform strategies that improve MTBF and increase efficiency. However, inconsistencies in reporting and differing views on the definition of asset failure can lead to inaccurate results.

Using tools such as OEE software that continually tracks the performance and productivity of each piece of equipment will help to improve the accuracy of your MTBF reporting. With accurate, real-time reporting, you will be able to make informed decisions that improve productivity and drive efficiency to new levels.

Continual monitoring of your equipment and processes enables you to reduce the costs associated with system downtime, improve maintenance procedures, and increase profitability. This can be achieved with the help of software featuring real-time tracking and the capabilities to take your manufacturing processes and provide the data you need to improve them.

If you are hoping to improve your production processes and achieve higher MTBF, the right software is crucial.