• 01276 855 847 Nationwide (UK)
  • info@bmscontrols.co.uk Email Us
  • Unit C1D, Fairoaks Airport Surrey, GU24 8HX

BMS Controls Articles

What is a Time Between Failures?

What is a Time Between Failures?

Understanding the concept of “time between failures” is essential for any company that relies on the reliability of its products and services. Time between failures (TbF) is a measure of how long a system can operate without failing, which is an important consideration for businesses because it helps them to determine the cost and potential risk associated with their operations. In this blog post, we’ll explore what time between failures really means and how it affects businesses. We will cover how TbF is used to measure product reliability, what factors affect it, and why it’s so important for companies to understand this concept. Ready? Let’s dive right in!

What is a Time Between Failures?

A time between failures (TBF) is a measure of reliability, usually denoting the expected time between two failures for a repairable system. It is often used in conjunction with mean time to repair (MTTR), which is a measure of maintainability. Together, these parameters provide valuable information about the health of a system.

TBF data can be used to identify areas in need of improvement and to assess the effectiveness of preventive maintenance measures. Additionally, TBF analysis can be used to calculate availability, which is a key metric in determining the feasibility of a system.

There are several different ways to calculate TBF, depending on the type of data available. One common method is to use failure rate data from field studies or experiments. This approach requires knowledge of the total number of failures and the total operating time for a given period. Another method is to use repair records from past events. This method relies on understanding not only when failures occurred, but also how long it took to repair them.

Whichever method is used, it is important to consider both MTTR and TBF when assessing system reliability. Together, these metrics provide insights into how likely it is that a system will experience downtime and how long that downtime might last.

How is a Time Between Failures Measured?

There are a few different ways that a time between failures can be measured. One common way is to simply measure the amount of time that passes between two failures. This can be done by either keeping track of downtime manually or by using software that automatically records downtime.

Another way to measure time between failures is to calculate the mean time to failure (MTTF). This is done by taking the total number of hours all devices have been operated for and dividing it by the number of failures. This gives you an average amount of time that passes before a failure occurs.

Yet another way to measure time between failures is to calculate the median time to failure (MTTF). This is similar to calculating the MTTF, but instead of using the total number of hours all devices have been operated for, you use the median number of hours. The median is the middle value in a set of data, so this method is more accurate if there are a lot of outliers in the data set.

No matter which method you use to measure time between failures, it’s important to remember that this metric only tells you how often devices fail—it doesn’t tell you why they’re failing or what can be done to prevent future failures.

What Causes Time Between Failures?

There are many factors that can lead to increased time between failures. Poor maintenance practices, lack of proper lubrication, and incorrect installation procedures are just a few of the things that can cause problems. In addition, inadequate training of personnel can also lead to an increased number of failures.

How to Reduce Time Between Failures

One of the best ways to reduce the time between failures is to have a comprehensive maintenance program in place. By regularly servicing and inspecting your equipment, you can identify potential issues before they cause a failure. Additionally, keeping spare parts on hand can help you quickly fix any problems that do arise.

Another way to reduce the time between failures is to implement proper training for all users of your equipment. By ensuring that everyone knows how to properly operate and care for your machinery, you can minimize the risk of human error causing a breakdown.

Finally, establishing clear procedures for responding to failures can help you get your equipment up and running again as quickly as possible. By having a plan in place, you can avoid unnecessary delays and keep disruptions to a minimum.


Time between failures is an important metric to understand when assessing the reliability of a system. It can help you determine how well it will perform in more demanding scenarios, and guide your decision-making when considering which systems or products to invest in. By understanding what time between failures is and how it’s calculated, you’ll be better equipped to make informed decisions about which systems or products are right for your needs.