Mean Time Between Failures: MTBF Guide and Template

MTTR MTBF MTTFDo you ever wonder how long a repair will last? Or how soon you will have to return to the same asset to fix it again?

Mean time between failures (MTBF) is a metric  that helps you predict failures and prepare for repairs, maximizing uptime and overall productivity. 

This guide will define MTBF, explain why it’s important, and share practical tips for how to calculate and improve it. Let’s go!

Mean time metrics overview

Failure is inevitable in the maintenance world. Understanding how to use incident or mean time metrics to plan for failure is critical to minimizing its negative effects. 

What are key failure metrics to pay attention to? 

In this post, we will discuss how to calculate and use MTBF. You will find, however, that using all three will provide you with the most useful data and KPIs (key performance indicators). 

Make sure you read our posts on MTTF and MTTR to get a complete understanding of their value, how and when to use them, and what they mean for your organization. 

What is MTBF, or mean time between failures?

Mean Time Between Failures is the average time that passes from the resolution of one equipment failure to the start of the next. Knowing your MTBF gives you an idea of how long a piece of equipment will keep running between unplanned breakdowns, helping you plan for the unexpected.

MTBF (Mean Time Between Failures)

Why MTBF metrics are important

Equipment failures can be expensive and damaging to an organization. MTBF helps you predict and prepare for breakdowns, enabling the quick and effective repairs that minimize the fallout from downtime. 

It is also an important indicator of overall performance. If your MTBF value is low, you are experiencing a high frequency of breakdowns. This likely means there are systemic issues to explore.

What MTBF means for your organization

Manufacturers use mean time between failures as a way to predict the reliability and failure rate of equipment during the different stages of production. It is also commonly used today in:

  • mechanical and electronic systems design
  • safe plant operations
  • product procurement

Calculating MTBF does not include planned maintenance, but it does help you plan inspections for preventive replacements. For instance, if it is known that an asset will likely run for a certain number of hours before the next failure, introducing preventive maintenance actions like lubrication or recalibration can help prevent that failure.

Knowing your MTBF helps save you money, increases total uptime, and makes you look good at your job – and who doesn’t want that?

When to measure your mean time to repair

Use MTBF to start conquering downtime. This is by far its most important application. But MTBF can also help predict, prevent and prevail over the bulk of your unplanned breakdowns. You’ll be able to use it for: 

  • Asset management, planning and forecasting your inventory of spare parts and maintenance tools
  • Budgeting CAPEX
  • Planning your maintenance schedule 
  • Indicating PM performance 
  • The quality of the information you have in your system and how it is being used 

Mean Time Metrics Calculator

Just getting started with maintenance metrics? Use this helpful calculator with formulas and calculations.

How to calculate MTBF 

Calculating MTBF doesn’t have to be hard. As long as you are tracking the total hours your asset has been operating and the total number of failures that have occurred, you have everything you need. You can even use easily accessible tools like Microsoft Excel to easily find your mean time between failure.  

The data needed to find your MTBF 

To calculate MTBF, you simply measure the total operating time of an asset in a given period, and divide that by the number of unplanned failures in that same timeframe. Therefore, you will need to track total operational time for a piece of equipment by simply making note of: 

  • The date and time an unplanned breakdown begins
  • The date and time the equipment resumes operation

Note: MTBF doesn’t take predictive and preventative maintenance into account.  While they can sometimes cause brief outages, they are do not qualify as breakdowns

A simple MTBF calculation

The equation for MTBF is simple. It is the sum of operating time divided by the number of failures.

How to calculate MTBF 

Remember that when representing time in these calculations, to always use the same unit of measurement (i.e. always in hours or always in minutes). For instance, let’s say you have a generator or set of generators that were operational for 750.5 hours (or 750 hours and 30 minutes), but experienced 4 failures within that same timeframe. 

Entering those numbers into our formula gives us: 

MTBF = 750.5 / 4

MTBF = 187.625 hours

How to calculate MTBF using software and other reporting tools

While it is good to know how to measure MTBF by hand, it is impractical to plan to do it that way every time. A simple spreadsheet makes calculating MTBF easy as long as you are making note of the correct data. But a CMMS software basically does all the work for you.

With a CMMS like Limble, equipment failures are logged through the work request process, tracking downtime and operational time automatically. As a result, your mean time metrics begin calculating the second you begin using the system, building a dashboard of useful KPIs. 

However, if you aren’t quite ready to take the CMMS plunge, we have created a handy calculator. Download it, and see how nice it is to have the work done for you!

How to increase MTBF and improve productivity

For MTBF, the longer the better. There are small things you can do to increase the time between failures. Some of them are:

  1. Do more proactive maintenance work. Assets that are well-maintained are less likely to have critical failures. By using Limble as your CMMS, you can create monthly maintenance schedules in minutes. 
  2. Use quality replacement parts. The cheapest part is not always the best. Make sure you are using quality, proven parts that will have the durability to keep working for a longer period of time
  3. Use recommended input material. Whether it is the size of the chicken in the poultry processing system or the thickness of the foil used for product packaging, every machine is designed to work within specific parameters. Respect those parameters.
  4. Ensure proper working conditions. Don’t push machines beyond their limits to make your productivity numbers look good. Misusing machines is a surefire way to decrease their useful life and increase the frequency of failures.
  5. Have a solid onboarding program for machine operators. Assets should be used according to their design. Improper handling is bound to shorten MTBF. Limble allows the user to log work orders and add detail about how the unit was being used at the time of failure, so you’ll be able to monitor asset usage. 
  6. Implement a structured root cause analysis process. Taking the time to understand the true causes of failures will help your team apply effective repairs more quickly.
  7. Understand the kinks of old equipment and aging assets. Sharing information and tips between maintenance technicians and machine operators helps keep assets in good shape. Limble keeps a complete maintenance history, asset log, and maintenance notes throughout the lifecycle, making it easy for anyone on your team to step in and save the day. 

Take the guesswork out of metrics

Knowing how to calculate and effectively use your incident metrics is key to your success as a maintenance team. In particular, understanding how to use your MTBF metric to your advantage. 

Whether you’re just getting started or you know your incident metrics like the back of your hand, tracking metrics can be time consuming and overwhelming if you don’t have reliable maintenance software. Not to mention, manual calculations leave a lot of room for human error. Let Limble make your life easier and help you automate your incident metrics!. 

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