Mean Time Between Failure (MTBF) Calculation, Explained

When trying to manage parts and equipment across business systems effectively, an unexpected parts failure can result in costly downtime and serious stress for business management. 

Without understanding the true reliability of your machinery, it can be a guessing game as to when equipment failures will occur, upending your production schedule and requiring expensive emergency maintenance in the process. Your business requires a strategy for predicting failures so that you can maintain smooth workflows and prepare accordingly for inevitable machine breakdowns.

That’s where mean time between failure (MTBF) comes into play. With simple calculations, you can predict with accuracy when equipment failures are expected to occur across business systems, allowing you to schedule preventive maintenance accordingly and replace parts that fail too frequently. Follow along for everything you need to know about calculating MTBF and how to create a comprehensive maintenance strategy that helps you plan better for potential failures.

What Is MTBF?

MTBF is a maintenance metric used for calculating the average time between system breakdowns. Used correctly, it is an effective measure for determining how reliable an asset is. A high MTBF indicates that an asset can operate for longer periods of time without failure; whereas, a low MTBF signals that equipment will need frequent maintenance and cause unexpected system breakdowns.

MTBF does not account for scheduled maintenance but rather only unplanned maintenance. MTBF is one half of the mean time to repair (MTTR) formula used for measuring the average amount of time required to repair an asset that failed. 

MTTF vs. MTBF vs. MTTR

There are a variety of maintenance calculations needed to accurately calculate important metrics about your equipment and systems, including mean time between failure (MTBF), mean time to repair (MTTR) and mean time to failure (MTTF). Let’s discuss the importance of each and how they differ.

As mentioned, MTBF is a formula for measuring the reliability of an asset and how often that asset has unplanned failures. 

What’s the Difference Between MTBF & MTTR?

MTTR measures the average time it takes to repair a system or piece of equipment after it failed; while MTBF shows a piece of equipment’s reliability, MTTR shows its maintainability. 

What’s the Difference Between MTBF & MTTF?

Mean time to failure calculates how long a piece of equipment has before complete failure. Unlike MTBF, this type of equipment failure cannot be repaired.

How Do You Calculate MTBF?

Calculating the average time between unplanned system breakdowns is integral to mitigating risk and understanding when failures may arise. The MTBF formula is simple: It’s calculated by dividing the number of operational hours (between failures) by the number of failures during that given period.

Let’s demonstrate this calculation with a simple example. Suppose you have an HVAC system that was operational for 1,200 hours in a year, and it broke down 10 times during that specific period of time. 

Using the formula, you divide total operational hours (1,200) by total number of failures (10). By calculating 1,200/10, the MTBF value is then 120 hours.

Why Should You Calculate MTBF?

Calculating MTBF is integral to effective asset management by determining the likelihood and frequency of an asset failure occurring. 

Here are the core ways performing MTBF can support a maintenance team’s asset management strategy:

• Set a baseline for preventative maintenance: By understanding the types of failures that are likeliest to occur and when, you can build a preventative maintenance plan for enhancing asset reliability and preventing the failure from even occurring in the first place. 
• Planning for specific types of failures: Understanding which failures happen most frequently allows you to plan accordingly to ensure costly delays or safety hazards don’t arise. 
• Better inventory management: If you know when an asset is likely to fail, you can pre-order replacement parts so that they’re in stock as needed for repairable items.
• Knowing when to replace an asset: If a piece of equipment has a worsening MTBF and a frequent failure rate, using this key performance indicator (KPI) can make it easy to dictate when replacing equipment is more worthwhile than repairing it. 

How to Improve MTBF

Investing in your infrastructure can help extend the total operating time between failures for core business systems. As such, here are the best ways to improve MTBF for your equipment and systems:

Invest in Better Quality Parts & Systems

Being cheap when it comes to equipment and parts come at a cost. Failures are likely to happen more frequently, requiring expensive repairs and causing unplanned downtime and outages. Consider a proactive approach by purchasing high-quality equipment at a higher cost to save money and to increase the total uptime for your assets in the long-term. 

Follow Manufacturer Recommendations 

Ensure your equipment is operated and maintained with optimal conditions. Manufacturers perform extensive testing to dictate the best ways to use and maintain their equipment, and proper usage ensures there is no misuse that can cause more frequent failures.

Create a Preventative Maintenance Plan

Proactively maintaining your equipment by checking on core components that commonly fail can ensure you catch minor issues before they turn into serious and costly system failures. Schedule maintenance tasks to regularly check on your equipment, especially on infrastructure with a low MTBF. 

Key Benefits of Improving MTBF 

By focusing on improving MTBF, businesses can reduce downtime, optimize maintenance costs and enhance overall operational efficiency. Here are major benefits that come with focusing on MTBF:

Increases Asset Reliability & Lifespan

Improving MTBF means less part failures and more reliable system operations. When equipment components operate functionally for longer periods, they deal with less stress and wear, leading to fewer repairs and longer service life.

Reduces Maintenance Costs

By reducing the total number of equipment failures, you won’t have to pay for costly emergency maintenance as frequently. Additionally, longer time frames between failures means you can optimize your recurring maintenance schedule to be more efficient and organized to prevent downtime and lower costs.

Enhances Quality 

When breakdowns and disruptions occur less frequently, machines will maintain optimal performance levels longer, leading to a consistent production output, less manufacturing errors and stability across business procedures.

Creates Workplace Safety

By reducing the likelihood of unanticipated equipment failures, there is a risk reduction of accidents caused by malfunctioning equipment. And with less emergency maintenance needs, you’re limiting the actual time maintenance workers need to spend in potentially dangerous work environments repairing broken parts. 

Makes Purchasing Decisions Easier

Having metrics on the reliability and functionality of equipment can help in making informed decisions across particular systems. By calculating MTBF when acquiring new equipment, business owners can determine the lifecycle costs of equipment beyond the initial purchase price, leading to more informed purchases of machinery that will function longer without frequent failures and costly repair needs. 

Using a CMMS for MTBF Calculations

Using a computerized maintenance management system (CMMS) like Coast can make calculating MTBF and managing your equipment substantially easier because it helps you automatically track data on equipment run times, failure occurrences and historical repairs. With access to this data in an easy-to-understand maintenance report, your MTBF calculation will be simple to calculate and much more accurate.

Beyond the calculation, once you understand how frequently recurring maintenance is needed to maintain your equipment and prevent failures and downtimes, you can automatically schedule maintenance work orders as needed to check on important equipment and maintain optimal operating conditions. 

Don’t wait to collect the maintenance data your business requires to calculate mean time before failure accurately. Get started with Coast today to organize all your maintenance needs in one simplified digital platform.