September 30, 2024

What Mean Time Between Failures Means

A maintenance department conducts asset management by analyzing several factors. One of those is the mean time between failure (MTBF). This calculation is key to asset/equipment performance, safety, design, and reliability. But what does mean time between failures mean? In this article, we’ll discuss the following:

• Definition.
• How to calculate it.
• The importance of the results.
• The advantages and disadvantages of the formula.
• How a computerized maintenance management system benefits.

Definition

MTBF helps measure a system's reliability. It's the average amount of time a system or component will operate before it fails. You see this metric often used in industries like manufacturing, technology, and aerospace to predict equipment lifespan and optimize maintenance schedules.

How to Calculate MTBF

Keep in mind that MTBF considers unplanned maintenance events. It does not factor in scheduled maintenance activities like inspections, recalibrations, or preventive parts replacements.

To calculate this, divide the total operation hours by the number of failures during a specific period.

For instance, let’s set the period for one year. Machine A operates for 2,000 during that year and experiences ten breakdowns. Therefore, 2000 divided by 10 equals 200 hours for MTBF.

This simple example doesn't take into account the individual asset's actual performance. You cannot consider this calculation a "one size fits all." You need to factor in aspects of design, assembly, preventive maintenance, and operational practices.

Importance of MTBF

You have the data from MTBF, failure codes, root cause analysis, and another metric, mean time to repair (MTTF) to consider. With this information, you adjust preventive maintenance strategies to:

• Reduce the number of incidents of unplanned breakdown.
• Reduce costs.
• Increase productivity and efficiency.

This also helps you with asset life cycles. For instance: the depreciation value versus the cost of replacement or a new machine.

MTBF utilization also enhances inventory management. You can refine your approach to maintenance, repair, and operations (MRO) inventory purchasing.

Advantages of MTBF

Other benefits of calculating MTBF:

• Manufacturers’ Perspective: MTBF helps manufacturers assess the expected product lifespan and product reliability.
• Risk Identification: The calculation helps to identify potential operational risks. This knowledge is important for both maintenance and production line personnel, as well as the manufacturer.
• Quality Assessment: MTBF serves as an indicator of the quality of materials and parts used in the production process.
• Effectiveness of Maintenance: Use it to gauge the effectiveness of preventive maintenance and repair processes. Are you doing the right maintenance activities within the appropriate time period to ensure the greatest amount of operational uptime?
• Performance Comparison: MTBF allows for performance comparisons between different models and brands of the same product.

Disadvantages of MTBF

While we’ve discussed the benefits, let’s look at two drawbacks to be aware of.

• Incomplete Insight: MTBF alone does not provide information about the causes or severity of failures. It offers only a limited perspective on asset reliability. Once again, you have to look at other factors and use other metrics as discussed above.
• Susceptible to Outliers: Be aware of outside factors that could skew the numbers. For instance, weather causes a tree to damage the roof of the main production building and break a machine.

Yes, this last represents an incident of unplanned breakdown. However, you wouldn’t necessarily add it to the MTBF when analyzing the effectiveness of maintenance, the design, etc. of that machine.

An analogy you can use: Many book-related sites have a review section. Someone submits a one-star book review because the product arrived with torn pages. You should consider this review and measurement unfair. The review doesn't relate to the writing or the story, but it throws off the star average.

CMMS

Many industries use CMMS software to help keep maintenance departments organized. But how does it help MTBR?

• Central Database: Assets, inventory, preventive maintenance (PM), work orders, and more. You have easy access to all asset information, maintenance history, and equipment readings.
• Equipment readings: Let's talk more about these. Set up regular cycles of recording various readings. PSI, temperature, lubrication amount, running speed, vibration level, and so many more. With these in hand, you chart the progress of asset operations. From there, you further refine your PM schedule.
• Inventory: Improve efficiency and MTBF with accurate stock information automated by the CMMS. It tracks quantities and helps you organize the stockroom.
• Reports: Generate key performance indicators (KPIs) reports, as well as others that give you better maintenance management oversight.

Conclusion

Understanding what mean time between failures means helps you mitigate unplanned downtime within your facility. Asset failures occur for numerous reasons. You need to analyze and resolve the underlying causes. Tracking and analyzing MTBF can provide essential data for improving asset reliability. Enhancing MTBF and asset reliability yields substantial benefits across your organization, from the shop floor to the executive suite.

MAPCON / 800-922-4336