What is Mean Time to Failure (MTTF)?

MTTF, or Mean Time To Failure, is an essential component of the three-legged stool of maintenance metrics along with MTBF (Mean Time Between Failures) and MTTR (Mean Time To Repair). When combined with these metrics, MTTF provides valuable insights for maintenance teams in anticipating and managing equipment failure. In this blog post, we will delve into the concept of MTTF, exploring how it is calculated, and its significance in helping organizations predict and effectively handle potential failures.

What is mean time to failure (MTTF)?

Mean time to failure serves as a measure of the average lifespan or operational duration of a component before it malfunctions. It becomes particularly significant when considering parts that cannot be repaired, but exist within repairable assets. For instance, you can calculate the MTTF of a fan belt on a forklift. If the fan belt breaks, you won’t be able to safely repair it, but once you replace it, the forklift will work properly again.

Hence, MTTF enables us to monitor and manage these smaller, replaceable elements that play a crucial role in maintaining the larger, repairable assets. While a single fan belt may seem inconsequential, its housing within the forklift holds the utmost importance in ensuring smooth operations. Therefore, acquiring comprehensive knowledge about such components, like fan belts, becomes increasingly valuable in optimizing operational efficiency.

How to use MTTF?

The MTTF formula is a crucial factor in incident management, helping companies identify issues with their systems and processes. It is a concept widely used in reliability engineering, which focuses on ensuring that equipment functions without failure by applying the best engineering practices.

Mean time to failure serves as a useful indicator of a part’s reliability, as it measures the lifespan of an asset which can’t be repaired. If you have a low MTTF, it may indicate that your organization should consider switching suppliers or investing in higher-quality parts. This can lead to longer MTTF values and cost savings in the long term. Essentially, Mean Time to Failure is an essential metric for tracking the performance of the small, replaceable parts that are crucial for keeping your large, high-value assets operational.

It’s important to mention that mean time to failure is closely linked to another metric known as mean time between failures (MTBF), which calculates the average lifespan of items that can be repaired. By enhancing the MTTF of low-cost, non-repairable items, you can effectively prolong the life cycle of your most valuable assets. As a result, an increase in MTTF typically leads to a higher MTBF value, indicating enhanced overall reliability.

When to use MTTF?

Understanding mean time to failure and its applications can greatly enhance your maintenance and asset management strategy. Here are a few scenarios where calculating MTTF proves beneficial:

1. Enhancing Maintenance Schedules: By calculating MTTF, you can effectively schedule maintenance for non-repairable assets. In cases where preventive maintenance can extend the lifespan of a part and contribute to the longevity of a mission-critical asset, MTTF helps determine the optimal timing for such maintenance tasks. For instance, lubricating bearings on a larger machine can be strategically planned based on the MTTF.
2. Making Informed Purchasing Decisions: MTTF calculations assist in making informed decisions regarding the purchase of parts and equipment. Materials that offer higher quality and durability tend to exhibit a higher MTTF value. Consequently, investing in such materials reduces the frequency of buying new parts and replacing old ones, ultimately saving valuable resources.
3. Just-in-Time Inventory Management: MTTF plays a crucial role in establishing a just-in-time inventory strategy. Suppose a facility is aware that a specific part has an MTTF of 10,000 hours, and it takes around 100 hours to procure a replacement. In such cases, by ordering a new part every 9,900 hours, the facility can effectively manage its inventory. This approach ensures that replacement parts are readily available just in time, minimizing downtime and optimizing operations.

How to Calculate MTTF?

To determine the mean time to failure, we can employ a straightforward calculation. Simply divide the cumulative number of operational hours by the total count of assets being utilized.

MTTF Formula:

MTTF = Total operational hours ÷ Total assets in use

For example, let’s consider a scenario where the total operational hours amount to 10,000 and 40 assets are being employed.

MTTF = 10,000 hours ÷ 40 assets

This calculation yields an MTTF of 250 hours.

It is important to note that when calculating the MTTF using a larger number of assets, the resulting value will provide a more accurate representation of the average time until failure occurs. This means that a higher number of assets being considered helps in obtaining a more reliable estimation of the expected time until an asset fails.

How to improve MTTF?

How can you increase the lifespan of your assets before they fail? Here are some practical tips to consider.

Choose Reliable Materials and Parts

It’s important to purchase assets and parts from reputable producers who adhere to strict quality standards. This way, you’ll acquire durable materials that can better withstand the test of time.

Utilize Assets for Their Intended Functions

Simply buying high-quality materials is not enough – you also need to use them specifically for their intended purposes to make their lifespans as long as possible. This means making sure operating conditions such as pressure, heat, and voltage are suitable for the asset. It’s also advisable to have qualified professionals handle the installation to avoid costly mistakes.

Establish an Effective Preventive Maintenance Program

Waiting for assets to fail before taking action is not ideal. That results in high costs in terms of money, time, and effort. Instead, if you want to improve MTTF, consider adopting a proactive maintenance approach that includes activities like regular cleaning and lubrication.

Maintain Proper Inventory Control

Surprisingly, inventory management can also impact MTTF. When you excessively stock your inventory and items remain in the warehouse for extended periods, they are more likely to get damaged, rusty, or expire. Faulty equipment and parts will inevitably have a shorter lifespan before experiencing breakdowns. For this reason, we recommend that organizations keep stock of their inventory in a timely and thorough manner.

How NEXGEN Can Simplify the Process?

Although it is beneficial to understand manual methods of calculating Mean Time to Failure (MTTF), relying on them for every instance is impractical. Luckily, there are more efficient alternatives such as using a spreadsheet or CMMS software. NEXGEN CMMS simplifies the process by automatically logging equipment failures through the work request process, and accurately tracking downtime and operational time. This automation enables the system to start calculating your meantime metrics immediately, providing you with a comprehensive dashboard of key performance indicators (KPIs).

By continuously monitoring your MTTF and other failure metrics, you gain valuable insights that empower you to maintain a healthy maintenance budget and prevent unexpected expenses related to equipment replacement. Implementing effective incident management can be a demanding task, but NEXGEN eases this burden by offering global-level assistance for all assets and detailed reporting for each asset. By ensuring that you update each task with the necessary data, the CMMS system automatically tracks these maintenance metrics for you.

FAQs

1. What is the difference between MTTF and MTTR?

   Unlike MTTF, which refers to how long it takes for an asset to fail, mean time to repair (MTTR) refers to the average amount of time required to fix a malfunctioning asset. By minimizing MTTR, we can effectively decrease both downtime and installation expenses. A high MTTR can result from factors like an insufficient workforce or inadequate inventory management, which often lead to delays in ordering and receiving replacement parts. To mitigate the impact of MTTR, numerous companies opt to proactively acquire spare parts, enabling swift installations when replacements are needed.

2. What is the difference between MTTF and MTBF?

   The concepts of mean time to failure (MTTF) and mean time between failures (MTBF) are interconnected. MTTF represents the average lifespan of a non-repairable asset, while MTBF quantifies the time between failures for repairable assets, usually measured in hours. When the parts of a significant, mission-critical asset have a high MTTF, it can positively impact the overall MTBF of that asset.

3. How do you calculate MTTF?

   To determine the mean time to failure, we can employ a straightforward calculation. Simply divide the cumulative number of operational hours by the total count of assets being utilized. MTTF = Total operational hours ÷ Total assets in use

4. What is the difference between lifetime and MTTF?

   Lifetime is the total duration an asset functions until it fails or is decommissioned. MTTF (Mean Time to Failure) is the average time an asset operates before it fails for the first time. MTTF is used mainly for non-repairable components.