5 Tools for Failure Analysis in Maintenance

Failure analysis is part of the maintenance process. That is, discovering why the failure occurred is crucial for addressing the cause and correcting the problem assertively, making the industry more efficient and productive.

According to NBR 5462 (Brazilian technical standard), failure is the end of an item’s ability to perform the required function. This same standard has established the general principles of maintenance management since 1994, making it one of the most important for the area.

When it comes to maintenance management, it is essential to investigate the cause of the failure. Thus, by identifying the root of the problem, repetition can be avoided, and a precise maintenance plan can be drawn up. For this, there are some tools that help in this process and allow for failure analysis in maintenance. Check it out!

Failure Analysis in Maintenance: Get to Know 5 Tools

There are several tools that contribute to investigating what may have caused a failure. The choice between them (or their combination) will depend on what best suits the objective at hand. That is, the techniques will mobilize certain information and offer respective clues to the problem. Therefore, it is important to have clarity about what is intended and how the tool works to make the most benefit from it.

Ishikawa Diagram

The Ishikawa Diagram is used to study and identify the causes of a failure. In this way, the opportunity for correction or learning is generated to prevent future occurrences. With this tool, it is possible to optimize the resolution process. That is, to focus on the solution to the failure and not just the consequences.

The method was created in 1943 by a Japanese engineer, Kaoru Ishikawa. Besides the tool, Ishikawa published several books and is considered one of the greatest authors of quality management.

Over time, the diagram has been refined, and the application of the cause-and-effect model has become applicable to different businesses and sectors. Thus, the method became widespread and received other names. Among them are: the Cause and Effect Diagram, 6 Ms, Cause Tree, PDCA, and Fishbone. Despite some specificities in one or the other, the essence of the tool remains the same.

How to Apply the Ishikawa Diagram

The application of the method is quite simple. However, there are some basic steps to achieve success with maintenance failure analysis.

• 1^st Select the failure or process to be analyzed:

The first step is to choose what you want to analyze. The Ishikawa Diagram allows you to understand the cause-and-effect relationship, that is, the set of factors that generated that result. Therefore, it can be useful for understanding failures as well as inefficient processes or those with many errors.

• 2^nd Draw the fishbone:

The next step is to draw the structure of the analysis. To do this, you need to place the problem to be investigated at the far right of the central line. From there, you need to write the possible primary and secondary causes on the transverse lines.

• 3^rd Analyze cause and effect:

This is the time to evaluate the set of causes and list the most critical ones. Thus, establishing prioritization for resolving each of them and later studying the impacts of their changes.

• 4^th Plan solutions:

After the analysis and prioritization, it’s time to plan the solutions. Here, it’s worth drawing up an action plan, starting from the most critical points and moving on to the less critical ones. Additionally, it’s important to establish the paths for this, identify the necessary resources (if applicable), and, of course, define the time for execution.

• 5^th Validate the results:

Finally, it is essential to evaluate the results of the changes. This way, it will be possible to verify if the method was carried out properly and if the causes were indeed those. The analysis should be recurrent and, therefore, undergo adjustments if the expected improvement is not identified.

Analysis of the 5 Whys

Perhaps this is one of the simplest methods of failure analysis, as the technique basically consists of building logical answers to the “whys.” Thus, starting from the problem and asking questions to discover what caused it.

The tool emerged in the 1950s, developed by the architect of the Toyota production system, Taiichi Ohno. The methodology gained space due to its efficiency and simplicity in solving internal problems.

However, if the team is not prepared or unaware of the most common failure modes, the analysis may be superficial or point to incorrect causes. Additionally, concerning assets, for some components, the 5 Whys method is suitable, while for others with multiple possible causes, it may be insufficient.

For example, components with well-defined construction and maintenance parameters can benefit from the 5 Whys analysis. Among them, we can mention seals, bearings, etc., as they have very characteristic failure modes and usually have a single cause.

However, failures caused by human, organizational, or a combination of factors may not benefit as much from the technique. In this case, it is advisable to consider another investigation method or associate it with other tools.

How to Apply the 5 Whys Analysis

• 1^st Describe the problem:

The first step is to describe the problem. That is, a bearing defect, strange noises in the hydraulic system, etc. It is essential to be objective and clear about defining the problem so that the root cause can be discovered.

• 2^nd Ask “why”:

At this point, you ask why the problem occurred. And then ask why again, and so on… The idea is that after 5 questions, you should obtain the root cause of the problem.

• 3^rd Plan and implement corrections:

Once the cause of the problem is discovered, it’s possible to think about possible resolutions. For example, if you discover that the strange noise in the hydraulic system was due to wear on the seal, you can then plan for replacement and implement a maintenance plan, if necessary.

• 4^th Evaluate and Monitor:

If the resolution eliminated the problem, the method was effective. Otherwise, either the measure was not effective, or the correct cause was not identified. Therefore, it’s important to monitor the process after executing the action to evaluate its effectiveness.

Fault Tree Analysis (FTA)

The FTA is a tool for mapping possible scenarios. It aids asset management by documenting potential failures and mapping the probability of occurrence. Thus, combined with the concept of criticality, the manager can make decisions regarding the choice of maintenance model, for example, among a series of other issues.

The method emerged around 1960 and continues to be used in various industry sectors. The tool allows the calculation of the probability of occurrence of basic events. From this information, it’s possible to construct the diagram following a logical sequence:

How to Apply Failure Tree Analysis (FTA)

• 1^st Define the problem to be analyzed:

At the top of the tree, you should place the problem or failure to be analyzed. It should be objective and concise so that the logical line that generated it can be outlined. For example, a water circulation pump shutdown.

• 2^nd List the intermediate causal events:

At this point, define the possible intermediate events that could indicate a failure. In this example, the pump shutdown can occur if any of the basic events are met. That is, in a pump shutdown case, the cause could have been cavitation, corrosion, or scaling.

• 3^rd Identify the main causal events:

A breakdown or second level of the Failure Tree should point out the root causes. That is, those that caused the intermediate events. For example, in the case of cavitation, the cause is insufficient pressure at the pump suction or liquid vaporization. Thus, air bubbles generate tension in the pump, causing mechanical damage.

Read more about Fault Tree Analysis here.

Pareto Analysis

The Pareto analysis gave rise to the 80-20 idea. That is, 80% of problems originate from 20% of causes. Therefore, the remaining 80% cause 20% of the problems. Thus, the method allows understanding and quantifying the causality of events.

The tool emerged in 1941, developed by Vilfredo Pareto in Italy. Pareto was an economist who found that 80% of his country’s wealth was concentrated in the hands of 20% of the population, causing economic imbalances.

In the case of maintenance, the principle is the same: a few causes generate the vast majority of failures. For example, almost 80% of failures in conveyor belts are practically due to only three causes.

How to Apply Pareto Analysis

• 1^st List the problem and causes:

The first step is to gather the problems and causes through data collection and organization. It’s possible to select a key problem, such as a failure in an electrical transformer. From there, identify the possible causes: manufacturing defects, short circuits, aging, corrosion, etc.

• 2^nd Order the list of possible causes:

Organize the causes from the most common to the least common. This way, you can investigate the most recurring ones that deserve more attention or correction as quickly as possible.

• 3^rd Organize the data:

The third step is to organize the data into a bar chart that relates problems to frequency. It will serve as a basis for maintenance planning and minimizing or solving the problem.

Failure Analysis in Maintenance: Automated Detection

The four tools presented so far are quite manual and have a high degree of subjectivity. After all, the decision on maintenance management will be based on technical knowledge, previous experiences, and even hunches.

Now, professionals who prefer to make decisions with more agility, accuracy, and reliability tend to choose tools that offer greater accuracy. One recommendation in this case is Dynamox’s automated detection tool (DynaDetect).

Although its goal is not to analyze the entire scenario or evaluate the factors that caused the failure, DynaDetect is valuable for pinpointing the problem accurately. Thus, professionals who want a macro analysis can use it in conjunction with other tools to increase the accuracy and agility of the diagnosis.

The DynaDetect acts as a specialist, analyzing information collected by sensors and diagnosing different failure modes quickly. Thus, it’s possible to create alerts categorized by criticality, and if there is any anomaly, the technician will be notified. In addition to diagnostics, it generates reports for faster maintenance planning.

Automated Failure Identification

The tool allows the identification of failures of different types, offering detailed information about the detection. From this, the decision-making process becomes more agile and accurate. Therefore, the tool is a powerful ally for failure analysis in maintenance.

Among the automatically detected failures are:

The goal, therefore, is to assist and increase the reliability and accuracy of technical analysis and support the manager in asset maintenance planning and decision-making. In this context of thousands of collected data points, it is essential that the analyst can focus on the machines and measurements that require the specialist’s attention.