What is FMEA?
Failure mode and effects analysis, or FMEA, is a common process analysis tool that many organizations use for process analysis and risk management. FMEA helps organizations assess ways in which failures can occur and how these failures can lead to negative results. Unlike root cause analysis, which is typically executed after effects occur, FMEA is typically done during the design stage so all possible failures can be identified before the processes are put into action. FMEA is divided into two factors:
- Failure modes, which are ways (both potential and actual) in which something could fail, and
- Effects analysis, during which you analyze the consequences of said failures.
There are a few different types of FMEA analyses: functional, design, and process. FMEA might also sometimes be called FMECA (failure mode, effects, and criticality analysis) if criticality analysis is also performed.
A brief history of FMEA
According to the American Society of Quality, FMEA was developed in the 1940s and was utilized by the U.S. military to identify and respond to potential production failures before they happened. The technique was effective enough to then be utilized by NASA for various programs, including Apollo and Voyager, in the 1960s.
In the following decade, FEMA began to spread to other industries, including the automotive, food, and wastewater treatment industries, as a direct result of its initial success. Nowadays, FMEA is applied in even more industries and is supported by the American Society for Quality as an effective way to ensure the quality and reliability of production results.
When to use FMEA
Though FMEA is certainly applicable to existing systems, FMEA is a great way to assess and prevent negative results and consequences when you are initiating a new process. This is because the intent of FMEA is to evaluate new processes before they are enacted to minimize the possibility of failures.
If you are planning on beginning a new process in any industry, FMEA is a highly recommended way to weed out any possible errors before they occur. Here’s a list of a few additional situations in which you might want to utilize FMEA:
- When an existing process or product is being applied in a new way
- When a process or product is failing and you need to know why
- As part of a routine quality check
The 4 key elements of FMEA
Each type of FMEA is composed of 4 elements. Each of them is listed below.
- Failure modes: These refer to any of the ways an asset can fail.
- Failure causes: FMEA involves assessing failure modes to identify any possible failure causes, which are what lead to said failures modes.
- Failure mode analysis: After identifying failure causes, the next part of FMEA is finding our how often and how severe their occurrences are.
- Action and review: The next element in FMEA involves acting on the FMEA’s results.
These elements tie directly into the five steps of the FMEA process, which are covered below.
What are the 5 steps of the FMEA process?
The FMEA process can be divided into five different steps. See below for a breakdown of each one.
Step 1: Identify possible failures and their effects.
The first step in the FMEA process is to analyze and identify a planned process so you can determine all potential areas of failure (or in other words, failure modes), and then use that information to assess any possible effects of these failures.
Step 2: Identify severity.
The next step in the FMEA process is to assess the severity of potential failures. This is typically done on a scale from one to ten, with one being the lowest level of severity and ten being the highest.
|Very minor severity
|Very high severity
Step 3: Gauge the likelihood of occurrence.
Examine and assess each failure mode to understand how often failure occurs by comparing them to similar processes or products and their historical failure modes. This is done on a one to ten scale, much like the criticality scale.
|Low – few failures
|Moderate – occasional failures
|High – several failures
|Very high – high probability of failures
|Extremely high – total failure, hazardous to safety
Step 4: Failure detection.
During this step, organizations can gauge the likelihood of identifying or detecting failures. The detection value (D) ranks the ability to fix or eliminate defects or failures. See the table below for the typical ranking system used.
|Fault will certainly be detected
|Fault will almost certainly be detected
|Fault is at high probability of being detected
|Fault is at moderate probability of being detected
|Low probability of detecting fault
|Fault will be undetected by user/customer
Step 5: Calculate the risk priority number (RPN).
The risk priority number, or RPN, is a number that describes the risk of a failure mode. This should be calculated and documented in the FMEA of the process or product you are assessing.
The RPN is found by using the formula below:
RPN = Severity x Occurrence x Detection (or RPN = S x O x D)
Once calculated, the RPN of an FMEA should give insight into what aspects of the processes are most problematic. From there, you can take corrective action to ensure that failures are reduced or even prevented, then calculate the RPN again for documentation in the FMEA.
Understanding FMEA scores
As outlined above, FMEA scores are defined by the three following attributes:
- Severity: The severity ranking helps those conducting FMEA prioritize failure modes.
- Detection: The detection ranking determines how likely prevention of potential failure might happen.
- Occurrence: The occurrence ranking shows how likely a failure mode is to occur during an asset’s life cycle.
As an example of an FMEA failure score, take an asset that has a severity rating of five, a detection rating of two, and an occurrence ranking of five. By using the RPN formula, we can see that the RPN of this asset is 50.
Note: Remember that severity can’t always be reduced. When evaluating an RPN score, focus on decreasing occurrence and increasing detection.
How does FMEA relate to maintenance?
FMEA is a great way for maintenance teams to better understand and streamline their maintenance practices. Here are a few ways FMEA can be applied to maintenance:
- FMEA can help you create effective preventive maintenance schedules. Not only can FMEA help you build out a PM schedule, but it can also help you to refine existing ones.
- FMEA can help prepare you for emergency maintenance. Reduced downtime and quick repairs make for much smoother asset operation.
- FMEA can help prioritize maintenance.
- By conducting FMEA, you can better assess which assets need maintenance sooner and better handle your maintenance backlog.
Furthermore, maintenance managers must regularly implement standard operating procedures in order to measure program progress. A mobile CMMS system is the most convenient approach to organizing, analyzing, and acting on program data.
What types of FMEA are there?
There are several types of FMEA, and though they all focus on risk assessment and mitigation, they all deal with different aspects of a system. See below for a brief list of the most common types of FMEA.
Functional (System) FMEA
Functional FMEA, also known as System FMEA, is applied to the functions of a system and their potential failures. This type of FMEA is meant to assess an entire system and whether its individual components work well.
Design-FMEA (DFMEA) is FMEA as applied to design failures. DFMEA is often used in production to prevent issues caused by said design failures, such as lawsuits from customers or product recalls.
Process-FMEA (PFMEA) is FMEA as applied to process failures. A PFMEA is often executed on a process on a routine basis to ensure that it is up-to-date and performing at its best.
As we have shown, FMEA is a valuable tool for businesses aiming to increase asset reliability, prioritize O&M initiatives, and streamline product design. So, in summary, what is the key to success when it comes to using it?
The key is to implement the recommendations that result from your task force and stick to a periodic data-review process. In addition, keep in mind that progress is not an overnight result, so make sure to keep up with revisiting FMEA-driven RPNs and team efforts.
NEXGEN software enables manufacturing teams to share crucial data points, enhance team communication, and glean insights from user-friendly advanced reporting. If you’re interested in seeing how NEXGEN can contribute to conducting FMEA on a granular level, click the button below to let us know.
What is the difference between a failure mode and a failure code?
A failure mode is something that might cause a system to fail or malfunction, such as corrosion on a machine. In contrast, a failure code is a way to distinguish failure modes from each other by way of using an alphanumeric tag, like an error code.
What is the difference between FMEA and FMECA?
FMECA is FMEA with the addition of a criticality assessment (hence the additional C in the acronym). FMEA focuses on qualitative data, whereas FMECA focuses on both quantitative and qualitative data to make prioritizing failure modes a possibility.
What is the difference between FMEA and FRACAS?
FMEA address possible failures and their potential consequences, making this analysis tool a proactive one. A failure reporting, analysis, and corrective action system, or FRACAS, however, is intended to address failures that have already happened and figure out how to prevent them in the future. This makes FRACAS more of a reactive analysis tool.