Failure mode and effects analysis (FMEA) is the process of reviewing as many components, assemblies, and subsystems as possible to identify potential failure modes in a system and their causes and effects.
For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet. There are numerous variations of such worksheets.
An FMEA can be a qualitative analysis but may be put on a quantitative basis when mathematical failure models are combined with a statistical failure mode ratio database. It was one of the first highly structured, systematic techniques for failure analysis. An FMEA is often the first step of a system reliability study.
There are two broad categories of FMEA, Design FMEA (DFMEA) and Process FMEA (PFMEA).
1- Design FMEA
Design FMEA relates to the way that a system, product, or service was conceptualized. As the name suggests, DFMEA focuses on the design aspect of a developmental process. It is primarily beneficial in testing out new product ideas before introducing them to real-life scenarios.
2- Process FMEA
The nature of PFMEA differs slightly as it investigates current processes and procedures that an organization is already performing. PFMEA would typically address potential failures that can have significant impacts on usual operations. Some examples of business impacts are process stalls, human errors, and environmental and safety hazards. Because of its nature, PFMEA can be performed more effectively when historical data is available.
1. It provides a documented method for selecting a design with a high probability of successful operation and safety.
2. A documented uniform method of assessing potential failure mechanisms, failure modes and their impact on system operation, resulting in a list of failure modes ranked according to the seriousness of their system impact and likelihood of occurrence.
3. Early identification of single failure points (SFPS) and system interface problems, which may be critical to mission success and/or safety. They also provide a method of verifying that switching between redundant elements is not jeopardized by postulated single failures.
4. An effective method for evaluating the effect of proposed changes to the design and/or operational procedures on mission success and safety.
5. A basis for in-flight troubleshooting procedures and for locating performance monitoring and fault-detection devices.
6. Criteria for early planning of tests.
From the above list, early identifications of SFPS, input to the troubleshooting procedure and locating of performance monitoring / fault detection devices are probably the most important benefits of the FMECA. In addition, the FMECA procedures are straightforward and allow orderly evaluation of the design.
There are several times at which it makes sense to perform a Failure Mode and Effects Analysis:
• When you are designing a new product, process, or service
• When you are planning on performing an existing process in a different way
• When you have a quality improvement goal for a specific process
• When you need to understand and improve the failures of a process
In addition, it is advisable to perform an FMEA occasionally throughout the lifetime of a process. Quality and reliability must be consistently examined and improved for optimal results.
FMEA works by collecting as much information from the production floor as possible. Maintenance and reliability teams, being closest to the equipment and processes, are valuable assets to provide a collection of ideas on how failures can potentially occur. The effects of each potential failure are then assessed. Finally, the severity of each of the effects is then rated and evaluated to form a weighted scale.
By assigning weights, FMEA effectively becomes an objective decision criterion that the organization’s functions can align to. A Risk Priority Number (RPN) refers to the risk value that each outcome amounts to. The RPN becomes the basis of whether teams should take actions to address a potential failure. It is important for the relevant teams to have the same level of understanding of the RPN and their corresponding actions.
As with most company-wide initiatives, introducing a process such as FMEA is usually first approved by higher management. While suggestions and proactive measures may start from the actual workers, starting the FMEA process would require collective action that involves the whole organization.
After a green light has been signaled from the higher-ups, the process of gathering all requirements then follows. The following high-level steps are commonly found in FMEA processes. Think of this as a general checklist for starting with FMEA:
1. Identify the component, equipment, system, or process to analyze.
2. Assign a team and team leader that would kick off the process. In this stage, it is important to involve the right people closest to the operation.
3. Describe what is being analyzed.
4. Identify potential failure modes.
5. Identify the effects related to the failure modes.
6. Set the criteria for evaluating the risk of each failure mode and their effects. This would include the probability of occurrence, detectability, and severity.
7. Design a method of prioritization based on the calculated Risk Priority Number from previously evaluated components.
8. Take the necessary actions to eliminate or reduce identified risks.
9. Measure the success of risk reduction after implementing the established actions.
The general steps to initiate FMEA in your organization have been enumerated in the previous sections. However, you are still left with a huge amount of freedom in terms of how you could apply a process such as FMEA to your organization.
To give you an idea of some ways to make this endeavor a guaranteed success, here are a few tips that might help:
1. Tailor-Fit the Evaluation Criteria
The way FMEA is carried out can vary widely from each organization, and they have certain differences for a reason. Companies will have their own business strategies and therefore focus on different aspects of their operations. To reflect this in your FMEA process, you should be strategic in assigning weights and identifying categories in your decision criteria.
2. Be Consistent with the Rating Scales Used Within the Organization
After identifying the criteria that best reflects your company’s objectives, it then helps to stick with a rating pattern. The consistency of your rating scales would be an effective way of aligning the organization towards common goals. Consistency allows you to seamlessly work within various groups and functions.
3. Identify Specific Risk Control Processes for Each Failure Mode
At the end of the day, FMEA is essentially a risk assessment tool. For it to be an effective tool, it is not enough to identify the failure modes and corresponding effects. Specific processes and procedures need to be in place to eliminate, or at least reduce, the risks identified.
4. Engage the Team
A lot of the information that goes into the FMEA process relies on the day-to-day experience of the workforce. By engaging the right people, you can ensure the reliability of your data. It is important to recognize the value that comes with the collective experience of your team.
5. Use Tools You Already Have
You can only gather so much information with the limitations imposed by our human capacities. A superpower that you might not realize is the tools that are running 24/7 in the background. CMMS programs that record equipment performance even when you’re not looking can provide you data sets that you might have overlooked manually. Coupled with a more-than-capable workforce, these tools can maximize the potential you already have.