What is Failure Mode and Effect Analysis?
In short, FMEA is a method used to identify potential failure modes within a system. FMEA helps us to understand what could potentially cause a problem and the effects of failure. It allows us to assess the likelihood of such an event occurring and its impact on our business if this does happen.
- FMEA can be applied to any process or product in your organization.
- It is a proactive tool (Before the problem happens / not the aftereffect analysis)
- It is a living document
In this blog post, I'm going to explain what FMEA is and how it's used.
Design FMEA vs. Process FMEA
The difference between these two terms is that design FMEA focuses on the design phase, whereas process FMEA focuses on all stages of the lifecycle of a product or service.
Identifies failures associated with the product design:
- Product malfunctions
- Product life
- Safety hazards
Identifies failures related to processes:
- Production quality
- Process reliability
- Customer dissatisfaction
Why use FMEA?
There are many reasons why we should use FMEA. Here are some examples:
- To identify potential risks early in the development cycle.
- To identify potential risks before they become problems.
- To reduce risk by identifying ways to prevent failures from happening.
- To improve quality by reducing defects.
- To ensure safety through understanding the consequences of failure.
Risk Priority Number Number in FMEA
An FMEA looks at three criteria when assessing a problem:
1) the severity level of the problem for the user/customer
2) the probability of occurrence of the problem and
3) Detection ranking - the probability of the problem getting detected if it happens
The first thing we want to do is rank the severity level of the potential failure. On a scale of 1 to 10, the higher the number, the more severe the problem.
Severity 1 - No effect/ client might not even notice it
Severity 10 - Serious safety hazard without warning
We also want to rank the frequency of the problem. If it only occurs rarely, you assign the rating as 1, and if the problem is inevitable, it is given a rating of 10.
Occurrence 1 - Rare event, no data of such type of failure in past
Occurrence 10 - Failure is almost inevitable
The lower the rating number, the more likely it is that the issue will get detected when it comes to detection. The rating will be high if the issue remains undetected even after the problem has happened.
Detection 1 - Current system almost certainly detect the problem (automation)
Detection 10 - Current system can not detect the problem
The RPN or the Risk Priority Number is the multiplication of these three ratings.
Risk Priority Number (RPN) = Severity (1 to 10) x Occurrence (1 to 10) x Detection (1 to 10)
How do we use FMEA?
In general, we would follow these steps to carry out an FMEA:
- Identify key process steps: Identify every step in the process. For this, you can use a flowchart to understand the process. If the process is complex, you might want to break it down into smaller chunks.
- Identify failure mode: Determine how the failure could occur. This means analyzing and brainstorming the process and determining where the failure could happen.
- Identify failure effects/severity: Rank each failure based on its impact. You may need help from other team members to come up with ideas.
- Identify the frequency of occurrence: Look at your historical record to determine whether or not there have been any similar occurrences in the past. If so, how frequent these failures were.
- Identify controls /detection: The probability that the failure will be detected even before it happens.
- Calculate Risk Priority Number (RPN): Calculate the RPN by multiplying the three factors (severity, occurrence and detection) together.
- Prioritize by RPN (higher RPN first): Prioritize the potential failures according to their RPN numbers. The higher the RPN number, the higher is the priority on that potential problem.
- Determine action plan: Based on the prioritized list, decide what actions should be taken. Execute the action plan.
- Recalculate RPN: After implementing the changes, repeat FMEA to assess effectiveness.
If we're using FMEA correctly, we'll end up with a list of potential failures and mitigation strategies.