A failure mode and effects analysis (FMEA) is a structured approach to identifying design failures in a product or process. Developed in the 1950s, the failure mode and effects analysis is one the earliest methodologies of its kind. It enables organizations to anticipate a range of potential failures during the design stage.
- Understanding a failure mode and effects analysis
- Conducting a failure mode and effects analysis
- Step 1 – Assemble a team
- Step 2 – Define the scope
- Step 3 – List failure mechanisms
- Step 4 – Assign severity rankings
- Step 5 – List and score potential causes of failure
- Step 6 – List and score current process controls
- Step 7 – Determine the risk priority number
- Step 8 – Propose recommended courses of action
- Key takeaways:
Understanding a failure mode and effects analysis
History is littered with examples of product recalls because of poorly designed products or processes.
One such example is the Takata airbag recall, the largest automotive recall in the world affecting an estimated 100 million vehicles. The recall was caused by design and manufacturing problems which lead to the airbag becoming highly explosive if exposed to high humidity.
Developed in the 1950s, the failure mode and effects analysis is one the earliest methodologies of its kind. It enables organizations to anticipate a range of potential failures during the design stage.
When conducting a FMEA, the team is prompted to evaluate the:
- Steps in the process.
- Failure modes – what could go wrong?
- Failure causes – why would the failure occur?
- Failure effects – what would be the consequences of failure occurrence?
Conducting a failure mode and effects analysis
Step 1 – Assemble a team
Start by creating a cross-functional team with a diverse range of knowledge about the process or product to be analyzed. This may include manufacturing, quality control, customer service, maintenance, or purchasing.
Step 2 – Define the scope
In other words, is the FMEA being used for a concept, system, process, or design? Where are the boundaries and what is the level of detail required? Process steps should be listed in rows at the far left of the spreadsheet.
Step 3 – List failure mechanisms
List the ways that each process step can fail through brainstorming or the reviewing of existing documentation. This list should be exhaustive and many steps will have multiple avenues to failing.
Then, repeat the same process for the potential effects of each failure.
Step 4 – Assign severity rankings
Using a scale of 1 to 10, rank the severity of the potential effect on the customer. A score of 9 would denote a high-impact event, while a score of 2 would denote a low-impact event.
Step 5 – List and score potential causes of failure
How could the failure effect occur? For example, a bank customer could become dissatisfied (failure effect) because of an ATM running out of cash (failure cause).
For each potential failure cause, rank it according to how frequently it is likely to occur. Rare occurrences receive low scores, while frequent events receive higher scores.
Step 6 – List and score current process controls
What are the existing controls that prevent the failure mode from occurring? Some controls may only detect failure modes after they occur.
Returning to the previous example, the bank might receive an internal alert that cash in the ATM is running low.
Each control should then be scored according to its ability to detect the occurrence of a failure event. A failure event that is easily detected by a control is given a low score while a higher score is assigned to an inconspicuous failure event.
Step 7 – Determine the risk priority number
The risk priority number (RPN) is the overall risk score of an event. It can be calculated by multiplying the severity, occurrence, and detection scores together.
A process step with a higher RPN demands immediate attention. Lower RPN steps are at less risk of failure.
Step 8 – Propose recommended courses of action
Lastly, the team should propose a course of action for:
- All process steps with a high RPN.
- All failure effects with a severity score of 9 or 10, or those effects associated with customer safety or regulation.
- All process steps scoring highly for both severity and occurrence – otherwise known as high criticality combinations.
Actions that reduce risk ultimately involve eliminating the failure or addressing the cause of the failure. Processes can also be improved by increasing design tolerance and reducing variation in process output quality.
Lastly, controls can be improved by making processes and tools mistake-proof (often achieved through automation). Enhanced inspection and evaluation techniques can also increase control effectiveness.
- A failure mode and effects analysis is a structured, evaluative approach to identifying failures in a product or process.
- A failure mode and effects analysis forces teams to critically evaluate each step in a process. This is achieved by considering the modes, causes, and potential effects of process failures.
- A failure mode and effects analysis can be performed using spreadsheet software. Teams must assign weighted scores to a range of variables and focus their efforts on process steps with the highest risk of failure.
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