What Is FMEA?
Failure Mode and Effects Analysis (FMEA) is a systematic, proactive method used to identify potential failure modes in a product, process, or system — and to assess the impact of those failures before they reach customers. Developed in the U.S. military in the 1940s and later adopted widely in automotive, aerospace, healthcare, and manufacturing, FMEA is one of the most powerful risk management tools in the quality professional's toolkit.
There are several types of FMEA, but the two most common are:
- Design FMEA (DFMEA) – Focuses on potential failures in a product's design
- Process FMEA (PFMEA) – Focuses on potential failures in a manufacturing or business process
Why Use FMEA?
The core value of FMEA lies in its preventive nature. Rather than reacting to failures after they occur, FMEA forces teams to think ahead. Key benefits include:
- Reducing defects and field failures before launch
- Prioritizing corrective actions based on risk
- Improving team knowledge of process or product risks
- Supporting compliance with standards like IATF 16949, ISO 9001, and FDA regulations
- Reducing liability and warranty costs
The FMEA Worksheet: Key Columns Explained
An FMEA is typically completed in a structured worksheet format. Here are the essential fields:
| Column | What It Captures |
|---|---|
| Process Step / Function | The step, component, or function being analyzed |
| Potential Failure Mode | How could this step fail? (e.g., "Weld breaks under load") |
| Potential Effects of Failure | What happens to the customer or next step if it fails? |
| Severity (S) | Rated 1–10: How serious is the effect? |
| Potential Causes | Why might this failure mode occur? |
| Occurrence (O) | Rated 1–10: How likely is this cause to happen? |
| Current Controls | What's already in place to detect or prevent it? |
| Detection (D) | Rated 1–10: How likely is the failure to be caught before reaching the customer? (1 = almost certain to detect) |
| RPN | Risk Priority Number = S × O × D |
| Recommended Actions | What should be done to reduce risk? |
Understanding the Risk Priority Number (RPN)
The Risk Priority Number (RPN) is the product of Severity, Occurrence, and Detection scores. It ranges from 1 to 1,000. Higher RPN values indicate higher risk and should be prioritized for action.
However, RPN alone can be misleading. A failure with a severity of 10 (catastrophic) should be addressed even if occurrence and detection keep the RPN relatively low. Always review high-severity items regardless of overall RPN.
Step-by-Step: How to Conduct a Process FMEA
- Assemble a cross-functional team – Include people from engineering, operations, quality, and customer-facing roles.
- Define the scope – Identify which process, product, or system you're analyzing.
- Map the process – Break it into discrete steps using a process flow diagram.
- Identify failure modes – For each step, brainstorm how it could fail.
- Assess effects and causes – Document what happens when it fails and why it might fail.
- Score S, O, and D – Rate each on a 1–10 scale using defined rating criteria.
- Calculate RPN – Multiply the three scores.
- Define and implement actions – Focus on high-RPN and high-severity items. Assign owners and due dates.
- Recalculate RPN after actions – Verify that improvements reduced the risk.
Common Mistakes in FMEA
- Conducting FMEA after design or process is already locked — it loses its preventive value
- Filling in forms without a real cross-functional discussion
- Ignoring high-severity failures because the RPN is low
- Never updating the FMEA as the process or product changes
Final Thoughts
FMEA is most effective when it's treated as a living document and a team conversation — not a compliance checkbox. When done well, it builds shared risk awareness, drives smarter design and process decisions, and helps organizations catch problems on paper rather than in production or in the field.