What is FMEA?
Failure Mode and Effects Analysis is a structured method for identifying potential failures in a design or process, rating them, and prioritising actions. Each failure mode is scored for Severity, Occurrence and Detection (1–10); multiplying them gives the Risk Priority Number (RPN).
How to run an FMEA
- Map the process steps.
- For each step, list ways it could fail (failure modes).
- Describe the effect of each failure and rate Severity (S).
- Identify causes and rate Occurrence (O).
- List current controls and rate Detection (D).
- Calculate RPN = S × O × D and act on the highest first.
- Re-score after actions.
FMEA example: cold-chain delivery
| Failure mode | S | O | D | RPN |
|---|---|---|---|---|
| Van fridge fails in transit | 9 | 3 | 7 | 189 |
| Wrong delivery address | 5 | 4 | 3 | 60 |
| Late dispatch | 6 | 5 | 2 | 60 |
Common mistakes to avoid
- Scoring by guesswork instead of data.
- Ignoring high-severity items with a low RPN.
- Never revisiting the FMEA after changes.
How DOOfy helps
Occurrence and Detection scores are better with data. AIMOS One and AIXON record how often failures actually occur and how quickly they're detected, giving your FMEA real numbers — and alerts that improve detection.
Frequently asked questions
What is a good RPN?
There's no universal threshold. Teams rank items by RPN and address the highest first, while always acting on anything with very high severity.
What is the difference between DFMEA and PFMEA?
Design FMEA looks at how a product design could fail; Process FMEA looks at how a manufacturing or business process could fail.