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FMEA

Failure Mode & Effects Analysis

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What is an FMEA?

Failure Mode and Effects Analysis is a structured way to ask, before failure happens: what could go wrong (failure mode), what happens if it does (effect), why would it happen (cause), and how would we catch it (controls)? Each risk is scored for Severity, Occurrence, and Detection on 1–10 scales, and the product — the Risk Priority Number (RPN) — ranks where to act first.

FMEA is a prevention tool, not paperwork. The value is the argument the team has while filling in the rows — do it with the operators, engineers, and quality people who actually know the failure history.
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Severity × Occurrence × Detection = RPN, the risk ranking that tells you where to act first

Want an editable copy?

Download the free FMEA template — the standard columns from process step through post-action re-scoring, with RPN calculated automatically and high-risk rows highlighted. Opens in Excel and Google Sheets.

What is FMEA?

Failure Mode and Effects Analysis asks, beforefailure happens: what could go wrong, how bad would it be, why would it happen, and would we catch it? It was developed in aerospace, standardized across the automotive industry (AIAG, and now AIAG-VDA), and is equally at home in a hospital medication process. The discipline is in the specificity — not "pump fails" but "pump delivers low flow", because different failure modes have different causes and different fixes.

The scoring turns a long worry list into a ranked work list. Severity — how bad is the effect? Occurrence — how often does the cause really happen? Detection— would today's controls catch it? Multiply the three and the Risk Priority Number tells you where to spend your next improvement hour.

The RPN trap

RPN is a ranking heuristic, not a verdict. A Severity-10 failure with optimistic O and D scores can hide below an RPN threshold while an annoying-but-harmless failure sits above it. Modern practice weights Severity first — and the practical rule this tool encodes in its color-coding: every Severity 9–10 row is high risk regardless of RPN, because you usually cannot make a failure less severe, only less frequent or better detected.

Where FMEA fits in an improvement project

FMEA sits between analysis and control. Map the process first — a SIPOC or value stream map gives you the process steps to interrogate. When a failure has already occurred, run the root-cause hunt with a Fishbone diagram and feed what you learn back into the FMEA. And the best actions are the ones that error-proof the cause away — reducing Occurrence beats improving Detection, because not making the defect beats catching it.

Frequently asked questions

What is an FMEA?
Failure Mode and Effects Analysis is a structured method for finding and fixing risk before failure happens. A team works through a process (Process FMEA) or a design (Design FMEA), listing each way it could fail, the effect if it does, the likely cause, and the current controls. Each failure mode is scored for Severity, Occurrence, and Detection on 1–10 scales, and the resulting Risk Priority Number ranks where to act first.
How is RPN calculated?
RPN = Severity × Occurrence × Detection, giving a number from 1 to 1000. Severity rates the impact of the effect (9–10 is a safety or regulatory issue). Occurrence rates how often the cause happens. Detection rates how likely current controls are to catch the failure before it escapes — inverted, so 1 means certain detection and 10 means undetectable. A common working threshold is to act on RPNs above 100 and on every Severity 9–10 regardless of RPN.
What is a good RPN score?
There is no universal pass mark — RPN is a ranking tool, not a certification. Most teams treat RPN above 200 as high risk, 100–200 as worth an action, and below 100 as monitor. But RPN alone can mislead: a Severity 10 failure with low Occurrence and Detection scores may show a modest RPN while still demanding action, because severity usually cannot be reduced. This is why the newer AIAG-VDA handbook replaced RPN thresholds with Action Priority tables that weight Severity first.
What is the difference between a Design FMEA and a Process FMEA?
A DFMEA analyzes how a product design could fail in use — its failure modes are functional (shaft fatigue, seal leak) and its causes are design decisions. A PFMEA analyzes how a manufacturing or service process could fail to build the product correctly — its failure modes are process errors (wrong torque, missed step, wrong dose) and its causes are process conditions. This tool works for both; the healthcare example is a service-process FMEA.
When should you do an FMEA?
Before the failure, which means: when designing a new process or product, before a significant change, when a new failure mode shows up in the field or on the floor, and as an input to control plans and PPAP submissions. An FMEA is a living document — re-score rows when actions close, and revisit it when the process changes. The before/after RPN pair is the evidence the risk actually dropped.
Is this FMEA tool free?
Yes. The builder runs in your browser with no sign-up — score failure modes, get RPNs and risk color-coding automatically, record actions and owners, re-score after actions close, and export a print-ready FMEA. A free editable Excel/Google Sheets FMEA template with the same columns and automatic RPN formulas is also available.

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