FMEA (Failure Mode and Effects Analysis)
A preventive analysis method that evaluates and prioritizes possible failures in a product or process before they ever occur.
FMEA is applied during the development or planning phase, before a product is manufactured or a process is put into operation. A team systematically works through everything that could go wrong instead of only reacting once failures have already happened.
For every conceivable failure mode, the team identifies the possible cause and its effect on the customer. It then rates three factors, each on a scale from 1 to 10: severity of the failure (S), probability of occurrence (O), and probability of detecting it before delivery (D).
These three ratings combine into the risk priority number. It is not meant as an absolute figure but as a ranking: failure modes with a high RPN are addressed first, for example through a more robust design or an additional inspection step.
In practice, two main variants are used: design FMEA, which focuses on the product itself, and process FMEA, which examines the manufacturing or work sequence.
Formula
RPN = S x O x D
Practical Example
For a bent sheet metal part, the failure mode 'sharp burrs on the bend edge' is examined. Severity S = 7 (injury risk during assembly), occurrence O = 4, detection D = 3. RPN = 7 x 4 x 3 = 84. After introducing a mandatory visual check right after bending, detection improves to D = 1, and the RPN drops to 28.
How Leanshift Helps
Leanshift's approach as a development workshop is about shaping quality ahead of time instead of repairing failures after the fact. FMEA fits exactly into that logic: think first, then build.
Frequently Asked Questions
When is an FMEA carried out?
Ideally before series production starts, during product or process planning. This allows risks to be avoided with little effort instead of causing costly rework or complaints later.
What does a high risk priority number mean?
A high RPN shows that a failure mode is particularly critical in the combination of severity, occurrence, and detection. It is treated with priority when planning countermeasures, regardless of any fixed threshold.
What is the difference between design FMEA and process FMEA?
Design FMEA examines possible weaknesses in the product design itself. Process FMEA instead looks at the manufacturing sequence, such as machine settings, handling, or inspection steps.