1. Method Name

FMEA (Failure Modes and Effects Analysis) / Analysis of Possible Failures and Their Consequences

2. Alternative Names

FMECA (adds "Criticality")

3. Brief Description

FMEA is a structured, proactive method for identifying and evaluating all possible ways in which a product or process might fail, and for prioritizing preventive measures. It is a systematic approach to risk management.

4. Purpose / When to Use

It is primarily used in two areas:
1. Design FMEA (DFMEA): When designing a new product, to identify potential design flaws.
2. Process FMEA (PFMEA): When designing or improving a manufacturing or service process to identify potential process failures.
The goal is to identify and resolve potential problems before they occur.

5. Procedure / How to Apply It

FMEA is conducted as a team and documented in a standardized table.
1. Identify a process step or product function.
2. Identify a potential failure mode: How could this step/function fail?
3. Identify potential effects: What will happen if a failure occurs? How will this impact the customer?
4. Assess severity (S): On a scale of 1–10, rate how severe the consequences are (1 = no impact, 10 = catastrophic, safety-related impact).
5. Identify potential causes: What could cause this failure?
6. Rate the Probability of Occurrence (O): On a scale of 1–10, rate how often the cause is likely to occur (1 = extremely unlikely, 10 = almost certain).
7. Identify Current Controls: What methods and controls do we already have in place to detect this error?
8. Assess the Probability of Detection (D): On a scale of 1–10, rate the likelihood that current controls will detect the error before it reaches the customer (1 = the error will definitely be detected, 10 = the error will not be detected).
9. Calculate the RPN (Risk Priority Number): RPN = S × O × D. The RPN is a value between 1 and 1,000 that helps prioritize risks.
10. Design and implement preventive measures: For the highest RPN values, propose actions to reduce S, O, or D. After implementation, recalculate the RPN.

6. A Real-World Example

Process step: Tightening a wheel on a car.
- Failure mode: Loose bolt.
- Consequence: The wheel may come loose while driving.
- Severity (S): 10 (safety risk).
- Cause: Incorrectly set torque wrench.
- Occurrence (O): 3 (occurs rarely; the wrench is checked once a week).
- Current inspection: The operator visually checks the tightness
.- Detection (D): 7 (visual inspection is unreliable).
- RPN = 10 x 3 x 7 = 210.
- Action: Implement Poka-Yoke—a smart torque wrench that gives a green signal only when the correct torque is reached and does not allow the process to continue until all screws are tightened. New D = 2, new RPN = 10 × 3 × 2 = 60.

7. Benefits

- A proactive approach to risk: Helps prevent problems rather than solve them
.- Resource prioritization: Focuses efforts and resources on the greatest risks.
- Improves product and process design: Leads to more robust and reliable solutions
.- Increases safety and reliability
.- Living documentation: Serves as a knowledge base of potential failures for future projects.

8. Risks / Limits

- Subjectivity of evaluation: S, O, and D ratings can be subjective. It is important for the team to use clearly defined evaluation criteria.
- "The Tyranny of RPN": Blindly following RPN can be misleading. An item with an RPN of 100 (S=10, O=2, D=5) may be much more critical than an item with an RPN of 120 (S=5, O=6, D=4) because it has a high severity rating. The S values themselves must always be considered as well.
- Time-consuming: A thorough FMEA can be very time-consuming, especially for complex products.
- Bureaucracy: An FMEA can become nothing more than a “paper exercise” for an auditor if it does not lead to concrete actions.

9. Practical Tips

- FMEA is a team effort: Never do it alone. You need the perspective of a designer, a process engineer, an operator, a quality specialist, etc.
- New AP (Action Priority) methodology: New standards (e.g., AIAG-VDA) favor “Action Priority” over RPN (High, Medium, Low), which is determined by a combination of S, O, and D and better accounts for high severity.
—Don’t forget to update: FMEA is a living document. Whenever a design or process changes, or when a new defect is discovered, the FMEA should be updated.