Effects of Failure in FMEA

In Step 4: Failure Analysis of the AIAG-VDA 7-Step FMEA approach, the second activity is identifying the Effects of Failure.

👉 An Effect of Failure answers the question:
“What happens if this failure mode occurs?”

Effects must be documented clearly, because they directly determine the Severity rating in FMEA. Without well-defined effects, risk prioritization becomes unreliable.

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What are Effects of Failure in FMEA? #

• An Effect of Failure describes the consequence of a failure mode on:
  1. The local element (part or process step).
  2. The next higher level (system or downstream process).
  3. The end-user or customer.

📌 A complete FMEA should consider all three levels of effects.

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Types of Failure Effects #

1. Local Effect

Impact on the immediate item or process step where the failure occurs.

• Example (Motor winding short circuit): Reduced torque output.
• Example (Weld not formed): Joint is weak.

2. Next Higher-Level Effect

Impact on the system or downstream process that depends on the failed element.

• Example (Motor torque loss): Vehicle acceleration reduced.
• Example (Weak weld): Assembly misalignment in next process.

3. End-User/Customer Effect

Impact on the final product performance, safety, or customer experience.

• Example (Motor failure): Vehicle will not start → customer stranded.
• Example (Weak weld): Vehicle structural failure in crash → safety risk.

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Examples of Effects of Failure #

Example 1 – DFMEA (Airbag System)

• Failure Mode: Airbag deploys late.
• Effects:
  • Local: Inflator function delayed.
  • Next level: Crash sensor timing mismatch.
  • End-user: Passenger not protected in time (safety risk).

Example 2 – PFMEA (Bolting Process)

• Failure Mode: Under-torque bolt.
• Effects:
  • Local: Bolt not secured properly.
  • Next level: Assembly loosens during vibration test.
  • End-user: Suspension failure while driving → accident risk.

Example 3 – PFMEA (Painting Process)

• Failure Mode: Coating too thin.
• Effects:
  • Local: Poor paint coverage.
  • Next level: Rust develops in assembly line storage.
  • End-user: Vehicle corrosion, warranty claims.

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Why Effects of Failure are Important #

1. Basis for Severity Rating: Severity in FMEA is always linked to the end effect on customer or safety.
2. Customer Focus: Effects show how failures impact real-world performance and trust.
3. Traceability: Helps connect function → failure mode → effect → severity.
4. Risk Prioritization: High-severity effects (e.g., safety issues) drive immediate preventive actions.

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Best Practices for Writing Effects of Failure #

• Always describe effects in real, customer-focused language (e.g., “vehicle does not start,” not “system fails”).
• Include all three levels (local, next level, end-user).
• Link effects to customer-specific requirements (CSRs) and regulations.
• Keep descriptions concise and specific.

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Common Mistakes to Avoid #

• Writing vague effects (“bad performance,” “not good”).
• Mixing failure mode with effect (e.g., “under-torque” is a mode, not an effect).
• Ignoring end-user impact → underestimates severity.
• Writing overly technical effects that auditors or customers cannot relate to.

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Case Study – PFMEA for Welding Process #

• Function: Join two steel sheets.
• Requirement: Weld strength ≥ 5 kN.
• Failure Mode: Weld nugget not formed.
• Effects:
  • Local: Weld joint weak.
  • Next level: Assembly misaligned during final fitment.
  • End-user: Vehicle structural failure in crash → Severity = 10.

👉 Because the end-user effect was clearly identified, the PFMEA team recognized this as a safety-critical risk and prioritized immediate preventive actions.

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Key Takeaways #

• Effect of Failure = What happens when a failure mode occurs.
• Always document local, next-level, and end-user effects.
• Effects directly drive the Severity rating in FMEA.
• Clear effects ensure FMEAs stay customer-focused and safety-oriented.

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Next Lesson #

👉 Continue with Lesson 3.5.3: Causes of Failure (Design vs Process)