In Step 5: Risk Analysis, risks were evaluated using Severity (S), Occurrence (O), Detection (D), and Action Priority (AP).
👉 Step 6: Optimization answers the next question:
“What actions can we take to reduce or eliminate the risk, and how effective are they?”
Optimization is about closing the loop: taking action, verifying effectiveness, and updating the FMEA with new ratings.
Objectives of Optimization #
- Define recommended actions to reduce risks.
- Assign responsibility and target dates for actions.
- Implement corrective or preventive measures.
- Re-evaluate S, O, D ratings after improvements.
- Document the effectiveness of actions.
Types of Actions in FMEA Optimization #
1. Preventive Actions
- Aim: Eliminate or reduce the cause of failure.
- Strongest type of action → reduces Occurrence rating.
- Examples:
- DFMEA: Use high-temperature resistant material.
- PFMEA: Add poka-yoke fixture to prevent wrong part loading.
2. Detection Actions
- Aim: Improve the ability to detect failures before they reach the customer.
- Reduces the Detection rating.
- Examples:
- DFMEA: Add automatic diagnostic software.
- PFMEA: Introduce 100% automated vision inspection.
3. Process/Design Improvements
- Aim: Make the system or process more robust.
- Can influence both Occurrence and Detection.
- Examples:
- DFMEA: Add redundancy (dual sensors).
- PFMEA: Upgrade tool with auto shut-off torque system.
Example – PFMEA Bolting Process #
- Failure Mode: Under-torque bolt.
- Cause: Torque wrench calibration drift.
- Effect: Suspension loosens → safety risk.
- AP Result: High (H).
👉 Optimization Actions:
- Introduce digital torque tool with auto-shutoff.
- Add automatic torque monitoring system.
- Increase calibration frequency.
📌 Re-Evaluation:
- Old O = 6, D = 7 → AP = High.
- New O = 3, D = 2 → AP = Low.
Result: Risk reduced significantly.
Example – DFMEA Electric Motor #
- Failure Mode: Winding overheats.
- Cause: Insulation breakdown at 150°C.
- Effect: Motor fails, vehicle cannot start.
- AP Result: High (H).
👉 Optimization Actions:
- Use insulation rated at 180°C.
- Add thermal cutoff sensor.
📌 Re-Evaluation:
- Old O = 5, D = 6 → AP = High.
- New O = 2, D = 3 → AP = Medium.
Result: Motor design robustness improved.
Re-Evaluation in Step 6 #
- After actions are implemented, Severity usually remains the same (effect doesn’t change).
- Occurrence and Detection ratings are updated based on the effectiveness of new controls.
- AP is recalculated to determine if the risk is now acceptable.
📌 Example:
- Before action → S=9, O=5, D=7 → AP = High.
- After action → S=9, O=2, D=3 → AP = Medium (acceptable).
Best Practices for FMEA Optimization #
- Focus on prevention first, detection second.
- Prevention reduces Occurrence → stronger impact.
- Assign ownership.
- Each action must have a responsible person and deadline.
- Track status.
- Open, In Progress, Completed → visible in FMEA worksheet.
- Re-evaluate ratings honestly.
- Don’t lower ratings without evidence (SPC, audits, validation tests).
- Document justifications.
- For every Medium/Low AP that is accepted without further action.
- Integrate with APQP/Control Plans.
- Optimization actions should flow into Control Plans for process control.
Common Mistakes to Avoid #
- Treating FMEA as a “one-time” exercise (not updating after changes).
- Adding vague actions like “improve process” instead of specific measures.
- Lowering ratings without data or proof.
- Ignoring supplier responsibilities in prevention controls.
- Closing actions without verifying their effectiveness.
Why Optimization is Critical #
- Turns FMEA into a living risk management tool.
- Ensures continuous improvement of design and processes.
- Builds customer trust by showing proactive action on high risks.
- Strengthens compliance with IATF 16949, ISO 9001, and OEM requirements.
Key Takeaways #
- Optimization = implementing actions to reduce risks.
- Prevention actions > Detection actions.
- Always re-evaluate O and D ratings after actions.
- Document responsibilities, due dates, and status in FMEA.
- This step ensures FMEA delivers real risk reduction, not just paperwork.
Next Lesson #
👉 Continue with Lesson 3.8: Step 7 – Results Documentation (Reporting & Lessons Learned)
