In manufacturing quality, PFMEA (Process Failure Mode and Effects Analysis) and the Control Plan work hand-in-hand to reduce process risk and improve product quality.
One of the most important connections between them is how Prevention and Detection Controls in PFMEA are transferred to the Control Plan. These controls serve as the foundation of process monitoring, helping organizations meet IATF 16949 requirements and deliver consistent results.
In this post, we’ll explain:
- What prevention and detection controls mean in PFMEA
- How they reduce risk
- How to effectively translate them into the Control Plan
- Practical examples and best practices
What Are Prevention and Detection Controls in PFMEA? #
In Step 5 (Risk Analysis) of the AIAG-VDA PFMEA 7-Step Approach, we evaluate each failure cause by:
- Occurrence (O) → How often the cause is likely to occur
- Detection (D) → How likely the control is to detect the failure before it escapes to the next operation or the customer
These are influenced by current controls, which are categorized into:
✅ Prevention Controls
Controls intended to prevent the cause or failure mode from occurring in the first place.
Examples:
- Process design (e.g., locating pin)
- Fixed parameter setting (e.g., torque-controlled tools)
- Poka-yoke devices
- Training and work instructions
✅ Detection Controls
Controls intended to detect the failure or cause after it has occurred, before it reaches the next step or customer.
Examples:
- Visual inspection
- SPC monitoring
- Leak testing
- End-of-line testing
Why Are These Controls Important? #
In PFMEA, the effectiveness of Prevention and Detection Controls directly affects the Occurrence and Detection ratings, which are critical for calculating:
- RPN (Risk Priority Number) in traditional FMEA
- Action Priority (AP) in AIAG-VDA FMEA
They help you determine:
- Whether a failure is under control
- Whether improvement actions are necessary
- What level of attention a process step requires
Linking PFMEA Controls to the Control Plan #
Once the PFMEA is finalized, the Control Plan becomes the execution document. It takes the prevention and detection controls from PFMEA and implements them on the shop floor.
Here’s how:
| PFMEA Control Type | Control Plan Column |
|---|---|
| Prevention Control | Control Method – Process |
| Detection Control | Control Method – Inspection |
🎯 Rule of Thumb:
Every current control in PFMEA must be reflected in the Control Plan, especially for high-risk failure modes.
Example: PFMEA Controls to Control Plan #
🔍 PFMEA Snippet
| Process Step | Function | Failure Mode | Cause | Prevention Control | Detection Control |
|---|---|---|---|---|---|
| Welding | Join components | Weak weld joint | Incorrect parameters | PLC-monitored weld current | Visual inspection – 100% |
📋 Corresponding Control Plan
| Process Step | Characteristic | Control Method | Frequency | Reaction Plan |
|---|---|---|---|---|
| Welding | Weld current | PLC – Real-time current monitoring | Continuous | Stop line, adjust settings |
| Weld appearance | 100% Visual inspection | 100% | Rework, inform supervisor |
✅ Direct traceability: Prevention = process control; Detection = inspection method
Benefits of Proper Linkage #
🔒 Risk Mitigation
Controls help eliminate or catch issues before they become customer complaints.
📄 Audit Readiness
IATF 16949 and customer-specific requirements often ask:
“Show how PFMEA and Control Plan are connected.”
With proper linkage, you’re always ready.
🔁 Continuous Improvement
Control Plans evolve from PFMEA recommendations (Step 6: Optimization). As new controls are implemented, the Control Plan gets updated.
Best Practices #
✅ Use the same process step numbering between PFMEA and Control Plan
✅ Transfer all current prevention/detection controls—no control should be missed
✅ Clearly mark special characteristics (SC, CC) with higher-level controls
✅ Include reaction plans in Control Plan for every detection method
✅ Train shopfloor staff on the meaning and execution of each control
Common Mistakes to Avoid #
❌ Using generic controls like “Visual inspection” without specifying method/frequency
❌ Not updating Control Plan when PFMEA actions are closed
❌ Missing documentation for special characteristics controls
❌ Treating PFMEA and Control Plan as independent documents
Conclusion #
Prevention and Detection Controls in PFMEA are more than just risk evaluation tools—they are the backbone of your Control Plan.
By translating them effectively:
- You ensure shopfloor compliance
- You create a closed-loop system from planning to execution
- You achieve better quality, fewer defects, and higher customer satisfaction
Always remember:
PFMEA finds the risk. Control Plan controls the risk.
FAQs #
Q1: Are all PFMEA controls required in the Control Plan?
Only current controls that impact risk reduction should be reflected. However, high-risk items must have traceable controls.
Q2: Can a Control Plan include controls not listed in PFMEA?
Yes, but ideally, all significant controls should originate from PFMEA analysis. Any new control should trigger a PFMEA review.
Q3: What if a recommended action adds a new control?
Once implemented, the Control Plan must be updated to reflect the new control.
