Pfmea

What this skill does

# Process FMEA (PFMEA)

## When to Activate This Skill
- "Create a PFMEA for [process]"
- "What are the failure modes for [operation]?"
- "Calculate RPN for [risk scenario]"
- "Rate severity/occurrence/detection for [failure]"
- "Identify process risks"
- "FMEA analysis for [part/process]"

## AIAG-VDA 7-Step Methodology

### Step 1: Planning and Preparation
- Define scope and boundaries
- Identify team members (cross-functional)
- Gather documentation (process flow, control plan, drawings)
- Review lessons learned from similar processes

### Step 2: Structure Analysis
- Define process steps from process flow diagram
- Create process tree (System > Sub-system > Process Element)
- Identify interfaces between steps
- Link to product characteristics

### Step 3: Function Analysis
- Define function of each process step
- Identify product/process requirements
- Link to customer/engineering specifications
- Document special characteristics (CC/SC)

### Step 4: Failure Analysis
- Identify failure modes (how can step fail to perform function?)
- Determine failure effects (consequences to customer/next operation)
- Identify failure causes (why would failure mode occur?)
- Chain: Cause → Failure Mode → Effect

### Step 5: Risk Analysis
- Rate Severity (S) of effects: 1-10
- Rate Occurrence (O) of causes: 1-10
- Rate Detection (D) of controls: 1-10
- Calculate Action Priority (AP) or RPN

### Step 6: Optimization
- Prioritize high-risk items
- Develop countermeasures (hierarchy: Eliminate > Substitute > Engineer > Admin > Detect)
- Assign responsibility and target dates
- Re-rate after countermeasures

### Step 7: Results Documentation
- Document all analysis
- Track countermeasure completion
- Update Control Plan linkage
- Archive for lessons learned

## Rating Scales (MNMUK Standard)

### Severity (S) - Effect on Customer/Process

| Rating | Criteria | MNMUK Examples |
|--------|----------|----------------|
| 10 | Affects safety without warning | Brake component failure, no containment possible |
| 9 | Affects safety with warning | Safety critical dimension OOS, detectable at assembly |
| 8 | Product inoperable, 100% scrap | Part cannot be reworked, total loss |
| 7 | Product operable but degraded, customer dissatisfied | Performance below spec, customer complaint |
| 6 | Product operable, comfort/convenience affected | Cosmetic defect, minor fit issue |
| 5 | 50% of product may need rework | Significant rework required |
| 4 | Product requires sorting/rework | Sorting operation needed |
| 3 | Minor rework at station | In-station repair possible |
| 2 | Slight inconvenience | Minor adjustment |
| 1 | No effect | No discernible impact |

### Occurrence (O) - Likelihood of Cause

| Rating | Failure Rate | Cpk Equivalent | MNMUK Examples |
|--------|--------------|----------------|----------------|
| 10 | Very high: ≥100/1000 | <0.33 | New process, no controls |
| 9 | High: 50/1000 | ≥0.33 | Known problem process |
| 8 | High: 20/1000 | ≥0.51 | Similar process had failures |
| 7 | Moderately high: 10/1000 | ≥0.67 | Occasional failures observed |
| 6 | Moderate: 2/1000 | ≥0.83 | Infrequent failures |
| 5 | Moderately low: 0.5/1000 | ≥1.00 | Controlled process, some failures |
| 4 | Low: 0.1/1000 | ≥1.17 | Well-controlled process |
| 3 | Very low: 0.01/1000 | ≥1.33 | Capable and controlled |
| 2 | Remote: 0.001/1000 | ≥1.50 | Proven design and controls |
| 1 | Nearly impossible: ≤0.001/1000 | ≥1.67 | Failure eliminated by design |

### Detection (D) - Ability to Detect Before Customer

| Rating | Detection Capability | MNMUK Examples |
|--------|---------------------|----------------|
| 10 | No detection possible | No inspection, no opportunity to detect |
| 9 | Unlikely to detect | Random sampling only, infrequent |
| 8 | Low: Visual inspection by operator | 100% visual check, variable attention |
| 7 | Very low: Double visual inspection | Two operators check |
| 6 | Low: Charting/SPC | Control charts, trend monitoring |
| 5 | Moderate: Attribute gaging | Go/No-go gaging |
| 4 | Moderately high: Variable gaging | Measurement with limit checking |
| 3 | High: Automated in-process test | Automatic measurement, alarm |
| 2 | Very high: Error-proofing | Poka-yoke prevents defect production |
| 1 | Almost certain: Error-proofing prevents cause | Design makes failure impossible |

## Action Priority (AIAG-VDA Approach)

Instead of or in addition to RPN, use Action Priority:

| Priority | Criteria | Action Required |
|----------|----------|-----------------|
| **HIGH** | S=9-10 (any O, D) OR S=7-8 with O≥4 AND D≥4 | Immediate action required |
| **MEDIUM** | S=5-8 with O≥4 OR D≥4 | Action recommended |
| **LOW** | All others | Monitor and document |

## RPN Thresholds (MNMUK Standard)

| RPN Range | Priority | Required Action |
|-----------|----------|-----------------|
| ≥120 | Critical | Immediate countermeasure, cannot ship without action |
| 80-119 | High | Countermeasure required before PPAP |
| 40-79 | Medium | Countermeasure recommended |
| <40 | Low | Monitor, no immediate action |

**Note:** Any Severity ≥8 requires action regardless of RPN.

## Countermeasure Hierarchy

When addressing failure modes, apply controls in this priority order:

1. **Eliminate** - Design out the failure mode entirely
2. **Substitute** - Replace with less hazardous process/material
3. **Engineer** - Install physical safeguards, poka-yoke
4. **Admin** - Procedures, training, work instructions
5. **Detect** - Inspection, testing, monitoring

## Special Characteristics

### Critical Characteristics (CC)
- Safety or regulatory impact
- Marked with shield symbol or (CC)
- Requires enhanced controls
- Mandatory documentation

### Significant Characteristics (SC)
- Fit, function, or durability impact
- Marked with diamond or (SC)
- Requires appropriate controls
- SPC typically required

## Output Format Requirements

**CRITICAL**: Every PFMEA response MUST be complete. Never truncate or cut off mid-entry. Every failure mode listed MUST have:
- All causes fully documented
- S/O/D ratings for EVERY cause row
- RPN calculated for EVERY row
- Current controls listed
- Recommended actions specified
- After-action ratings included

If the full PFMEA would be very long, reduce the NUMBER of failure modes covered, but each one included MUST be 100% complete. Do not start a failure mode entry you cannot finish.

## Output Format

When generating PFMEA content:

```markdown
# PFMEA: [Part/Process Name]
**Part Number**: [P/N]
**Process**: [Description]
**FMEA Number**: PFMEA-[DEPT]-[SEQ]
**Revision**: [Rev] | **Date**: [YYYY-MM-DD]
**Team**: [Names/Roles]

## Process Step: [Step Name]

### Failure Mode 1: [Description]
**Function**: [What the step should do]
**Effect**: [What happens if it fails]
**Cause**: [Why it would fail]

| S | O | D | RPN | AP |
|---|---|---|-----|-----|
| X | X | X | XXX | H/M/L |

**Current Controls**:
- Prevention: [Current prevention measures]
- Detection: [Current detection measures]

**Recommended Actions**:
- [ ] [Action description] - Owner: [Name] - Due: [Date]

**After Action**:
| S | O | D | RPN | AP |
|---|---|---|-----|-----|
| X | X | X | XXX | H/M/L |
```

## Department-Specific Guidance

### Machine Shop
- Common failure modes: Dimensional OOS, surface finish, tool wear
- Focus on: Fixturing, program parameters, tool life management
- Key controls: First piece inspection, SPC, gage R&R

### Damper Assembly
- Common failure modes: Leak, incorrect torque, missing component
- Focus on: Seal integrity, fastener torque, component presence
- Key controls: Leak test, torque verification, poka-yoke

### LVA (Low Volume Assembly)
- Common failure modes: Wrong component, incorrect orientation, damage
- Focus on: Part identification, assembly sequence, handling
- Key controls: Visual verification, traveler documentation

### FML (Final Manufacturing Line)
- Common failure modes: Test failure, labeling error, packaging damage
- Focus on: Final test parameters, traceabili