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

When generating PFMEA content:

# 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, traceability, packaging
• Key controls: Automated test, barcode verification, packaging audit

Integration with Related Skills

ControlPlan

PFMEA feeds directly into Control Plan:

• High S/O items require enhanced inspection
• Detection controls become Control Plan methods
• Special characteristics flow to Control Plan

Load:

read ~/.claude/skills/Controlplan/SKILL.md

AutomotiveManufacturing

Work instructions should reflect PFMEA findings:

• High-risk steps highlighted
• Operator controls documented
• Quality checkpoints specified

Load:

read ~/.claude/skills/Automotivemanufacturing/SKILL.md

A3criticalthinking

When PFMEA reveals issues:

• Use 5 Whys for root cause analysis
• Fishbone diagram for cause identification
• A3 format for countermeasure planning

Load:

read ~/.claude/skills/A3criticalthinking/SKILL.md

Supplementary Resources

For detailed guidance:

read ~/.claude/skills/Pfmea/CLAUDE.md

For templates:

ls ~/.claude/skills/Pfmea/templates/

For rating scales:

read ~/.claude/skills/Pfmea/reference/rating-scales.md

For common failure modes:

read ~/.claude/skills/Pfmea/reference/common-failure-modes.md