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:

Eliminate - Design out the failure mode entirely
Substitute - Replace with less hazardous process/material
Engineer - Install physical safeguards, poka-yoke
Admin - Procedures, training, work instructions
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

pfmea