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]

Current Controls:

• Prevention: [Current prevention measures]
• Detection: [Current detection measures]

Recommended Actions:

• [Action description] - Owner: [Name] - Due: [Date]

After Action:

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