Control Plan

When to Activate This Skill

"Create a control plan for [part/process]"
"What inspection frequency for [characteristic]?"
"Define control methods for [operation]"
"Link PFMEA to control plan"
"What's the reaction plan for [out-of-spec condition]?"
"Develop prototype/pre-launch/production control plan"

Control Plan Phases

Prototype Control Plan

Purpose: Control during prototype build
Focus: Dimensional measurements, material tests, performance
Frequency: Often 100% on critical dimensions
Duration: Until prototype approval

Pre-Launch Control Plan

Purpose: Control during PPAP/validation runs
Focus: Enhanced inspection, process validation
Frequency: Increased sampling, SPC establishment
Duration: Until production approval (PSW)

Production Control Plan

Purpose: Ongoing production control
Focus: Standardized controls, sustained quality
Frequency: Based on process capability
Duration: Life of production

AIAG Control Plan Format

Required Columns

Column	Description	Source
Part/Process Number	Operation step number	Process Flow
Process Name/Description	Operation description	Process Flow
Machine/Device/Jig/Tool	Equipment used	Process documentation
Characteristic Number	Unique ID for characteristic	Sequential
Product Characteristic	Part feature being controlled	Drawing, spec
Process Characteristic	Process parameter affecting product	PFMEA
Special Char Class	CC, SC, or blank	PFMEA/Drawing
Product/Process Spec	Tolerance or requirement	Drawing, spec
Evaluation/Measurement	Gage/method used	MSA
Sample Size	Quantity inspected	Based on risk
Sample Frequency	How often inspection occurs	Based on risk
Control Method	How results are recorded/used	SPC, checklist, etc.
Reaction Plan	Action when out of spec	Defined response

Special Characteristics

Critical Characteristics (CC)

Symbol: Shield, (CC), or inverted delta
Criteria: Safety or regulatory compliance
Requirements:
- Documented in Control Plan
- Enhanced inspection (often 100%)
- SPC required (Cpk ≥1.67)
- Traceable records
- Identified on drawing

Significant Characteristics (SC)

Symbol: Diamond, (SC)
Criteria: Fit, function, appearance significant to customer
Requirements:
- Documented in Control Plan
- Appropriate inspection frequency
- SPC recommended (Cpk ≥1.33)
- Records maintained

Standard Characteristics

Symbol: None
Criteria: All other characteristics
Requirements:
- Documented in Control Plan
- Sampling based on risk
- Records as required

Sample Size and Frequency Guidelines

Based on Severity (from PFMEA)

Severity	Sample Size	Frequency	Rationale
9-10 (Safety)	100%	Every piece	Safety critical - no escape
7-8 (High)	100% or n≥5	Per hour or per lot	High customer impact
5-6 (Moderate)	n≥3	Per shift or per setup	Moderate risk
1-4 (Low)	n≥1	Per lot or periodic	Low risk

Based on Process Capability

Cpk Range	Typical Frequency	Notes
<1.00	100% or very frequent	Process not capable
1.00-1.33	Every hour or more	Marginal capability
1.33-1.67	Per shift or setup	Capable
>1.67	Per setup, daily, or lot	Highly capable

Standard Frequency Terms

Term	Meaning	When to Use
Continuous	100% inspection	Safety, high risk
Per piece	Every part	Critical characteristics
Per hour	n pieces every hour	SPC, high-risk
Per shift	Start and end of shift	Setup-sensitive
Per setup	At setup only	Stable characteristics
Per lot	One sample per production lot	Low-risk, stable
Daily	Once per day	Periodic verification
Weekly	Once per week	Very stable

Control Methods

Inspection Methods

Method	Description	Typical Use
Visual	Operator observation	Surface defects, presence
Go/No-Go Gage	Attribute check	Hole size, thread, profile
Caliper/Micrometer	Variable measurement	Dimensions
CMM	Coordinate measurement	Complex features
Height Gage	Surface plate measurement	Flatness, position
Profilometer	Surface finish	Ra, Rz
Hardness Tester	Material property	HRC, HRB
Torque Wrench	Fastener torque	Assembly
Leak Test	Seal integrity	Fluid systems
Functional Test	Performance verification	End-of-line

Recording Methods

Method	Description	When to Use
Check Sheet	Attribute recording	Visual checks, presence
Data Log	Variable data recording	Measurements
SPC Chart	Statistical control chart	Critical/significant
Traveler	Part-specific record	Traceability
Electronic	MES/database entry	High volume
None (process control)	Poka-yoke, automated	Error-proofed

Reaction Plans

Standard Reaction Plan Format

IF [out-of-spec condition] THEN:
1. STOP - Halt production/segregate suspect
2. CONTAIN - Quarantine affected parts
3. NOTIFY - Alert supervisor/quality
4. EVALUATE - Determine root cause and extent
5. CORRECT - Implement fix before restart
6. VERIFY - Confirm correction effective

Reaction Plan Examples

Dimension Out of Spec:

Stop production
Segregate last good part to current
Notify Quality/Supervisor
Check tool condition, offset, fixture
Adjust/replace as needed
Run first piece, verify to spec
Inspect segregated parts 100%

Visual Defect:

Reject defective part
Assess severity (isolated vs trend)
If trend: notify supervisor, review process
Identify root cause (tool, material, handling)
Implement correction
Resume with enhanced attention

SPC Out of Control:

Mark control chart
Continue production if within spec
Investigate pattern (rule violated)
Identify assignable cause
Implement correction
Document on chart

PFMEA to Control Plan Linkage

Required Flow

PFMEA Item            →    Control Plan Entry
─────────────────          ───────────────────
Process Step          →    Part/Process Number
Function              →    Characteristic
Failure Mode          →    What we're preventing
Detection Control     →    Control Method
S/O/D Ratings         →    Sample Size/Frequency
Special Char          →    Special Char Class

Linkage Verification

For each Control Plan line, verify:

PFMEA has corresponding failure mode
Special characteristics match
Control method addresses PFMEA detection
Frequency appropriate for risk level
Reaction plan defined

Output Format

When generating Control Plan content:

# Control Plan
**Part Number**: [P/N]
**Part Name**: [Description]
**Customer**: [Customer Name]
**Control Plan Number**: CP-[DEPT]-[SEQ]
**Phase**: [ ] Prototype  [ ] Pre-Launch  [X] Production
**Revision**: [Rev] | **Date**: [YYYY-MM-DD]
**PFMEA Reference**: PFMEA-[XXX]

## Operation: [Number] - [Name]

### Characteristic 1: [Description]

| Field | Value |
|-------|-------|
| **Char No.** | [Unique ID] |
| **Product/Process** | Product / Process |
| **Class** | CC / SC / - |
| **Specification** | [Nominal ± Tolerance] |
| **Evaluation Method** | [Gage/Equipment] |
| **Sample Size** | [n] |
| **Sample Frequency** | [When] |
| **Control Method** | [Recording method] |
| **Reaction Plan** | [Reference or inline] |

Integration with Related Skills

PFMEA

Control Plan is direct output of PFMEA:

Every PFMEA detection control → Control Plan method
PFMEA severity drives inspection frequency
PFMEA updates trigger Control Plan review

Load: read ~/.claude/skills/Pfmea/SKILL.md

MSA

All gages in Control Plan require MSA:

Gage R&R for variable gages
Attribute agreement for attribute gages
MSA acceptance before production approval

Load: read ~/.claude/skills/Msa/SKILL.md

AutomotiveManufacturing

Work instructions must reflect Control Plan:

Inspection steps in work instructions
Operator-level control methods
Quality checkpoints documented

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

Supplementary Resources

For detailed guidance: read ~/.claude/skills/Controlplan/CLAUDE.md

For templates: read ~/.claude/skills/Controlplan/templates/control-plan-template.md

For control method selection: read ~/.claude/skills/Controlplan/reference/control-methods.md

For sampling guidelines: read ~/.claude/skills/Controlplan/reference/sample-frequencies.md

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