SC/CC Special Characteristics

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What SC/CC Classification Means

Think of SC/CC classification as a “quality passport” that follows a design characteristic from initial specification through manufacturing and delivery. When a characteristic receives SC or CC designation, it triggers a cascade of mandatory activities: tighter tolerances, enhanced measurement systems, 100% inspection requirements, documented reaction plans, and operator training records. Special Characteristic (SC): A product characteristic or manufacturing process parameter that could affect safety, regulatory compliance, vehicle function, fit/form/finish, or customer satisfaction if not controlled within specified limits. Examples include brake pedal travel distance, airbag deployment force, or emission control valve timing. Critical Characteristic (CC): A product characteristic or manufacturing process parameter that could directly affect safety or regulatory compliance. CC is the highest classification — a subset of SC with more stringent control requirements. Examples include brake caliper piston bore diameter, seatbelt anchor strength, or battery cell voltage consistency. The distinction is crucial: all CC characteristics are SC, but not all SC characteristics are CC. CC items face the most rigorous production controls including 100% inspection, statistical process control (SPC), and immediate line-stop authority if out-of-specification conditions occur.

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Why SC/CC Classification Matters

IATF 16949 clause 8.5.1.1 requires organizations to identify Special Characteristics and implement appropriate controls. Customer-specific requirements from OEMs (Ford, GM, VW, Toyota, etc.) mandate specific SC/CC symbols on engineering drawings and control plans. Failure to properly classify and control SC/CC characteristics can result in:

• PPAP submission rejection
• Customer production stop notifications
• Supplier quality holds
• Containment costs and sorting expenses
• Warranty claims and field failures

In TestAuto2, SC/CC classification creates the “golden thread” connecting three critical artifacts: This traceability ensures every safety-critical or quality-critical design parameter has documented failure analysis and verified production controls.

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Classification Criteria and Decision Matrix

TestAuto2 implements a structured decision tree for SC/CC assignment based on AIAG Control Plan methodology:

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Visual Encoding in TestAuto2

The solution uses color-coded badges and row highlighting to make SC/CC classification immediately visible: Color Coding Standard:

• CC (Critical Characteristic): Red badge (#c62828 text, #ffcdd2 background) + light red row highlighting
• SC (Special Characteristic): Orange badge (#ff8c00 text, #ffe0b2 background) + light orange row highlighting

This visual treatment appears consistently across:

• Characteristics PowerSheet — design specification view
• PFMEA Risksheet — process failure analysis
• Control Plan Risksheet — production controls
• FMEA Coverage Report — gap analysis dashboard

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How SC/CC Flows Through the Lifecycle

SC/CC classification is not a one-time assignment — it evolves through the product development lifecycle:

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SC/CC Coverage Validation

The FMEA Coverage Report dashboard automatically validates SC/CC traceability: Coverage Check Logic:

1. Query all characteristic work items where classification enum = 'sc' OR 'cc'
2. For each SC/CC characteristic, verify at least one failureMode work item exists with incoming link
3. Flag characteristics with zero linked failure modes as coverage gaps

Why This Matters: If a characteristic is classified as SC or CC but has no FMEA analysis, it indicates either:

• Missing failure mode analysis (compliance risk)
• Over-classification (unnecessary cost — the characteristic should be downgraded to standard)

The dashboard provides drill-down links to close gaps: either create the missing failure mode or reassess the SC/CC classification.

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Practical Examples from TestAuto2 AEB System

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Example 1: Camera Lens Focal Length (CC Classification)

Characteristic: Camera Module Optical Focal Length
Target: 3.6 mm ± 0.1 mm
Classification: CC (Critical Characteristic) Rationale:

• Linked to Failure Mode: “Incorrect focal length causes object distance miscalculation”
• DFMEA Severity: 10 (misidentified obstacle distance → no braking → collision)
• Safety Goal: SG-02 “Ensure obstacle detection reliability” (ASIL D)
• Control Plan: 100% optical bench measurement, Cpk ≥1.67 required, line-stop authority

This characteristic receives CC classification because focal length error directly causes a severity 10 failure with no downstream detection opportunity before the camera is sealed.

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Example 2: Housing Screw Torque (SC Classification)

Characteristic: Camera Housing Fastener Torque
Target: 2.0 N⋅m ± 0.3 N⋅m
Classification: SC (Special Characteristic) Rationale:

• Linked to Failure Mode: “Insufficient torque → housing vibration → camera misalignment”
• DFMEA Severity: 8 (degraded detection range)
• Multiple failure modes required: under-torque AND vibration AND misalignment threshold
• Control Plan: Sample torque audit (1 per 50 units), torque wrench calibration records

This receives SC (not CC) classification because the failure chain requires multiple contributing factors and has detection opportunities during end-of-line camera calibration tests.

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Integration with Other Classification Systems

TestAuto2 manages three parallel classification dimensions: How They Relate:

• ASIL D requirements often cascade to CC characteristics on implementing components
• High Action Priority failure modes often identify which characteristics need SC/CC classification
• But the relationships are NOT one-to-one: a characteristic can be ASIL QM but still CC (e.g., airbag cover tear seam — not functional safety during normal operation, but critical for deployment)

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Common Pitfalls

Pitfall 1: Classifying Every Characteristic as SC “To Be Safe”
Over-classification drives unnecessary cost (enhanced measurement equipment, 100% inspection labor, SPC monitoring resources). Use the decision matrix rigorously. Pitfall 2: Design Assigns SC/CC Without Consulting Manufacturing
Manufacturing engineers may lack the measurement capability or process control to achieve Cpk ≥1.67 for CC items. Early collaboration prevents PPAP delays. Pitfall 3: Changing SC/CC Classification Without FMEA Update
If a characteristic is downgraded from CC to SC (or SC to standard), the linked DFMEA and PFMEA must be updated to reflect the reduced risk justification. Otherwise, traceability audits fail. Pitfall 4: Missing the “Why” in Control Plans
Control plans must reference the specific failure mode each control prevents or detects. TestAuto2 enforces this through mandatory characteristic → failureMode → controlPlanItem link chains.

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Related Documentation

How-To Guides:

• Classify Requirements (SC/CC) — step-by-step SC/CC assignment workflow
• Link Characteristics to Failure Modes — establish FMEA traceability
• Create a Control Plan — define production controls for SC/CC items
• Configure Measurement Methods — specify inspection equipment and frequency
• Check Traceability Coverage — validate SC/CC FMEA linkage

Reference Pages:

• Characteristic Work Item Type — data model and custom fields
• Characteristic Custom Fields — classification enum definition
• Control Plan Item Work Item Type — production control specification
• PFMEA Risksheet Configuration — SC/CC rendering and formulas
• Control Plan Risksheet Configuration — unified classification display

Concept Pages:

• IATF 16949 and APQP — automotive quality management context
• AIAG-VDA FMEA Methodology — failure analysis framework
• Action Priority Methodology — FMEA risk prioritization
• System Element Hierarchy — multi-level design decomposition
• Verification vs Validation — production vs design validation