Auto Parts Quality Analysis

Core Workflow

1. Quality Issue Analysis

When analyzing quality issues, follow this structure:

A. Problem Definition

• Part name, part number, supplier
• Symptom description (field failure, customer complaint, in-process defect)
• Failure rate / population affected
• Timeline (when discovered, volume shipped)

B. Evidence Collection

• Photos / microscope images
• Measurement data (dimensional, roughness, hardness)
• Cleanliness analysis results (particle size, composition)
• Test reports (8D, PPAP, material certs)

C. Failure Mode Identification

• Surface failure (honing pattern, wear, scoring)
• Dimensional failure (out of tolerance)
• Material failure (crack, corrosion, contamination)
• Assembly failure (mating, sealing)

D. Root Cause Analysis

• Use 5-Why or Fishbone diagram logic
• Distinguish internal vs external causes
• Check for process drift vs sudden change
• Verify with data (SPC, correlation analysis)

E. Countermeasures & Verification

• Short-term containment (sorting, 100% inspection)
• Long-term corrective action (process change, design change)
• Effectiveness verification (pilot run, SPC monitoring)
• Closure criteria definition

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2. 8D Report Review Checklist

When reviewing 8D reports from suppliers:

Section	What to Check
D1	Team formed, problem severity acknowledged
D2	Problem description with data (quantity, affected lots)
D3	Interim containment actions (sorting, 100% audit)
D4	Root cause identification (why-level 5, verified with data)
D5	Permanent corrective actions selected
D6	Implementation & verification plan
D7	Prevent recurrence (FMEA update, control plan revision)
D8	Team recognition & lessons learned

Red flags:

• Root cause stated as "human error" without systemic fix
• Countermeasures not linked to root cause
• No data supporting root cause conclusion
• No effectiveness verification plan

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3. Key Automotive Quality Metrics

Metric	Formula	Threshold
PPM	Defects per million	< 100 PPM typical
CPK	Process capability index	≥ 1.33 acceptable
DPMO	Defects per million opportunities	Track trending
Lot reject rate	Rejected lots / total lots	< 1% target

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4. Common Failure Modes for HPFP/Fuel System Parts

Seizure/Jamming:

• Insufficient honing pattern (RVK too shallow, angle wrong)
• Lubrication failure (oil starvation, contamination)
• Thermal overload (clearance too tight)
• Material mismatch (surface hardness)

Internal Leakage:

• Valve seat damage (contamination, wear)
• Spring failure (fatigue, corrosion)
• Foreign material embedded in sealing surfaces

External Leakage:

• Seal damage (installation damage, aging)
• Connector fitting issues (thread debris, torque)
• Housing crack (stress concentration)

Performance Degradation:

• Pressure drop (restricted flow, pump wear)
• Noise/vibration (bearing failure, cavitation)
• Calibration drift (sensor issues, contamination)

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5. Supplier Quality Assessment

When evaluating supplier capability:

Area	Assessment Points
Process Control	SPC data availability, Cpk levels, control plan existence
Measurement System	MSA results, gauge R&R, calibration records
PPAP Level	Documentation completeness (typically Level 3)
FMEA	Current version, action prioritization (RPN threshold)
Cleanliness	In-process cleaning, particle control, packaging
Traceability	Lot tracking, raw material certs, process parameters

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6. Report Structure for Quality Analysis

When presenting quality analysis results:

## 质量分析报告

### 1. 问题概述
- 零件信息
- 问题现象
- 影响范围

### 2. 根本原因分析
- 证据链
- 5-Why分析
- 原因验证

### 3. 改善对策
- 短期措施（围堵）
- 长期措施（纠正）
- 实施计划

### 4. 验证结果
- 改善效果
- 后续跟进

### 5. 行动项
| 行动项 | 负责人 | 截止日期 |
|--------|--------|----------|

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Reference Files

• references/qc-tools.md - SPC, MSA, FMEA templates and guidelines
• references/failure-modes.md - Detailed failure mode library for fuel system components

Load reference files only when specific detailed guidance is needed.