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:

SectionWhat to CheckD1Team formed, problem severity acknowledgedD2Problem description with data (quantity, affected lots)D3Interim containment actions (sorting, 100% audit)D4Root cause identification (why-level 5, verified with data)D5Permanent corrective actions selectedD6Implementation & verification planD7Prevent recurrence (FMEA update, control plan revision)D8Team 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#

MetricFormulaThresholdPPMDefects per million< 100 PPM typicalCPKProcess capability index≥ 1.33 acceptableDPMODefects per million opportunitiesTrack trendingLot reject rateRejected 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:

AreaAssessment PointsProcess ControlSPC data availability, Cpk levels, control plan existenceMeasurement SystemMSA results, gauge R&R, calibration recordsPPAP LevelDocumentation completeness (typically Level 3)FMEACurrent version, action prioritization (RPN threshold)CleanlinessIn-process cleaning, particle control, packagingTraceabilityLot tracking, raw material certs, process parameters

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6. Report Structure for Quality Analysis#

When presenting quality analysis results:

text

## 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.