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
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
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 |
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)
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 |
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 |
|--------|--------|----------|
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.