Scenario
A Quality Assurance Engineer audits a supplier, using a 50-question checklist. After completing it, the total score is 85, which passes.
Upon returning, an audit report is written and submitted to the supervisor for archiving.
Three months later, the incoming material defect rate rises from 0.5% to 2.3%. During the next audit, the supplier asks, "Didn't we get 85 points last time?"
The problem is: those 85 points did not reflect the true process control capability.
Three Types of Audits
System Audit
- Confirms whether the quality management system is fully established (e.g., ISO 9001 / IATF 16949 compliance)
- Reviews documents, procedures, and systems
- Typically conducted annually
Process Audit
- On-site verification that processes are executed according to the control plan
- Reviews production site, measurement records, SPC control charts
- Quarterly or semi-annually
Product Audit
- Samples finished products to confirm dimensions and performance meet specifications
- Usually combined with IQC (Incoming Quality Control) data
Scoring System Design
A differentiating scoring system is not merely "Pass/Fail" but involves weighted scoring:
| Category | Weight | Key Scoring Points |
|---|---|---|
| Quality System | 30% | Document completeness, SPC, MSA, FMEA |
| Process Control | 30% | Control plan execution, speed of abnormal condition handling |
| Delivery Performance | 20% | On-time delivery rate, timeliness of shipping notices |
| Responsiveness | 10% | Customer complaint response speed, 8D quality |
| Continuous Improvement | 10% | Number and effectiveness of improvement items |
Scoring Levels:
- 90-100: Preferred Supplier
- 70-89: Approved Supplier
- 50-69: Conditional Supplier — Requires an improvement plan
- Below 50: Suspended/Disqualified
Follow-up Tracking for Audit Findings
An audit's conclusion is merely the beginning. Without follow-up, deficiencies will always remain deficiencies.
CAR (Corrective Action Request) Process:
- On audit day: List all deficiencies, categorize by severity (Critical / Major / Minor)
- Within 3 business days after audit: Issue official CAR
- Supplier responds within 5-10 business days: Root cause + Improvement plan
- Quality Engineer reviews CAR response for reasonableness
- Tracking period (typically 30-60 days): Confirm effective execution of improvements
- Audit score adjustment: Update supplier score upon completion of improvements
Decision-making Incorporating IQC Data
Audit scores should be reviewed in conjunction with IQC data:
- Audit score 85 + IQC Defect Rate 3% → Audit questions not deep enough, improve audit tools
- Audit score 65 + IQC Defect Rate 0.1% → System documentation is poor but product is acceptable, focus on improving documentation
- Audit score 60 + IQC Defect Rate 5% → Immediately initiate supplier replacement procedure
Golden Quote
"An audit is not for suppliers to pass, but to find vulnerabilities in their processes and then ensure those vulnerabilities are rectified. The score is merely a starting point; the subsequent CAR tracking is where the true value of an audit lies."