Metal Stamping Parts Inspection Standards
1. Purpose
To standardize the quality inspection standards for metal stamping parts and ensure that product dimensions, appearance, performance, and assembly meet customer requirements and industry standards, thereby improving product consistency and stability.
2. Scope of Application
Applicable to:
- Precision Metal Stamping Parts
- Stainless Steel Stamping Parts
- Automotive Metal Parts
- Electronic Metal Components
- Sheet Metal Stamping Parts
- Deep Drawn Parts
- Bending Parts
- Progressive Die Stamping Parts
3. Inspection Basis
Inspection shall be carried out according to the following documents:
- Product Drawings
- Technical Specifications
- Customer Samples
- BOM Documentation
- Industry Standards (GB / ISO / DIN / JIS)
- PPAP / FAI Documents (if applicable)
4. Inspection Items
4.1 Appearance Inspection Standards
Inspection Content
| Inspection Item | Standard Requirement |
|---|---|
| Burrs | Sharp burrs are not allowed |
| Scratches | Not visible on Class A surfaces |
| Dents | Obvious dents are not allowed |
| Deformation | Must not affect assembly |
| Cracks | Not allowed |
| Oxidation | Significant oxidation is not allowed |
| Rust | Not allowed |
| Oil Stains | Visible oil contamination is not allowed |
| Color Difference | Must match the approved sample |
4.2 Dimensional Inspection Standards
Inspection Content
- Overall Dimensions
- Hole Diameter
- Hole Distance
- Bending Dimensions
- Forming Height
- Flatness
- Perpendicularity
Common Tolerance Standards
| Dimension Range | General Tolerance |
|---|---|
| 0–10mm | ±0.05mm |
| 10–50mm | ±0.10mm |
| 50–100mm | ±0.15mm |
| ＞100mm | ±0.20mm |
Precision Stamping Tolerance
Precision metal stamping parts can achieve:
- ±0.01mm
- ±0.02mm
4.3 Burr Inspection Standards
Burr Height Requirements
| Material Thickness | Allowable Burr Height |
|---|---|
| ≤0.5mm | ≤0.03mm |
| 0.5–1.0mm | ≤0.05mm |
| ＞1.0mm | ≤0.10mm |
Inspection Methods
- Manual Touch Inspection
- Profile Projector Inspection
- Microscope Inspection
4.4 Bending Inspection Standards
Inspection Items
- Bending Angle
- Bending Radius
- Springback
- Cracks
Standard Requirements
| Item | Requirement |
|---|---|
| Bending Angle | ±1° |
| Cracks | Not allowed |
| Bending Deformation | Not obvious |
4.5 Deep Drawn Parts Inspection Standards
Inspection Items
- Surface Scratches
- Wrinkling
- Cracking
- Wall Thickness Uniformity
Standard Requirements
| Item | Standard |
|---|---|
| Cracking | Not allowed |
| Wrinkling | Not obvious |
| Wall Thickness Reduction | ≤15% |
5. Surface Finishing Inspection Standards
Electroplated Parts
| Item | Standard |
|---|---|
| Missing Plating | Not allowed |
| Blistering | Not allowed |
| Peeling | Not allowed |
| Salt Spray Test | 24–96 Hours |
Powder Coated Parts
| Item | Standard |
|---|---|
| Color Difference | Must match approved sample |
| Sagging | Not allowed |
| Particles | Not obvious |
| Coating Thickness | 60–120μm |
Anodized Parts
| Item | Standard |
|---|---|
| Color Difference | Uniform |
| Scratches | Not obvious |
| Coating Thickness | Must meet requirements |
6. Assembly Inspection Standards
Inspection Content
- Fit Dimensions
- Hole Position Alignment
- Riveting Strength
- Welding Strength
Standard Requirements
| Item | Standard |
|---|---|
| Assembly Interference | Not allowed |
| Looseness | Not allowed |
| Misalignment | ≤0.10mm |
7. Functional Inspection Standards
Applicable to electronic metal parts, automotive metal parts, etc.
Inspection Items
- Electrical Conductivity
- Continuity Testing
- Strength Testing
- Fatigue Testing
8. Inspection Equipment
Common inspection equipment includes:
| Equipment | Application |
|---|---|
| Vernier Caliper | Dimensional Inspection |
| Micrometer | Precision Measurement |
| Height Gauge | Height Measurement |
| Vision Measuring System | Precision Inspection |
| CMM (Coordinate Measuring Machine) | Precision Measurement |
| Salt Spray Tester | Corrosion Resistance Test |
| Hardness Tester | Hardness Inspection |
9. Sampling Inspection Standards
Commonly adopted standards:
- GB/T 2828
- ANSI/ASQ Z1.4
AQL Reference
| Defect Level | AQL |
|---|---|
| Critical Defect (CR) | 0 |
| Major Defect (MA) | 0.65 |
| Minor Defect (MI) | 1.0 |
10. Defect Classification Standards
10.1 Critical Defects (CR)
Affect:
- Safety
- Product Function
- Regulatory Compliance
Examples:
- Cracks
- Sharp Burrs
- Missing Processing Operations
10.2 Major Defects (MA)
Affect:
- Assembly
- Product Performance
Examples:
- Dimensional Out-of-Tolerance
- Hole Position Deviation
- Severe Surface Scratches
10.3 Minor Defects (MI)
Minor cosmetic issues such as:
- Slight Color Difference
- Minor Dent Marks
11. Outgoing Quality Control (OQC) Requirements
Before shipment, the following items must be inspected:
- Quantity
- Labels
- Packaging
- Appearance
- Dimensions
- Anti-Rust Condition
Ensure that:
- Products match the drawings
- Packaging complies with transportation requirements
- Inspection reports are included
12. Common International Standards for Metal Stamping Parts
| Standard | Description |
|---|---|
| ISO 9001 | Quality Management System |
| IATF 16949 | Automotive Industry Standard |
| ISO 2768 | General Tolerances |
| RoHS | Environmental Compliance |
| REACH | Chemical Compliance |
| ASTM | Material Standards |
