Inspection standards and descriptions for appearance defects of precision stamped parts

1. **Irregular Corner Rounding Inspection Method:** Visual inspection and tool measurement. Uneven or unclear corner radii are unacceptable. This is especially true for outer cover parts. Uneven corner rounding on some assembly surfaces and overlaps of inner cover parts not only affects the appearance of precision stamped parts but can also severely impact welding and assembly.

2. **Dent Inspection Method:** Visual inspection. Dents severely affect the appearance quality of painted cover parts and are unacceptable defects to customers. Large-area dents can also affect the strength and fatigue resistance of precision stamped parts and are irreparable.

3. **Material Defect Inspection Method:** Visual inspection. Standards include: material strength not meeting requirements, traces left by rolling mill, overlaps, orange peel texture, streaks, loose galvanized surfaces, and peeling galvanized layers.

4. **Deformation (Protrusions, Dents, Wavy Texture) Inspection Method:** Visual inspection, oilstone polishing, touch, and oiling. Class A defects are unacceptable to users and can be noticed even by untrained users. Upon discovery of Class A dents, the precision stamped part must be immediately frozen. Category B defects: These are unpleasant defects that are tangible and visible on the outer surface of precision stamped parts and can be identified. Category C defects: These are defects requiring correction; most are ambiguous and only become visible after oilstone polishing.

5. Inspection methods for roughening, indentation, and scratches: Visually, roughening, scratches, and indentations are not allowed on the outer surface of the outer cover. Scratches and indentations that affect the quality of the outer surface are not allowed on the inner surface of the outer cover. Severe scratches and indentations that could potentially cause the part to crack are not allowed on the surface of the inner cover.

6. Inspection methods for wrinkles: Visually, wrinkles that are easily noticeable to the customer are not allowed on the outer cover. Severe wrinkles that could cause material overlap are not allowed on the inner cover.

7. Inspection methods for burrs: Visually, the length of burrs should be less than 10% of the sheet thickness. Any burrs that affect the fit of welded edges are unacceptable. Any burrs that could easily cause personal injury are unacceptable. Any punching burrs that affect part positioning and assembly are unacceptable.

8. **Overlap Inspection Method:** Visual inspection is required for exterior body panels. Overlap defects of varying degrees on interior body panels can lead to customer complaints. For functional precision stamped parts, they also affect assembly and body strength.

9. **Rust Inspection Method:** Visual inspection and cross-section. Rust is caused by prolonged or improper storage of precision stamped parts and has a crucial impact on their function, strength, and fatigue resistance.

10. **Grinding Defects and Marks Inspection Method:** Visual inspection and oilstone polishing. Category A defects: Grinded through, clearly visible on the outer surface, immediately visible to all customers. Category B defects: Visible and tactile, and can be proven even after grinding in disputed areas. Category C defects: Visible after oilstone polishing.

11. **Crack Inspection Method:** Visual inspection. Any cracking on exterior body panels is unacceptable. For interior body panels, only minor cracking is permitted for repair by welding, but the repaired area must be difficult for the customer to detect and must meet the repair standards for precision stamped parts.

12. Neck Inspection Method: Visual inspection and dissection. Neck is a potential dangerous fracture point in the forming process of precision stamped parts, and it has a crucial impact on the function, strength, and fatigue resistance of precision stamped parts. The degree of necking determines whether a precision stamped part is qualified, requires rework, or is scrapped. Necking of outer body panels affects the overall appearance of the vehicle, which is unacceptable to customers.

13. Pinhole Inspection Method: Visual inspection, oilstone polishing, touch, and oiling. Class A Defect: Pinholes are concentrated, distributed over more than 2/3 of the entire area. Class B Defect: Pinholes are visible and tactile. Class C Defect: Individually distributed pinholes are visible after polishing; in Zone 1, the distance between pinholes must be 300mm or greater.