1. Weld defect: The weld defect is serious, and it is compensated by the manual mechanical grinding method. The resulting grinding marks cause uneven surface and affect the appearance.
2. Inconsistent surface: only the pickling passivation of the weld seam, also caused uneven surface, affecting the appearance
3. Grinding and polishing passivation unevenness: pickling and polishing after manual polishing and polishing, it is difficult to achieve uniform and uniform treatment effect on products with a large area
4. Limited pickling ability: Pickling passivation paste is not a panacea, it is difficult to remove for plasma cutting, flame cutting, and black scale.
5. Scratches caused by human factors are more serious: in the process of hoisting, transportation, and structural processing, scratches caused by human factors such as bumping, dragging and hammering are more serious.