1. Scratch. There are two types of scratches before and after plating, which are caused by the mechanical equipment passing over the surface of the strip.
2. Zinc particles. When there is too much slag in the zinc pot, it is floated by mechanical agitation or the zinc slag is not removed in time, and the zinc liquid adheres to the surface of the zinc plate.
3. Air knife strip marks. Due to the partial blockage of the air knife, the sweep is uneven, and a convex band mark is generated on the corresponding portion of the strip.
4. Air knife scratches. Due to the poor shape of the color corrugated steel sheet and the too small tension of the strip, the strip is too close to the nozzle of the air knife and the continuous or intermittent impression caused by the contact of the air knife nozzle.
5. Embossing. The finishing roller or other pressure roller adheres to the zinc particles or has mechanical damage, causing a certain periodic impression on the corresponding position of the strip surface.
6. Zinc undulation (zinc wave). The zinc layer exhibits a wave-like wave pattern. It is related to the control of air knife purging, overheating of zinc pot, and excessive thickness of zinc layer.
7. Thick edges. The zinc layer at the edge of the color corrugated steel sheet is obviously thickened, which is caused by poor control of the air knife purging edge.
8. Wrinkles (curly wrinkles, taro marks). This is a horizontal stripe that is visible to the naked eye, has no obvious hand, and is dense. The reason for this is the yield deformation caused by repeated bending of the strip after the operation of the strip.
9. Jitter streaks. Due to the misalignment of the equipment, the rollers are not rotated uniformly, forming a periodic beating, which causes the strip to produce laterally equidistant streaks.
10. Corrosion. The storage time of the substrate before plating is too long, and it is affected by the storage environment and the rust and overprint corrosion caused by the residue of the original board surface. Severe corrosion of the original plate can make the adhesion of the zinc layer worse or even fall off. The corrosion of the color corrugated steel sheet is due to the fact that the plated surface is not passivated or oil-coated, and a white zinc layer is rusted during storage and transportation.