In the cold bending forming industry, galvanized sheet and color-coated galvanized sheet are the two most common types of raw materials. Although they both are based on galvanized steel plates, there are significant differences in performance and application. More importantly, it is generally not recommended to process both types on the same equipment.

1. Differences in material
Galvanized sheet (GI)
Based on cold-rolled steel coils, a zinc layer is applied on the surface through the hot-dip galvanizing process.
Features: Corrosion-resistant, relatively low cost, widely used in structural components, guardrails, pipes, etc.
Coated galvanized sheet (PPGI/PPGL)
An additional organic coating (such as polyester, PVDF) is added to the surface of the galvanized sheet.
Features: It has both the corrosion resistance of the zinc layer and the decorative and weather resistance of the coating, often used in roof panels, wall panels, etc. for building exteriors.

2. Why is it not suitable to process on the same equipment?
1）Zinc particle residue issue
During the forming process, zinc particles tend to adhere to the surface of the galvanized sheet on the roller wheel.
If the same equipment is used again for the production of color-coated galvanized sheets, these particles will scratch the color-coated surface, resulting in coating damage.
2）Different surface quality requirements
Galvanized sheets are mostly used for structural components and have relatively low requirements for appearance;
Color-coated galvanized sheets are used for roofs or decorative panels, and have extremely high requirements for surface smoothness. Any scratches will affect the usability and appearance.
3）Difficult maintenance of roller wheels
The equipment needs to frequently clean the surface of the roller wheels, but even so, it is still difficult to completely avoid residual particles.
Long-term mixed use will shorten the lifespan of the roller wheels and increase maintenance costs.

3. Customer's Suggestions and Choices
If the production requirements involve two types of materials, it is recommended to configure separate units for galvanized sheet and color-coated sheet.
In scenarios where compatibility is truly necessary, strict processes for roller wheel cleaning and surface inspection should be established, but this will significantly increase downtime and maintenance costs.
When purchasing equipment, it is necessary to inform the manufacturer of the types of materials to be processed in advance, so as to carry out more reasonable roller wheel design and surface treatment.