How to choose color coated sheet, processing should pay attention to what problems

In order to improve the corrosion resistance of hot-dip galvanized steel sheet, improve its surface colorability, and make the surface zinc layer not directly contact the air, it should be painted. According to different uses, the appropriate substrate and coating should also be selected, and the appropriate coating method should be used to produce the color coated plate that meets the requirements.

In order to make the coating and galvanized sheet surface have good adhesion, it is necessary to chemically treat the galvanized surface. First, clean the oil and dirt adhering to the surface of the galvanized sheet, otherwise it will affect the adhesion of the coating, so degreasing and cleaning are required. This is followed by a chemical conversion treatment, usually to produce complex oxides or phosphates on the galvanized surface. The former has good paint film adhesion, and the latter has good corrosion resistance. After chemical conversion treatment, it should be completely dry and painted without moisture.

Under normal circumstances, there are usually two aspects to be aware of.

1. Selection of substrate (substrate strength, galvanizing amount, surface finishing, etc.)

2. Choice of coating.

Due to the coating on the surface of the prepainted plate, there are many differences from ordinary cold-rolled sheet and galvanized sheet in the forming process. Sufficient attention should be paid to some mechanical properties (such as yield strength, elongation) and partial coating properties (such as pencil hardness, T bending value, impact work) of the prepainted plate. The following points should be noted when post-processing:

(1) The shape of the part is complex. When the degree of deformation is large, multiple forming should be used. If formed once, the adhesion of the coating may be damaged by excessive deformation.

(2) Set the appropriate gap according to the mold shape, deformation characteristics, process conditions and other factors, and the coating thickness should be considered when setting the gap.

(3) The VI section generated during processing is easy to corrode, and necessary protective measures such as coating protective coatings and embedded rubber seals should be taken.

(4) During processing, the burr of the cutting surface should be minimized to prevent the burr from scratching the surface.

(5) The construction method should be pre-installed by the factory as much as possible, and then sent to the site for installation should take protective measures to prevent damage to the coating.

(6) If the surface of the coating is found to be damaged, it should be repaired with a special repair coating in time to prevent corrosion at the damaged place.