During the coating construction process, operators often encounter various coating defects, which may affect the quality and appearance of the coating, and even affect the service life of the product. This article will introduce several common coating defects in coating construction, including color difference, hard lumps or pitting, film loss, uneven coating thickness, etc., and propose corresponding solutions.
1. Color difference
reason:
The paint itself has a large color difference, and the paint type needs to be replaced.
Improper film thickness control leads to coating color difference, and the film thickness needs to be adjusted in time.
Improper control of PMT (coating curing temperature) leads to color difference in the coating, and the furnace temperature needs to be adjusted.
Improper control of baking time and air speed in the furnace will also cause color difference in the coating, requiring adjustment of production process parameters.
Solution:
Change paint types promptly.
Adjust film thickness and furnace temperature to eliminate color difference.
Adjust the control according to the PMT adjustment range provided by the paint manufacturer.
Adjust the production process speed and balance the air inlet and outlet flow in the furnace.
2. Hard lumps or pitting
reason:
The substrate is rough or defective, and the substrate needs to be replaced.
Before painting, if the paint is contaminated and affects the coating surface, the paint needs to be replaced or filtered in time.
During painting, the air inside the coating machine is dirty and contaminates the coating surface, so it is necessary to purify the air inside the coating machine.
Too much acid gas in the furnace causes the paint to harden, and the furnace temperature needs to be adjusted.
Dirty air in the furnace will contaminate the coating surface and cause pitting, requiring the machine to be shut down to clean the air in the furnace.
The cooling water is too dirty and will contaminate the coating surface during the cooling process. Clean cooling water needs to be replaced.
Solution:
Replace the base board.
Replace or filter paint in time.
Purify the air inside the coating machine.
Adjust oven temperature.
Shut down the machine to clean the air in the furnace.
Replace with clean cooling water.
3. Film loss
reason:
Improper PMT control causes coating film loss, requiring adjustment of furnace temperature.
The roller speed ratio does not match and the roller speed ratio needs to be adjusted.
The applicator roller is defective and the applicator roller needs to be replaced.
Improper paint viscosity causes the coating to lose film, and the paint viscosity needs to be adjusted.
Solution:
Adjust oven temperature.
Adjust the roller speed ratio.
Replace the applicator roller with a good one.
Adjust paint viscosity.
4. Uneven coating thickness
reason:
The roller speed ratio does not match and the roller speed ratio needs to be adjusted.
The applicator roller is defective and the applicator roller needs to be replaced.
Solution:
Adjust the roller speed ratio.
Replace applicator roller.
5. Horizontal stripes, namely âhead linesâ, are found on the surface of the wet coating.
reason:
The base plate is galvanized with horizontal stripes.
The roller speed ratio does not match and the roller speed ratio needs to be adjusted.
Solution:
Replace the base board.
Adjust the roller speed ratio.
During coating construction, operators must always pay attention to the quality of the coating and promptly discover and solve various coating defects to ensure the quality and stability of the coating, thereby improving product quality and market competitiveness.
