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 paper will introduce several common coating defects in coating construction, including color difference, hard or pitting, loss of film, uneven coating thickness, itp., and put forward corresponding solutions.
1. Różnica barw
The reason:
The paint itself has a large color difference, and the paint variety needs to be replaced.
Improper control of film thickness leads to coating color difference, and it is necessary to adjust the film thickness in time.
Improper control of PMT (curing temperature of coatings) leads to coating color difference, and the furnace temperature needs to be adjusted.
Improper control of baking time and air speed in the furnace will also cause coating color difference, and the production process parameters need to be adjusted.
The solution:
Timely change of paint varieties.
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 the balance of air flow in and out of the furnace.
2. Clumps or pitting
The reason:
The substrate is rough or defective, and the substrate needs to be replaced.
Before coating, the coating surface is affected by pollution, and the coating needs to be replaced or filtered in time.
During painting, the air inside the coating machine is dirty and pollutes the coating surface, and the air inside the coating machine needs to be purified.
The acid gas in the furnace is too heavy to cause the paint to harden, so the furnace temperature needs to be adjusted.
The air in the furnace dirty pollution coating surface caused pitting, need to shut down to clean the air in the furnace.
The cooling water is too dirty, contaminating the coating surface during the cooling process, and clean cooling water needs to be replaced.
The solution:
Replace the substrate.
Replace or filter paint in time.
Purify the air inside the coating machine.
Adjust the furnace temperature.
Stop the machine to clean the air in the furnace.
Replace the clean cooling water.
3. Loss of film
The reason:
The improper control of PMT leads to the loss of coating film, and the furnace temperature needs to be adjusted.
Roll speed ratio does not match, need to adjust the roll speed ratio.
The coating roll is defective and needs to be replaced.
Improper viscosity of the coating causes the coating to lose film, and the coating viscosity needs to be adjusted.
The solution:
Adjust the furnace temperature.
Adjust roll speed ratio.
Replace the coating roller in good condition.
Adjust the viscosity of the paint.
4. Uneven coating thickness
The reason:
Roll speed ratio does not match, need to adjust the roll speed ratio.
The coating roll is defective and needs to be replaced.
The solution:
Adjust roll speed ratio.
Replace the coating roller.
5. Horizontal stripes are found on the wet coating surface, to znaczy, “forehead stripes”.
The reason:
Transverse strip strip of galvanized substrate.
Roll speed ratio does not match, need to adjust the roll speed ratio.
The solution:
Replace the substrate.
Adjust roll speed ratio.
In the coating construction, the operator should always pay attention to the quality of the coating, find and solve various coating defects in time to ensure the quality and stability of the coating, so as to improve the quality of the product and market competitiveness.