The quality control of coatings on color coated sheets is usually carried out in three stages. That is, the control before coating, the process of coating construction and the control after coating according to the failure degree of coating. The control
before coating and during coating construction is very important, which can be said to play a decisive role, while the quality control after coating is actually feedback to the first two stages, which is a means to find the cause of quality defects.
Therefore, during the whole coating construction process, operators should strictly follow the process regulations and operation rules.
The pre-coating control of color coated sheet mainly includes the following inspection links:
(1) Check whether the strip has been tested and analyzed for surface defects and flatness before surface treatment.
(2) Check the degreasing cleaning
effect of steel strip surface.
(3) Check whether the chemical liquid film thickness on the surface of steel strip is in accordance with the national or industrial standards.
(4) Check whether the surface of the strip meets the surface temperature
and humidity requirements of the coated substrate.
(5) Types and specifications of coatings and diluents, and viscosity before boarding.
(6) The ambient temperature of the coating chamber.
The control of coating construction process
of color coated sheet mainly includes the following checking links
(1) Wet film thickness of primer and topcoat.
(2) Wet film is missing or discontinuous.
(3) Whether the speed ratio of the rollers on the coating head to the production
line meets the technological requirements.
(4) Th drying temperature of each section of the curing furnace.
After coating, the control of color-coated panel mainly includes the following several inspection links
(1) Check the surface
condition of the coating, including whether there are surface defects, gloss and color, etc.
(2) check whether the total dry film thickness meets the design requirements according to the national or industrial standards.
(3) Check the adhesion
between the coating and the substrate.
(4) Check other properties of the coating according to the quality standard of the coating.