The quality control of the steel strip before coating is mainly the control of the entire surface treatment process, that is, the control of the degreasing section and the forming section. The quality of the surface treatment directly determines the quality of the coating, and even affects the flexibility of the coating. , impact resistance and other coating physical performance indicators, not only that, it also determines the coating adhesion of color-coated board products.
Therefore, quality control assurance before coating is a very important step in the entire coating process, and is the basis for quality control of color-coated board products.
1. Degreasing section
The degreasing section mainly controls the alkalinity, temperature, spray pressure, spraying conditions of nozzles, friction effect of scrubbing rollers and conductivity of deionized water, etc.
2. Formation section
The chemical forming section mainly controls the roller pressure of the chemical roller coater, the concentration of the chemical solution, the wet film thickness of the chemical coating and the appearance color of the film, the drying temperature of the drying furnace and the circulation of hot air, etc.
The inspection method of the chemical liquid film layer is as follows:
The appearance of the film layer should be a dense, continuous and uniform light gray to dark gray film. The following defects are allowed:
Slight water stains, traces of chromate, slight scratches.
If the film layer is yellowed and rusted, the film layer is loose or there is no film at the bottom of the exposed part, and the phenomenon of serious ash is not allowed.