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 (degreasing and forming) determines the quality of the coating and directly affects The physical indicators such as the flexibility and impact resistance of the coating also determine the coating adhesion of the color-coated board product.
Therefore, the quality control before coating is the first step to ensure the entire coating process, and it is also the basis for ensuring the quality of color-coated board products.
(1) Degreasing section. The degreasing section mainly controls the alkalinity, temperature, spray pressure, spraying conditions of the nozzles, the friction effect of the scrubbing roller and the conductivity of the degreasing water, etc.
(2) into segments. 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.
Inspection method of chemical liquid film layer: 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 dusting. 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 serious dust is not allowed.
