Defect and cause analysis of color coated steel
2020年11月6日
- Get In Touch: +86-18115459757
Defect and cause analysis of color coated steel
A. surface paint missing
The surface was partially unpainted, usually no primer, or the top and the back paint is not applied. There are reason is the foreign matter stuck to the paint roller and the base original plate is in bad shape, the result is that the primer does not adhere to the substrate better.
B. lacquer layer scratch
Surface of vertical and horizontal groove, most of the time it is vertical, groove depth differs, the width is different, the light of the invisible strip no feel did not destroy the coating, heavy damage coating, more serious visible substrate. The reason is the relative movement of the steel belt and the equipment causes scratches and there are hard and hard impurities in the paint and the steel strip plate is not good, waviness exceeds the standard value.
C. peeling of paint coating
The finish or back is detached from the primer or the organic coating is detached from the substrate. The reason is : 1.the lye concentration too high when cleaning the substrate. 2.The primer does not match the base steel, finish coating, and back coating. 3.the coating is not cured completely or over cured. 4.the coating is not cooled sufficiently. 5.furnace temperature is too high or drying time is too long. 6.excessive amount of diluent in coating causes the adhesion to drop.
D. surface bubble
The surface has raised a small point, has the feeling, the face and the place is uncertain. Most of them are softcore convex or hollow convex. The reason is 1.the paint coating is too thick. 2.the temperature of the first layer coating and prime coating is too high, the solvent has no time to evaporate, causing boiling in advance. 3.there is too much dust in the coating furnace. 4.the primary coating is not thoroughly dry before entering the prime coating, the internal solvent is heated to expand the coating.
E. uneven coating
The surface is speckled, striped, coating is not uniform. The reason is 1.there is dirt on the base steel plate surface. 2.Paint dispersancy is bad or paint agitates is uneven. Improper setting of speed ratio of coating roller and dipping roller.
F. uneven colors
the color of the surface coating is markedly inconsistent. The season is 1.the same color of paint, not the same batch of production, resulting in two batches of paints have a different colors. 2.Paint before use, not enough stirring, or viscosity adjustment is inconsistent. 3.The paint mixed with other colors. 4.The paint from different manufacturers, cross-use.
G. pinholes appear in the coating
A small circular ring on the surface, such as a pinprick, or a larger pitting point. The reason is 1.bubbles in the coating. 2.The coating is not stirred evenly and is too thick. 3.Coating is too thin. 4.The surface of the primary coating is contaminated. 5.The first furnace temperature is too high.
H. coating with roller stripes
Horizontal stripes appear on the surface. The reason is 1.If the fringe is uniform and continuous, it may be the coating grinding roughness is not up to the requirement. 2.The fringe appears periodically, which may be due to the shape accuracy of the coating roller not meeting the requirement or the roller surface deformation.
