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What are the common quality defects of color coated plates

Update:02-07-2020
Summary:

Color-coated sheet is also called pre-coated steel shee […]

Color-coated sheet is also called pre-coated steel sheet. It uses metal strip as the base material (such as cold-rolled steel plate, galvanized plate, aluminum plate, etc.), through strict process control, it is coated with various polymer coatings (such as polyester, silicon to polyester, partial Polyvinyl fluoride resin, polyvinyl chloride, acrylic resin, epoxy resin, etc.) or products made by pasting various plastic films (such as polyvinyl chloride film, polyethylene film, etc.). Color-coated plate is an important product of surface treatment engineering combining metallurgy and chemical industry. Color-coated plate as a surface technology treatment product, its product quality is not limited to the physical and chemical properties of the product (film thickness, gloss, flexibility, reverse impact resistance) Resistance, solvent resistance, corrosion resistance, weather resistance, etc.), and also include the coating surface quality of color-coated products. The combination of physical and chemical properties of color-coated board products and coating surface quality determine the overall quality of color-coated board products. This paper analyzes the causes of quality defects in the production of color-coated plates in combination with the raw materials, process equipment, and operation control of color-coated plates in the actual production of color coating lines in Pangang, and proposes solutions.

Scratched surface

Surface scratches are a type of product surface defects in the production of color-coated boards. It not only affects the appearance of color-coated products, but also reduces the corrosion resistance of the color-coated products. It can be divided into raw material scratches and production process scratches according to the source.
Raw material scratches

The roll coating plate is generally used for a ceiling veneer

Refers to the quality defects that occur when the substrate is produced by galvanizing. When using scratched substrates to produce color-coated boards, it is easy to produce quality defects on the surface of the color-coated boards produced, such as color difference or even missed coating. The control measure is to check the production quality in the previous process and prevent raw substrates with scratches from entering the factory.

Missed coating

Missing coating refers to a quality defect caused by the steel plate not being coated by the coating machine in the production process of the color coated plate. It is one of the most common product quality defects in the production of color coated plate. It not only directly affects the color The appearance of the coated product, and affect the performance of the color coated board products, it will also reduce the corrosion resistance of the color coated board products, and lose the characteristics that the color coated board products should have, so we must be aware of the leakage in the production process The reason for coating, so that the most effective measures can be taken to prevent and control the occurrence of missing coating defects.

 

Bump coating

The coating is not attached to the steel plate due to debris on the rollers of the raw material or color coating line. It can be divided into two situations: concave dot leakage coating and convex dot leakage coating. Debris on the raw material will cause convex dot leakage coating after coating. The solution is to check the raw material cleaning before coating after strip cleaning quality. Debris on the roller will cause pits to be missed after coating. It can be judged that the missing coating caused by the debris on the roller can be carried out according to the distance between the stamping and the circumference of the roller (distance S=ΠD). The solution is to clean the rollers of the color coating line before starting production to prevent debris from appearing on the rollers.

Strip steel edge wave, middle wave leak coating

Due to the side waves or the medium waves being too large, the coating roller of the coating machine cannot contact the strip steel and the leakage coating phenomenon occurs, and the edge wave leakage coating mainly occurs on the back coating surface of the strip steel. There are several methods to control the side and middle wave leakage coating of strip steel.

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