Color steel coil is a great building material with a wide range of applications and is highly favored by people. However, it always has quality issues, so what are the characteristics and reasons behind it? Let’s take a look together below!
1. Convex point
Characteristics: Due to external impact on the steel strip, the surface of the plate may protrude or sink, with some having a certain distance and others not.
Reason for occurrence: 1. Foreign objects were mixed in on the roller during painting. 2. The tie marks of thin sheet products during bundling. 3. External impact during rewinding.
2. Edge bubbles
Features: Both sides are coated with paint, and after drying, bubbles appear.
Reason for occurrence: The raw material has burrs and is heavily coated with paint, resulting in gaps on both sides.
3. Puncture
Characteristics: Foreign objects or dust mixed in from the outside have rice like protrusions on some or all surfaces after painting.
Reason for occurrence: 1. Mixing of other types or coatings from other companies into the coating. 2. Foreign objects mixed in the paint. 3. Poor water washing during the pre-treatment process.
4. Poor bending (T-bend)
Characteristic: During the 180 degree bending test of steel, the coating on the processed area cracks and peels off.
Reason for occurrence: 1. Excessive mastery of pre-processing. 2. The coating thickness is too thick. 3. Excessive baking. 4. The manufacturer of the lower coating is different from that of the upper coating, or the use of thinner is improper.
5. Poor hardness (pencil hardness)
Characteristic: Use a drawing pencil to draw a scratch on the surface of the coating, and after wiping it off, leave a scratch on the surface.
Reason for occurrence: 1. Low furnace temperature and insufficient coating curing. 2. The heating conditions are not appropriate. 3. The coating thickness is thicker than the specified thickness.
Post time: Jul-29-2024