Color coated steel coil is a very good building material. It has a wide range of uses and is deeply loved by people. However, it always has problems in quality, so what are the characteristics and reasons? Let's take a look!
1. bump
Features: Due to the external impact of the steel strip, the surface of the plate appears protruding or dented, some have a certain distance, and some do not.
Causes: 1. Foreign matter was mixed on the roller during painting. 2. The tie marks of thin-plate products during strapping. 3. It is subject to external shocks during rewinding.
2. Edge bubbles
Features: Coating on both sides, after drying, bubbles appear.
Cause: The raw material has burrs and lots of paint, and there are gaps on both sides.
3. Pockmark
Features: After painting, some or all of the surface of foreign matter or dust mixed in from the outside has the appearance of rice grains.
Reasons: 1. Other types of paint or other company's paint are mixed into the paint. 2. It is caused by the mixing of foreign matter in the paint. 3. Poor washing in the pre-treatment process.
4. Poor flexibility (T-bend)
Features: When the steel is bent at 180 degrees, the coating of the processed part is cracked and the coating peels off.
Reasons: 1. Too much mastery of pre-processing. 2. The coating thickness is too thick. 3. Excessive baking. 5. The manufacturer of the bottom coating is different from that of the top coating, or the thinner is used improperly.
6. Poor hardness (pencil hardness)
Features: Use a drawing pencil to draw a line on the surface of the coating forcefully, leaving a scratch on the surface after wiping it off.
Causes: 1. The furnace temperature is low, and the coating is not cured sufficiently. 2. The heating conditions are inappropriate. 3. The coating thickness is thicker than specified.
The above are the quality problems that usually occur in pre-painted steel coils. Have you learned?
