Sharing of technical issues on color-coated galvanized steel coils
1. A phenomenon caused by the poor lifting properties of the paint itself.
2. Cause: When the linear speed increases, the roller speed ratio remains unchanged, and the speed of the sticking roller increases, so the paint in the tray is prone to faults. When the faults reach between the sticking roller and the coating roller, surface cracks are prone to occur. Flower phenomenon.
3. Shape: water stripes or strips
4. Regularity: There is no specific location or regularity. Observe the paint curtain from the material tray or observe the status of the sticky roller during the reverse coating process
5. Features: Uneven film thickness
Solution: Reduce the speed of the rubber roller; increase the viscosity; slow down.
Note: The wax content of the paint is inappropriate, and there are watermark-like patterns (flakes) on the surface of the light-facing board.
2. Floating color (glossy line)
1. The pigment contained in the paint itself floats on the surface of the paint because it has not been stirred for a long time.
2. Cause: Due to insufficient paint flow in the tray, the lower-density colors in the paint float to the surface.
3. Shape: spots or color difference stripes
4. Regularity: close to the feed port
5. Features: No obvious change in film thickness
B. Solution: Stir the tray from time to time; add baffles; increase the painting speed to make the paint in the tray flow back as quickly as possible; change the position of the feed port or overflow port to change the overflow
3. Coating roller
1. Printing or roller printing occurs during the use or grinding of the coating roller.
2. Causes: Occurrence during use; Improper operation of the grinder; Damage during transportation.
4. Board surface
1. There is water, oil and passivation liquid on the surface of the board
2. Cause: There is oil and passivation liquid on the substrate. When passing through the coating machine, the coating cannot be coated on the substrate normally, resulting in frosting or missed coating on the board’s surface. 3. Shape: dots or strips
4. Regularity: irregular
5. Features: Uneven film thickness
5. The viscosity is too low
1. The board surface looks like a zinc leakage pattern
2. Cause: viscosity is too low
3. Regularity: The feed port is lighter, and the throttle port is heavier.
4. Features: The thickness of the film cannot be increased, and the speed ratio of the rubber roller cannot be increased.