The characteristics and causes of common quality problems of color-coated steel platesColor

1. Poor flexibility (T-bend)

 

Features:

 

When the steel was bent at 180 degrees, the coating on the processed part was cracked and peeled off.

 

cause:

 

1. Too much pre-processing.

 

2. The coating thickness is too thick.

 

3. Excessive baking.

 

4. The manufacturer of the lower coating is different from the manufacturer of the upper coating, or the thinner is not used properly.

 

2. Poor hardness (pencil hardness)

 

Features:

 

Use a drawing pencil to make a strong scratch on the surface of the coating, leaving a scratch on the surface after wiping.

 

cause:

 

1. The furnace temperature is low and the coating is not sufficiently cured.

 

2. The heating conditions are inappropriate.

 

3. The coating thickness is thicker than specified.

Three, bumps

 

Features:

 

Due to the external impact of the steel belt, the surface of the board appears protruding or recessed, some with a certain distance, and some without.

 

cause:

 

1. There is foreign matter mixed on the roller during painting.

 

2. Puncture marks of sheet products during bundling.

 

3. External impact during rewinding.

 

Fourth, the side bubbles

 

Features:

 

There is paint on both sides, and after drying, bubbles appear.

 

cause:

 

The original material has many burrs and paint, and there are gaps on both sides.

 

Five, pitting

 

Features:

 

After painting, the foreign objects or dust mixed in from the outside may have some rice-like protrusions on part or all of the surface.

 

cause:

 

1. The paint is mixed with other types or paints of other companies.

 

2. There is foreign matter mixed in the paint.

 

4. Poor water washing during pretreatment.

Six, orange peel

 

Features:

 

The dried surface coating is rough and uneven like orange peel.

 

cause:

 

1. The wet film is too thick.

 

2. When the viscosity of the coating is high.

 

7. Poor solvent resistance (MEK)

 

Features:

 

The methyl ethyl ketone wiped off the paint a bit.

 

cause:

 

1. The baking temperature does not meet the requirements.

 

2. There is a problem with the curing of the paint.

 

3. The pretreatment cleaning is not clean.

 

Eight, the impact is not qualified

 

Features:

 

After the impact of the paint film, the paint is partially or completely removed after being adhered by the adhesive tape.

 

cause:

 

1. Poor pre-treatment.

 

2. Check whether the curing temperature of the topcoat is reasonable.

 

9. Shrinkage

 

Features:

 

The paint film is uneven and partially exposed.

 

cause:

 

1. The surface of the steel belt is not clean.

 

2. The primer cooling water is not clean.

 

3. The viscosity of the paint does not meet the requirements of the machine.

 

10. Missing coating

 

Features:

 

The topcoat is not applied.

 

cause:

 

1. The top coat is not applied, the board shape is not good or the pressure between the coating roller and the large back roller is insufficient.

 

2. The top coat of the middle of the board is not coated, and there is water or other foreign objects on the board after the primer is cooled.

11. Color Difference

 

Features:

 

The color of the standard board is different.

 

cause:

 

1. The coating thickness is too thick or too thin.

 

2. Not a batch of paint.

 

3. Uneven mixing during viscosity dilution.

 

12. Poor gloss

 

Features:

 

The gloss range is abnormal.

 

cause:

 

1. The coating thickness is inappropriate.

 

2. The curing conditions are inappropriate.

 

3. Insufficient stirring.

 

13. Rolling

 

Features:

 

After coiling, the inner diameter of the steel coil is deformed during storage in the warehouse.

 

cause:

 

1. The steel coil is influenced by external force after being wound.

 

2. The winding tension is incorrect.

 

3. Uneven load.

 

14. Anti-sticking

 

Features:

 

There is a slight peeling during unwinding, and the back-coating of the primer will appear like millet-like granules.

 

cause:

 

1. Not enough cooling before coiling.

 

2. Insufficient baking.

 

3. Some loads are too heavy.

 

15. Bruise

 

Features:

 

Press pit after coating.

 

cause:

 

1. The raw material roll is crushed.

 

2. Crush by various rollers before coating.

 

3. Crushing with paint after application.