Quality Problems Of Color Coated Board Analysis

1.Bendability

Features: When the steel is bent at 180 degrees, cracks and peeling of the coating occur on the processed part.
cause:
a. Too much mastery of pre-processing.
b. Coating thickness is too thick.
c. Over baking.
d. The manufacturer of the bottom coating is different from the manufacturer of the top coating, or the thin material is not used properly.

2. Hardness

Features: Use a drawing pencil to make a strong scratch on the coating surface, leaving a scratch on the surface after wiping it off
cause:
a. The furnace temperature is low, and the coating is not sufficiently cured.
b. Inappropriate heating conditions
c. Coating thickness is thicker than specified

3. Bump

Features: due to external impact of the steel strip, the surface of the board protrudes or dents, some have a certain distance, some have
cause:
a. Foreign matter is mixed in the roller during coating.
B. Streak of thin plate products during bundling.
c. External shock during rewinding.

4. Edge bubbles

Features: Paint is stained on both sides, and air bubbles appear after drying.
Cause: There are burrs on the original material, there is a lot of paint, and there are gaps on both sides.

5. Pitting

Features: Foreign matter or dust mixed in from the outside has rice-like protrusions on part or all of the surface after painting
cause:
a. Paints of other types or other companies are mixed in the paint.
b. Foreign matter is mixed in the coating.
c. Poor washing during pre-treatment.

6. Orange Peel

Features: The dried surface coating is as rough and uneven as orange peel
cause:
a. The wet film is too thick.
b. When the viscosity of the coating is high.

7. Poor solvent resistance

Features: Methyl ethyl ketone wipes off a bit of paint
cause:
a. The baking temperature does not meet the requirements
b. There is a problem with the curing of the coating
c. The pre-treatment is not clean

8. Impact failed

Features: After the paint film is impacted, some or all of the paint will fall off after the tape is stuck
cause:
a. Poor pre-treatment
b. Check if the topcoat curing temperature is reasonable

9. Shrinkage

Features: Uneven paint film, partial exposed bottom
cause:
a. The surface of the steel strip is not clean
b. Primer cooling water is not clean
c. Coating viscosity does not meet the requirements of the machine

10. Missing coating

Features: Unpainted
cause:
a. The top surface paint is not applied, the shape of the substrate is not good, or the pressure between the coating roller and the large back roller is insufficient.
b. The middle surface of the board is not coated, and there is water or other foreign matter on the board after the primer is cooled.

11. Color difference

Features: color difference from standard board
cause:
a. Coating thickness is too thick or too thin.
b. Not a batch of paint
c. Uneven stirring during viscosity dilution.

12.Gloss

Features: Abnormal range of gloss
cause:
a. Inappropriate coating thickness.
b. Inadequate curing conditions.
c. Insufficient stirring.

13. Collapse

Features: The inner diameter of the coil is deformed when stored in the warehouse
cause:
a. Influence of external force after coiling
b. The winding tension is incorrect
c. Uneven load

14. Re-stain

Features: There is a slight peeling when uncoiling, the grains similar to millet will appear when the primer is re-stained.
cause:
a. Insufficient cooling before coiling
b. insufficient baking
c. Partial load is too large

15. Crush

Features: pitting after coating
cause:
a. The raw material roll is crushed
b. Injured by various rollers before coating
c. Crushing with paint after application