Analysis of common quality problems in color coated rolls

1. Poor bending (T-bend)

Features:

When the steel is bent at 180 degrees, the coating at the processing site is cracked and the coating is peeled off.

  cause:

1. Excessive amount of pre-processing.

2. The coating thickness is too thick.

3. Excessive baking.

4. The undercoating paint is different from the manufacturer of the top coating, or the thinner material is not used properly.

2, poor hardness (pencil hardness)

Features:

Use a drawing pencil to force the surface of the coating and wipe the back surface to leave a scratch.

  cause:

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

2. The heating conditions are not appropriate.

3. The thickness of the coating is thicker than specified.

3, bumps

Features:

Due to the external impact of the steel strip, the surface of the board appears protruding or concave, some have a certain spacing, and some do not.

  cause:

1. Foreign matter is mixed in the roller during painting.

2, the thin plate products are tied when tied.

3. External impact when rewinding.

4, edge bubbles

Features:

The paint is stained on both sides and dried.

  cause:

There are many burrs on the raw materials, and there are many gaps on both sides.

5, pitting

Features:

Foreign matter or dust mixed in from the outside, after painting, part or all of the surface, there is a rice-like protrusion.

  cause:

1. Mix paints of other types or other companies into the paint.

2. In the paint, foreign matter is mixed in.

3. Poor water washing during pre-treatment.

6, orange peel

Features:

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

  cause:

1. The wet film is too thick.

2. When the viscosity of the paint is high.

7, poor solvent resistance (MEK)

Features:

Butanone wiped a bit off the paint.

  cause:

1. The baking temperature did not meet the requirements.

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

3. The pre-treatment cleaning is not clean.

8, the impact is not qualified

Features:

After the paint film is impacted, some or all of the paint is removed after being stuck by the tape.

  cause:

1. Poor pre-treatment.

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

9, shrinkage hole

Features:

The paint film is uneven and partially exposed.

  cause:

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

2. The primer cooling water is not clean.

3, the viscosity of the paint did not meet the requirements of the machine.

10, missed coating

Features:

The topcoat was not painted.

  cause:

1. The side finish is not coated, the substrate plate type is not good or the pressure between the coating roller and the large back roller is insufficient.

2. The middle surface paint of the board surface is not coated. After the primer is cooled, there is water or other foreign matter on the board surface.

11, color difference

Features:

There is a difference in color from the standard board.

  cause:

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

2, not a batch of paint.

3. Stirring is uneven when the viscosity is diluted.

12, bad gloss

Features:

The range of gloss is abnormal.

  cause:

1. The coating thickness is not appropriate.

2. The curing conditions are not appropriate.

3. Stirring is not sufficient.

13, collapse

Features:

After the coil is taken up, the inner diameter is deformed when stored in the warehouse.

  cause:

1. The coil is affected by external force after coiling.

2. The winding tension is not correct.

3. Uneven load.

14, anti-stick

Features:

There is a slight peeling when unwinding, and there will be grainy particles similar to millet when the primer is applied. After the topcoat is applied, the surface is uneven.

  cause:

1. Cooling is not enough before coiling.

2. Insufficient baking.

3. Part of the load is too large.

15, crush injury

Features:

The crater after coating.

  cause:

1. The raw material roll is crushed.

2. Injure by various rollers before application.

3. A crush on the piece of paint after application.