Analysis of common quality problems in color coating

- May 25, 2018 -

1, poor flexural (T bending)

Characteristic:

When the steel is bent for 180 degree test, the coating of the processing part is cracked and the coating is stripped.

Cause:

1. The mastery of preprocessing is too much.

2, the thickness of the coating is too thick.

3. Excessive baking.

4. The coating on the bottom coating is different from that of the coating, or the improper use of the thinner.

2. Poor hardness (pencil hardness)

Characteristic:

Draw the pencil on the surface of the coating with a drawing pencil, wipe the surface and leave a scratch.

Cause:

1, the temperature of the furnace is low, and the coating is not fully cured.

2. The heating conditions are not suitable.

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

3, convex point

Characteristic:

Due to the external impact of the steel strip, the surface of the plate appears prominent or concave, some of which have a certain distance, and some do not.

Cause:

1. The rolls are mixed with foreign objects on the roll.

2. The ligation of the sheet products at the time of binding.

3. The reel is subjected to external shocks.

4, edge bubble

Characteristic:

There are coatings on both sides, and bubbles appear after drying.

Cause:

The raw material has burrs covered with paint, and cracks appear on both sides.

5.

Characteristic:

The foreign matter or dust from the outside is covered with rice grains after being painted.

Cause:

1, paint mixed with other kinds or other company's paint.

2, there is a mixture of foreign objects in the paint.

3. The water washing is bad during the process of pretreatment.

6, orange peel

Characteristic:

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

Cause:

1. The wet film is too thick.

2, the viscosity of the coating is high.

7, poor solvent resistance (MEK)

Characteristic:

The butanone wipes a spot and drops the paint.

Cause:

1, the baking temperature did not meet the requirements.

2, the curing of the paint has problems.

3, pre treatment cleaning is not clean.