FAQ Of Powder Coatings

1. How does a large number of shrinkage cavities in the coating result?

1) There is residual foreign matter or oil on the surface of workpiece before spraying;

2) The compressed air used for spraying contains impurity dust or oil stain;

3) High voltage of electrostatic spraying equipment causes electrostatic breakdown;

4) In the spraying process, the distance between the spray gun and the workpiece is too close, resulting in breakdown;

5) The coating is too thin to achieve the best leveling effect;

6) Thick film pinholes appear on the edge after coating;

7) The coating curing is not enough;

8) Rapid cooling occurs in the curing process of coatings.

2. What kind of temperature distribution is more ideal in the curing process?

The curing condition of radiator powder coating is the surface of the coated workpiece, that is, the coating temperature reaches 180 ℃ for 15-20 minutes. If the fixed furnace is used, the heating speed should be increased as much as possible, and the workpiece should stay for 15-20 minutes after the temperature reaches 180 ℃. The pipeline should try to use the bridge furnace, the temperature in the furnace should be balanced as far as possible, the heating speed should be fast, the whole process should be completed in 10-15 minutes, the temperature in the furnace can be slightly higher than 180 ℃ to help the temperature of the workpiece itself reach 180 ℃, the furnace temperature should be balanced after rising to the highest temperature, the time from entering to discharging should be about 30 minutes, and the constant temperature period should be more than 10 minutes.

3. How to use recycled powder in spraying?

The spray chamber should be kept clean and the ground powder recovery should be as pure as possible. After passing through a 100 mesh sieve, the pure recycled powder is mixed with the new powder according to 20% of the added amount. Or in the process of double spraying, directly use recycled powder for the first primer.

The spray chamber should be kept clean and the ground powder recovery should be as pure as possible. After passing through a 100 mesh sieve, the pure recycled powder is mixed with the new powder according to 20% of the added amount. Or in the process of double spraying, directly use recycled powder for the first primer.

4. What are the factors that affect the loss of light in the final coating?

The main causes of light loss are the pollution and unstable surface tension of the film during curing, and the light loss is caused by the uneven surface after curing. The main forming factors are as follows:

1) The environmental sanitation of spraying is poor, and there are a lot of smoke and dust;

2) The coating is not pure and contains a lot of impurities or powder;

3) The coating quality is poor, and the surface is not smooth

4) There are still a lot of foreign matters on the surface after pretreatment;

5) There is a quench phenomenon in the curing process;

6) If the heating rate is too slow, some of the coatings begin to react in the incomplete melting state;

7) There are defects in the coating, and excessive small molecular substances are released during the reaction;

8) The coating surface fullness is not enough in the design.