What are the requirements of air compressor in spray painting industry?
The air spraying process has the advantages of convenient operation, easy color change, high production efficiency, good atomization effect and good high-quality surface spraying. Since the compressed air is in direct contact with the coating, it is required that the compressed air must be dry, clean, oil-free and water-free, so as to improve the spraying quality. Now let’s introduce it in detail.
1. The sprayed surface shall be free of impurities
Particle impurity is the natural enemy of spraying, and its existence will affect the appearance quality of the film. Especially in the coating occasions of high-grade decorative products, the paint surface must be flat and smooth, without particles and as bright as a mirror.
2. There is no oil or water on the sprayed surface
Oil or water in compressed air will cause quality defects such as shrinkage, pinhole, bubble and pitting. Shrinkage not only affects the appearance quality of the film, but also the exposed shrinkage will destroy the integrity of the film, which can not be eliminated by general polishing and polishing methods.
3. Constant pressure air supply
During spraying construction, the pressure of compressed air of screw air compressor must be kept within a certain range without large fluctuation. If the air pressure is too low, the atomization of paint solution will be insufficient and the paint film will be uneven; If the air pressure is too high, the paint atomization is good, but the paint fog speed will be too fast, resulting in increased paint loss. If the high-pressure air flow is sprayed on the uncured paint film, it is easy to produce paint film defects such as pits and small bubbles.
Therefore, the air compressed by screw air compressor must be treated before it can be used. The air compressed is a high-temperature air containing oil, moisture and dust. In order to ensure the qualified rate of spraying, it is generally required that the pressure dew point of the air compressor shall not be higher than – 40 ℃ and the impurities shall be less than 0.5-1 μ m. Secondly, the oil content shall not be higher than 0.01mg/m.
Of course, the air consumption of different spray guns is also different. Enterprises can reasonably configure screw air compressors according to the actual situation.