Electrostatic powder coating is based on the principle of high voltage electrostatic corona field. The metal guiding cup on the powder coating gun is connected with a high voltage negative electricity, and is coated with the workpiece to form the positive electrode. A strong electrostatic field is formed between the powder spraying gun and the workpiece. When the carrier gas (compressed air) delivers the powder coating from the powder feeding barrel to the guide cup of the powder coating gun through the powder feeding pipe, dense charges are generated around the powder. Under the action of electrostatic force and compressed air, the powder is uniformly adsorbed on the workpiece, heated, melted and solidified (or plasticized) to form a uniform, continuous powder. Continuous, smooth coating.
As the spray voltage increases, the amount of powder attachment increases, but the increase rate of adhesion decreases when 90Kv exceeds. The initial growth rate of film thickness increases with the increase of voltage, but the effect of voltage on film thickness decreases with the increase of spraying time. The influence of voltage on film thickness decreases with the increase of spray distance. The high voltage of spraying will cause powder breakdown and affect the quality of powder. The general powder coating voltage is controlled within 60~90kV.