(1) Advantages
①There is no selectivity for powder coatings, and it is highly versatile. Almost all types of powder coatings can be sprayed with a corona Spray Gun. It is suitable for spraying objects that require large-scale spraying such as refrigerators, washing machines, and metal cabinets.
②Wide range of application, through the use of different types of nozzles, the corona Spray Gun can meet the coating requirements for workpieces of different shapes and sizes.
③The coating efficiency is relatively high.
④The thickness of the coating film is easy to control, and satisfactory film thickness can be obtained on both manual spraying and automatic assembly lines.
⑤ The rate of powder coating at one time is relatively high, and the sprayed powder coating can be recycled and reused.
(2) Disadvantages
① When the thickness of the coating film is not controlled properly, the appearance of the coating film is poor.
②Due to the existence of Faraday shielding effect, it is difficult to apply paint on the concave part of the object to be coated, as shown in Figure 6-19. Between the corona Spray Gun needle and the workpiece, the electric force lines formed by the high-voltage electrostatic field are always arcs starting from the Spray Gun needle and pointing to the outer surface of the workpiece. There is no distribution of electric force lines inside the concave part of the workpiece, and the powder coating is always Flying along the direction of the power line to the workpiece, it causes uneven spraying, and the concave part is difficult to be covered by the paint. This phenomenon is called Faraday shielding effect. In order to increase the coverage of the paint on the concave part, the method of shortening the distance between the Spray Gun and the workpiece is generally adopted, and the spraying is carried out for a long time, but this will not only increase the amount of paint used, but also increase the thickness of the coating film on the protruding part of the workpiece. Moreover, it will also cause counter-ionization phenomenon, reduce the coating efficiency, and make the coating film appear orange peel and other disadvantages.
