Spraying processing: the process flow and advantages and disadvantages of electrostatic sprayingThe technical principle of electrostatic spraying:
The appearance of corona discharge is used to make the powder coating adsorb on the workpiece. The process is as follows: the powder coating is fed into the spray gun from the powder supply system by compressed air gas, and the high voltage generated by the high voltage electrostatic generator is added to the front of the spray gun. Because of the corona discharge, a full charge occurs in the vicinity of the spray gun. When the nozzle ejects, it forms charged paint particles, which are attracted to the workpiece with the opposite polarity under the action of electrostatic force. As the sprayed powder increases, the more the charge accumulates. When it reaches a certain thickness, static electricity occurs. Overhead action does not continue to absorb, and then all the workpieces obtain a certain thickness of powder coating, and then the powder is melted, leveled, and solidified by heat, that is, a strong coating film is formed on the surface of the workpiece.
Benefits of electrostatic spraying:
1. There is no or very little paint mist flying into the air, so it can improve the working environment of workers.
2. It can automate the spray painting technology, and the production efficiency is high.
3. Compared with other spraying methods, it can save a lot of paint.
4. The quality of the paint film, including the smoothness and adhesion of the coating, has improved greatly.
Disadvantages:
1. The equipment is messy.
2. It has strong selectivity to solvents, and temperature and humidity also affect the quality of the coating.
3. Because the DC voltage is as high as 100kV, more attention must be paid to safe operation.
4. The shape of the surface of the coated object is different (such as the corrugation of the steel barrel and the head circle), which will cause changes in the strength of the electric field, and then affect the uniformity of the paint film.
Intent: Spray the powder coating evenly on the surface of the workpiece, especially the workpiece (including the position prone to electrostatic shielding) should use a high-performance electrostatic spraying machine to complete the spraying.
laser cutting of powder spraying processing:
Establish a spray room in the spray workshop. It is required to use bright lighting panels on the roof and walls of the spray room to avoid powder adsorption. Four powder recovery machines are placed in the four corners of the spray room to recover the remaining powder while avoiding powder floating. Using the principle of electrostatic adsorption, spray a layer of powder coating evenly on the surface of the workpiece;
The fallen powder is recovered through the recovery system and can be reused after being sieved
3. High temperature curing
Intent: Heat the powder coating on the surface of the workpiece to a regular temperature and keep it warm at the corresponding time to melt, level, and solidify, and then get the appearance of the workpiece we want.
Push the sprayed workpiece into the curing furnace (electric oven), heat it to the predetermined temperature (usually 185 degrees), and keep it warm for the corresponding time (15 minutes); open the furnace and take it out and cool it to get the product.
Plastic spraying is also the electrostatic powder spraying we often talk about. It uses an electrostatic generator to charge the plastic powder and adsorb it on the surface of the iron plate. Then it is baked at 180 to 220 ℃ to make the powder melt and adhere to the metal surface, and the paint film appears Flat or matte effect. The spray powder mainly includes acrylic powder, polyester powder and so on.
