The working principle of electrostatic powder spraying method is almost the same as that of general liquid spraying method, except that powder spraying is dispersed rather than atomized. The electrostatic powder spraying process requires three processes, namely surface pretreatment, electrostatic spraying, and curing. Today, I would like to share with you what a surface pretreatment program is.

1. What is surface pretreatment?

Surface pretreatment, also known as pretreatment, aims to remove oil, dust, and rust from the surface of the workpiece and form a corrosion-resistant "phosphating layer" or "chromium plating layer" on the surface of the workpiece, which can increase the adhesion of the sprayed coating.

2. Surface pretreatment process steps

Main process steps: degreasing, rust removal, phosphating (chromate treatment) and passivation. After pretreatment, not only the workpiece surface is free of oil, rust and dust, but also a uniform and rough gray phosphating film (chromate film) that is not easy to rust is produced on the original silver white shiny surface, which can both prevent rust and increase the adhesion of the spraying layer.

3. Precautions for surface pretreatment

① The quality inspection after pre-treatment and phosphating should be carried out in accordance with the provisions of GB/T 6807.

② The powder coating should be completed within 24 hours after surface treatment.

③ For workpieces with special anti-corrosion requirements, chemical methods are also required to form a anti-corrosion layer on the metal surface.

④ The parts on the workpiece that do not require spraying can be covered with protective measures such as covering operations.

The product quality of electrostatic spraying technology is often closely related to the quality of spraying powder. Today, the editor will share with you what is the appearance recognition method, which can identify the quality of electrostatic powder from the appearance.

Appearance identification method:

1. Touch: A good powder feel is silky smooth, loose, and floating. Grab a handful of powder in your hand, the smoother and looser the powder, the better the quality; On the contrary, if the powder feels rough, heavy, heavy, poor quality, difficult to spray, and there are many secondary powder droplets, it is easy to cause waste.

2. Volume: The larger the volume of powder with poor quality, the less fillers in the powder coating, and the higher the cost. The better the quality of the powder, the smaller the volume, the higher the filler in the powder coating, and the lower the cost. Poor quality powder is not easy to spray, with more secondary powder falling, large waste, small spraying area, and high usage cost.

3. Storage time: Good powder can be stored for a long time, and the effect of powder flow remains unchanged. Poor quality powder cannot be stored for a long time. After 3 months, the leveling performance of inferior powder deteriorates, and other effects deteriorate. The shelf life of ordinary powder at room temperature is 12 months, and the quality of low-end raw materials is unstable and prone to deterioration. The use of inferior raw materials to produce powder will accelerate the crushing and aging of the sprayed surface after six months.

Electrostatic powder spraying typically has the following ranges:

1. Various industrial and agricultural machinery, metal parts, pipe and machine tools.

2. Various metal brackets, columns, street lights, and road signs.

3. Various automotive components, motors, electric tools, and pneumatic tools.

4. Various box casings, such as switch cabinets, instrument cabinets, computer casings, and their peripheral equipment casings.

5. Household appliances and steel furniture, such as fans, refrigerators, sewing machines, washing machines, irons, pot shells, rice cookers, water heaters, vacuum cleaners, electric stoves, lighting fixtures, microwaves, bicycles, umbrellas, locks.

6. Various building materials. For example: steel windows, aluminum doors and windows, beams, elevators, steel doors, military doors.