Powder coating application process
In the application of powder coatings for metal objects, the most commonly used method is the use of electrostatic powder gun, or Corona gun. Gun powder to the people, and then grounded object to achieve a positive charge of the machinery or spraying compressed air spraying, and then to a strong electrostatic charge in the workpiece speed. There is a nozzle, can be used for a wide range electrostatic spraying. The use will depend on the shape of the workpiece nozzle type, in order to paint and coating consistency. The object, and then heated, and the powder into a uniform film to melt, and then cooled to form a hard coating. This is a common metal substrate is heated to heat the first and dusting. Preheating can help to achieve a more uniform results, but can bring other problems, such as the operation caused by the excess flour. See “Fusion Bonded Epoxy Powder Coatings”
Another type of gun is called the friction guns, which charge (triboelectric) friction of the powder. In this case, pick up the powder a positive charge, while the friction along the wall inside the barrel of a gun Teflon. These costs powder particles, and then insist on the basis of substrate. The use of friction the more common Corona guns need a different formula powder guns. Friction gun from a number of corona discharge of firearms-related issues, however, such as back ionization and Faraday cage effect.
Powder can also be applied particularly suitable for the use of static CD-ROM.
Another way to apply powder coating, known as the fluidized bed method is heated by the substrate, and then immersed into a gas, powder packed bed of the. Powder sticks and melted into the hot object. Further heating is usually curable coatings needs to be done. This method is typically used when the thickness of the coating will be more than 300 microns. This is the most of the dishwasher rack coating.
Electrostatic fluidized bed coating: electrostatic fluidized bed application uses the same streaming technology and traditional fluidized bed dip process much less, but the powder bed depth. Electrostatic charging media is placed in the bed, so that powder materials, such as the flow of air becomes charged lift it. Charged powder particles move up and formed the above-mentioned allegations of fluidized bed powder cloud. When the grounding part by clouds of charged particles to attract to its surface. This section does not warm, because they dropped the traditional fluidized bed process.
Static electromagnetic brush (EMB) Coating: a flat coating materials, innovative ways to apply powder coating roller technology to enable 5-100 relatively high speed and very precise micron layer thickness. This process is based on the traditional copier technology. At present, some high-tech coating applications and very flat tanque board powder coatings business prospects (steel, aluminum, medium density fiberboard, paper, cardboard), and in the work sheet table and / or roll to roll process. This process may be integrated into any existing coating line.
Curing
When the thermosetting powder exposed to high temperatures, it begins to melt, flow, and then a chemical reaction to form a high molecular weight polymer in a network-like structure. This treatment process, known as cross-linking, to pay a certain length of time a certain degree of temperature, in order to achieve adequate treatment, and the establishment of a complete design of thin-film material properties. Under normal circumstances, powder curing at 200 ℃ (390 ° F for 10 minutes). Curing time can be due to the manufacturer’s specifications.
The energy to apply to be cured of the products can be cured by convection microwave oven, or infrared curing oven.