Powder coating is also called powder painting. Electrostatic powder coating is the most common process of thermo curing paints with a wide variety of decorative and protective features. It has much more durable finish than traditional liquid paints and is environmentally friendly because there are no solvents.
The powder is held by a fluid bed in a feed hopper. Fluidized powder can be pumped pneumatically to a spray gun which is designed to impart an electrostatic charge to the powder. The work-piece, having been pretreated, is electrically grounded. When sprayed, the charged powder particles are firmly attracted to the grounded workpiece’s surface, due to the principal of “opposites attract”. The work piece is then conveyed into a curing oven where the powder melts and cross-links into a hard, smooth coating at approximately 120-220C for about 15-20 minutes.
Electrostatic Powder Coating Process:
Pretreatment > Dry Off > Powder Applying > Cured Up > Cooling Down
While some applications require a thicker layer or work-pieces come with complex interior geometry, fluidized bed powder coating of thermo plastic powders is applied. The work-piece is preheated upto 200-300C and dipped into a fluidized powder hopper for a moment. Then, usually, no further process is needed.