The main stages of powder coating

Author: Robert Gombos
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The most common way of preventing a metallic object from corrosion is by applying paint on the object’s surface. However, there are disadvantages to using paint on the object’s surface. The drawback of painting is that the coating can be uneven. Moreover, it drips more, and wiping it from the floor can be tedious.

Of late, powder coating has increased as the method offers an even surface coat that gives the object’s surface a fantastic finished look. Many companies designate powder coatings because of;

  • Allowing for maximized production of high-quality
  • Improved efficiencies
  • Simplified environmental compliance and
  • Durable finish

Far from the liquid coating method, which uses liquid suspension, powder coating is a dry process that utilizes coating powder. In this process, the powder is applied to a body’s surface, melted, dried, and then hardened into a protective and decorative coating. The process has three main stages. Namely:

Preparation of surface

Before powder application, the object’s surface must be treated and cleaned to ensure that it is free of dust, debris, and dust. If the surface is not sufficiently prepared, any residues or deposits could negatively affect the adhesion of the powder and, eventually, the quality of the finish. Preparation treatment mainly depends on the material being powder coated. Nonetheless, the steps that are often employed in this stage include;

  • cleaning
  • rinsing
  • etching
  • blasting
  • drying

The commonly used equipment includes;

  • Blast rooms
  • Wash stations
  • Dry-off ovens

Weak alkali and neutral detergents can remove grease, Oil, solvent, and residue in dip tanks. Wash stations can spray parts with steam, detergent, hot water, and other pretreatment solutions.

Sections with debris such as existing paint, rust, finish, or scaling will generally need the use of a blast room. A blast room uses pressurized fluid, mostly compressed air power abrasive material, like sand, shot, or grit, against a surface. The abrasive material gets rid of surface debris, producing a smoother and cleaner surface to apply powder coating material.

Some powder coating applications utilize dry-off ovens. This dry-off oven vaporizes remaining liquids and heats the body for an optimum temperature in preparation for the powder application stage.

If, in any case, surface design needs some sections to remain uncoated, you mask such sections before the application stage. The masking products come in various custom shapes, standards and forms. Nonetheless, they are made of paper or plastic layers coated with a pressure-sensitive adhesive that allows them to stick to the substrate.

Application Stage

There are two types of powder coating materials. The type of powder coating material used partly determines the method of application. There are two primary powder coating methods used by finishing service providers and manufacturers. They are fluidized bed coating and electrostatic disposition.

  • Fluidized bed coating: this method involves dipping preheated parts into the powder material in a fluidized bed. An alternative option referred to as an electrostatic fluidized bed consists of generating a cloud of charged powder particles above the fluidized bed through which you pass the to be coated.
  • Electrostatic deposition; This application method uses a powder feeder, electrostatic spray gun, powder spray booth, and a powder unit depending on the nature of the gun used.

The spray booth provides an area for powder application and acts as an overspray containment, filter, and recovery and powder system.

Curing Stage

The powder coating curing process is mainly determined by how the powder coating is applied and the type of powder coating material employed.

  • Curing coated parts: The Part that is painted through electrostatic disposition should be cured in a powder coating oven. The smaller the powder-coated parts, the lesser the curing time.
  • Curing fluidized bed coated parts: In this case, you heat the pieces before the coat application stage. You then immerse the substrate in the coating material. Here the powder particles liquefy and flow upon coming into contact with the heated surface.