Overview of Powder Coat Process and Equipment

Powder coatings are a dry finishing process. The main components in powder coatings are a resin and a pigment. During the process, the powder is applied to a substrate’s pretreated surface and melted. The melted powder is then dried on the surface and hardened in the process.

The coating material is spread over the base material to provide protection for the base material, then dried to form a smooth, even surface that will allow the paint to adhere. Heat is applied to accelerate curing.

Types of Powder Coatings There are three types of powder coatings: solvent-based, waterborne, and radiation cured. There are also a variety of pigments and additives available for these types of coatings. Solvent-based Powder Coatings Solvent-based powder coatings require the use of a solvent. The solvent is then evaporated from the coated product, leaving behind a hard finish. Solvent-based powder coatings include: Aqueous Powder Coating Systems Waterborne powder coatings are those that do not contain solvents.

Preparation Stage

Before the application of any powder coating material, the surface of the substrate must be prepared. This is done using a variety of different techniques depending on the type of powder coating, the coating conditions, and the desired result.

There are five main steps in the complete preparation stage of treatment, but not every step is necessarily necessary to achieve a particular result. Cleaning, rinsing, etching, blasting, and drying are the most common steps in the complete preparation process, and the most widely used equipment include wash stations, blast rooms, and dry-off ovens.

An oil, grease, solvent, and residue can be removed from a part’s surface with weak alkali and neutral detergents in dip tanks or with wash stations.

If the component design requires certain sections to remain uncoated, a number of methods exist to prevent these areas from being coated during the component assembly process. For example, if the design calls for the use of a clear substrate, then masking dots can be applied to prevent a patterned coating on the substrate.

However, in most cases, they are constructed of paper or plastic film coated with a pressure-sensitive adhesive, which allows them to adhere to the substrate and protect the covered area from coming into contact with powder material during powder coating operations.

Application Stage

There are two different types of powder coatings, which is determined by the type of material being coated. Electrostatic powder coating works by electrically charging the powder and then applying it to an object through electrostatic forces. Fluids bed powder coating uses heated air or gas to aid in coating the object.

Electrostatic spray coating is one of the easiest methods of applying coatings to metals. This process is typically done in a powder spray booth, powder feeder, electrostatic spray gun, and power unit. It is used on most types of metals and most types of coatings.

Electrostatic deposition (ESD) is used to apply a layer of paint or thin film to an object such as a metal or plastic part. The coating material is first stored in a powder form. The powder is fed through a tube that brings it into the spray zone where it is atomized by air pressure and sprayed onto the object that is moving past it.

The powder coating process is the process of applying powder material, usually in the form of a paint or varnish, to a surface by spraying it on.

There are 3 types of electrostatic guns commonly used—corona, triboelectric, and Bell. The electrically charged particles can then adhere to the part’s electrically grounded surface and will remain adhered as long as they maintain some of their charge.

Curing Stage

The particularities and characteristics of the powder coating process’s curing stage is mainly determined by the method in which the dry powder is applied, as well as the type of powder coating material employed.

A curing oven is used to cure and bake food in order to give it a uniform texture. While a small part might only require a few minutes, large parts are usually baked for a longer period of time. Depending on the size, shape and thickness of the part, the oven’s temperature will vary. A cure of less than ten minutes is considered short, while one of over an hour is called long.

As the diameter of the part increases, the cure time and volume of heated air to cure a part also increase. For smaller parts, less of a problem.