Powder coating is an extremely popular finishing method across industrial and commercial applications. This common finishing technique provides metal or plastic components with an attractive, durable coating. The finish looks similar to paint, but uses a dry powder that adheres to the substrate through electrostatic charging. While typically applied to metal, powder coating can be used on any substrate that tolerates heat and electrical grinding—two necessary components of the coating procedure.
How Powder Coating Works
The success of powder coating depends on two factors: the powder coating itself and the application process.
The coating powder consists of chemical agents that can be altered based upon the needs of the end application. The base is a polymer resin, but various curatives, pigments, and additives are typically added to achieve different properties. These components are ground into a fine powder, which is then applied to a substrate.
Application of powder coating requires that the substrate first be prepared in a multi-step process that allows the coating to adhere properly. The coating is evenly applied through either electrostatic spray deposition, which uses a spray gun, or fluidized bed application, in which the powder behaves like a liquid and components can be individually dipped or coated.
Powder coating offers several advantages, including:
Strong protective finish
Powder coating is not only decorative, but functional. The powder coat finish is equally attractive to paint, but more durable.
Excess powder can be collected and reused, decreasing waste. Powder coating produces no harmful volatile organic compounds (VOCs), which means no additional VOC disposal expenses.
Powder is most commonly applied to metal products, but may also be used on various plastics, fiberboard, and other materials that can withstand the process.
Steps in a Typical Metal Powder Coating Process
The specific steps used in industrial powder coating procedures vary slightly depending on the method and substrate used. The process to powder coat a metal component involves the following stages:
- Cleaning: The cleaning process removes surface contaminants in preparation for finishing. A soak in an alkaline cleaning tank is typically sufficient to remove most dirt, grease, and oils that would otherwise interfere with adhesion.
- Rinsing: Proper rinsing removes the remnants of the alkaline bath. The process typically involves various stages of spraying and immersion designed to optimize water usage.
- Phosphating: While not strictly necessary, phosphating is often performed after rinsing to improve the metal’s finish. The technique induces a chemical reaction that results in a phosphate coating. This coating improves adhesion between the surface and the powder while also serving as an additional layer of corrosion protection.
- Drying: Specific drying procedures depend on part geometry. Simpler parts can be dried using infrared heating, which is less energy-intensive. Oven heating may be necessary to fully dry larger or more complex components.
- Powder Coating: Once these preparatory steps are completed, the powder itself can be applied. This involves charging the powder and workpiece with an electrostatic charge within a special coating booth, then spraying the powder onto the substrate.
- Curing: Curing typically requires high levels of heat and, like drying, can be accomplished in either a convection oven or through infrared heating. Infrared curing is particularly helpful as it is quicker and reduces the chance of defects.
Southern Spring Powder Coating
At Southern Spring and Stamping, we pride ourselves on providing a full range of manufacturing services. Powder coating is just one of the secondary services we offer to complement our metal components, offering attractive, high-quality finishes suitable for diverse applications. To learn more about our metalwork services and finishes, request a quote today.