What is Powder Coating?
Powder coating is the process of coating a surface in which a powder material is applied using an electrostatic or compressed air method, or sometimes a fluidized bed.
The applied powder is then heated (cured) in an oven to its melting point, after which it flows to form a smooth film which dries to a firm, durable finish very resistent to scratches, cracking, peeling, UV rays and rust.
The entire powder coating process involves several steps. Very generally:
- After determining the substrate you are working with, you will begin with the cleaning step - abrasive blasting or chemical cleaning - to insure the substrate is free of any oils, dirt, rust, mill scale, etc.
- The substrate must be fully cleaned to avoid defects in the finish and rejects by the customer resulting in lost income and time.
- A pretreatment step (an important step not done by all coaters) during which the product is treated with a pretreatment chemical or conversion coating, usually phosphate or zinc based, to further protect it and improve the surface for powder adherence.
- Rinse, rinse, rinse...then dry completely.
- Mask areas you don't want coated. This is done with high-temperature tape specially designed for powder coating, and/or caps and plugs.
- Rack the items. Now we're ready to coat.
- Select your coating. Choosing the right coating for your application and end use of the item is very important. A variety of powder formulations exist to choose from depending on the type item you will be coating.
- Powder coat the parts, usually done with an electrostatic gun, corona or tribo, in a powder booth, but sometimes in a fluidized bed.
- Finally, FULLY cure the powder in the oven, usually convection cure ovens generally at 375-400 deg. F, 15-20 minutes (varies), in an infrared oven, or a combination of both. Failing to preheat and cure the part properly can result in several kinds of defects such as outgassing.
Advantages of Powder Coating
Because of the advanced method with which powder coatings are applied, all types of powder coating provide a durable, uniform and attractive finish. All powder coatings are decorative and protective, and different formulations of powder coatings are available to provide extra protection from ultra-violet rays, corrosion, abrasion, and chemicals. Some types are even approved for use by the FDA in food grade applications.
What's more, they provide good electrical insulation properties and can also have special characteristics like electrostatic discharge.
Powder Coating: The Coating of Choice
Powder coating has become the coating of choice for consumer goods from lawn mowers, bicycles, and lawn furniture and office furniture, to kitchen appliances and automobiles. Powder coatings are available in an amazing variety of decorative colors and textures to stretch the limits of the most imaginative designer; the application options are virtually endless.
Powder coating is now the fastest-growing finishing technology in North America, representing over 15% of all industrial finishing applications.
Quality of Powder Coating
The unique method with which powder coating is applied results in superior consistency and uniformity of the finish without sags, drips, runs, or bubbles. The finish an extremely tough, durable coating which enhances the value of any consumer product to which it is applied.
In general, the performance properties - impact resistance, flexibility, and corrosion resistance - of powder coating are better than with liquid paints.
Powder coated parts resist cracking, peeling, and marring during handling and normal service use. In many cases, merchandise is specifically advertised as "Powder Coated" because of the quality image it projects.
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