The Basics of Powder Coating and How It Works
Powder coating is a dry finishing process which was first introduced in the United States in the 1960s. Since then, this technology has quickly become the preferred method over the use of liquid paint in most industrial applications. According to the Powder Coating Institute, it represents over 15% of the total industrial finishing market to date.
Powder coating has been found to create a harder finish that is tougher than conventional paint. It is mainly used for coating metals, such as appliances, automotive parts, and other hardware. Since it is not a liquid product, it requires no solvent to keep the binder and filler components in a liquid suspension form.
Types of Coating
There are two types of powder coating: thermosets and thermoplastics. The primary difference between the two is that thermoplastics can be remelted back into a liquid, whereas thermoset plastics will remain in a permanent solid state.
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The layman’s way of understanding this is to think of thermoplastics as butter, which can be melted and cooled multiple times to form various shapes, while thermosets can only be set once.
There are numerous pros and cons to the use of each, so you need to do extensive research on both to see which application is best for the products you want to coat.
How Is Powder Coating Applied?
Powder coating is applied electrostatically with the use of electrostatic guns, also known as corona guns. The gun releases a positive electrical charge which reacts with the powder. A wide variety of spray nozzles are available, depending upon the size and shape of the component being coated. The object is heated, melting the powder into a uniform consistency and coverage.
The next step is the curing process, where heat creates what is known as the “skin”. When the powder coat is baked onto the metal, it reacts with other chemical groups in the powder to polymerize, creating a stronger and higher-performing coating. Once it is cooled you have a far superior product than a liquid paint could provide.
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Other methods of applying powder include the tribo gun, which uses triboelectric friction to charge the powder, electrostatic disc application, and a method called the fluidized bed method, where the component is dipped in an aerated, powder-filled bed. The powder then sticks to the hot metal. One common example of this method is in coating dishwasher racks.
Why Choose Powder Coating?
This coating method has been proven more durable and attractive in protecting products. These products are less susceptible to environmental damage such as moisture, extreme weather conditions, chemicals, and ultraviolet light and are less likely to fade, scratch, chip or wear in general. The products look great and last a long time. To learn more about coating and lubrication, contact Coating Systems today.