Finishing: Powder Coating
What is Powder Coating?
Powder coating is a finishing process in which an object is coated with a dry powder then heated to form a high quality finish. The powder coating process offers strength and durability, and is available in an almost limitless range of colors and textures making it one of the most popular finishing processes.
Types of Powder Coating
The powder coating process can be done using two different types of polymers:
*Thermosets undergo a chemical change when heated, making the bonding process irreversible. Due to the ability to withstand heat, thermosets are often used for electronics and household appliances.
*Thermoplastics do not undergo a chemical change, therefore can be reheated and remolded at any time.
Powder Coating Processes
The powder coating process involves three steps: pretreatment /cleaning of the object, powder application, and curing.
Powder can be applied using two different processes: electrostatic coating, or fluidized bed coating.
*Electrostatic coating is the most common method of applying powder coating. An electrostatic gun is used to apply an electrostatic charge to the powder. The powder is then sprayed towards the object and accelerated by the charge causing the particles to adhere to the object. The object is then heated to the powder’s melting point (usually 350-375 degrees) for 10-15 minutes forming a smooth continuous film.
*Fluidized bed coating can be used to create a thicker coating. The object is preheated and dipped into the fluidized powder causing it to melt and adhere to the object. Further heating is usually required in order to attain the desired result.
The object is then cooled resulting in a strong, smooth, and attractive finish.
Benefits of Powder Coating
The powder coating process provides strength and durability along with an aesthetically pleasing finished product. Different formulations allow for coatings that are resistant to scratches, cracking, rust, U-V rays, corrosion, chemicals, etc. Powder coating is also environmentally and economically friendly since it’s almost entirely pollution-free and leaves little to no waste.