There are several types of powder coating equipment used for coating metal. The most common types of equipment for applying powder coating include the electrostatic spray gun and the fluidized bed. These are used to evenly coat the workpiece with powder, creating a chip-resistant finish that is more durable than a traditional paint finish. Other types of powder coating equipment include recovery systems, spray booths and cure ovens.
One of the oldest methods for applying powder coat is the fluidized bed dipping process. A basic fluidized bed is made up of a tank, an air supply and a plenum, or membrane that allows air to pass but not solids. As air is introduced to the plenum, thermoplastic powder is suspended, or fluidized. The heated workpiece is then dipped into the fluidized powder. Some fluidized beds also have the ability to electrostatically charge the powder, allowing the use of a tougher thermoset polymer instead of thermoplastic powder.
Among the newer and more commonly used types of powder coating equipment are electrostatic spray guns. There are three basic types of powder coating spray guns. All of them rely on a fluidized bed or tank to hold the powder and an air supply to fluidize the powder and deliver it to the gun. The main difference between these three types of powder coating equipment is the mechanism used for applying the charge to the thermoset polymer.
The most widely used powder coating gun is the corona gun. This type of gun uses an electric power source to impart an electrostatic charge as the powder leaves the gun. Tribo guns create the charge with friction by accelerating the powder through a narrow passage before exiting the gun, and bell charging guns simply fling the powder from the rim of a bell-shaped opening.
Other types of powder coating equipment used during the spraying process include spray booths and recovery equipment. The spray booth is an enclosure that is designed to keep the powder contained in one area during the coating process. A powder coating spray booth can be small enough to accommodate a single operator or large enough to contain a conveyor system for moving large quantities of parts.
Many spray booths incorporate a recovery system. Usually contained within the shell of the booth, the recovery system uses a fan to pull fresh air into the spray booth and prevent overspray from escaping the booth. This piece of powder coating equipment can help save money as well, because the collected overspray can often be reused.
If thermoset polymer is used, there is an additional step in the process. The coated part must be cured. This step requires a piece of powder coating equipment called a cure oven. It raises the temperature of the part high enough for the powder to undergo a chemical change called crosslinking. Cure ovens are available in either convection or infrared designs.