Applying powder is fairly simple and can be learned by […]
Applying powder is fairly simple and can be learned by most practical people as long as you have access to the following equipment. You will need: powder gun, clean dry compressed air, power supply and spray powder.
The powder is sucked out of a container by a powerful pump, which can be a manufacturer's box or a hopper, depending on the type of equipment. To obtain a constant smooth flow, two methods are used: vibration and fluidization. Vibration helps keep the powder level towards the straw; fluidization allows the powder to flow easily through the pump.
The powder is drawn vertically into the pump from the container and then passed along the powder tube; this can vary, but is usually around three meters. The powder will then enter the gun body. Hand guns are shaped for ease of handling and comfort, often allowing powder to enter the bottom of the handle. On automatics, powder usually enters from the rear because the gun body is straight.
There are many types and variations of application equipment to accommodate specialized application methods, but the two main types of guns that are commonly used are friction charging and corona charging. Both rely on the powder to gain an electrical charge, which in turn enables the material to attract to the surface of the object to be coated.
Friction charges rely on powder passing through a tube and through a special plastic in the gun body to create friction. The surface of the powder attracts charges of opposite polarity, which in turn attract each other, even after separation. However, this method is limited to certain types of powders.
The corona charge relies on a very high voltage (up to 100kv) charge that is released into the powder cloud the moment it is released from the spray gun. The charge is delivered to the gun through a low voltage (10-12v) cable, which then doubles the voltage in the gun handle to the very high voltage required. It is then discharged into the powder cloud at the outlet. The powder on this type of equipment also absorbs a certain amount of triboelectric charge along its route, thus making this type of equipment the first choice for most coaters.
The fully charged powder will now leave the gun as a fine dust cloud and be attracted to anything that can accept a charge from a distance of 100 - 300mm; it will then remain as a powder on the surface of the component until cured.
Of course, the more convenient way is to buy a Powder Coating Machine, which can help you very well.