In the powder coating process, powder is suspended in a container using compressed air to make it suitable for spraying. Once suspended in the air, the powder is pumped into spray guns using injectors or chamber pumps. It becomes electrically charged by being sprayed through an electric field onto the target. The electric field is created using a high voltage cascade in the powder gun.
The component to be coated is earthed, so an electric field forms between it and the electrode at the tip of the gun. As the powder is sprayed through the electric field, the powder adheres electrostatically to the target.
After spraying, the powder is heated in a cure oven in order to polymerise it and form the desired surface coating on the component in question. The curing temperature is typically 180–200 degrees Celsius and the curing time is 12 minutes.
Benefits of powder coating
Being solvent-free, the compounds used in powder coating are more environmentally friendly than liquid coatings. Powder coatings emit zero volatile organic compounds (VOCs). Furthermore, the powder can be recycled and reused, increasing the efficiency of the process.