Corona Charging Method-How It Works
In corona charging, a high voltage potential is developed at an electrode located in or near the powder stream. With most corona guns this occurs as the powder exits the gun. (See diagram #l.) An ion field is generated between the electrode and the grounded product. Powder particles passing through this field are bombarded with ions, become charged, and are attracted to the grounded product. The charged powder particles accumulate on the grounded product and are electrostatically retained long enough for the product to pass through a cure oven where it flows into a continuous coating. Most corona guns charge the powder to a negative potential, however, guns are available to positively charge the powder.
Different types of power supplies, electrode placement, and nozzle configurations have been used for corona charging methods over time. The power supply generates the high voltage supplied to the electrode In some equipment the power supply is located away from the gun and is connected to it by a high voltage cable In other equipment the power supply is actually built into the gun or the mounting bracket for the gun. The placement of the charging electrode in relationship to the powder stream is critical in achieving effective powder charging Some guns have the electrode directly in the powder stream while others are adjacent to it The electrode placement is often dictated by the nozzle configuration used. All different types of nozzles have been used to effectively coat products that have intricate corners, flat surfaces or unusual shapes .Two of the more typical nozzles are deflectors which create a round spray cloud and fan spray which create a flat spray cloud, Nozzles have been developed that have swirl or forward air to affect the powder cloud shape. Others nozzles have two or more heads on them to apply powder in specific areas Many of these possibilities have been mixed and matched to create effective powder coating guns.
[Thanks for Michael J.Thies,please contact us if any doubt]