Powder coating gun is one of the most important equipment in the powder coating process. There are many types of guns to choose from. The best thing is that none of the guns pose a health hazard to the painter. Spraying technique is the most used application technique. The electrostatic powder spray gun has several functions which include imparting an electrostatic charge to the paint, determining the density of the spray particles, shaping and guiding the flow of the powder paint, controlling the size of the pattern, and controlling the deposition of the powder spray on the surface being sprayed.
There are two main types of powder coating guns, automatic and manual. Manual guns are mostly used in automatic systems that are used for complex and difficult-to-reach parts, the applications that do not require automatic guns, and stand-alone units. Since the painter carries the spray gun for a long duration, the weight, flexibility, durability, and efficiency are some of the factors to consider when acquiring a manual powder coating gun. These guns are used for low production while the automatic guns are used for high production.
Automatic guns are more expensive than the manual guns. These guns spray a surface blindly regardless of whether there is a surface to be sprayed or not. Therefore, for maximum benefits, products to be sprayed should be loaded densely onto the conveyor. Some triggering systems which use light curtains or photo eyes can be used to identify when there is a surface to be coated. Guns with a triggering system cost more than those without.
Types of Powder Coating Guns
1. Corona spray guns: These are the most common guns used in the application process. The guns can generate a low-amperage, low-voltage electrostatic field between the product being coated and the electrode. Powder particles are charged as they pass through the ionized electrostatic field and are deposited on the electrically earthed surface.
Corona guns pose a few challenges. First, it is difficult to recoat a part that is already cured. Secondly, it is difficult to cover tight corners and buried areas with the powder. However, the second challenge can be overturned by the use of a high-quality powder which retains a high-voltage charge.
2. Corona bells: Corona bells are applied when large flat areas have to be coated high speed. These devices use the same charging technique as the corona guns. When necessitated to spray a lot of powder on a flat surface within a short period, corona bells would be the preferred application devices. The bells are used in application such as automotive car bodies.
3. Tribo guns: Unlike corona guns, tribo guns lack an electrostatic field. The epoxy powder is charged through friction between the powder particles and the conductor or a solid insulator inside the gun. The final charge is obtained by stripping electrons from the epoxy powder particles, producing a powder with positive charges. Since there is no electrostatic field, the charged particles move toward the grounded surface, and they are free to deposit in a thin coating.
These guns have two disadvantages. First, it operates well with epoxy powder only and secondly; it has a low coating speed as compared to a corona-charge powder gun. It is advisable to select the appropriate gun accessories and attachments to increase the efficiency of the gun.