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Powder coating ovens are devices used in the dry-coating process. After an item is dry coated, it is placed in one of these ovens, where the coating will cure. This causes a chemical reaction that makes the coating bond with the surface of the work piece. After the coating is fully cured, it is nearly part of the original item. There are two main types of powder coating ovens, convection ovens and infrared ovens.
Convection ovens work much like a common household oven. Heating elements, or heat vents, create zones of intense heat. This heat warms the air and creates air movement. As the air moves, it cycles around within the oven and eventually warms the entire interior area.
Infrared powder coating ovens work very similarly to a convection oven with a few minor exceptions. The most important difference is the focus on an infrared oven. The elements used in these systems have a more focused method of channeling the heat. The results in more of the heat going into the object and less lost to the air.
The process of powder coating typically begins with a metal object. Some types of powder coating will work on non-metallic materials, but that makes up a small fraction of the powder-coating industry. The work piece has any molding material or burs removed to make it as close to finished quality as possible. Afterward, it is cleaned with industrial solvents or sandblasting.
The next step in the powder coating process is applying the actual powder. There are a number of different ways to do this, but most forms involve generating positive or negative charges in the work piece or powder. One of the more common methods is called electrostatic coating. In this process, the work piece is grounded and the powder is negative. The powder is naturally drawn to the work piece as a result of the polarity difference.
After the material is covered in powder, it enters the powder coating ovens. During this part of the process, the work piece is heated to a temperature hot enough to melt the powder but cool enough to prevent damage to the object. As the powder melts, it evenly coats the work piece and both mechanically and chemically changes. Often, the work piece will be in the oven for less than 20 minutes.
In most cases, the powder is made of a man-made material such as polyester or epoxy. When this material melts together, it flows into the work piece’s tiny nooks and crannies. This mechanical change creates an environment-proof barrier. In addition to the mechanical protection, the melted material forms a molecular lattice shape. This lattice is exceptionally durable to damage and wear.