Wagner Spraytech Benelux B.V. [The Powder Cycle]

The Powder Cycle

1. Fluidizing the powder

Coating powder is best conveyed to the sprayguns if it is fluidized first. This is done in the Powder Feed Center, whose suction system (2) submerges into the container and ads fluidizing air to the powder. The container is placed on a special shaker table. As soon as it begins to vibrate a homogenous powder-air mixture forms.

During the normal coating process powder is consumed, which leads to a lowering of the powder level inside the container. A probe measures the level and lowers the suction system when required in order to ensure a continuous powder flow. In the case of powder shortage, an alarm is triggered.

Depending on the type of powder feed center, the consumption of coating powder is compensated either automatically or by manually adding fresh powder into the container.

2. Powder delivery

The fluidized powder is fed by the suction system (2) from the container to the injectors and finally to the sprayguns by means of fluidizing air. The amount of powder that flows to the guns can be increased by applying more feeding air. The addition of dosage air speeds up the powder flow.

If the feeding air is turned off and the dosage air is opened completely, the powder supply to the guns stops, while the powder hose will be flushed with air. As soon as the feeding air is turned on and the dosage air is set to a normal level, the powder starts flowing again.

3. The sprayguns

Depending on the application, Tribo or Corona sprayguns are used for industrial powder coating. The powder particles are charged inside the gun and then applied evenly to the object to be coated.

Different shapes and objects like wire goods, gratings or aluminum cross sections require different powder clouds for high quality coating. This is why sprayguns must be able to be equipped with a great variety of nozzles systems, such as deflector cones, fan spray nozzles etc.

4. Overspray recovery

A considerable amount of powder does not stick to the object during the coating process. The so called overspray is sucked from the spray booth through the exhaust air conduct (4) and conveyed to the cyclone (5).

5. Separating the powder-air mixture

The cyclone sets the powder-air mixture in rotation. This creates centrifugal forces which push the powder particles outwards onto the cyclone walls.

The powder subsequently slides onto the screen surface of the screening unit, where coarse impurities are held back. By means of a peristaltic conveyer, the recycled powder is finally supplied back to the container in the powder feed center.

6. Filtering of the exhaust air

The clean gas rotating in the cyclone tube is conveyed upwards to the after filter (6). This is where dust and powder residues are separated from the air, allowing it to be released into the environment again. The waste powder falls in a container or a bag underneath the after filter unit and is finally disposed of.

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			2. The Powder Cycle

			3. Powder coating of MDF