The Tribo process is based on frictional charging. In this case, the fluidised powder/air mixture in a powder tube, usually PTFE, is charged by means of friction against the inside tube wall. Due to its excellent electrical insulation properties (negative), PTFE is well-suited to charging the particles and its good anti-frictional properties prevent sintering on the walls. Frictional charging in the powder tube generates a uniform charge and charge separation. This means that for a certain quantity of positively charged powder particles, the same number of negatively charged particles remain in the powder tube. This negative charge must be conveyed out of the spray device. It is conducted via a measurement sensor and, as a Tribo current, provides information on the quality of the powder and the charge. Because of the frictional charging, this procedure requires special Trbo powder. In WAGNER Tribo guns, the charge can be influenced and magnified by means of a special Tribo air supply. In this way, for example, even powder that is resistant to charging can still be applied.
In the corona charging process, negatively charged air ions attach themselves to the powder particles during atomisation. The air ions are generated in the high-voltage electrode of the powder gun. The high voltage is generated by means of a high voltage cascade that is installed in the gun body. The high voltage can be varied in a range from 30 - 100 kV. The voltage level is matched to the geometry of the work piece, or to the powder coating system in use. The charged particles move along the field lines to the earthed workpiece. Because the field line density is higher at the edges of a component than at the surfaces, powder coat thicknesses are greater in these areas. Conversely, three dimensional components have surfaces to which field lines do not extend, an effect referred to as the Faraday cage. Powder is only deposited to a limited degree in these areas. As the powder coat is deposited, air ions are „built into" the layers. This can lead to backspray effects when the charge density is excessive. The goal is therefore to minimise these air ions. This is accomplished by means of an additional earth that is applied to the powder atomiser. In the advanced WAGNER HiCoat C4 spray system, these effects can be reduced, even for complex workpieces, by setting a wide range of parameters that affect the high voltage, the current limitation and the cascade characteristic lines.HiCoat guns thus ensure optimal coating results.