Tribo-Charging Spray Method
This method of powder coating is the latest invention up to now. It has not gained as much acceptance as the conventional Electrostatic Powder Spray system. Unlike the electrostatic spray gun, the tribo-matic gun does not have an electrode. The charging of the powder particles is achieved by friction-rubbing between the particles and the transfer tube. At present, most of the tubes are made of Teflon PTFE. It induces a positive charge to the powder particle.
With the absence of strong electrostatic field, the charged particles are able to penetrate into the deep recesses of complicated-shaped objects, overcoming the ‘Faraday Cage’ effect.
This system also produces a more even coating with superior finishes – less pin-holes and craters due to the ‘back-ionisation’ effect.
The main set-back of this method of application is the poorer charging capacities of each gun compared to the conventional electrostatic gun – i.e. more tribo guns are needed for the same through-put of total area coated.
The charging ability also depends on the type of resin system used.
