Triboelectric powder coating: A practical approach for industrial use

In the finishing industry the powder charge generated by friction in a tribe system is a useful alternative to the corona charging method. The charge by friction is called tribe-charge and is the result of frequent contacts of the powder particles with the interior insulating surfaces of the tribe gun. Different geometrical designs are incorporated for different systems e.g. through several holes or a ring slit. Significant differences can be observed in the charging behaviour by either holes or slits which relate to the flow conditions. The dependence of the internal geometry and turbulent flow, particle velocity, powder mass flow rate and the volume of air flow influence the charging characteristics. An interesting new aspect is the growth of charge and the local distribution of charge during powder flow through a tribe gun. An examination has been made of the triboelectrical characteristics, the saturation charge and the charge/mass ratio.