Method for applying lubricating materials to metallic substrates

Abstract

Method for generating and substantially uniformly electrostatically dispersing very finely divided spheroidally shaped lubricating particles onto the moving surface of metal or other electrically conducting substrate. A lubricant material in its liquid state is drawn by airflow through a small venturi orifice where it is sheared into droplets of various sizes. Larger droplets are filtered out of the continuing post-venturi airflow by gravity, baffles, airflow forces and/or inertia effects, leaving only a mist cloud of extremely small spheroid particles which are then migrated within a charged plasma so as to transfer electrical charge thereto in sufficient quantities to achieve a desired uniform high charge/mass ratio and thus insure a uniform eventual electrostatic dispersion of substantially all the spheroids over the substrate surface. The mist cloud is controllably generated for each of a plurality of longitudinal sections of the substrate and permitted to drift or migrate relatively slowly between transversely positioned electrodes and the conducting substrate spaced therefrom in respectively corresponding longitudinally partitioned sections of a non-conducting enclosure. A corona discharge is maintained by a voltage differential between the electrodes and the substrate to form an electrically charged plasma within the non-conducting enclosure which, in turn, multiply bombards and charges the individual particles of the slowly migrating mist cloud. Thusly charged to uniform charged states, the particles are then uniformly dispersed substantially only by electrostatic forces onto the surface of the longitudinally moving substrate.