Method of treating parts by vibratory action

A method of treating the surface of parts comprising introducing said parts and a finishing media into a first zone at normal level, subjecting said mixture of parts and media to vibratory action whereby said parts and media travel in one direction in an orbital path, introducing a barrier across the path of travel of the parts and media whereby the parts and media pile up in advance of the barrier to an upper level above the normal level to clear the barrier, allowing the parts and media to fall sharply from the upper level to a lower level below normal level upon clearance of the barrier, screening the parts and media immediately beyond the barrier at a level below normal level but above the lower level to separate the parts on the surface of the screen while enabling the media to pass therethrough for return to normal level.