JPS5141638

A process and an apparatus within which there is provided at least one, or a plurality of tanks in series relation, depending upon the type of member being treated, each tank having one or more openings within its walls, respectively, which are provided in alignment with each other. With this apparatus, one or more metal members such as for example, a bar, rod, pipe, or tube, is rotatably fed through the aforenoted openings into the tank or tanks, thereby enabling a continuous automatic-etching process of the outer surface of the metal members to be performed. As an alternative, there is provided within each tank, a triple walled cylindrical body or solution flow guide, whereby a solution for etching may uniformly flow in the direction of the metal member being conducted through the tank or tanks, and along the outer surface thereof, so that a desired surface condition of the bar, rod, pipe or tube may be obtained in an efficient manner.