Pickling
1. Purpose: to remove the oxide film on the surface of the wire, and to form a phosphate film on the metal surface to reduce the scratches on the tool and die during the wire drawing and cold pier or forming process.
2. Operation process:
Pickling: Immerse the entire disk element in three hydrochloric acid tanks with a concentration of 20-25% at room temperature for several minutes, the purpose is to remove the oxide film on the surface of the wire.
Clearwater: Remove the hydrochloric acid corrosion products on the surface of the wire.
Oxalic acid: increase the activity of metals to make the film produced in the next step denser
Coating treatment: immerse the disk element in phosphate, contact the steel surface with the chemical treatment solution and dissolve the steel to form insoluble compounds (such as Zn2Fe(Po4)2·4H2o), which adhere to the steel surface to form a coating.
Clearwater: remove residues on the surface of the film.
Lubricant: Since the friction coefficient of the phosphate film is not very low, it cannot give sufficient lubricity during processing, but it reacts with metal soap (such as sodium soap) to form a hard metal soap layer, which can increase its lubricating performance.
