Phosphorus removal process for high-strength fasteners before heat treatment

- Nov 24, 2020-

Phosphate coating during phosphating and cold forming


     During the cold forming of steel, parts such as fasteners, steel wires and pipes usually need to be phosphated and coated with lubricants. The phosphate layer acts as a carrier for the lubricant and acts as a barrier between the workpiece and the tool.

     The principle is based on the formation of a phosphate layer, which is firmly fixed on the metal surface and carries a special lubricant. On the one hand, it combines the adhesion and separation effect of the carrier layer, and on the other hand the separation and sliding performance of the special lubricant, so that the metal forming can achieve high quality, excellent surface quality, long service life of auxiliary tools, and moderate pressing performance.

After the metal is formed, there will be a layer of "phosphate pressing shading" on the surface of the cold formed workpiece, which is composed of zinc or zinc calcium phosphate coating and lubricants (such as metal soap, polymer, molybdenum disulfide, graphite).