Thierry Heynen – Sirio Wire Srl
The steel material phosphating process has the purpose to produce a surface conversion layer, at thin and compact thickness strongly anchored on the surface, in order to facilitate the cold deformation or the further drawing operations. It exists with different types of phosphate. For rod wire, the most frequently used is the zinc phosphate. After phosphating, an opportune covering with lubricating layer on the phosphated surface is necessary.
It is unavoidable that the surface to be phosphated results in perfectly clean, without oil and grease, metallic oxides and acidity. This is usually guaranteed through the use of a chemical pickling operation (with H2SO4 or HCl) along with subsequent strong water washing or by means of a shot blasting operation.
The phosphating process is generally carried out by the material being dipped into a hot solution tank with dipping time linked to the expected layer thickness.