What is the purpose of phosphating on wires that need cold forming? In this process, it actually creates a coating of zinc phosphate on the wires, which is firmly attached to the metal surface and reduces friction in the mold. reduces during the cold drawing process and allows this operation to be done easily. In addition, it forms a coating layer against wire rusting after the drawing operation. Also, in the process of cold forming in the mold, the friction between the wire and the mold is reduced to a great extent, and it causes a longer life of the mold and the production of a quality product.
The phosphating of wires is usually based on the immersion method, where coils of wire are lowered into separate tubs.
In stretching the steel wires, the thickness of the phosphate coating should be carefully used to use the appropriate coating thickness. If it is too much, in the first stage friction tension will increase and as a result whiteness and unevenness will occur. On the other hand, however, the phosphate coating should be sufficient so that its benefits remain even at the last stage of stretching. As a general rule, for multi-stage drawing of high-carbon wires, a residual phosphate layer after final drawing of 0.5-1.0 g/m2 is desirable. The exception to this is those steel wires where a phosphate coating is useful in some subsequent forming processes. Therefore, the wires of the cold forming operation need a phosphate coating of 5-15 grams per square meter, which is measured after the completion of the phosphating operation. Below, I will mention the steps of this operation in Carizan company.
1- The first step is a hot degreasing tub
2- The second step is to wash the tub and spray it with water
3- The third stage of the acid washing bath with 30% sulfuric acid
4- The fourth step is to wash the tub and spray it with water
5- The fifth step is a bath of zinc phosphate solution
6- The sixth stage of the neutralization tank
7- The seventh stage of drying
Wire sizing and stretching operations
In Carizan company, according to the type of product process or the customer’s request, wire drawing and sizing operations for use in bolt and nut production units are carried out under the supervision of experienced experts and transferred to the raw material depot station.