We supply cold drawn spring steel wire mainly in following seven coatings / finishes:
Phosphate coated (ph) dry drawn or wet drawn;
Copper coated (cu);
Zinc (Z) coated, or galvanized;
Zinc/aluminium (ZA) coated / Galfan coated;
Aluminized steel;
Ungalvanized black.
Oiled: All steel wires can be with an oiled surface for all surface finishes.
All SINORAY spring steel wire is finished according to international quality standards, as following or similar.
Wire Surface Condition
The surface of the wire shall be smooth and as free as possible from grooves, tears, rust and other surface defects, which have a noticeable adverse effect on the application of the wire.
Surface quality tests is applied to wires intended for use in dynamic duty springs only.
The radial depth of the seams or other surface defects shall be not greater than 1% of the nominal diameter of the wire.
The cross-section of spring wire grades of medium and high tensile strength shall show no completely decarburized layer. Partial decarburization as indicated by grain boundary ferrite of an amount in excess of that present in the main portion or “core” of the section, shall not have a radial depth greater than 1,5% of the nominal diameter of the wire.
Drawing Condition
All cold drawn spring wire is commonly shaped by drawing. A distinction as to the method of drawing can be made between:
dry drawn (d) : drawn through pulverized lubricants such as soap, stearates or similar substances;
paste drawn (ps) : drawn through very viscous greases of mineral oil base, tallow, synthetic waxes or similar substances;
grey bright (gr) : drawn through rape oil, thin-bodied mineral oils or similar substances;
wet drawn (w) : drawn through aqueous emulsions of greases or oil emulsions;
liquor finished (l) : drawn through aqueous solutions with or without addition of metal salts.
Surface Coating:
The surface for spring wire generally has a coating for facilitating wire drawing and spring forming.
Common surface coatings are :
bright (b) : without any special coating : standard borax coating or lime-coating may be applied;
phosphate coated (ph) : the wire has been treated in a solution to form a metal-phosphate layer on the surface;
reddish (rd) : the surface is covered with a thin copper, generally a conversion coating;
copper plated (cu) : the surface is covered with a (uniform) thick copper coating;
galvanised (Z) : the surface is covered with a zinc coating;
zinc/aluminium coated (ZA) : the surface is covered with a Zn 95/Al 5 coating;
yellow coated (y) : this applies only to liquor finished products whereby a mixture of tin salts and copper salts are added at the liquor finishing;
white (liquor finished) (wh) : this applies to liquor finished products whereby tin salts are added for liquor finishing.
For zinc or zinc/aluminium coated spring wire, the amount of zinc or zinc/aluminium on the wire surface shall satisfy the minimum values specified in following table.
Other levels may be agreed between our factory and purchaser. The adherence of the coating shall be tested by a wrapping test according to EN 10244-2.
The usual coating processes may alter the properties of the steel wire. The ductility and endurance of the wire may thereby be reduced so that one cannot guarantee for zinc coated spring steel wire the same torsion values or expect the same dynamic performance as for the respective uncoated material.
| Diameter (mm) | Coating mass g/m2a |
| 0,20 d < 0,25 | 20 |
| 0,25 d < 0,40 | 25 |
| 0,40 d < 0,50 | 30 |
| 0,50 d < 0,60 | 35 |
| 0,60 d < 0,70 | 40 |
| 0,70 d < 0,80 | 45 |
| 0,80 d < 0,90 | 50 |
| 0,90 d < 1,00 | 55 |
| 1,00 d < 1,20 | 60 |
| 1,20 d < 1,40 | 65 |
| 1,40 d < 1,65 | 70 |
| 1,65 d < 1,85 | 75 |
| 1,85 d < 2,15 | 80 |
| 2,15 d < 2,50 | 85 |
| 2,50 d < 2,80 | 95 |
| 2,80 d < 3,20 | 100 |
| 3,20 d < 3,80 | 105 |
| 3,80 d 10,00 | 110 |
| The requirements for the zinc coating correspond to class C of EN 10244-2 | |