High Carbon Steel Bonnell Coil Spring Unit 2026

High carbon steel wire is the industry standard for mattress springs because its high tensile strength (1,400-2,050 MPa) lets springs support weight and recover their shape after years of compression. Grades such as 82B, 72A, and 70B are widely used; the right choice depends on the spring type and required firmness.-

Pocket spring wire is usually 1.6-2.0 mm (commonly 1.8 or 2.0 mm). Bonnell spring wire is slightly thicker at 1.8-2.3 mm (commonly 2.0 or 2.2 mm). Helical lacing wire that ties springs together is thinner at 1.3-1.5 mm, and border frame wire is much thicker at 4.0-5.0 mm.

Helical (spiral) wire is used to fasten individual Bonnell springs together into a complete spring net, forming the core of the mattress. It is shaped like a snake/coil and is typically 1.3-1.5 mm in diameter (commonly 1.30, 1.35 or 1.4 mm).

Both options are available. The standard finish is ungalvanized (black) high carbon steel with anti-rust treatment. Galvanized (zinc-coated) wire can be supplied on request for higher corrosion resistance in humid environments.

Our high carbon mattress spring steel wire is manufactured to GB4357-2009, with controlled chemical composition (C, Mn, Si, P, S, B) and tensile strength of 1,400-2,050 MPa by diameter.