From Wire to Chain: The Manufacturing Process of Round-Link Chains

Ever wondered how a simple steel wire becomes a strong, reliable round‑link chain? Whether for anchoring a boat or lifting heavy loads, the process involves precision, heat, and rigorous testing. Here

1. Raw Material Selection

It all starts with the right steel.

Low‑carbon steel for general industrial use

Alloy steel (heat‑treated) for lifting chains Grade 80/100

Stainless steel AISI 304L/316L for corrosion‑resistant marine chains

Each batch is chemically and mechanically tested before production.

2. Wire Drawing

The steel coil is cold‑drawn to the exact diameter required for the chain links. This ensures uniform thickness and a smooth surface.

3. Bending & Linking (Chain Forming)

Automatic chain bending machines shape the wire into individual links and simultaneously thread each new link through the previous one. Modern electronic controls guarantee consistent pitch and shape.

4. Welding

Each link is flash‑butt welded. Electronic monitoring systems inspect weld quality in real time. After welding, burrs are ground off for a clean finish.

5. Calibration (Sizing)

The chain passes through a sizing die that compresses each link from the sides. This corrects any distortion from bending/welding and ensures uniform pitch and internal width – critical for smooth windlass or sprocket engagement. Calibration is done before heat treatment, when the steel is still soft.

6. Heat Treatment (for alloy steel)

The chain is quenched and tempered to achieve its final mechanical strength (e.g., Grade 80/100). This step transforms the steel’s internal structure for high tensile strength and wear resistance. Stainless steel chains instead undergo solution annealing to restore corrosion resistance.

7. Proof Loading (Pre‑stretching)

The entire chain is pulled along its axis with a force equal to a percentage of its breaking load (typically 25‑50%). This permanently stretches the chain by about 0.5‑1.5%, removing residual stresses and preventing future elongation in service.

Proof loading is different from calibration: calibration shapes the link, while proof loading stabilises the whole chain.

8. Surface Finishing

Depending on the application, the chain may be:

Hot‑dip galvanized (ISO 1461) for marine use

Electro‑galvanized for light corrosion protection

Polished (stainless steel) for hygiene and aesthetics

Left raw (uncoated) for internal industrial applications

9. Inspection & Marking

Each batch is proof‑tested, measured, and visually inspected. Certified chains are stamped with grade and standard (e.g., DIN 766, Grade 50). Finally, they are packed and shipped.

Why does this matter? A chain is only as good as its manufacturing. From correct calibration to proper heat treatment, every step ensures you get a product that is safe, durable, and fit for purpose – whether on a yacht, in a factory, or on a farm.

Boyuan Metal supplies high‑quality round‑link chains in stainless steel and galvanised finishes.