Anchor Chain Making Machine

Raw material preparation is the foundation of chain quality. The main goal is to process the metal wire into specifications that meet chain-making requirements to ensure stability during forming and welding.

Wire Material Selection:
Choose materials based on the chain’s application. Common options include:

• Low-carbon steel wire (for standard industrial chains, tensile strength ≥400 MPa)

• Stainless steel wire (304/316) (for corrosion-resistant applications such as outdoor use or food machinery)

• Copper alloy / aluminum alloy wire (for lightweight decorative chains such as jewelry chains)

• High-strength alloy steel wire (for heavy-duty chains such as lifting equipment, tensile strength ≥800 MPa)

The wire diameter must match the chain specification, with a tolerance of ±0.02 mm.

Pre-processing Steps

Rust & Oil Removal:
Use pickling (for industrial chains) or ultrasonic cleaning (for precision/decorative chains) to remove oxide layers and oil. After pickling, neutralization, rinsing, and drying are required to ensure no acidic residue remains (pH 6.5–7.5). Decorative chains may include an additional polishing step to improve surface smoothness.

Wire Drawing:
Send the cleaned wire through a drawing machine to achieve the required diameter (e.g., 2.0 ± 0.01 mm wire for a 2 mm chain link). Control drawing speed at 5–10 m/min to avoid breakage or surface scratches. After drawing, wire roundness must be ≤0.03 mm.

Cut-to-Length:
According to link size, use an automatic cutting machine to cut the drawn wire into equal sections (length tolerance ±0.1 mm). Cut surfaces must be flat and burr-free to avoid affecting the accuracy of chain forming.

The core of chain forming is to use an anchor chain-making machine to process the cut wire segments into chain links and automatically assemble them into a continuous chain. The key is to ensure link size consistency and smooth linking.

Equipment Setup:
Install the appropriate molds according to the chain type (round link chain, oval link chain, side chain, etc.) and adjust parameters such as forming pressure, bending angle, and feeding speed.
For example, when producing round link chains, the mold radius must match the link radius (tolerance ≤0.05 mm), and the forming pressure should be set between 30–50 tons to ensure that the links are formed without deformation or cracks.

Automatic Chain-Making Process

1. Feeding:
The cut wire segments are fed into the machine through an automatic feeder with a feeding accuracy of ±0.03 mm to avoid length variation between links.

2. Bending & Forming:
Under hydraulic pressure, the mold bends the wire into the preset link shape (round, oval, etc.).
Bending speed is controlled at 1–2 cycles per second to prevent wire breakage caused by stress concentration.

3. Linking:
The formed link is precisely connected to the previous one by the machine’s automatic linking mechanism.
The connection gap must be ≤0.1 mm to ensure smooth chain rotation without jamming.

4. Quality Inspection:
During production, one sample is checked for every 100 links.
Measurements include:

• inner width

• outer width

• pitch

Acceptable pitch error is ±0.2 mm.
The operator must also check for deformation, cracks, or surface scratches. Defective links must be removed immediately and machine parameters adjusted accordingly.

Welding is a critical process in chain manufacturing. Its purpose is to permanently join the link’s interface, ensuring the chain’s tensile strength and service life. The appropriate welding method must be selected based on the chain’s material and intended application.

3.1, Flame Welding

Applicable Scenarios:
Mainly used for low-carbon and medium-carbon steel industrial chains (such as lifting chains and conveyor chains). It is suitable for large-size chain links (diameter ≥5 mm). The equipment cost is low, operation is flexible, and on-site repair is possible.

Key Process Points:

Welding Materials:
Use welding wire that matches the base material (e.g., ER50-6 wire for low-carbon steel chains). Select the wire diameter according to the chain link diameter (for chain link diameters of 5–10 mm, use welding wire with a diameter of 1.2–2.0 mm).

Flame Adjustment:
Use an oxygen–acetylene flame and set it to a neutral flame (oxygen to acetylene ratio 1:1). Control flame temperature at 2800–3100°C to avoid oxidizing flames (which cause excessive metal burn-off) and carburizing flames (which increase carbon content in the weld and reduce toughness).

Welding Operation:
Align the chain link joint at the center of the flame and heat it until it reaches a molten state (≥1538°C). Feed welding wire to fill the joint. Control welding speed at 5–10 mm/s to ensure a full, defect-free weld with no porosity or slag inclusion. The weld height should be ≥1/3 of the chain link diameter. Allow the weld to cool naturally or cool slowly (to avoid cracking caused by rapid cooling).

Quality Standards:
Tensile strength of the weld shall be no less than 90% of the base material. In the bending test, the chain should withstand 10 repeated bends without weld failure. The weld surface must be free from significant depressions and porosity (pore diameter ≤0.5 mm, no more than 3 pores per meter).

3.2, Laser Welding

Applicable Scenarios:
Suitable for materials such as stainless steel, copper alloys, and aluminum alloys. It is especially ideal for precision chains (e.g., jewelry chains, medical instrument chains) and small-size chain links (diameter ≤5 mm). It offers high welding accuracy, a small heat-affected zone, and aesthetically clean welds.

Key Process Points:

Equipment Parameters:
Use a fiber laser welding machine (500–1500 W). Adjust the laser power according to the chain link diameter (500–800 W for 2 mm links; 1000–1500 W for 5 mm links). Welding speed: 10–20 mm/s; laser spot diameter: 0.2–0.5 mm; focal length: 150–200 mm.

Welding Preparation:
Fix the chain on a special clamping fixture to ensure the chain link joint is properly aligned (alignment error ≤0.05 mm). The welding area must remain clean (free of oil and dust). Use argon shielding gas when needed (flow rate 5–10 L/min) to prevent weld oxidation.

Welding Operation:
Use continuous or pulsed laser welding (pulsed mode recommended for precision chains, pulse frequency 10–20 Hz). Scan evenly along the joint to ensure full weld penetration and avoid incomplete fusion. Precision chains require no post-grinding; industrial chains may need light grinding.

Quality Standards:
Weld tensile strength must be no less than 95% of the base material. Weld width ≤0.8 mm; heat-affected zone ≤1 mm; surface roughness Ra ≤1.6 μm. No oxidation discoloration should appear (when using shielding gas).

The core purpose of annealing is to eliminate internal stresses after welding, reduce chain hardness, and improve flexibility and ductility, preventing fractures caused by stress concentration during use.

Process Selection:

• Low-carbon steel chains: full annealing (heat to 730–800°C, hold for 1–2 hours, cool with the furnace).

• Stainless steel chains: solution annealing (1050–1100°C, hold for 30–60 minutes, water or air cooling).

• Copper alloy chains: low-temperature annealing (300–400°C, hold for 2–3 hours, natural cooling).

Operation Points:

• Place welded chains neatly in the annealing furnace, leaving gaps between chains (≥5 mm) to ensure uniform heating and avoid local overheating or insufficient annealing temperature.

• Strictly control the heating rate (5–10°C/min) to prevent deformation from sudden temperature rise. Maintain stable furnace atmosphere during holding (use nitrogen for industrial chains, vacuum for precision chains).

• Cooling must follow process requirements: full annealing should cool with the furnace to below 200°C before removal; solution annealing requires rapid cooling (water quench) to ensure corrosion resistance of stainless steel.

Quality Effects:
After annealing, chain hardness is reduced (low-carbon steel HB ≤180, stainless steel HB ≤200), flexibility improves, and the chain can withstand repeated 180° bending 5 times without breaking. Internal stress relief rate ≥90%.

Straightening and Cleaning aim to correct the chain’s straightness and link flatness, and remove residual oil, welding slag, oxide scale, and other impurities from production, providing a clean surface for subsequent finishing.

5.1 Straightening

• Equipment and Operation: Use a chain-specific straightening machine. Feed the annealed chain between the straightening rollers, adjusting roller pressure (10–30T) and spacing to achieve chain straightness error ≤0.5 mm/m and link flatness error ≤0.1 mm. For precision chains, manual straightening assistance can be applied to ensure each link rotates smoothly without tilting.

• Quality Check: After straightening, measure chain straightness with a straightness tester and link flatness with a straightedge. Severely deformed links should be individually corrected or removed.

5.2 Cleaning

• Cleaning Methods:

  • Industrial Chains: Use ultrasonic cleaning (frequency 28–40 kHz, power 500–1000 W) with an alkaline cleaning solution (5–10% concentration). Clean at 50–60°C for 10–15 minutes to remove welding slag and oil. Rinse three times with water and dry in an oven at 80–100°C for 30 minutes.

  • Precision / Decorative Chains: Use vacuum cleaning or organic solvents (e.g., ethanol, acetone) to avoid residue affecting surface luster. After cleaning, dry with hot air at 60–80°C for 15 minutes.

• Cleaning Standards: After cleaning, the chain surface should be free of oil, welding slag, and oxide scale. No water marks should remain after rinsing, and pH should remain neutral (6.5–7.5).