Introduction

When you lift a heavy load with a Grade 80 or Grade 100 chain, you're placing your trust—and your safety—in a product that has undergone a complex, multi-stage manufacturing process. From raw steel rod to finished, tested, and certified chain, each step is critical to ensuring the final product meets the stringent safety and performance standards required for overhead lifting.

Understanding how lifting chains are manufactured not only helps you appreciate the engineering behind these essential tools but also enables you to make more informed purchasing decisions. This guide walks you through the complete lifting chain manufacturing process—from raw material inspection to final packaging—explaining what happens at each stage and why it matters.

Raw Material Inspection and Selection

The lifting chain manufacturing process begins with the most fundamental element: the raw material. High-quality lifting chains start with high-quality steel.

For Grade 80 and Grade 100 alloy steel chains, manufacturers use premium alloy steel containing specific amounts of chromium (Cr), nickel (Ni), and molybdenum (Mo) . These alloying elements are essential for achieving the strength, toughness, and wear resistance required for overhead lifting applications.

What Happens at This Stage:

  Incoming material inspection: When raw steel coils or rods arrive at the factory, samples are cut for testing

  Chemical analysis: Spectral testing verifies that the chemical composition meets the required specifications for the target chain grade

  Hardness testing: Samples are tested to ensure consistent material properties

  Visual inspection: Workers examine the raw material for surface defects

Why It Matters: The chemical composition of the steel directly determines the chain's final mechanical properties. Chains made from substandard materials cannot achieve the required strength or heat treatment response, regardless of how carefully they are processed later.

Standards Reference: Grade 80 chains must conform to ASTM A391/A391M, which specifies chemical requirements for carbon, phosphorus, sulfur, nickel, chromium, and molybdenum. Grade 100 chains are governed by ASTM A973/A973M.

Cutting the Steel Rod

Once the raw material is approved, the steel rod or wire is prepared for the forming process.

The steel is cleaned and drawn to the exact wire diameter required for the specific chain size. It is then cut into precise lengths—each piece will become one link of the chain.

Key Considerations:

    Diameter consistency: The wire diameter must be uniform to ensure consistent chain strength

    Length precision: Each cut piece must be the correct length to form a link of the specified dimensions

    Surface quality: The cut surfaces must be clean and free from defects that could affect welding

The cut pieces are then stored and fed into the chain-making equipment as needed.

Forming the Chain Links

This is where individual links begin to take shape. The cut steel pieces are fed into a chain-forming machine that bends them into the characteristic oval or round shape of a chain link.

The Forming Process:

    The cut steel piece is heated (in some processes) or cold-formed into a "U" shape

    The piece is bent around a former to create the link's final shape

    The link is interlocked with the previously formed link, creating a continuous chain

    The ends of the link are brought together for welding

Full automatic equipment in chain production produces superior results compared to semi-automatic equipment or manual welding. Automated systems ensure consistent link geometry, precise dimensions, and repeatable quality.

Quality Checks During Forming:

    Pitch accuracy: The distance between links must be consistent

    Outside width: Each link must meet dimensional specifications

    Interface clearance: The gap where the link ends meet must be within tolerance

Electric Flash Butt Welding

Welding is one of the most critical stages in the lifting chain manufacturing process. The quality of the weld directly determines the chain's strength and safety.

Most high-quality lifting chains use electric flash butt welding—a sophisticated welding process that joins the ends of each link without adding any filler material.

How Flash Butt Welding Works:

    The two ends of the formed link are brought together

    An electric current is passed through the ends, heating them

    The ends are pressed together under high pressure, forging them into a solid joint

    Excess material (flash) is trimmed away

Advanced techniques such as pulsed flash butt welding have been developed specifically for producing high-strength chain, allowing for consistent weld quality across large production runs.

What Makes a Good Weld:

    Full penetration: The weld must extend through the entire cross-section of the link

    No defects: The weld area must be free from cracks, glitches, or scratches

    Smooth surface: The welded area should be as smooth as the rest of the link

Quality Verification: Samples of welded chain are cut from the production run several times per shift and tested to verify weld integrity.

Calibration (First Proofreading)

After welding, the chain undergoes its first calibration or proofreading process.

What Calibration Achieves:

    Dimensional consistency: Ensures each link meets the specified dimensions

    Link alignment: Corrects any minor distortions from the welding process

    Strength verification: The calibration process also tests the strength of the chain, particularly at the welded sections

During this stage, the chain may also receive identification markings—such as the grade and traceability codes—stamped into the links. These markings are essential for traceability and regulatory compliance.

Heat Treatment (Quenching and Tempering)

Heat treatment is the core of the lifting chain manufacturing process—the stage that transforms ordinary steel into a high-strength alloy lifting chain.

For Grade 80 and Grade 100 chains, heat treatment involves two key processes: quenching and tempering.

Quenching:

The chain is heated to a very high temperature—typically between 1600°F and 1700°F (870°C to 927°C) —and then rapidly cooled in water or oil. This process:

    Increases hardness dramatically

    Transforms the steel's microstructure to a martensitic structure

    Significantly increases tensile strength

Tempering:

After quenching, the chain is reheated to a lower temperature—typically 400°F to 600°F (200°C to 315°C) —and then cooled. This process:

    Reduces brittleness caused by quenching

    Relieves internal stresses

    Increases toughness while maintaining high strength

Quality Verification After Heat Treatment:

    Surface hardness testing: Verifies that the heat treatment achieved the required hardness

    Breaking tension testing: Confirms the chain meets minimum breaking force requirements

    Extension force testing: Checks elongation characteristics

Why Heat Treatment Matters: The heat treatment process is what gives Grade 80 and Grade 100 chains their superior strength-to-weight ratio and resistance to wear and fatigue. Without proper heat treatment, even the best alloy steel cannot achieve the performance required for overhead lifting.

Calibration (Second Proofreading) and Proof Testing

After heat treatment, the chain undergoes a second calibration (or proofreading) process.

Second Calibration:

    The chain is stretched under controlled tension

    Typically, 5 to 7 links are calibrated at a time

    The tension applied is greater than 2.5 times the rated load

Proof Testing:

Proof testing is a critical quality control step in the lifting chain manufacturing process. It involves applying a tensile force to the chain that is higher than the working load but lower than the breaking load.

    The proof test force is typically twice the Working Load Limit (WLL) 

    The test is applied under constantly increasing force in direct tension

    The purpose is to:

        Eliminate residual stresses from manufacturing

         Detect any hidden defects

        "Shape" the chain to ensure consistent performance

Automatic proof testing is standard in modern chain manufacturing facilities.

Bow Test (Long-Length Consistency Check)

For longer chain lengths, a bow test may be performed.

What Is a Bow Test?

    A length of chain (typically 6 meters) is pulled with 2.5 times the rated load

    The test checks the consistency of the entire length of chain

    It can reveal any variations in heat treatment or manufacturing quality along the chain

This test is particularly important for chains that will be used in long lengths, such as those used in hoists or conveyor systems.

Cutting to Customer Specifications

At this stage, the chain is cut to the specific lengths required by customers—such as 6 meters, 10 meters, 20 meters, or custom sizes.

Quality Checks During Cutting:

    A chain breaking test is performed on samples

    The cut ends are inspected for any damage

    Length accuracy is verified

Surface Treatment

After cutting, the chain undergoes surface treatment based on customer requirements and the intended application environment.

Common Surface Treatment Options:

Purpose of Surface Treatment:

    Prevent rust and corrosion

    Extend service life

    Improve appearance

    Provide additional wear resistance

Customers should choose the appropriate surface treatment based on their specific use environment.

Final Inspection and Quality Control

Before any chain can be shipped, it must pass a comprehensive final inspection.

Final Inspection Includes:

Non-destructive testing (NDT) —such as magnetic particle inspection—may also be performed to detect surface and near-surface cracks that are not visible to the naked eye.

Each test result is recorded for traceability and quality records.

Packaging and Warehousing

After passing final inspection, the chain is ready for packaging and warehousing.

Packaging Options:

    Tons bags: For bulk quantities

    Wooden cases: For export or high-value orders

    Iron drums: For heavy or large quantities

    Plastic drums: For smaller quantities or corrosion-sensitive applications

Proper packaging protects the chain during transport and storage, preventing damage and corrosion.

Quality Standards for Lifting Chain Manufacturing

High-quality lifting chains are manufactured and tested according to international safety standards that specify everything from material composition to testing procedures.

Alloy steel chain shall be manufactured and tested in accordance with these standards. Chains that meet these standards are marked with the grade, WLL, manufacturer ID, and batch traceability information.

How TOPONE CHAIN Manufactures Lifting Chains

At TOPONE CHAIN, we follow a rigorous lifting chain manufacturing process that ensures every chain meets the highest standards of quality and safety.

TOPONE's Manufacturing Capabilities:

    Premium raw materials: Alloy steel containing chromium, nickel, and molybdenum

    Quenched and tempered heat treatment: Applied to every Grade 80 and Grade 100 chain

    Full testing and certification: Every chain is tested according to EN 818, NACM, and ASME B30.9 standards

    4:1 safety factor: All chains are designed with a 4:1 safety factor

    2.5 times proof load: Each chain is proof tested to 2.5 times its WLL

    Complete traceability: Every chain is marked and documented

TOPONE CHAIN's factory began large-scale production of Grade 80 and Grade 100 high tensile lifting chains according to EN818-2, ASTM80, NACM96, and Australian standards. Today, TOPONE delivers certified alloy sling chain solutions that meet the stringent safety requirements of the world's most demanding industries.

Conclusion

The lifting chain manufacturing process is a complex, multi-stage operation that transforms raw alloy steel into a precision-engineered safety product. From material inspection and forming to welding, heat treatment, proof testing, and final inspection, every step is critical to ensuring the chain's strength, durability, and safety.

Understanding this process helps you appreciate why high-quality lifting chains—like those manufactured by TOPONE CHAIN—command a premium price and, more importantly, why they are essential for safe overhead lifting operations.

When you choose a lifting chain, you're not just buying a product—you're investing in safety, reliability, and peace of mind.

Interested in learning more about TOPONE CHAIN's lifting chain manufacturing capabilities? Contact TOPONE CHAIN for more information about our Grade 80 and Grade 100 alloy steel lifting chains.

About TOPONE CHAIN

TOPONE CHAIN specializes in the manufacture of high-strength alloy steel lifting chains for overhead lifting, rigging, and heavy-duty material handling. All products are manufactured and tested according to EN 818, NACM, ASTM A391/A391M, ASTM A973/A973M, and ASME B30.9 standards, ensuring safety, reliability, and regulatory compliance. With a commitment to quality and customer satisfaction, TOPONE delivers lifting chain solutions that meet the demands of the most challenging industrial environments.