Sealing Wire Manufacturing Process

1. Raw Material Selection

The manufacturing process begins with careful selection of the base material. The choice of raw material determines the sealing wire's mechanical properties, corrosion resistance, and suitability for specific applications. Anruoya sources wire rod from certified steel mills, ensuring consistent composition and metallurgical quality.

Stainless Steel 304 (SS304) — the most widely used material for sealing wire, offering excellent corrosion resistance, good ductility, and reliable tensile strength. It is ideal for general-purpose sealing, food industry applications, and outdoor use where moisture exposure is a concern. Browse our SS304 sealing wire products →

Stainless Steel 316 (SS316) — contains molybdenum, providing superior resistance to chlorides and harsh chemical environments. SS316 sealing wire is the preferred choice for marine applications, pharmaceutical facilities, and coastal installations. Explore SS316 wire options →

Galvanized Steel — carbon steel wire coated with a protective zinc layer. It offers excellent strength at a lower cost point, making it suitable for high-volume sealing applications where extreme corrosion resistance is not required. View galvanized wire products →

Copper — selected for applications requiring high electrical conductivity, non-sparking properties, or distinctive visual identification. Copper sealing wire is often used in security seals and tamper-evident packaging for high-value goods.

2. Wire Drawing Process

Once the raw material is selected, the wire rod undergoes a multi-stage wire drawing process to achieve the precise diameter required for sealing wire applications. This is one of the most critical steps in the manufacturing process.

Step 1 — Surface Preparation: The wire rod is pickled in acid solution to remove scale and oxides, then washed and coated with a lubricant carrier (typically lime or borax) to facilitate smooth drawing.
Step 2 — Rough Drawing: The prepared rod is drawn through a series of tungsten carbide dies, progressively reducing its diameter. Each pass through a die reduces the cross-section by approximately 20–25%. Multiple passes are required to reach intermediate gauges.
Step 3 — Intermediate Annealing: After several drawing passes, the wire work-hardens and becomes brittle. It is annealed (heat-treated) to restore ductility before further reduction.
Step 4 — Fine Drawing: The semi-finished wire passes through additional diamond or polycrystalline dies to reach the final specified diameter — commonly 0.18 mm to 0.80 mm for sealing wire applications.
Step 5 — Final Lubricant Removal: The finished drawn wire is cleaned to remove all drawing lubricants, leaving a clean surface ready for the next process stage.

3. Annealing & Heat Treatment

Annealing is a controlled heat treatment process that relieves internal stresses accumulated during wire drawing and restores the wire's ductility. The wire is passed through a continuous bright annealing furnace under a protective atmosphere (typically hydrogen or nitrogen) to prevent oxidation. This process ensures the wire can be further processed — twisted, stranded, or bent — without cracking or breaking. It also refines the grain structure, improving the wire's overall mechanical consistency.

4. Stranding & Twisting

Most sealing wire products are not single-strand but are twisted or stranded from multiple individual wires to increase strength, flexibility, and tamper evidence. The stranding process is meticulously controlled to maintain uniform tension and consistent twist pitch.

Single Wire (1 strand): Used for basic sealing applications where a simple loop-and-lock mechanism is sufficient.
3-Strand Construction: Three individual wires twisted together, offering a balance of strength and flexibility. Common in security seals for containers and cabinets.
5-Strand Construction: Increased tensile strength and resistance to cutting, suitable for higher-security applications.
7-Strand Construction: The most robust standard configuration, delivering maximum strength, flexibility, and tamper resistance. The 7-strand rope-like structure makes it extremely difficult to cut or break without detection.

Stranding is performed on planetary or tubular stranding machines that rotate the wire bobbins around a central axis, laying each wire in a precise helical pattern around a core (if present). The number of twists per meter is specified to meet the end-use requirements.

5. Coating Application

Depending on the intended application, sealing wire may receive one or more coatings to enhance performance, corrosion resistance, or visual identification.

Galvanizing (Hot-Dip or Electro-Galvanizing): A zinc coating is applied to carbon steel wire to provide sacrificial corrosion protection. Hot-dip galvanizing creates a thicker, more durable coating ideal for outdoor use, while electro-galvanizing produces a smoother, more uniform finish suitable for indoor sealing applications.

Polymer Coating: A layer of nylon, PVC, or polyethylene is extruded or dip-coated onto the wire surface. Polymer-coated sealing wire offers additional chemical resistance, electrical insulation, color coding for easy identification, and a smooth finish that reduces damage to packaged goods. See our polymer-coated galvanized wire →

6. Quality Control & Testing

Every batch of sealing wire undergoes rigorous testing before it is approved for shipment. Our quality control procedures include:

Tensile Strength Testing: Samples from each production lot are pulled to failure on calibrated testing machines to verify they meet specified breaking loads.
Diameter Verification: Laser micrometers and optical gauges measure wire diameter at multiple points along the length to ensure dimensional consistency within ±0.01 mm tolerances.
Coating Thickness Measurement: For galvanized and polymer-coated wires, coating thickness is measured using magnetic induction and eddy current methods.
Twist & Structure Inspection: Stranded wires are examined for uniform twisting pitch, consistent strand tension, and surface defects under magnification.
Corrosion Resistance Testing: Salt spray testing (ASTM B117) is conducted on coated wires to validate corrosion protection performance.

7. Packaging & Export

The final stage of the manufacturing process is packaging. Sealing wire is wound onto spools, coils, or reels depending on the customer's requirements. Each spool is labeled with the material grade, diameter, strand count, coating type, lot number, and net weight. Products are packed in export-grade cartons, wooden crates, or palletized bundles with moisture-barrier liners to protect against corrosion during ocean freight. Anruoya ships to customers worldwide, with strict adherence to international packaging standards.

From Raw Material to Finished Product

The journey from raw wire rod to finished sealing wire involves precision engineering, metallurgical expertise, and rigorous quality control at every step. Whether you need stainless steel 304 for food-grade sealing, stainless steel 316 for marine environments, galvanized wire for cost-effective high-volume applications, or polymer-coated wire for added protection, understanding the manufacturing process helps you make an informed purchasing decision.

At Anruoya, we control every stage of production — from material sourcing to final packaging — ensuring consistent quality that our customers can rely on.