Factory Tour: The Complete Production Process of a Power Cord – From Copper Rod to Finished Product

—— A behind-the-scenes look at how Shanghai Fengy Cable transforms raw copper into the cables you use every day

When you plug in a device and flip the switch, electricity flows through the wire to power your equipment. But have you ever wondered how that ordinary-looking power cord is made – from a thick copper rod to the finished cable in your hand? Today, we invite you to walk through our production facility and see the complete journey of a power cord, step by step.

Step 1: Wire Drawing – The Copper Rod's "Slimming" Journey

The journey begins with purple-red copper rods, approximately 8mm in diameter. These rods are fed into wire drawing machines, where they pass through a series of progressively smaller dies. The cross-sectional area decreases while the length increases, ultimately transforming the rods into strands as fine as hair. Precision is critical throughout this process – the finest copper strands can be controlled to within ±0.01mm in diameter.

The drawing process generates significant heat, so drawing oil is applied for both lubrication and cooling. This protects the dies from excessive wear and prevents the copper from oxidizing due to high temperatures. After this stage, the once-rigid copper rods become thin and pliable – but also hard and brittle.

Step 2: Annealing – Restoring Flexibility and "Life" to the Copper

While the drawn copper strands are now thin, the cold-working process has left them hard and brittle. If used immediately, they would be prone to breaking under bending or twisting. This is where annealing comes in.

Annealing involves heating the copper wire to approximately 1000°F, then rapidly cooling it. This process realigns the copper's crystalline structure, restoring its ductility and flexibility. The cooling is typically done in a water bath, which prevents oxidation and ensures rapid temperature reduction. After annealing, the copper becomes soft and pliable – ready to serve as a reliable conductor.

Step 3: Stranding – Combining Strength with Flexibility

A single copper strand is flexible but lacks strength and tensile resistance. To improve both flexibility and mechanical strength, multiple strands are twisted together in a specific pattern and direction.

During this stage, stranding machines – some capable of handling up to 36 spools simultaneously – twist the individual strands into a compact, uniform conductor core. Fully automatic tension control systems ensure consistent twisting tension throughout the process. For larger cables, dozens or even hundreds of strands may be combined. The resulting stranded conductor is not only more flexible and easier to install but also offers superior tensile strength and electrical performance compared to a solid conductor of the same cross-section.

Step 4: Insulation Extrusion – Giving the Copper Core a "Protective Jacket"

Once the conductor core is formed, the next step is to apply the insulation layer – the wire's first line of defense.

On an extrusion production line, PVC or PE insulation pellets are heated to approximately 150°C until molten. The molten material is then forced through an extrusion head, where it is uniformly coated onto the copper conductor to form the insulation layer. This process demands exceptional precision – the thickness of the insulation layer must be controlled within extremely tight tolerances, the surface must be smooth and free of contaminants, and no voids or pinholes can exist inside. Any imperfection can compromise the cable's electrical performance and service life.

The freshly extruded insulation is still hot and pliable, so it passes through a cooling water bath to solidify. At this point, a complete wire – conductor plus insulation – is born.

Step 5: Cabling and Filling – Building Multi-Core Cables

For multi-core cables, individual insulated cores must be twisted together into a single assembly. The cabling process is similar in principle to conductor stranding, but with a larger lay length. Simultaneously, fillers are added to maintain the cable's roundness and stability, and binders are applied to prevent the core assembly from loosening.

For cables with special requirements, an additional inner sheath may be applied at this stage to protect the insulated cores from damage during subsequent manufacturing steps.

Step 6: Outer Sheath Extrusion – The Final Armor

After the core assembly is complete, the cable receives its final protective layer – the outer sheath.

The primary function of the outer sheath is to shield the cable from environmental factors: chemical corrosion, moisture, water ingress, flame spread, and physical abrasion. The extrusion machine melts PVC or other sheath compounds and coats them over the cable core. The sheathed cable then passes through a cooling water bath to solidify the outer layer. The quality of the outer sheath directly impacts the cable's service life and overall safety.

Step 7: Printing and Inspection – The Cable's "ID Card"

During the outer sheath extrusion, an inkjet printer applies product specifications, brand information, and certification marks onto the cable surface. This printed information serves as the cable's "ID card," documenting its specifications and manufacturing origin.

Quality control is woven into every stage of production. From incoming material inspections on raw copper, to resistance tests and spark tests (which detect pinholes or bare spots in the insulation) on semi-finished products, to voltage withstand tests and insulation thermal elongation tests on finished goods – each cable undergoes at least eight separate inspections before it can be released to the market.

The Final Step: Packaging and Shipping

After passing all quality inspections, the finished cables are wound onto spools, automatically packed by robotic arms, labeled with certificates and shipping tags, and prepared for dispatch.

And just like that, a power cord completes its full production journey – from copper rod to finished product. It will be shipped to destinations around the world, powering homes, offices, factories, and data centers with safe and reliable electricity.

Why We Do It This Way

At Shanghai Fengy Cable Technology Co., Ltd. , we believe that the quality of every cable begins with the precision of every step.

From the precise control of wire drawing, to the careful temperature management of annealing, to the uniform extrusion of insulation and outer sheaths, to the 100% electrical testing of finished products – every stage is held to rigorous standards. This commitment is why we have earned ISO 9001 certification and why our products carry CE, TUV, SAA, and SGS approvals. It's also why we export to over 50 countries and regions worldwide.

The next time you plug in a device, take a moment to consider the journey that cable has traveled. It carries not just electricity – but the dedication of an entire factory to quality and reliability.

Want to see it for yourself? Contact us for a factory tour video or to schedule an in-person visit.