Unveiling the Mysterious Veil of Wires and Cables - Detailed Explanation of Manufacturing Process Flow

Wire and cable are measured in length as the basic unit of measurement. All wire and cable products are made by adding insulation, shielding, cabling, protective layers, etc. layer by layer around the outer periphery of the conductor, starting from the processing of the conductor. The more complex the product structure, the more layers are stacked.

Let's take a look at the production process of wires and cables with the editor below.

Production process flow of wires and cables

1. Copper and aluminum monofilament drawing

Copper and aluminum rods commonly used in wires and cables are drawn through one or several stretching molds using a drawing machine at room temperature to reduce their cross-section, increase their length, and improve their strength. Drawing is the first process of various wire and cable companies, and the main process parameter of drawing is mold matching technology.

2. Single wire annealing

Copper and aluminum monofilaments are heated to a certain temperature to improve their toughness and reduce their strength through recrystallization, in order to meet the requirements of wire and cable for conductive cores. The key to annealing process is to prevent oxidation of copper wire

3. Twisting of conductors

In order to improve the flexibility of wires and cables for easy installation, the conductive core is made up of multiple single wires twisted together. From the twisting form of the conductive wire core, it can be divided into regular twisting and irregular twisting. Irregular twisting can be divided into bundle twisting, concentric compound twisting, special twisting, etc.

In order to reduce the occupied area of wires and shrink the geometric dimensions of cables, a compression form is adopted while twisting conductors, transforming ordinary circles into semicircles, sectors, tile shapes, and compressed circles. This type of conductor is mainly used in power cables.

4. Insulation extrusion

Plastic wires and cables mainly use extruded solid insulation layer. The main technical requirements for plastic insulation extrusion are:

4.1. Eccentricity: The deviation value of the extruded insulation thickness is an important indicator of the extrusion process level, and most product structural dimensions and their deviation values are clearly specified in the standard.

4.2. Smoothness: The surface of the extruded insulation layer should be smooth, and there should be no adverse quality problems such as surface roughness, burning, or impurities.

4.3. Density: The cross-section of the extruded insulation layer should be dense and firm, without visible pinholes, and the presence of bubbles should be eliminated.

5. Cable formation

For multi-core cables, in order to ensure formability and reduce the shape of the cable, it is generally necessary to twist them into a circular shape. The mechanism of twisting is similar to that of conductor twisting, and due to the larger pitch diameter of twisting, most of them adopt the non backstepping method. Technical requirements for cable formation: firstly, to prevent the twisting and bending of cables caused by the flipping of irregular insulated wire cores; The second is to prevent the insulation layer from being scratched.

Most cables are completed with two additional processes during cabling: one is filling to ensure the roundness and stability of the cable after cabling; One is tying to ensure that the cable core is not loose.

6. Inner protective layer

In order to protect the insulated wire core from being damaged by armor, it is necessary to provide appropriate protection for the insulation layer. The inner protective layer is divided into extruded inner protective layer (isolation sleeve) and wrapped inner protective layer (cushion layer). The wrapping cushion layer replaces the binding tape and is synchronized with the cable forming process.

7. Armor

Laying underground cables may withstand certain positive pressure during operation, and an inner steel belt armor structure can be chosen. When laying cables in situations where there is both positive pressure and tensile force (such as in water, vertical shafts, or soil with large drops), structural types with internal steel wire armor should be selected.

8. Outer sheath

The outer sheath is a structural part that protects the insulation layer of wires and cables from environmental factors. The main function of the outer sheath is to improve the mechanical strength, chemical corrosion resistance, moisture resistance, water immersion resistance, and prevent cable combustion of wires and cables. According to different requirements for cables, use an extruder to directly extrude plastic sheaths.