Let me show you the manufacturing process of wires and cables

Wire and cable is based on the length as the basic unit of measurement. All wires and cables are made into wire and cable products by adding insulation, shielding, cable forming, protective layer, etc. layer by layer on the periphery of the conductor from the processing of the conductor. The more complex the product structure is, the more layers are superimposed.

Wire and cable production process

Copper and aluminum single wire drawing

The common copper and aluminum rod materials of wires and cables can reduce the section, increase the length and improve the strength by using the wire drawing machine to pass through the die hole of one or more stretching dies at room temperature. Wire drawing is the first process of wire and cable companies, and the main process parameter of wire drawing is die matching technology.

Monofilament annealing

When copper and aluminum monofilament are heated to a certain temperature, recrystallization is used to improve the toughness and reduce the strength of monofilament, so as to meet the requirements of wire and cable for conductor core. The key of annealing process is to eliminate the oxidation of copper wire.

Stranding of conductors

In order to improve the flexibility of wires and cables and facilitate laying and installation, the conductive wire core is twisted by multiple single wires. From the stranding form of conductor core, it can be divided into regular stranding and irregular stranding. Irregular stranding is divided into bundle stranding, concentric compound stranding, special stranding, etc.

In order to reduce the occupied area of the conductor and reduce the geometric size of the cable, the form of compression is adopted while stranding the conductor, so that the ordinary circle can be changed into semicircle, fan-shaped, tile shaped and compressed circle. This kind of conductor is mainly used in power cables.

Insulation extrusion

Extruded solid insulation layer is mainly used for plastic wires and cables. The main technical requirements of plastic insulation extrusion are as follows:

▶  Eccentricity: the deviation value of the extruded insulation thickness is an important sign of the extrusion process level. Most product structure dimensions and their deviation values are clearly specified in the standard.

▶  Smoothness: the surface of the extruded insulating layer shall be smooth, and there shall be no poor quality problems such as surface roughness, scorching and impurities.

▶  Density: the cross section of the extruded insulating layer shall be dense and solid, and there shall be no needle holes visible to the naked eye, so as to eliminate the existence of bubbles.

Cabling

For multi-core cables, in order to ensure the molding degree and reduce the shape of the cable, they generally need to be twisted into a circle. The mechanism of stranding is similar to that of conductor stranding. Due to the large pitch diameter of stranding, no untwisting mode is mostly adopted.

Technical requirements for cable forming: first, prevent the twisting of the cable caused by the turning over of the special-shaped insulating core; The second is to prevent the insulating layer from being scratched.

Most cables are completed with the completion of two other processes: one is filling to ensure the roundness and stability of cables after cable completion; One is binding to ensure that the cable core is not loose.

Inner sheath

In order to protect the insulated wire core from being damaged by armor, it is necessary to properly protect the insulating layer. The inner protective layer is divided into extruded inner protective layer (isolation sleeve) and wrapped inner protective layer (cushion). Wrapping cushion instead of binding belt shall be carried out simultaneously with cable forming process.

Armor

If the cable is laid underground, it may bear certain positive pressure during work, and the inner steel strip armored structure can be selected. When the cable is laid in the situation with both positive pressure and tension (such as in water, vertical shaft or soil with large drop), the structural type with inner steel wire armor shall be selected.

Outer sheath

The outer sheath is a structural part to protect the insulating layer of wires and cables from environmental factors. The main function of the outer sheath is to improve the mechanical strength, chemical corrosion prevention, moisture-proof, water-proof and human immersion of wires and cables, and prevent cable combustion. According to the different requirements for cables, the plastic sheath is directly extruded by the extruder.