The basic process flow of plastic wire and cable manufacturing

1. Copper, aluminum monofilament drawing

Copper and aluminum rods, commonly used for wire and cable, are stretched through one or more passes at room temperature using a wire drawing machine to reduce their cross-sections, length, and strength. Drawing is the first process of each wire and cable company, and the main process parameter of drawing is the matching technology.

2. Monofilament annealing

Copper and aluminum monofilaments are heated to a certain temperature to increase the toughness of the monofilaments and reduce the strength of the monofilaments in a manner of recrystallization to meet the requirements of the wire and cable for the conductive cores. The key to the annealing process is to eliminate the oxidation of the copper wire.

3. Stranding of the conductor

In order to improve the flexibility of the wire and cable, in order to facilitate the laying and installation, the conductive core is formed by twisting multiple monofilaments. From the twisted form of the conductive core, it can be divided into regular twisting and irregular twisting. Irregular twisting is further divided into bundle strands, concentric twin strands, and special strands.

In order to reduce the occupied area of â€‹â€‹the wire and reduce the geometric size of the cable, a tightly-pressed form is adopted while the conductor is stranded, so that the ordinary round shape is mutated into a semicircle, a fan shape, a tile shape, and a tightly-pressed round shape. This type of conductor is mainly used in power cables.

4. Insulation extrusion

Plastic wire and cable are mainly extruded solid insulation layer, the main technical requirements for plastic insulation extrusion:

4.1. Eccentricity: The deviation of the extruded insulation thickness is an important indicator of the level of extrusion process. Most of the product's structural dimensions and their deviations are clearly defined in the standard.

4.2.Smoothness: The surface of the extruded insulating layer is required to have a smooth surface, and there must be no unfavorable quality problems such as surface roughness, scorching, and impurities.

4.3. Density: The cross-section of the extruded insulation must be dense and solid, not visible to the naked eye, and the presence of bubbles must be avoided.

5. Cable

For the multi-core cable, in order to ensure the degree of molding and reduce the appearance of the cable, it is generally required to strand it into a circle. The mechanism of stranding is similar to that of conductor stranding. Due to the large diameter of the twisted section, most of the strands are not twisted back. The technical requirements for cabling are as follows: First, to prevent the twisting of the cable caused by the inconvenience of the insulated wire core; and secondly, to prevent the insulating layer from being scratched.

Most of the cables are completed with the completion of two other processes at the same time: one is padding to ensure roundness and stability of the cable after the cable is laid, and the other is lashing to ensure that the cable core is not loose.

6. Inner sheath

In order to protect the insulated wire core from being scratched by armouring, proper protection of the insulating layer is required. The inner protective layer is divided into: an inner sheath (separator sheath) and an inner sheath (cushion). The padding layer instead of the binding band is synchronized with the cabling process.

7. Installation

Laying in underground cables, the work may be subject to a certain positive pressure, the choice of internal steel armored structure. When cables are laid in places where there is both positive pressure and tensile force (such as in water, vertical shafts, or in soils with large gaps), the structural type with internal steel wire armor should be used.

8. Outer sheath

The outer sheath is the part of the structure that protects the insulation of the wire and cable from environmental factors. The main role of the outer sheath is to improve the mechanical strength of the wire and cable, prevent chemical corrosion, moisture, water leaching, and prevent the cable from burning. According to the different requirements of the cable, the plastic jacket is directly squeezed by the extruder.

The support grid is made of several Johnson screen sieve plates. Specification and size is customized. Material: 304, 321, 316 L, 904 L, duplex steel 2205, duplex steel 2207, Monel, Ti.etc.

Due to the good mechanical strength, it effectively prevents its own damage and tear in contact with the filler (quartz sand or porcelain ball, etc.) and catalyst ensuring the safe and smooth operation of the reactor in a long period. Therefore, it has gradually replaced the traditional stainless steel woven mesh and perforated plate tray, and has been widely used in petrochemical field.

Johnson Screen Support Grid
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Xinxiang Shengda Filtration Technique Co., Ltd. , https://www.filtrations.nl