Production process of wires and cables

Overview of Wire and Cable Manufacturing Process
The manufacturing of wires and cables is completely different from the production method of most electromechanical products. Mechanical and electrical products are usually assembled into components, multiple components are then assembled into a single product, and the product is measured in units or pieces. Wire and cable are measured in length as the basic unit of measurement. All wires and cables start from the processing of conductors, and are made into wire and cable products by adding insulation, shielding, cabling, protective layers, etc. layer by layer on the periphery of the conductors. The more complex the product structure, the more layers it overlaps.
1、 Process characteristics of wire and cable product manufacturing:
1. Large length continuous stacking combination production method
The production method of large length continuous superposition combination has a global and controllable impact on the production of wires and cables, which involves and affects:
(1) Production process flow and equipment layout
The various equipment in the production workshop must be reasonably discharged according to the required process flow of the product, so that the semi-finished products in each stage can be circulated in sequence. Equipment configuration should consider the balance of production capacity based on different production efficiency. Some equipment may have to be configured with two or more units in order to balance the production capacity of the production line. Therefore, the reasonable selection and combination of equipment and the layout of production sites must be balanced and comprehensively considered based on products and production volume.
(2) Production organization management
Production organization and management must be scientific, reasonable, meticulous, accurate, and strict. Operators must strictly follow the process requirements. Any problem in any link will affect the smoothness of the process flow, affecting product quality and delivery. Especially for multi-core cables, if a pair or basic unit length is short or there is a quality issue, the entire cable will not be long enough, resulting in scrapping. On the contrary, if a certain unit is too long, it must be sawn off to cause waste.
(3) Quality management
The production method of continuous stacking and combination with large lengths can affect the quality of the entire cable if any problem occurs at any stage or instantaneously during the production process. The more quality defects occur in the inner layer and are not detected and terminated in a timely manner, the greater the losses caused. Because the production of wires and cables is different from assembled products, they can be disassembled, reassembled, and replaced with another component; The quality problem of any component or process of a wire or cable is almost irreparable and irreparable for this cable. The handling afterwards is very negative, either sawing it short or degrading it, or scrapping the entire cable. It cannot be disassembled and reassembled.
The quality management of wires and cables must be integrated throughout the entire production process. The quality management inspection department should conduct patrol inspections of the entire production process, self inspection of operators, and mutual inspection of upper and lower processes, which are important guarantees and means to ensure product quality and improve the economic benefits of the enterprise.
2. Multiple production processes and large material flow
The manufacturing of wires and cables involves a wide range of processes, from the melting and pressure processing of non-ferrous metals to chemical technologies such as plastics, rubber, paint, etc; The textile technology of fiber material wrapping and weaving, as well as the metal material wrapping and longitudinal wrapping of metal strips, as well as the metal forming processing technology of welding, etc.
The various materials used in the manufacturing of wires and cables are not only of various types, varieties, specifications, but also in large quantities. Therefore, the dosage, reserve quantity, batch cycle, and batch size of various materials must be verified. At the same time, as an important part of management, the decomposition, recycling, reuse, and waste disposal of waste products should be well managed, with a focus on material quota management and conservation.
In the production of wires and cables, from the incoming and outgoing storage of raw materials and various auxiliary materials, the transfer of semi-finished products in each process to the storage and delivery of products, the flow of materials is large, so it must be reasonably arranged and dynamically managed.
3. Multiple specialized equipment
The manufacturing of wires and cables uses specialized production equipment with the characteristics of the industry's processes to adapt to the structural and performance requirements of cable products, meet the requirements of large length continuous and high-speed production as much as possible, thus forming a series of specialized equipment for cable manufacturing. Such as extrusion machine series, wire drawing machine series, stranding machine series, wrapping machine series, etc.
The manufacturing process of wires and cables is closely related to the development of specialized equipment, promoting each other. New process requirements promote the emergence and development of new specialized equipment; On the contrary, the development of new specialized equipment has promoted the promotion and application of new processes. Such as wire drawing, annealing, and extrusion series lines; Special equipment such as physical foaming production lines have promoted the development and improvement of wire and cable manufacturing processes, improving the product quality and production efficiency of cables.
2、 Main processes of wires and cables
Wire and cable are produced through three processes: drawing, twisting, and wrapping. The more complex the model and specification, the higher the repeatability.
1. Drawing
In metal pressure processing, the process of forcing metal through a mold (pressure wheel) under external force, compressing the cross-sectional area of the metal, and obtaining the required cross-sectional area shape and size is called metal drawing.
The drawing process is divided into single wire drawing and twisted drawing.
2. Twisting
In order to improve the flexibility and integrity of wires and cables, it is called stranding to interweave two or more single wires in the specified direction.
The twisting process includes conductor twisting, cable forming, weaving, steel wire armor, and winding.
3. Wrapping
According to different performance requirements for wires and cables, special equipment is used to wrap different materials on the outer surface of the conductor. Coating process:
A. Squeezing: Materials such as rubber, plastic, lead, aluminum, etc.
B. Vertical packaging: rubber, wrinkled aluminum strip material.
C. Wrapping: Ribbon paper tape, mica tape, alkali free glass fiber tape, non-woven fabric, plastic tape, etc., and linear cotton yarn, silk and other fiber materials.
D. Dip coating: insulation paint, asphalt, etc
3、 The basic process flow of plastic wire and cable manufacturing
1. Copper and aluminum single wire drawing
The commonly used copper and aluminum rods for wires and cables are reduced in cross-section, increased in length, and increased in strength at room temperature by using a wire drawing machine to stretch the mold holes through one or several channels. Wire drawing is the first process of various wire and cable companies, and the main process parameter of wire drawing is mold matching technology.
2. Single wire annealing
Copper and aluminum single wires are heated to a certain temperature and recrystallized to improve their toughness and reduce their strength, in order to meet the requirements of wires and cables for conductor cores. The key to the annealing process is to prevent oxidation of copper wires
3. Twisting of conductors
In order to improve the flexibility of wires and cables and facilitate installation, the conductive wire core is made by twisting multiple single wires. From the stranding form of the conductor core, it can be divided into regular stranding and irregular stranding. Irregular stranding can also be divided into bundle stranding, concentric compound stranding, special stranding, etc.
In order to reduce the occupied area of the wire and reduce the geometric size of the cable, a compact form is adopted while twisting the conductor, which transforms the ordinary circular shape into a semicircle, fan shaped, tile shaped, and compact circular shape. This type of conductor is mainly used in power cables.
4. Insulation extrusion
Plastic wires and cables mainly use extruded solid insulation layers, and 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 must be smooth and free from poor quality issues such as surface roughness, burning, and impurities
4.3. Density: The cross-section of the extruded insulation layer should be dense and sturdy, without visible pinholes, and the presence of bubbles should be avoided.
5. Cabling
For multi-core cables, in order to ensure formability and reduce the appearance of the cable, it is generally necessary to twist them into a circular shape. The mechanism of stranding is similar to that of conductor stranding, but due to the large pitch diameter of stranding, most of them adopt a non untwisting method. The technical requirements for cable formation are: firstly, to prevent twisted cables caused by the overturning of abnormal insulated cores; The second is to prevent the insulation layer from being scratched.
Most cables are completed simultaneously with two other processes: one is filling to ensure the roundness and stability of the cables after completion; One is binding to ensure that the cable core is not loose.
6. Inner protective layer
In order to protect the insulation 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
When laying underground cables, they may withstand certain positive pressure during work, and an inner steel strip armor structure can be selected. When laying cables in situations where there is both positive pressure and tensile force (such as in water, vertical shafts, or soil with a large drop), a structural type with inner 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, waterproof immersion, and prevent cable combustion of wires and cables. According to different requirements for cables, use an extrusion machine to directly extrude the plastic sheath