Cable manufacturing

Wire drawing is a cold metal forming process in which 8 mm diameter copper rod is passed through a series of drawing dies, gradually reducing its diameter and giving it the required shape and dimensions for the subsequent stages of production. As the diameter decreases, the length of the wire increases. Products manufactured by drawing are characterized by a high-quality surface finish and precise dimensional accuracy. During the drawing process, the copper rod is not preheated; it enters the drawing channel at room temperature. The heat generated in the die due to deformation and external friction is removed by continuously cooling the dies with a cooling emulsion. As a result of this cold drawing process, a finished copper semi-product with a diameter of 3 mm is obtained, featuring a smooth, bright surface and high geometric precision.

This technological process is known as final wire drawing and extrusion, while the equipment used is referred to as extruders. The production line consists of two sections. 1. Final wire drawing section – where a 3 mm copper rod is drawn down to obtain a copper conductor of the required diameter. 2. Extrusion section – where insulation is applied. The extruder consists of a cylinder and a screw with complex geometry. The insulating material is melted using ring heaters mounted on the cylinder, heaters in the extruder head area, as well as heat generated during the compression of the plastic mass. As the screw rotates inside the cylinder, the molten material is forced through the extruder die and applied onto the current-carrying copper conductor. After extrusion, the insulated conductor is cooled by passing it through a water bath. The product is then inspected to ensure compliance with diameter, eccentricity, and insulation integrity requirements. In addition, the conductor undergoes high-voltage insulation testing.

Working pairs for LAN cables are formed by twisting insulated conductors together. To achieve the required cable performance characteristics, each pair is twisted with a different pitch that is neither equal nor a multiple of the others within the future cable bundle. For communication cables designed to transmit high-frequency signals, pair twisting is essential as it provides protection against electromagnetic interference. In addition, for easier installation on-site, each twisted pair within the cable bundle has a unique color coding.

At this stage of the production cycle, the final cable bundle is formed by stranding the prepared twisted pairs together. Modern LAN cables may contain from 1 up to 100 pairs, and the required pair count of the cable core is achieved during this bundle stranding stage. At this stage, a common shield or an overall binder/insulation layer may also be applied to the cable bundle.

The finished cable bundles are fed to an extrusion line for the application of the protective outer sheath. The molten sheath compound surrounds the cable bundle and exits through a specially designed die that ensures accurate centering of the bundle within the sheath. The newly formed cable is then cooled by passing it through a water bath. At this stage, the cable jacket is marked using an inkjet printing method.

After the jacketing stage, the finished cable is wound onto large process reels in lengths of up to 14 km. It is then coiled into standard commercial lengths according to customer orders. For LAN cables, the standard unit of sale is typically a coil or reel of 1,000 feet (305 m). Different product types are packaged in different ways. Cables containing 1 to 4 pairs are usually packed in cardboard boxes with a built-in pull-out sleeve, allowing the cable to be easily dispensed during installation. Heavier cable types containing 16 to 100 pairs are coiled onto plywood reels and wrapped in protective film for safe transportation and storage.

Quality control is carried out at all stages of the production process. During the preliminary stages — wire drawing and insulation extrusion — the geometric parameters are monitored, including the diameter of the current-carrying conductor, the insulated conductor diameter, insulation eccentricity, conductor color, the twist pitch of pairs, and the arrangement of pairs within the cable bundle. At the pair twisting stage, monitoring of the basic electrical parameters begins, including DC conductor resistance and the characteristic impedance of the pair. The finished product undergoes a full cycle of testing to verify compliance with high-frequency, low-frequency, and geometric parameters in accordance with GOST R 54429-2011. Based on the test results, a conformity approval for the finished product is issued, accompanied by a quality certificate.