Cables - Types of Cores

Cables – Types of Cores

The function of the core is to serve as the base of the cable, conserving its shape, supporting the pressure of the strands and keeping the distances and spaces correct between them.

There are two main types of cores:

Fibers (Natural and synthetic)
Steel (Strands or independent cables)

Natural Fiber Cores: These cores can be of sisal or Manila, both of which are fibers that are long and hard. Cores also exist of yuté, cañamo, or cotton. These are not recommended due to their softness and tendency to decompose rapidly, but they are recommended as filler in certain types of applications and constructions. In general, cores of natural fiber are used for engineering cable (elevators and cables for mines), because they lessen the loads caused by rapid accelerations or decelerations.

Synthetic Fiber Cores: Many synthetic fiber cores have been tested, but the most satisfactory synthetic fiber has been propylene. This material has physical characteristics very similar to Manila or sisal, and it has a much greater resistance to corrosion caused by salinity. Its only disadvantage is that it is a very abrasive material, and thus, it tends to lose its consistency after many operation cycles with large amounts of tension. For this reason a core of polypropylene is not recommended for use in elevator cables or mining. Generally, it is used in galvanized cables for fishing and maritime use.
This cable should not be used in climates with high temperatures

Steel Wire Core: A cable with a core of steel wire is a cable in which the core is formed by a single wire, in which the construction of the cable is the same as the wires on the outside of the cable.

Independent Steel Core: This is in reality, another cable in which the core in the nucleus or center of the cable generally consists of seven strands with seven wires each. (7x7) A cable with an independent steel strand core has resistance against traction and crushing superior to that of a cable with a fiber core, but it has less elasticity. This cable is recommended for use in climates with high temperatures and high pressures.

Plasticized Steel Core: Ultimately, there have been many kinds of plasticized steel cores in which the principal characteristic is eliminating the friction between the wires and the strands of the cable. (This cores main use is in compacted cables)

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