Core Wire Rope Principles

When browsing the General Purpose Wire Rope page of our website, you may notice that we offer two different 6x19 highly flexible cables, and two different 6x37 flexible cables. When looking at the product illustrations, commonly referred to as snowflakes, you may notice a large black area in the center of some wire ropes, and an additional strand in the center of others. How can they be so similar yet so different at the same time? What sets them apart is their cores, and the distinctions between IWRC and Fiber Core.

Cable_Icons_6x25The foundation of a wire rope starts with its core. The core runs straight through the center of the wire rope, allowing all other strands to layer around it. The outer strand, which can be made in different wire configurations and layed in either direction to the core, allow the wire rope to exhibit different physical properties such as anti-rotation or decreased stretch. (To learn more about lay direction, check out our blog article, What's the Difference Between Regular Lay and Lang Lay?) Together, the core and outer strands balance flexibility, strength, and elasticity to create a wire rope that can endure heavy lifting, repeated bending, or a combination of both. Though there are many different types of cores, two of the most common styles are IWRC and Fiber Core.

The term IWRC stands for Independent Wire Rope Core. An IWRC is a full wire rope that can be either the same, or different construction as the outer layer strands. It adds strength to the total length of rope, and withstands crushing forces more effectively than other types of cores. It also reduces the amount of stretch a wire rope may undergo during service. IWRC wire ropes are often found in heavy lifting applications such as dredging and logging due to these strength qualities.

Cable_Icons_6x37Despite the black appearance in snowflake illustrations, the centers of these wire ropes are neither empty nor hollow. In reality, the black area depicts the presence of a fiber core. Fiber cores can be made of either synthetic or natural material, and the pliable texture adds increased flexibility to wire rope. As with wire rope construction and material choice, core selection varies depending on application requirements and demands. In situations that require less strength but increased flexibility, fiber cores may be a more suitable choice than wire rope cores. In situations that require more robust durability, wire rope cores may be required.

To learn more about 6x19 IWRC or 6x19 Fiber Core wire rope, visit or contact us with any questions.

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