Wire rope 101: Material and construction optionsAugust 12, 2015 REDWIRE is news you can use from leading suppliers. Powered by FRASERS.
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Bergen Cable knows that different applications for wire rope present varying demands for strength, abrasion and corrosion resistance. To meet these requirements, the Fairfield. N.J.-based company produces wire rope in a number of different materials and styles — each with its own ideal applications.
For applications where corrosion is a concern, stainless steel wire rope is the best option. Type 302 (18 per cent chromium and eight per cent nickel alloy) is the most common grade accepted because of its corrosion resistance and high strength. Other frequently used stainless steel types are 304, 305, 316 and 321, each with its own set of pros and cons. Type 305, for example, is used where non-magnetic properties are required; however, there is a slight loss of strength. Users must determine where their priorities lie in the application, and if the compromise is worth it.
For applications where strength is required and corrosion resistance is not great enough to justify the cost of stainless steel, galvanized carbon steel is an option. Wires used in these wire ropes are individually coated with a layer of zinc, which offers some protection from corrosive elements.
In addition to wire rope material, cable construction is also a consideration. The greater the number of wires the strand or cable has, the more flexible it is. A 1×7 or a 1×19 strand, with seven and 19 wires respectively, is used as a fixed member, straight linkage or where flexing is minimal. The 1×7 offers the least stretch, while the 1×19 is fairly flexible and resists compressive forces.
Cables designed with 3×7, 7×7 and 7×19 construction are more flexible; however, they have decreased abrasion resistance. These cables are ideal for applications where continuous flexing is a requirement. The 7×19 is the strongest and most flexible cable.