Introduction to Wire Rope
Wire rope is a machine with dozens–even hundreds– of individual wires which are formed and fabricated to move or operate at close tolerances to one another. When a wire rope bends, each of its many wires slides and adjusts to accommodate the differences in length between the inside and outside of the bend. The sharper the bend, the greater the movement.
Every wire has three basic components: the wires, strands and core.
The core may be either fiber (FC) such as sisal, manila or jute, or
an Independent Wire Rope Core (IWRC), which is actually a smaller
wire rope within the strands of the outer wire rope.
The wires are predominantly constructed from high-carbon steel, but may also be formed from various metals such as iron, stainless steel, monel or bronze. Carbon steel wire rope is manufactured in various grades, including Improved Plow Steel (IPS), Extra Improved Plow Steel (EIPS) and Extra Extra Improved Plow Steel (EEIPS), which designate the nominal strength of the wire rope. EIPS is the most commonly used and manufactured grade today.
Wire rope generally comes with a "bright" or uncoated finish but several other options are available. A galvanized, zinc coating, a tin coating or a synthetic coating such as vinyl or nylon may also be applied to the rope's surface. Ropes with plastic coatings and plastic-filled interiors are also obtainable. It should be understood that these coatings can affect the characteristics and breaking strength of the wire rope.
Wire ropes are identified by classifications based upon the number of strands and nominal number of wires in each strand. A 6 x 19 classification for example, includes six strands with each strand consisting of 15-26 individual wires. The six strands of a 6 x 37 class wire rope are constructed of 27-49 individual wires. Other popular classifications include 19 x 7, 7 x 19 and 8 x 19