Now that Mytee is offering rigging supplies, we are beginning to see an increase in the number of questions for these products. Our customers need to know what they are purchasing before they complete their purchase, and want to ensure that all their questions are answered correctly. For example, we sell a number of different kinds of wire rope for rigging.
Two examples of wire rope products would be our peerless galvanized aircraft cable and peerless fiber core wire rope. If you were to view either of these products on our site, you would see a description complete with a set of numbers that you might not understand. Unfortunately, there is a certain nomenclature assigned to wire ropes that you may not be familiar with unless you have extensive experience with rigging.
Wire rope is normally identified using three features:
- The number of wires in each strand
- The number and/or configuration of strands in each rope
- An indicator of the construction or arrangement of the wires in the rope.
For example, a product designated as ‘6×7 fiber core’ would consist of six strands of seven wires per strand, surrounding a core made of a synthetic fiber. To an experienced rigger, the product designation would be enough to tell him or her whether the product is suitable for his/her purposes or not. Someone who does not possess the same kind of knowledge might look at the product designation and think nothing of it.
Different Rope Cores
The core, or center of a wire rope, indicates how that rope is used and what its capabilities are. Riggers have to fully understand load requirements in order to know what kind of core is most suitable to the needs of the job at hand. There are three primary core options to choose from:
- Strand Center – This core is made up of a strand of wires either similar or identical to the outer strands. It is the weakest kind of core, yet it is still strong enough to be used for guy wires, suspension bridge cables, and aircraft cable. It is the core of choice for applications in which crushing weights are a concern.
- Fiber Center – This core consists of pre-lubricated plastic fibers made of a material such as propylene. The advantage of a fiber core is that it stands up to tremendous amounts of pressure. It also tends to do very well against caustic substances that might be damaging to a strand center rope. It is not a good choice for applications involving crushing weight.
- Independent Center Core – Known formally in the industry as IWRC (independent wire rope center), this kind of core is essentially a separate wire rope made with its own strands and core. Wire ropes made with IWRC cores are the strongest of all. They are generally accepted to be 7% stronger than comparable strand center wire ropes. The increased strength makes IWRC the preferred core for wire ropes that will be used to carry heavy loads.
One last thing riggers need to consider is the lay of wire strands within a rope. A regular lay rope is one in which the individual strands of the rope run opposite to the rope itself. A lang lay rope consists of strands that are laid in the same direction as the completed rope.
Finally, the alternate lay configuration utilizes equal numbers of regular and lang lay strands, woven together alternately. You can see this alternating pattern by laying the wire rope on a flat surface and inspecting the individual strands.