WIRE ROPE SELECTION GUIDE

A wire rope is a complicated mechanical device with numerous moving pieces that work in unison to assist in supporting and moving an object or load. In the lifting and rigging industries, wire rope is coupled to a crane or hoist and fitted with swivels, shackles, or hooks to securely attach to and move a weight. Additionally, it can be used to raise and lower elevators and to support suspension bridges and towers. In reality, a wire rope is a highly complex mechanical device. A standard 6×25 rope contains 150 wires, each of which moves independently and in unison around the core as the rope bends. For a variety of reasons, wire rope is the favored method of hoisting. Its one-of-a-kind design features several steel wires strung in a spiral arrangement around a central core. This structure combines strength and flexibility, as well as the capacity to withstand bending loads. Different configurations of the material, wire, and strand structure will offer distinct advantages depending on the lifting application.

What is Wire Rope? Understanding the Specifications and Construction: Components of Wire Rope

A finished wire rope has four essential components:

  • Metal wires that form a single strand
  • Helicoidal multi-wire strands surrounding a core
  • a steel or fiber core
  • Lubrication

Wire
Wires are the smallest component of wire rope and form the strands. Wires can be formed of steel, iron, stainless steel, monel, and bronze. The wire ropes come in a number of grades based on their strength, wear resistance, fatigue resistance, corrosion resistance, and curve.

Wires can be coated, but are most usually found untreated or “bright”.

Strands

Wire rope strands are made up of two or more wires twisted together. The strands are then helical placed around the rope’s center.

Larger diameter wire strands are more abrasion resistant, while smaller diameter wire strands are more flexible.

Core
The core of a wire rope supports the strands and keeps them aligned during loading and bending. Cores might be made of natural or synthetic fibers, or steel.

Lubrication
During manufacturing, lubricant is applied to the core. It has two main advantages:

Provides corrosion protection and lubrication in the core, inside wires, and outside surface

Diverse types of wire rope are available for a variety of hoisting applications. The photos below illustrate various methods for connecting the wires – each with its own set of pros and disadvantages in terms of usage.

Rotation Resistant Wire Rope is exactly as the name implies: it resists twisting, spinning, and rotating.

Compacted Wire Rope is produced by compacting the layers, resulting in a smoother, stronger rope.

Swaged Wire Rope is likewise crushed, but after the rope is closed, using a rotary swager machine. It is stronger and more resistant to crushing, but may be less resistant to bending fatigue.

Plastic-coated or plastic-impregnated wire rope is available. Plastic is used as a coating to provide resistance to abrasion, external wear, and corrosion. Plastic impregnated wire rope has plastic on the inside of the rope to aid in bending and reduce wear on both the inside and outside of the rope. Individual wire rope cores might be coated or filled with plastic prior to being included into a finished wire rope.

Diverse types of wire rope are available for a variety of hoisting applications. The photos below illustrate various methods for connecting the wires – each with its own set of pros and disadvantages in terms of usage.

Rotation Resistant Wire Rope is exactly as the name implies: it resists twisting, spinning, and rotating.

Compacted Wire Rope is produced by compacting the layers, resulting in a smoother, stronger rope.

Swaged Wire Rope is likewise crushed, but after the rope is closed, using a rotary swager machine. It is stronger and more resistant to crushing, but may be less resistant to bending fatigue.

Plastic-coated or plastic-impregnated wire rope is available. Plastic is used as a coating to provide resistance to abrasion, external wear, and corrosion. Plastic impregnated wire rope has plastic on the inside of the rope to aid in bending and reduce wear on both the inside and outside of the rope. Individual wire rope cores might be coated or filled with plastic prior to being included into a finished wire rope.

 

Size
This is the nominal diameter of the wire rope that has been defined, and it can be provided in inches or millimeters.

Strand Pattern
The number of wire layers, the number of wires per layer, and the size of the wires per layer all have an impact on the sort of strand pattern that is created. Wire rope can be made using one of the designs shown in the illustration, or it can be made using two or more of the patterns shown.

Preformed or Non-preformed

The strands and wires of a prepared wire rope are shaped during the production process into the helical shape that they will assume in the completed wire rope. Preformed ropes can be helpful in certain applications where it is required to spool more equally on a drum, to be more flexible, or to have superior fatigue resistance when bending.

Type of Lay

The direction and kind of lay refer to the order in which the wires are laid to make a strand (right or left) and the arrangement of the strands around the core (regular lay, lang lay, or alternate lay).

CORE OF THE ROPE
Because the center core of a wire rope serves as the basis for its construction, it has a significant impact on the wire rope’s qualities and its ability to be used in a variety of applications. There are three sorts of cores that are widely employed:

Natural sisal rope or synthetic polypropylene rope can be used as the fiber core (FC).

Independent wire rope core (IWRC): This is a wire rope made up of wires and strands that is independent of the main rope.

a wire strand core (WSC) is a single wire around which a ring of wires of the same diameter is wrapped

A wire rope’s end tends to fray easily and cannot be easily connected to machinery. There are several ways to secure wire rope ends to prevent fraying. Turning the end back to form a loop is a common and useful wire rope end fitting. The loose end is then reattached. The efficiency of a Flemish eye alone ranges from roughly 70% to nearly 90%, while potted ends and swagings are 100% efficient. [needed]

Especially when the loop is connected to a device that concentrates the load on a small area, there is a risk of the wire rope bending too tightly. A thimble can be installed inside the loop to protect the cable from pinching and abrasion. Industry standard is to use thimbles in loops. The thimble keeps the load from touching the wires.

Rope clips

Wire rope clamps for logging equipment
A wire rope clip (or clamp) secures the loop’s loose end to the wire rope. It has a U-bolt, forged saddle, and two nuts. The U-bolt receives two layers of wire rope. The saddle is then bolted over the ropes (the saddle includes two holes to fit to the U-bolt). The nuts hold the arrangement. Depending on the rope’s diameter, two or more clips are used to secure it. For a 2 in (50.8 mm) rope, up to eight may be required.

To install clips, the saddle portion of the assembly is placed on the load-bearing or “live” side of the cable, not the non-load-bearing or “dead” side. So the rope doesn’t get crushed or abused. The body’s extended prongs and flat bearing seat protect the rope and are always placed against the live end. [18]

The US Navy and most regulatory bodies advise against using permanent terminations unless regularly checked and tightened.

Flemish eye splice

After splicing, the ends of each strand of this eye splice are served with natural fiber cord to help protect seamen’s hands.
An eye splice can be used to close a loop in a wire rope. The strands of a wire rope are unwound and then bent around to form an eye. An eye splice is formed by plaiting the unwrapped strands back into the wire rope.

A Flemish eye, or Dutch Splice, is made by unwrapping three strands of wire and keeping them off to one side. To form the eye, the remaining strands are bent around the “V” where the unwrapping ended. The strands kept to one side are now re-wrapped from the wire end to the eye’s “V”. These strands are rewrapped along the wire in the opposite direction. This type of rope splice is called a “Molly Hogan” and is sometimes called a “Dutch” eye instead of a “Flemish” eye. [19]

Swaged ends

A swage or crimp on a wire rope sleeve
Swaging is a wire rope termination technique. Swaging wire rope fittings are used to join two wire rope ends or to connect one wire rope end to another. A swager compresses and deforms the fitting to create a permanent connection. Swaged terminations include threaded studs, ferrules, sockets, and sleeves. [20][21] Swaging fibre-cored ropes is not advised.

Wedges
A wedge socket termination is useful when replacing fittings frequently. For example, a wire rope’s end may need to be trimmed periodically, requiring the termination hardware to be removed and reapplied. On the ends of drag ropes on a dragline. The wire rope’s end loop enters a tapered opening in the socket, wrapped around a wedge component. The load is gradually eased onto the rope. The wedge becomes more secure as the wire rope load increases.

Ends poured or potted
Poured sockets are made by inserting the wire rope into the narrow end of a conical cavity oriented in the intended direction of strain. This is followed by filling the cone with molten lead-antimony-tin (Pb80Sb15Sn5) solder, or “white metal capping”, or more commonly, an unsaturated polyester resin compound. [23] [24]

UNGALVANIZED

Ungalvanized wires are intended to be flexible and to have a long fatigue life, hence they are not coated. Ungalvanized wires are widely utilized in a variety of applications across a wide range of industries, including crane ropes, winch ropes, hoist ropes, wire ropes, and rigging.

 

GALVANIZED

To avoid corrosion, galvanized cable wires are made of steel wires coated with a thin layer of zinc. Because of its resistance to corrosion and the elements, galvanized wire rope is an excellent choice for outdoor applications.

Galvanized steel wire rope is the most cost-effective alternative to stainless steel wire rope, however the level of corrosion protection is less than that of stainless steel wire rope. When compared to a stainless steel wire rope of the same size, galvanized steel cable is somewhat more durable. A vinyl coating can be applied to some wire ropes, such as 7 x 9 galvanized aircraft cable. Airlines frequently utilize vinyl-coated, galvanized cable because it is lightweight and easy to handle while still maintaining flexibility.

Irrigation, agriculture, erosion management, and maritime applications all use galvanized cable.

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