Wire Rope

About Wire Ropes and Wire Rope Suppliers Including: Aircraft Cables, Cable Assemblies, Cable Railing, Push Pull Cable, Stainless Steel Cable, Steel Cables & Stranded Cable and Wire.

Wire ropes have three basic elements: wires, strands and a core. The wires are bundled together to form strands. Strands consist of two or more wires that are arranged in one of various geometric arrangements. The strands are helically laid around the core, or center. Strands can be a blending of steel wires with other materials like synthetic or natural fiber. The core, which is the foundation of the wire rope, provides support to the strands for normal operating conditions. Core material includes steel or various fibers, such as synthetic or hard vegetable fibers.
 
Wire rope suppliers classify their products in terms of the direction in which the strands are wound around the core. This classification is also known as the lay, which can be right or left. Further classifications of regular and lang lay refer to the way the wire and the strands are laid in relation to each other. In a regular lay, the wires and the strands are laid in opposite directions. They are laid in the same direction for lang. Wire rope suppliers classify the construction of the wire rope with two sets of numbers. The first number represents the number of strands and the second, the number of wires per strand. There are four standard construction classifications: 6x7, 6x19, 6x37 and 8x19.
 
Wire ropes and slings are used in a variety of applications. Mining operations use steel wire rope for winding in shafts and underground hauling, as well as safety hoists. Wire rope is necessary in oil drilling operations for crane operations, air hoists, rotary drilling lines and mast-raising lines. Ski and chair lifts depend on specially designed wires from wire rope suppliers. The construction industry utilizes wire rope as rigging for cranes. Commercial fishing boats use various types of wire ropes for applications, such as trawling. Other applications for wire rope include elevator operations, aircraft cables, marine control, garage doors, supporting, or guy, wires and winches.
 
When selecting wire rope, some important considerations will help in choosing a construction that will provide long service while minimizing cost. The resistance of the rope to breaking refers to the actual normal workload that the wire rope will carry. Select a rope that is able to carry five to ten times greater than that amount. Flexibility refers to the resistance of the wire rope to bending. Other determining factors include size, material, core and construction. Vibrational fatigue, abrasion resistance and resistance to crushing are also considerations. It is important to realize that it is impossible to maximize all of the above factors in relation to the task of the rope.

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Wire Ropes and Wire Rope Suppliers Image Provided by Bergen Cable Technology, LLC

Types of Wire Ropes

• Aircraft cables are strands, cords and wire ropes composed of special strength wire. Aircraft cables are mainly for aircraft controls and various aircraft industry uses.
  
• Cable assemblies are fittings which are attached to the end of bundled wires.
  
• Cable railing is used in the barriers that run along the edge of stairs and landings, especially in industrial or outdoor locations.
  
• Push pull cable are used as remote-access latch release cables and safety break cables.
  
• Stainless steel cable is resistant to corrosion.
  
• Steel cables are strong metal ropes used for various applications.
  
• Steel wire rope is composed of non-galvanized carbon steel (bright), stainless steel wire, or galvanized carbon steel. The scope of diameters and compositions of steel wire rope include 1/16 inch to five inches or greater. But, whichever the kind of steel, diameter, or the specific composition, all stainless steel wire has the same physical construction of multiple strands of wire wound helically about a central core.
  
• Stranded cable and wire consists of a cable that is made up of strands of wires and is identified by the number of strands and the amount of wires per strand; a 7 x 18 cable would have seven strands with 18 wires in each strand.
  
• Wire rope assemblies are wires ropes that have their ends changed through a splice or fittings add-on. Their uses include running controls, incorporation into machinery and equipment or as slings or hoists.
  
• Wire rope hoists are hoists that use wire ropes as the means for lifting and consist of a rope storage drum, motors, gearbox and braking system. A trolley suspends the hoist from a bridge beam or monorail, although a stationary mounting is also possible.
  
• Wire rope slings are short lengths of wire rope made especially to accommodate lifting attachments. Slings use Independent Wire Rope Cores (IWRC) and may consist of Improved Plow Steel, Extra Improved Steel, or Extra, Extra Improved Plow Steel.

Common Terms Related to Wire Ropes

Breaking Strength – A calculation of the load necessary to break a wire rope that is in tension.

Core – Element of a wire rope around which the strands are helically laid. The core could be made of fiber (cloth), independent wire rope or wire strand.

Drum – A round and flanged barrel, which is tapered or uniform in diameter for storage or operation, around which rope is wound.

Extra Improved Plow Steel – Steel that is designed for applications, which require greater safety features with no increase in diameter size and the highest resistance to abrasive wear. This steel is fifteen percent stronger than Improved Plow Steel, and the tensile strength of this grade ranges from 280,000 to 340,000 psi.

Fitting – Any accessory that serves to attach wire ropes.

Galvanize – To coat with zinc for the protection of the wire, strand or rope from corrosion.

Grade – A classification according to breaking strength.

Guy Line – Steel wire or strand, typically galvanized, that braces or supports a structure.

Improved Plow Steel (IPS) – A high-carbon steel having a tensile strength of approximately 260,000 psi that is roughly fifteen percent stronger than Plow Steel. Most commercial wires are made from IPS.

Independent Wire Rope Core (IWRC) – Wire rope that serves as the core for a greater rope.

Iron – A low carbon steel wire of approximately 10,000 psi, which is pliable and capable of repeated stresses from bending around small sheaves. This grade is effective for tillers, guys and sash ropes.

Lay/Laid – The manner in which the wires are helically wound to form rope. Lay refers specifically to the direction of the helical path of the strands in a wire rope; for example, if the helix of the strands are like the threads of a right-hand screw, the lay is known as a right lay, or right-hand, but if the strands go to the left, it is a left lay, or left-hand.

Rope Grades – A classification of wire rope according to its breaking strength. The rank of grades according to increasing breaking strengths is as follows: Iron, Traction, Mild Plow Steel, Plow Steel, Improved Steel, Extra Improved Steel.

Sheave – A pulley wheel with a channel, mounted in a frame, that guides or alters the direction of the cable or rope.

Strand – An assembly of wires that are helically wound around an axis, fiber or wire center (core) to create a symmetrical portion.

Strand Grades – Classification of strands according to breaking strength. The ranking of increasing breaking strengths is as follows: Common, Siemens Martin, High Strength and Extra-High Strength; a utility's grade strand is available for certain requirements.

Swage – The act of fastening a termination to a wire rope through physical deformation of the termination about the rope via a hydraulic press or hammering. The strength is one hundred percent of the wire rope rating.

Swaged Fittings – Fittings into which wire rope can be inserted and fastened through a cold flow method.

Traction Steel – A grade of rope material that has a tensile strength range of 180,000 to 190,000 psi. Traction steel has great resistance to bending fatigue with a minimum of abrasive force on sheaves and drums, which contributes to its long use in elevators, from which the steel gets its name.

Wire – A continual span of metal that has been cold drawn from a rod.

Wire rope From Wikipedia, the free encyclopedia

Wire rope consists of several strands laid (or 'twisted') together like a helix. Each strand is likewise made of metal wires laid together like a helix. Initially wrought iron wires were used, but today steel is the main material used for wire ropes.

Lay of wire rope

Left-hand ordinary lay (LHOL) wire rope (close-up). Right-hand lay strands are laid into a left-hand lay rope.

Right-hand Lang's lay (RHLL) wire rope (close-up). Right-hand lay strands are laid into a right-hand lay rope.

The lay of a wire rope describes the manner in which either the wires in a strand, or the strands in the rope, are laid in a helix.

Left and right hand lay

Left hand lay or right hand lay describe the manner in which the strands are laid to form the rope. To determine the lay of strands in the rope, a viewer looks at the rope as it points away from them. If the strands appear to turn in a clockwise direction, or like a right-hand thread, as the strands progress away from the viewer, the rope has a right hand lay. The picture of steel wire rope on this page shows a rope with right hand lay. If the strands appear to turn in an anti-clockwise direction, or like a left-hand thread, as the strands progress away from the viewer, the rope has a left hand lay.

Ordinary, Lang's and alternate lay

Ordinary and Lang's lay describe the manner in which the wires are laid to form a strand of the wire rope. To determine which has been used first identify if left or right hand lay has been used to make the rope. Then identify if a right or left hand lay has been used to twist the wires in each strand.

Ordinary lay The lay of wires in each strand is in the opposite direction to the lay of the strands that form the wire.
Lang's lay The lay of wires in each strand is in the same direction as the lay of the strands that form the wire.
Alternate lay The lay of wires in the strands alternate around the rope between being in the opposite and same direction to the lay of the strands that form the wire rope.
Regular lay Alternate term for ordinary lay.
Albert's lay Archaic term for Lang's lay.
Reverse lay Alternate term for alternate lay.
Spring lay This is not a term used to classify a lay as defined in this section. It refers to a specific construction type of wire rope.

Construction and specification

Wire rope construction

The specification of a wire rope type – including the number of wires per strand, the number of strands, and the lay of the rope – is documented using a commonly accepted coding system, consisting of a number of abbreviations.

This is easily demonstrated with a simple example. The rope shown in the figure "Wire rope construction" is designated thus: 6x19 FC RH OL FSWR

6 Number of strands that make up the rope
19 Number of wires that make up each strand
FC Fibre core
RH Right hand lay
OL Ordinary lay
FSWR Flexible steel wire rope

Each of the sections of the wire rope designation described above is variable. There are therefore a large number of combinations of wire rope that can be specified in this manner. The following abbreviations are commonly used to specify a wire rope.

Terminations

The end of a wire rope tends to fray readily, and cannot be easily connected to plant and equipment. A number of different mechanisms exist to secure the ends of wire ropes to make them more useful. The most common and useful type of end fitting for a wire rope is when the end is turned back to form a loop. The loose end is then fixed by any number of methods back to the wire rope.

Thimbles

When the wire rope is terminated with a loop, there is a risk that the wire rope can bend too tightly, especially when the loop is connected to a device that spreads the load over a relatively small area. A thimble can be installed inside the loop to preserve the natural shape of the loop, and protect the cable from pinching and abrasion on the inside of the loop. The use of thimbles in loops is industry best practice. The thimble prevents the load from coming into direct contact with the wires.

Wire rope clamps(DOG CLAMPS)

A wire rope clamp, also called a clip, is used to fix the loose end of the loop back to the wire rope. It usually consists of a u-shaped bolt, a forged saddle and two nuts. The two layers of wire rope are placed in the u-bolt. The saddle is then fitted over the ropes on to the bolt (the saddle includes two holes to fit to the u-bolt). The nuts secure the arrangement in place. Three or more clamps are usually used to terminate a wire rope.

Swaged terminations

Swaging is a method of wire rope termination that refers to the installation technique. The purpose of swaging wire rope fittings is to connect two wire rope ends together, or to otherwise terminate one end of wire rope to something else. A mechanical or hydraulic swager is used to compress and deform the fitting, creating a permanent connection. There are many types of swaged fittings. Threaded Studs, Ferrules, Sockets, and Sleeves a few examples.

Sockets

A socket termination is useful when the fitting needs to be replaced frequently. For example, if the end of a wire rope is in a high-wear region, the rope may be periodically trimmed, requiring the termination hardware to be removed and reapplied. An example of this is on the ends of the drag ropes on a dragline. The end loop of the wire rope enters a tapered opening in the socket, wrapped around a separate component called the wedge. The arrangement is knocked in place, and load gradually eased onto the rope. As the load increases on the wire rope, the wedge become more secure, gripping the rope tighter.

The ends of individual strands of this eye splice used aboard a cargo ship are seized with natural fiber cord after the splicing is complete. This helps protect seaman's hands when handling.

An eye splice may be used to terminate the loose end of a wire rope when forming a loop. The strands of the end of a wire rope are unwound a certain distance, and plaited back into the wire rope, forming the loop, or an eye, called an eye splice.