what is the difference between strand and wire rope free sample

Have you ever wondered why aircraft cable is called aircraft cable instead of aircraft strand? Do you use the words cable and wire rope interchangeably when you’re not sure which is correct? The world of manufacturing is chock-full of words to describe wire products, and while it may seem confusing to keep track of them at first, having some background knowledge about cable construction will help you understand each component. Let’s take a moment to differentiate our terms by starting small.

Wire: In its simplest form, wire is a single, flexible, string-like rod. It begins life as a metal such as stainless steel or carbon steel that becomes narrower in diameter as it is drawn through a series of small holes called dies. Used in everything from electrical equipment and coat hangers to art projects and nails, wire is the foundation of many wide and varied items.

Strand: Strand is made of two or more wires laid around a single center wire. In general, “1 by…” products are considered strand, like 1x7 and 1x19, which are two common configurations.

Notice how this 1x7 strand is a unit comprised of individual wires. It is 1 strand of 7 wires.1x19, as another example, is 1 strand of 19 wires. Like wire,strand can exist as its own product, or it can be laid around a core in multiples to become cable or wire rope.

Cable:Cables are made by concentrically wrapping groups of strands. A 7x7 cable, for example, is comprised of seven strands, each made of 7 wires. 7x19 cable, as another example, has seven strands with 19 wires in each one. Wire rope is technically also a group of strands wrapped around a core, which is why the terms cableand wire rope are often used interchangeably. Professions will argue that wire rope is designated for products with a diameter larger than 3/8 inch while cableis designated for all smaller diameters, but in practical application, the terms are somewhat interchageable.

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Wire rope and cable are each considered a “machine”. The configuration and method of manufacture combined with the proper selection of material when designed for a specific purpose enables a wire rope or cable to transmit forces, motion and energy in some predetermined manner and to some desired end.

Two or more wires concentrically laid around a center wire is called a strand. It may consist of one or more layers. Typically, the number of wires in a strand is 7, 19 or 37. A group of strands laid around a core would be called a cable or wire rope. In terms of product designation, 7 strands with 19 wires in each strand would be a 7×19 cable: 7 strands with 7 wires in each strand would be a 7×7 cable.

Materials Different applications for wire rope present varying demands for strength, abrasion and corrosion resistance. In order to meet these requirements, wire rope is produced in a number of different materials.

Stainless Steel This is used where corrosion is a prime factor and the cost increase warrants its use. The 18% chromium, 8% nickel alloy known as type 302 is the most common grade accepted due to both corrosion resistance and high strength. Other types frequently used in wire rope are 304, 305, 316 and 321, each having its specific advantage over the other. Type 305 is used where non-magnetic properties are required, however, there is a slight loss of strength.

Galvanized Carbon Steel This is used where strength is a prime factor and corrosion resistance is not great enough to require the use of stainless steel. The lower cost is usually a consideration in the selection of galvanized carbon steel. Wires used in these wire ropes are individually coated with a layer of zinc which offers a good measure of protection from corrosive elements.

Cable Construction The greater the number of wires in a strand or cable of a given diameter, the more flexibility it has. A 1×7 or a 1×19 strand, having 7 and 19 wires respectively, is used principally as a fixed member, as a straight linkage, or where flexing is minimal.

Cables designed with 3×7, 7×7 and 7×19 construction provide for increasing degrees of flexibility but decreased abrasion resistance. These designs would be incorporated where continuous flexing is a requirement.

Selecting Wire Rope When selecting a wire rope to give the best service, there are four requirements which should be given consideration. A proper choice is made by correctly estimating the relative importance of these requirements and selecting a rope which has the qualities best suited to withstand the effects of continued use. The rope should possess:Strength sufficient to take care of the maximum load that may be applied, with a proper safety factor.

Strength Wire rope in service is subjected to several kinds of stresses. The stresses most frequently encountered are direct tension, stress due to acceleration, stress due to sudden or shock loads, stress due to bending, and stress resulting from several forces acting at one time. For the most part, these stresses can be converted into terms of simple tension, and a rope of approximately the correct strength can be chosen. As the strength of a wire rope is determined by its, size, grade and construction, these three factors should be considered.

Safety Factors The safety factor is the ratio of the strength of the rope to the working load. A wire rope with a strength of 10,000 pounds and a total working load of 2,000 pounds would be operating with a safety factor of five.

It is not possible to set safety factors for the various types of wire rope using equipment, as this factor can vary with conditions on individual units of equipment.

The proper safety factor depends not only on the loads applied, but also on the speed of operation, shock load applied, the type of fittings used for securing the rope ends, the acceleration and deceleration, the length of rope, the number, size and location of sheaves and drums, the factors causing abrasion and corrosion and the facilities for inspection.

Fatigue Fatigue failure of the wires in a wire rope is the result of the propagation of small cracks under repeated applications of bending loads. It occurs when ropes operate over comparatively small sheaves or drums. The repeated bending of the individual wires, as the rope bends when passing over the sheaves or drums, and the straightening of the individual wires, as the rope leaves the sheaves or drums, causing fatigue. The effect of fatigue on wires is illustrated by bending a wire repeatedly back and forth until it breaks.

The best means of preventing early fatigue of wire ropes is to use sheaves and drums of adequate size. To increase the resistance to fatigue, a rope of more flexible construction should be used, as increased flexibility is secured through the use of smaller wires.

Abrasive Wear The ability of a wire rope to withstand abrasion is determined by the size, the carbon and manganese content, the heat treatment of the outer wires and the construction of the rope. The larger outer wires of the less flexible constructions are better able to withstand abrasion than the finer outer wires of the more flexible ropes. The higher carbon and manganese content and the heat treatment used in producing wire for the stronger ropes, make the higher grade ropes better able to withstand abrasive wear than the lower grade ropes.

Effects of Bending All wire ropes, except stationary ropes used as guys or supports, are subjected to bending around sheaves or drums. The service obtained from wire ropes is, to a large extent, dependent upon the proper choice and location of the sheaves and drums about which it operates.

A wire rope may be considered a machine in which the individual elements (wires and strands) slide upon each other when the rope is bent. Therefore, as a prerequisite to the satisfactory operation of wire rope over sheaves and drums, the rope must be properly lubricated.

Loss of strength due to bending is caused by the inability of the individual strands and wires to adjust themselves to their changed position when the rope is bent. Tests made by the National Institute of Standards and Technology show that the rope strength decreases in a marked degree as the sheave diameter grows smaller with respect to the diameter of the rope. The loss of strength due to bending wire ropes over the sheaves found in common use will not exceed 6% and will usually be about 4%.

The bending of a wire rope is accompanied by readjustment in the positions of the strands and wires and results in actual bending of the wires. Repetitive flexing of the wires develops bending loads which, even though well within the elastic limit of the wires, set up points of stress concentration.

The fatigue effect of bending appears in the form of small cracks in the wires at these over-stressed foci. These cracks propagate under repeated stress cycles, until the remaining sound metal is inadequate to withstand the bending load. This results in broken wires showing no apparent contraction of cross section.

Experience has established the fact that from the service view-point, a very definite relationship exists between the size of the individual outer wires of a wire rope and the size of the sheave or drum about which it operates. Sheaves and drums smaller than 200 times the diameter of the outer wires will cause permanent set in a heavily loaded rope. Good practice requires the use of sheaves and drums with diameters 800 times the diameter of the outer wires in the rope for heavily loaded fast-moving ropes.

It is impossible to give a definite minimum size of sheave or drum about which a wire rope will operate with satisfactory results, because of the other factors affecting the useful life of the rope. If the loads are light or the speed slow, smaller sheaves and drums can be used without causing early fatigue of the wires than if the loads are heavy or the speed is fast. Reverse bends, where a rope is bent in one direction and then in the opposite direction, cause excessive fatigue and should be avoided whenever possible. When a reverse bend is necessary larger sheaves are required than would be the case if the rope were bent in one direction only.

Stretch of Wire Rope The stretch of a wire rope under load is the result of two components: the structural stretch and the elastic stretch. Structural stretch of wire rope is caused by the lengthening of the rope lay, compression of the core and adjustment of the wires and strands to the load placed upon the wire rope. The elastic stretch is caused by elongation of the wires.

The structural stretch varies with the size of core, the lengths of lays and the construction of the rope. This stretch also varies with the loads imposed and the amount of bending to which the rope is subjected. For estimating this stretch the value of one-half percent, or .005 times the length of the rope under load, gives an approximate figure. If loads are light, one-quarter percent or .0025 times the rope length may be used. With heavy loads, this stretch may approach one percent, or .01 times the rope length.

The elastic stretch of a wire rope is directly proportional to the load and the length of rope under load, and inversely proportional to the metallic area and modulus of elasticity. This applies only to loads that do not exceed the elastic limit of a wire rope. The elastic limit of stainless steel wire rope is approximately 60% of its breaking strength and for galvanized ropes it is approximately 50%.

Preformed Wire Ropes Preformed ropes differ from the standard, or non-preformed ropes, in that the individual wires in the strands and the strands in the rope are preformed, or pre-shaped to their proper shape before they are assembled in the finished rope.

This, in turn, results in preformed wire ropes having the following characteristics:They can be cut without the seizings necessary to retain the rope structure of non-preformed ropes.

They are substantially free from liveliness and twisting tendencies. This makes installation and handling easier, and lessens the likelihood of damage to the rope from kinking or fouling. Preforming permits the more general use of Lang lay and wire core constructions.

Removal of internal stresses increase resistance to fatigue from bending. This results in increased service where ability to withstand bending is the important requirement. It also permits the use of ropes with larger outer wires, when increased wear resistance is desired.

Outer wires will wear thinner before breaking, and broken wire ends will not protrude from the rope to injure worker’s hands, to nick and distort adjacent wires, or to wear sheaves and drums. Because of the fact that broken wire ends do not porcupine, they are not as noticeable as they are in non-preformed ropes. This necessitates the use of greater care when inspecting worn preformed ropes, to determine their true condition.

Similar to regular lay, the right hand vs left hand is merely the way the wire rope closes with the strands in left hand lay rotating counterclockwise and right hand lay rotating clockwise. With lang lay rope, the wires in each strand lie in the same direction as the strands. When looking along a length of lang lay cable, the wires will appear to angle across the rope, following the general flow of the strands. Lang lay cables are more susceptible to pinching and kinking than regular lay, which best suits hoisting applications where the cable only moves along one axis. Lang lay is typically more flexible than regular lay. The third image down on the left is an example of right hand lang lay and the image below is left hand lang lay.

Now that you know about the differences and capabilities of each wire rope lay type, you can feel confident in purchasing the right lay for your wire rope applications! If you would like to check out our wire rope options, visit our website here. Alternatively, our team is happy to help if you have any questions! Reach out to us by email at sales@loosco.com or by phone at (860) 928-7981.

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. (The rope in the left hand lay photo shows one left hand lay rope from left to right and top to bottom, with 5 right hand lay strands, and part of a sixth in the upper left. It is not 5 right hand lay ropes adjacent to each other.)

Ordinary and Ducay"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. (On ordinary lay, the outer wires approximately follow the alignment of the rope: with Lang"s lay they are cross at an angle of about 45�.) Lang"s laid rope is able to flex over sheaves more easily (with less damage) but it has the disadvantage of having a high torque tendency (it tends to untwist when tension load is applied) compared with ordinary laid rope. Untwisting can be dangerous with a steel-cored rope: load is shed from the strands and may cause the core to fail as it becomes higher loaded. For this reason, swivel termination units can be dangerous.

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.

In stricter senses, the term wire rope refers to a diameter larger than 9.5 mm (3⁄8 in), with smaller gauges designated cable or cords.wrought iron wires were used, but today steel is the main material used for wire ropes.

Historically, wire rope evolved from wrought iron chains, which had a record of mechanical failure. While flaws in chain links or solid steel bars can lead to catastrophic failure, flaws in the wires making up a steel cable are less critical as the other wires easily take up the load. While friction between the individual wires and strands causes wear over the life of the rope, it also helps to compensate for minor failures in the short run.

Wire ropes were developed starting with mining hoist applications in the 1830s. Wire ropes are used dynamically for lifting and hoisting in cranes and elevators, and for transmission of mechanical power. Wire rope is also used to transmit force in mechanisms, such as a Bowden cable or the control surfaces of an airplane connected to levers and pedals in the cockpit. Only aircraft cables have WSC (wire strand core). Also, aircraft cables are available in smaller diameters than wire rope. For example, aircraft cables are available in 1.2 mm (3⁄64 in) diameter while most wire ropes begin at a 6.4 mm (1⁄4 in) diameter.suspension bridges or as guy wires to support towers. An aerial tramway relies on wire rope to support and move cargo overhead.

Modern wire rope was invented by the German mining engineer Wilhelm Albert in the years between 1831 and 1834 for use in mining in the Harz Mountains in Clausthal, Lower Saxony, Germany.chains, such as had been used before.

Wilhelm Albert"s first ropes consisted of three strands consisting of four wires each. In 1840, Scotsman Robert Stirling Newall improved the process further.John A. Roebling, starting in 1841suspension bridge building. Roebling introduced a number of innovations in the design, materials and manufacture of wire rope. Ever with an ear to technology developments in mining and railroading, Josiah White and Erskine Hazard, principal ownersLehigh Coal & Navigation Company (LC&N Co.) — as they had with the first blast furnaces in the Lehigh Valley — built a Wire Rope factory in Mauch Chunk,Pennsylvania in 1848, which provided lift cables for the Ashley Planes project, then the back track planes of the Summit Hill & Mauch Chunk Railroad, improving its attractiveness as a premier tourism destination, and vastly improving the throughput of the coal capacity since return of cars dropped from nearly four hours to less than 20 minutes. The decades were witness to a burgeoning increase in deep shaft mining in both Europe and North America as surface mineral deposits were exhausted and miners had to chase layers along inclined layers. The era was early in railroad development and steam engines lacked sufficient tractive effort to climb steep slopes, so incline plane railways were common. This pushed development of cable hoists rapidly in the United States as surface deposits in the Anthracite Coal Region north and south dove deeper every year, and even the rich deposits in the Panther Creek Valley required LC&N Co. to drive their first shafts into lower slopes beginning Lansford and its Schuylkill County twin-town Coaldale.

The German engineering firm of Adolf Bleichert & Co. was founded in 1874 and began to build bicable aerial tramways for mining in the Ruhr Valley. With important patents, and dozens of working systems in Europe, Bleichert dominated the global industry, later licensing its designs and manufacturing techniques to Trenton Iron Works, New Jersey, USA which built systems across America. Adolf Bleichert & Co. went on to build hundreds of aerial tramways around the world: from Alaska to Argentina, Australia and Spitsbergen. The Bleichert company also built hundreds of aerial tramways for both the Imperial German Army and the Wehrmacht.

In the last half of the 19th century, wire rope systems were used as a means of transmitting mechanical powercable cars. Wire rope systems cost one-tenth as much and had lower friction losses than line shafts. Because of these advantages, wire rope systems were used to transmit power for a distance of a few miles or kilometers.

Steel wires for wire ropes are normally made of non-alloy carbon steel with a carbon content of 0.4 to 0.95%. The very high strength of the rope wires enables wire ropes to support large tensile forces and to run over sheaves with relatively small diameters.

In the mostly used parallel lay strands, the lay length of all the wire layers is equal and the wires of any two superimposed layers are parallel, resulting in linear contact. The wire of the outer layer is supported by two wires of the inner layer. These wires are neighbors along the whole length of the strand. Parallel lay strands are made in one operation. The endurance of wire ropes with this kind of strand is always much greater than of those (seldom used) with cross lay strands. Parallel lay strands with two wire layers have the construction Filler, Seale or Warrington.

In principle, spiral ropes are round strands as they have an assembly of layers of wires laid helically over a centre with at least one layer of wires being laid in the opposite direction to that of the outer layer. Spiral ropes can be dimensioned in such a way that they are non-rotating which means that under tension the rope torque is nearly zero. The open spiral rope consists only of round wires. The half-locked coil rope and the full-locked coil rope always have a centre made of round wires. The locked coil ropes have one or more outer layers of profile wires. They have the advantage that their construction prevents the penetration of dirt and water to a greater extent and it also protects them from loss of lubricant. In addition, they have one further very important advantage as the ends of a broken outer wire cannot leave the rope if it has the proper dimensions.

Stranded ropes are an assembly of several strands laid helically in one or more layers around a core. This core can be one of three types. The first is a fiber core, made up of synthetic material or natural fibers like sisal. Synthetic fibers are stronger and more uniform but cannot absorb much lubricant. Natural fibers can absorb up to 15% of their weight in lubricant and so protect the inner wires much better from corrosion than synthetic fibers do. Fiber cores are the most flexible and elastic, but have the downside of getting crushed easily. The second type, wire strand core, is made up of one additional strand of wire, and is typically used for suspension. The third type is independent wire rope core (IWRC), which is the most durable in all types of environments.ordinary lay rope if the lay direction of the wires in the outer strands is in the opposite direction to the lay of the outer strands themselves. If both the wires in the outer strands and the outer strands themselves have the same lay direction, the rope is called a lang lay rope (from Dutch langslag contrary to kruisslag,Regular lay means the individual wires were wrapped around the centers in one direction and the strands were wrapped around the core in the opposite direction.

Multi-strand ropes are all more or less resistant to rotation and have at least two layers of strands laid helically around a centre. The direction of the outer strands is opposite to that of the underlying strand layers. Ropes with three strand layers can be nearly non-rotating. Ropes with two strand layers are mostly only low-rotating.

Stationary ropes, stay ropes (spiral ropes, mostly full-locked) have to carry tensile forces and are therefore mainly loaded by static and fluctuating tensile stresses. Ropes used for suspension are often called cables.

Track ropes (full locked ropes) have to act as rails for the rollers of cabins or other loads in aerial ropeways and cable cranes. In contrast to running ropes, track ropes do not take on the curvature of the rollers. Under the roller force, a so-called free bending radius of the rope occurs. This radius increases (and the bending stresses decrease) with the tensile force and decreases with the roller force.

Wire rope slings (stranded ropes) are used to harness various kinds of goods. These slings are stressed by the tensile forces but first of all by bending stresses when bent over the more or less sharp edges of the goods.

Technical regulations apply to the design of rope drives for cranes, elevators, rope ways and mining installations. Factors that are considered in design include:

Donandt force (yielding tensile force for a given bending diameter ratio D/d) - strict limit. The nominal rope tensile force S must be smaller than the Donandt force SD1.

The wire ropes are stressed by fluctuating forces, by wear, by corrosion and in seldom cases by extreme forces. The rope life is finite and the safety is only ensured by inspection for the detection of wire breaks on a reference rope length, of cross-section loss, as well as other failures so that the wire rope can be replaced before a dangerous situation occurs. Installations should be designed to facilitate the inspection of the wire ropes.

Lifting installations for passenger transportation require that a combination of several methods should be used to prevent a car from plunging downwards. Elevators must have redundant bearing ropes and a safety gear. Ropeways and mine hoistings must be permanently supervised by a responsible manager and the rope must be inspected by a magnetic method capable of detecting inner wire breaks.

The end of a wire rope tends to fray readily, and cannot be easily connected to plant and equipment. There are different ways of securing the ends of wire ropes to prevent fraying. The common and useful type of end fitting for a wire rope is to turn the end back to form a loop. The loose end is then fixed back on the wire rope. Termination efficiencies vary from about 70% for a Flemish eye alone; to nearly 90% for a Flemish eye and splice; to 100% for potted ends and swagings.

When the wire rope is terminated with a loop, there is a risk that it will bend too tightly, especially when the loop is connected to a device that concentrates the load on 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 abrading 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.

A wire rope clip, sometimes called a clamp, is used to fix the loose end of the loop back to the wire rope. It usually consists of a U-bolt, a forged saddle, and two nuts. The two layers of wire rope are placed in the U-bolt. The saddle is then fitted to the bolt over the ropes (the saddle includes two holes to fit to the U-bolt). The nuts secure the arrangement in place. Two or more clips are usually used to terminate a wire rope depending on the diameter. As many as eight may be needed for a 2 in (50.8 mm) diameter rope.

The mnemonic "never saddle a dead horse" means that when installing clips, the saddle portion of the assembly is placed on the load-bearing or "live" side, not on the non-load-bearing or "dead" side of the cable. This is to protect the live or stress-bearing end of the rope against crushing and abuse. The flat bearing seat and extended prongs of the body are designed to protect the rope and are always placed against the live end.

The ends of individual strands of this eye splice used aboard a cargo ship are served with natural fiber cord after splicing to help protect seamens" 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, then bent around so that the end of the unwrapped length forms an eye. The unwrapped strands are then plaited back into the wire rope, forming the loop, or an eye, called an eye splice.

A Flemish eye, or Dutch Splice, involves unwrapping three strands (the strands need to be next to each other, not alternates) of the wire and keeping them off to one side. The remaining strands are bent around, until the end of the wire meets the "V" where the unwrapping finished, to form the eye. The strands kept to one side are now re-wrapped by wrapping from the end of the wire back to the "V" of the eye. These strands are effectively rewrapped along the wire in the opposite direction to their original lay. When this type of rope splice is used specifically on wire rope, it is called a "Molly Hogan", and, by some, a "Dutch" eye instead of a "Flemish" eye.

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. Threaded studs, ferrules, sockets, and sleeves are examples of different swaged terminations.

A wedge 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.

Poured sockets are used to make a high strength, permanent termination; they are created by inserting the wire rope into the narrow end of a conical cavity which is oriented in-line with the intended direction of strain. The individual wires are splayed out inside the cone or "capel", and the cone is then filled with molten lead-antimony-tin (Pb80Sb15Sn5) solder or "white metal capping",zincpolyester resin compound.

Koetsier,Teun; Ceccarelli, Marc (2012). Explorations in the History of Machines and Mechanisms. Springer Publishing. p. 388. ISBN 9789400741324. Archived from the original on 31 March 2017. Retrieved 9 April 2014.

Donald Sayenga. "Modern History of Wire Rope". History of the Atlantic Cable & Submarine Telegraphy (atlantic-cable.com). Archived from the original on 3 February 2014. Retrieved 9 April 2014.

A distinction is made between the nominal rope diameter and the effective rope diameter. The nominal wire rope diameter is an agreed theoretical value for the diameter of the smallest circle circumscribing the outer strands.

The effective rope diameter, also called actual rope diameter, is the diameter of the smallest circle enclosing all outer strands, as measured on the rope itself. The tolerance range for the effective rope diameter is specified in related national and international standards. According to EN 12385-4 it is between -0{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} and +5{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} (for nominal rope diameters ≥ 8mm)

This means that the effective rope diameter upon delivery must neither be smaller nor bigger than 5{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} than the nominal rope diameter. The tolerance range is often higher for smaller ropes like 3mm to 7mm nominal diameter. In the Oil and Gas industry, which is firmly based on US regulations, a tolerance range from -1{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} to 4{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} is applied. The effective rope diameter changes depending on the load applied. Therefore the effective rope diameter should in critical cases be measured on a rope that is loaded with 5{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} of the calculated breaking strength. verope® produces standard tolerances of +2{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} to +4{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} and special tolerances upon request.

By the design of a wire rope, one understands the formation principle according to which the elements of the wire rope (the wires and the strands) are arranged relative to each other. The designation of a fiber core is FC, for an independent steel wire rope core it is IWRC. As an example all round strand ropes of the 6×19 Warrington design with a fiber core have the construction 6 x [1-6-(6-6)] – FC.

The fill factor of a rope is defined as the ratio of the metallic cross section of the rope (or a simplified calculation of the sum of the single wire cross sections) related to the nominal rope diameter. The fill factor specifies which amount of space the wires and strands take in the rope (figure 16).

The fill factors of the most common ropes are between 0,46 and 0,75. This means, that the amount of steel in the rope volume is about 46{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} to 75{a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02}. Wire ropes with a wire rope core have higher fill factors than ropes with a fiber core.

Usually fill factors of wire ropes with a fibre core (FC) decrease with an increasing number of outer strands. A rope of the design 6×25 Filler-FC has a fill factor of 0,50, a rope of the design 8×25 Filler-FC has only a fill factor of 0,445.

Usually fill factors of wire ropes with a wire rope core increase with an increasing number of outer strands. A rope of the design 6×25 Filler-IWRC has a fill factor of 0,58 and a rope of the design 8×25 Filler-IWRC has a fill factor of 0,587.

Two lay types are to be considered: Regular or ordinary lay and lang’s lay. In regular lay ropes, the lay direction of the wires in the strands is opposite to the lay direction of the strands in the rope. We distinguish between right hand ordinary lay RHOL (right hand strand, left hand rope, zS) (figure 17) and left hand ordinary lay LHOL (left hand strand, right hand rope, sZ) (figure 18). In lang’s lay ropes, the lay direction of the wires in the strands is equal to the strands in the rope. We distinguish between left hand lang’s lay LHLL (left hand strand, left hand rope, sS) (figure 19) and right hand lang’s lay RHLL (right hand strand, right hand rope, zZ) (figure 20).

In the stranding process the initially straight wires are forced into a helical or double-helical form. Therefore, the wires in a rope are always under tension, even in an unloaded rope. Such a rope must be sealed very tightly left and right of the joint before cutting the rope because otherwise the free ends of the wires will spring open. By using a “preforming tool”, the wires and strands can be heavily plastically deformed during the stranding, so are laying nearly without tension in the rope, the rope now is preformed. The ropemakers consider such ropes to be “dead”. Preformed ropes can be cut much easier, also secured by seizings of course, than nonpreformed ropes.

Usually wire ropes have either a fiber core (FC) or a steel/wire core. The steel/wire core can be a strand (WC) or a small rope, named as independent wire rope core (IWRC). The IWRC can be made in a separate operation or during the closing operation of the wire rope (PWRC). The wire core can also have a plastic coating (EPIWRC). Cores made of compacted strands have the additional designation (K). An independent wire core made of compacted strands is therefore called IWRC (K). A rope closed in a single operation and made out of compacted strands both in the core and the outer strands is called PWRC (K).

wire ropes and their free rope end rotate to a greater or lesser extent around its longitudinal axis under the influence of tension. Wire ropes having a core lay direction opposite to the lay direction of the outer strands and 3- or 4-strand regular lay wire ropes rotate considerably less than wire ropes with the same lay direction of the wire core and the outer strands and wire ropes with fiber cores. According to VDI 2358, a wire rope is semi rotation-resistant when: “the wire rope which turns around its longitudinal axis when subjected to unguided load and/or hardly transmits a torque to the attachment at the end in the event of guided rope ends.”

According to ISO 21669 and DIN EN 12385-3: “a rope is considered to be semi rotation resistant if it rotates at least once and at most four times around its axis at a length of 1000 x d under a load of 20 {a889db705b9dbdba2a8d0dbcfc2b631547dc85af52ef75a70f044d2486ae0f02} of the minimum breaking force. In terms of rotation angle, the defined limits are between 360° and 1440°.”

According to the regulation of VDI 2358, a wire rope is rotation-resistant, when: “the wire rope, which hardly turns around its longitudinal axis when subjected to unguided load and/or hardly transmits a torque to the attachment at the end in the event of guided rope ends.”

The wire rope lubricant has two major tasks: it should protect the rope from corrosion and minimize the friction between the rope elements themselves and between the rope and the sheave or the drum. A reduction of the friction reduces the actuating power and minimizes the wear of the rope, the sheaves and the drums. We differentiate between wax-based lubricants and oil-based lubricants. While wax-based lubricants offer a better handling of the ropes, the oil-based lubricants advantage is a better closing of the lubrication film due to the gravitational force of the oil. The quality of the wire rope lubricant has a great impact on the fatigue resistance of a wire rope (figure 22).

Wire rope is a complex mechanical device that has many moving parts, all working in tandem to help support and move an object or load. In the lifting and rigging industries, wire rope is attached to a crane or hoist and fitted with swivels, shackles or hooks to attach to a load and move it in a controlled matter. It can also be used to lift and lower elevators, or as a means of support for suspension bridges or towers.

A wire rope is a machine with many moving parts. It has a unique design consisting of steel wires that form individual strands laid in a helical pattern around a center core.

Wire rope is a preferred lifting device for many reasons. Its unique design consists of multiple steel wires that form individual strands laid in a helical pattern around a core. This structure provides strength, flexibility and the ability to handle bending stresses. Different configurations of the material, wire, and strand structure will provide different benefits for the specific lifting application, including:

However, selecting the proper wire rope for your lifting application requires some careful thought. Our goal is to help you understand the components of a wire rope, the construction of wire rope and the different types of wire rope and what they might be used for. This will allow you to select the best performing and longest-lasting wire rope for the job at hand.

A finished wire rope is comprised of individual wires, which make up individual strands, which are then laid in a helical pattern around a synthetic or steel core.

A wire rope is a machine with many moving parts. From childhood, many of us have been conditioned to think of a machine as some device with gears, shafts, belts, cams and assorted whirring parts. Yet, by the rules of physics, an ordinary pry bar is a simple machine, even though it has only one part.

A wire rope is, in reality, a very complicated machine. A typical 6 by 25 rope has 150 wires in its outer strands, all of which move independently and together in a very complicated pattern around the core as the rope bends. Clearances between wires and strands are balanced when a rope is designed so that proper bearing clearances will exist to permit internal movement and adjustment of wires and strands when the rope has to bend. These clearances will vary as bending occurs, but are of the same range as the clearances found in automobile engine bearings.

Understanding and accepting the “machine idea” gives a rope user a greater respect for rope, and enables them to obtain better performance and longer useful life from rope applications. Wire rope is a complex piece of mechanical machinery with a number of different specifications and properties that can affect its performance and service life.

A finished wire rope is comprised of individual wires, which make up individual strands, which are then laid in a helical pattern around a synthetic or steel core. There are four basic components that make up the design of a finished wire rope:

Wires are the smallest component of wire rope and they make up the individual strands in the rope. Wires can be made from a variety of metal materials including steel, iron, stainless steel, monel, and bronze. The wires can be manufactured in a variety of grades that relate to the strength, resistance to wear, fatigue resistance, corrosion resistance, and curve of the wire rope.

Strands of wire rope consist of two or more wires arranged and twisted in a specific arrangement. The individual strands are then laid in a helical pattern around the core of the rope. Strands made of larger diameter wires are more resistant to abrasion, while strands made of smaller diameter wires are more flexible.

The core of a wire rope runs through the center of the rope and supports the strands and helps to maintain their relative position under loading and bending stresses. Cores can be made from a number of different materials including natural or synthetic fibers and steel.

The construction of wire rope falls into one of these strand pattern classifications. The number of layers of wires, the number of wires per layer, and the size of the wires per layer all affect the strand pattern type. Wire rope can be constructed using one of the following patterns, or can be constructed using two or more of the patterns below.

Filler Wire – Two layers of uniform-size wire around a center with the inner layer having half the number of wires as the outer layer. Small filler wires, equal to the number in the inner layer, are laid in valleys of the inner wire.

Seale – Two layers of wires around a center with the same number of wires in each layer. All wires in each layer are the same diameter. The large outer wires rest in the valleys between the smaller inner wires.

Warrington – Two layers of wires around a center with one diameter of wire in the inner layer, and two diameters of wire alternating large and small in the outer later. The larger outer-layer wires rest in the valleys,and the smaller ones on the crowns of the inner layer.

Remember, wire rope is a complex piece of mechanical machinery. There are a number of different specifications and properties that can affect the performance and service life of wire rope. Consider the following when specifying the best type of wire rope for your lifting application:

When you select a piece of rope that is resistant to one property, you will most likely have a trade-off that affects another property. For example, a fiber core rope will be more flexible, but may have less crushing resistance. A rope with larger diameter wires will be more abrasion resistant, but will offer less fatigue resistance.

A rope with larger diameter wires will be more crush resistant and abrasion resistant, while a rope with smaller diameter wires will be more bendable and fatigue resistant.

On a preformed wire rope, the strands and wires are formed during the manufacturing process to the helical shape that they will take in a finished wire rope. Preformed rope can be advantageous in certain applications where it needs to spool more uniformly on a drum, needs greater flexibility, or requires more fatigue-resistance when bending.

Direction and type of lay refer to the way the wires are laid to form a strand (either right or left) and how the strands are laid around the core (regular lay, lang lay, or alternate lay).

Regular Lay – The wires line up with the axis of the rope. The direction of the wire lay in the strand is opposite to the direction of the strand lay. Regular lay ropes are more resistant to crushing forces, are more naturally rotation-resistant, and also spool better in a drum than lang lay ropes.

Lang Lay – The wires form an angle with the axis of the rope. The wire lay and strand lay around the core in the same direction. Lang Lay ropes have a greater fatigue-resistance and are more resistant to abrasion.

A fiber core can be made of natural or synthetic polypropylene fibers. Fiber cores offer greater elasticity than a steel core but are more susceptible to crushing and not recommended for high heat environments.

A steel core can be an independent wire rope or an individual strand. Steel cores are best suited for applications where a fiber core may not provide adequate support, or in an operating environment where temperatures could exceed 180° F.

The classifications of wire rope provide the total number of strands, as well as a nominal or exact number of wires in each strand. These are general classifications and may or may not reflect the actual construction of the strands. However, all wire ropes of the same size and wire grade in each classification will have the same strength and weight ratings and usually the same pricing.

Some types of wire rope, especially lang lay wire rope, are more susceptible to rotation when under load. Rotation resistant wire rope is designed to resist twisting, spinning, or rotating and can be used in a single line or multi-part system. Special care must be taken when handling, unreeling, and installing rotation resistant wire rope. Improper handling or spooling can introduce twist into the rope which can cause uncontrolled rotation.

Compacted strand wire rope is manufactured using strands that have been compacted, reducing the outer diameter of the entire strand, by means of passing through a die or rollers. This process occurs prior to closing of the rope.This process flattens the surface of the outer wires in the strand, but also increases the density of the strand. This results in a smoother outer surface and increases the strength compared to comparable round wire rope (comparing same diameter and classification), while also helping to extend the surface life due to increased wear resistance.

A swaged wire rope differs from a compacted strand wire rope, in that a swaged wire rope’s diameter is compacted, or reduced, by a rotary swager machine after the wire rope has been closed. A swaged wire rope can be manufactured using round or compacted strands.The advantages of a swaged wire rope are that they are more resistant to wear, have better crushing resistance, and high strength compared to a round strand wire rope of equal diameter and classification. However, a swaged wire rope may have less bending fatigue resistance.

A plastic coating can be applied to the exterior surface of a wire rope to provide protection against abrasion, wear, and other environmental factors that may cause corrosion. However, because you can’t see the individual strands and wires underneath the plastic coating, they can be difficult to inspect.

Plastic filled wire ropes are impregnated with a matrix of plastic where the internal spaces between the strands and wires are filled. Plastic filling helps to improve bending fatigue by reducing the wear internally and externally. Plastic filled wire ropes are used for demanding lifting applications.

This type of wire rope uses an Independent Wire Rope Core (IWRC) that is either filled with plastic or coated in plastic to reduce internal wear and increase bending fatigue life.

Asteel wire rope is defined not only by its basic elements (wires, strands, core), but also by the way in which the individual wires are laid together to create a strand and the way in which the strands are laid around the core, etc. The steel wire rope’s construction is ­defined when the following criteria have been determined:

The steel wire rope is designated according to the number of strands, the number of wires in each strand, the design (type) of the strand, and the type of core.

The number of wires in a strand varies between three and approx. 139, although there are most commonly 7, 19, 24 or 36 wires. The number of wires and their thickness depend on the design of the strand and affects the characteristic of the steel wire rope.

The type of strand is characterised by the way in which the wires in the strand are arranged. There are four basic types of strand design that are used in all steel wire ropes, either in their original form or as a combination of two or more types. The four basic types are:

The Standard construction (fig. 3) is characterised by the fact that all wires are of equal thickness, although the core wire may be thicker. The wires are also laid together in such a way that all of them, with the exception of the centre wire, are of equal length. In this way all the wires are subjected to an equal distribution of load when pulled straight.

The geometric wire distribution consists of one centre wire, onto which one or more layers are laid. Each layer is produced in a separate operation. If there are several layers, the number of wires increases by six for each layer.

The designation for a Standard strand with e.g. seven wires is (1-6), i.e. one centre wire with six external wires in one operation. If there are 37 wires it is known as (1-6/12/18), i.e. one centre wire with six external wires from the first operation, 12 from the second operation and 18 from the third operation.

The Seale construction (fig. 5) is characterised by the way in which the strand consists of two layers of wire produced in one operation. Also, the number of wires in the first and second layer is identical.This construction is somewhat stiffer than a corresponding Standard construction (with the same number of wires). This is because the outer wires in the Seale construction are considerably thicker.

The Filler construction (fig. 7) is characterised by a strand ­consisting of two layers of wires produced in one operation. Also, the number of wires in the second layer is twice the number in the first layer. This is, however, only possible if filler wires are inserted between the first and the second layers, to prevent the strand becoming hexagonal in shapes.

This construction is more flexible than a corresponding Standard construction and considerably more flexible than a corresponding Seale construction (with the same number of wires excluding filler wires).

A Filler strand with e.g. 25 wires ­(including 6 filler wires) is known as (1-6+6F-12), i.e. one centre wire with six wires in the first layer and 12 wires in the second layer. There are six filler wires between the first and the second layers.

The Warrington construction (fig. 9) is characterised by a strand consisting of two layers of wire produced in one operation. The second (outer) layer contains wires of two dimensions, and the number of wires in the second layer is twice the number in the first.

This construction is very compact and flexible. A Warrington strand with e.g. 19 wires is known as (1-6-6+6), i.e. one centre wire with six wires in the first layer and a total of 12 wires of two dimensions in the second layer. The centre wire may be replaced by several wires or a fibre core (fig. 10).

As previously mentioned, there are also strands that are a combination of one or more of the above four basic types of strand. One of these is the Warrington-Seale (fig. 11).

The Warrington-Seale construction is characterised by a strand consisting of three layers of wire produced in one operation. The number of wires in the third (outer) layer matches the number of wires in the second layer. Also, the layers below the outer layer are built as a Warrington construction.

A Warrington-Seale strand with e.g. 36 wires is known as (1-7-7+7-14), i.e. one centre wire with seven wires in the first layer, 14 wires made up of two dimensions in the second layer, and 14 wires in the third layer.

The strands and the wires in the strands do not necessarily have to be round. Examples of this are shown in fig. 12. The strands are special strands (i.a. with profiled wire), designed to meet extremely unusual requirements.

The number of strands in a steel wire rope varies between three and approx. 36, although most commonly there are six strands. The more strands a steel wire rope contains, the more rounded and flexible it is, although the wires in the strand are also thinner (less durable).

Fibre cores are the most commonly used, as not only do they provide a good, elastic base but also enable lubrication of the rope from the inside, since it is possible to add oil and/or grease to the fibre core during production. This reduces the risk of rust attacking from the inside. The fibre core is normally produced from polypropylene (PP) or sisal. PP can withstand weaker acids and alkalis and it does not rot. The advantage of a sisal core is that it can absorb oil/grease to a greater degree for lubrication of the steel wire rope from the inside.

Randers Reb recommends the use of a steel core, in the event that it is not certain that a fibre core will provide satisfactory support for the strands, e.g. if thesteel wire rope is spooled on to a drum in several layers under a considerable load, or at high temperatures.

The word “lay” has more than one meaning in this context. It is used to describe the process of interweaving the wires and strands and also to describe the appearance of the finished steel wire rope. The four most common terms to describe the lay of a steel wire rope are:

Right hand regular lay steel wire rope. In this instance the wires in the strand are laid in the opposite direction to the strands in the rope. The wires are laid helically left, while the strands are laid helically right (see fig. 13).

Right hand Lang lay steel wire rope. Here the wires are laid in the same direction as the strands in the rope. The wires in the strands and the strands are laid helically right (see fig. 15).

Multi layer steel wire rope (low rotation/rotation resistant). Here there are usually two layers of strands, the inner layer as a rule a left hand Lang lay, while the outer layer is a right hand regular lay.

Cable laid steel wire rope. The strands are normally 6-lay steel wire rope with a fibre or steel core. The core is a fibre core or a 6-lay steel wire rope with a fibre or steel core.

Flat braided steel wire rope. This steel wire rope is flat braided from strands or consists of parallel strands or steel wire ropes that are bound together by sewing (belt strap).

Right hand lay steel wire rope is also known as Z-lay, and left hand as S-lay. Similarly, a right hand lay strand is known as z-lay and left hand as s-lay. Fig. 17 shows why. Of the types of lay described, right hand regular lay is the most common.

“Preformed” refers to steel wire ropes in which the strands have been permanently formed during the laying process (see fig. 18), so that they are completely stress-free within the unloaded steel wire rope.

All Randers Reb steel wire ropes are supplied preformed, with the exception of certain individual special constructions (e.g. low-rotation/rotation resistant).

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Wire rope and cable, is there a difference? The terms are often used interchangeably, but are they different? Each is considered a machine. Wire ropes are usually ⅜” in diameter or larger, while cables or cords are smaller. Though this little distinction exists in aircraft and marine cables, wire ropes and cables are synonymous in most other ways.

A strand is made up of two or more wires twisted around a center wire. Each strand is made up of 7, 19, or 37 wires. Cable or wire rope is made when a group of strands is twisted around a center wire or rope. They are named for the numbers of wires and strands. A 7×7 cable has 7 strands with 7 wires in each strand wrapped around a central core. A 7×19 cable would include 7 strands with 19 wires in each cable.

Different wire rope applications require different demands for abrasion, strength, and corrosion resistance. Different materials are used to meet different needs. Sizes under ⅜ “ are considered aircraft cable, sizes over 3/8 “ in diameter are considered wire rope.Stainless Steel – Type 302, made up of 18% chromium and 8% nickel alloy, is the most common grade because of its high strength and resistance to corrosion. When non-magnetic properties are required, type 305 is employed. Other common types used in wire rope are 304, 305, 316, and 321. Each has specific advantages and disadvantages. Stainless steel is the stronger of the two, so its cost is higher but well worth it.

Galvanized Carbon Steel – To protect from the elements, a coating of zinc is applied to wire ropes used in the making of this wire rope. It is the wire rope of choice when strength is necessary, but corrosion resistance is not significant enough to warrant the use of stainless steel. Galvanized carbon steel is the go-to for cost-effectiveness.

If you require flexibility, you need wires that have more strands, more strands equal more flexibility. Look for 3×7, 7×7, and 7×19; these will give you more flexibility. However, as the degrees of flexibility increase, the abrasion resistance decreases. These cables are most useful where you require continuous flexing. Basic cable construction:

1×19 cable – This cable is still reasonably flexible, yet it resists compressive forces. It is smooth on the outside, and sizes above 3/32” diameter are the strongest.

It is essential to correctly estimate the qualities necessary for the work the wire rope will be doing. To decide the importance of the essential attributes to do the job, you need to look for quality and figure out whether it can withstand how it will be used and the length of time it can be used in this capacity. In choosing a wire rope for the job at hand, these four things must be considered:Sufficient strength to lift the load and then some, keeping safety in mind. Always overestimate.

Whether it is a crane, a pulley, or some other machine, be sure to choose the proper size, construction, and grade of wire rope appropriate for the job.

To find the wire rope or cable you need for the job, contact us atSilver State Wire Ropefor all of your wire rope and rigging needs. We have all sizes of cable and wire rope; whether you need it for aircraft, marine, or land use, we have it all!

Wire rope forms an important part of many machines and structures. It is comprised of continuous wire strands wound around a central core. There are many kinds of wire rope designed for different applications. Most of them are steel wires made into strands wound with each other. The core can be made of steel, rope or even plastics.

Wire ropes (cables) are identified by several parameters including size, grade of steel used, whether or not it is preformed, by its lay, the number of strands and the number of wires in each strand.

A typical strand and wire designation is 6x19. This denotes a rope made up of six strands with 19 wires in each strand. Different strand sizes and arrangements allow for varying degrees of rope flexibility and resistance to crushing and abrasion. Small wires are better suited to being bent sharply over small sheaves (pulleys). Large outer wires are preferred when the cable will be rubbed or dragged through abrasives.

There are three types of cores. An independent wire rope core (IWRC) is normally a 6x7 wire rope with a 1x7 wire strand core resulting in a 7x7 wire rope. IWRCs have a higher tensile and bending breaking strength than a fiber core rope and a high resistance to crushing and deformation.

A wire strand core (WSC) rope has a single wire strand as its core instead of a multistrand wire rope core. WSC ropes are high strength and are mostly used as static or standing ropes.

Wire ropes also have fiber cores. Fiber core ropes were traditionally made with sisal rope, but may also use plastic materials. The fiber core ropes have less strength than steel core ropes. Fiber core ropes are quite flexible and are used in many overhead crane applications.

The lay of a wire rope is the direction that the wire strands and the strands in the cable twist. There are four common lays: right lay, left lay, regular lay and lang lay. In a right lay rope the strands twist to the right as it winds away from the observer. A left lay twists to the left. A regular lay rope has the wires in the strands twisted in the opposite direction from the strands of the cable. In a lang lay rope, the twist of the strands and the wires in the strands are both twisted the same way. Lang lay ropes are said to have better fatigue resistance due to the flatter exposure of the wires.

Wire ropes are made