A wire rope is a type of cable that includes several wire strands laced together to form a single wire. Generally, both the terms “wire” and “rope” are used interchangeably with “wire rope”; however, according to the technical definition, to be labeled a wire rope, the cable must have a thickness of at least 9.52 mm. As a versatile, high load capacity alternative to natural fiber ropes such as hemp and manila, wire rope provides motion transmission through nearly all angles, tie down, counterbalance, guidance, control, or lift.
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The History of Wire Rope
Modern wire rope was invented by Wilhelm Albert, a German mining engineer, between 1831 and 1834. He developed them in order for work in the mines in the Harz Mountains. This rope replaced weaker natural fiber ropes, like hemp rope and manila rope, and weaker metal ropes, like chain rope.
Albert’s rope was constructed of four three-stranded wires. In 1840, a Scot named Robert Stirling Newall improved upon this model. A year later in the United States, American manufacturer John A. Roebling started producing wire rope, aimed at his vision of suspension bridges. From there, other interested Americans, such as Erskine Hazard and Josiah White, used wire rope in railroad and coal mining applications. They also applied their wire rope techniques to provide lift ropes for something called the Ashley Planes project, which allowed for better transportation and increased tourism in the area.
Approximately twenty-five years later, back in Germany in 1874, the engineering firm Adolf Bleichert & Co. was founded. They used wire rope to build bicable aerial tramways for mining the Ruhr Valley. Years later they built tramways for both the Wehrmacht and the German Imperial Army. Their wire rope systems spread all across Europe, and then migrated to the USA, concentrating at Trenton Iron Works in New Jersey.
Over the years, engineers and manufacturers have created materials of all kinds to make wire rope stronger. Such materials include stainless steel, plow steel, bright wire, galvanized steel, wire rope steel, electric wire, and more. Today, wire rope is a staple in most heavy industrial processes. Wherever heavy duty lifting is required, wire rope is there to facilitate.
Advantages of Wire Rope
Wire rope is strong, durable, and versatile. Even the heaviest industrial loads may be lifted with a well-made wire rope because the weight is distributed evenly among constituent strands.
Wire Rope Design
There are three basic elements of which wire ropes are composed: wire filaments, strands, and cores. Manufacturers make wire rope by taking the filaments, twisting or braiding them together into strands, and then helically winding them around a core. Because of this multiple strand configuration, wire rope is also often referred to as stranded wire.
The first component, the filaments, are cold drawn rods of metal materials of varying, but relatively small diameter. The second component, the strands, can individually consist of as few as two or as many as several dozen filaments. The last component, the core, is the central element around which strands are wrapped; wire rope cores maintain a considerable amount of flexibility, while increasing strength by at least 7.5% over the strength of fiber core wire ropes.
Lay of a Rope
The helical winding of the strands around the core is known as the lay. Ropes may be right hand lay, twisting strands clockwise, or they may be left hand lay, twisting strands counter-clockwise. In an ordinary lay, the individual strands are twisted in the opposite direction of the lay of the entire rope of strands to increase tension and to prevent the rope from coming unwound. Though this is most common Lang's lay has both the strands and the rope twisted in the same direction while alternate lays, as the name suggests alternate between ordinary and Lang style lays. While alternative rope designs are available, the helical core design is often favored, as it allows a wire cable to hold a lot of weight while remaining ductile.
There are many design aspects that wire rope manufacturers consider when they are creating custom wire rope assemblies. These include: strand gauge (varies based on application strength, flexibility, and wear resistance requirements), wire rope fittings (for connecting other cables), lay, splices, and special coatings. Specially treated steel cable and plastic coated cables, for instance, are common to many application specific variations of wire rope such as push pull cable assemblies used in transferring motion between two points.
Types of Wire Rope
Suppliers typically identify wire cable by listing both the number of strands and the amount of wires per strand respectively, though stranded cable may alternatively be measured by their lay and length or pitch. For example, a door-retaining lanyard wire rope is identified by its 7 x 7 construction, and wire rope used for guying purposes is identified by its 1 x 19 construction. The most common types are 6 x 19, 6 x 25, 19 x 7, 7 x 7, 7 x 19, 6 x 26, and 6 x 36.
Identification codes can also be extended to specifics which are abbreviated to quickly denote core type, work load limit, and more.
The following are some identified types of wire rope cable, not identified by the above.
- Bright Wire Rope
- Bright wire rope is an ungalvanized steel wire rope variety. This uncoated wire rope can also be designed to resist spinning or rotating while holding a load; this is known as rotation resistant bright wire rope.
- Coiled Cable
- Also called a coiled wire rope, a coiled cable is a rope made from bundles of small metal wires, which are then twisted into a coil. Wire rope and cable can come in a huge variety of forms, but coiled cables specifically provide the benefits of easy storage and tidiness. Unlike other wire ropes, coiled cables do not require a spool for storage. Because it has been coiled, the cable will automatically retract into its spring-like shape when it is not in use, making it incredibly easy to handle.
- Cable Wire Rope
- Cable wire rope is a type of high strength rope, made of several individual filaments. These filaments are twisted into strands and helically wrapped around a core. One of the most common types of wire rope cable is steel cable.
- Wire Rope Chain
- Wire rope chain is wire rope made not as one solid piece, but as a piece made up of a series of metal links. Wire rope chain is flexible and strong, but it is more prone to mechanical failure than wire rope.
- Push Pull Cable
- Push pull cables and controls are a particular type of control cable designed for the positive and precise transmission of mechanical motion within a given system. Unlike their counterpart pull-pull cables, these wire rope assemblies offer multidirectional control. Additionally, their flexibility allows for easy routing, making them popular in a number of industrial and commercial applications.
- Steel Wire Rope
- Iron and steel are the two most common materials used in producing wire ropes. A steel wire is normally made from non-alloy carbon steel that offers a very high strength and can support extreme stretchable forces. For even more strength and durability, manufacturers can make stainless steel wire rope or galvanized steel wire rope. The latter two are good for applications like rigging and hoisting.
- Spiral Rope
- Technically, spiral ropes are curved or round strands with an assemblage of wires. This gathering of wires has at least one cord situated in the opposite direction of the wire in the outer layer of the rope. The most important trait of this rope is that all the wires included are round. The biggest benefit of this category of rope is that it does not allow the entrance of pollutants, water, or moisture.
- Stranded Rope
- Stranded ropes contain an assemblage of strands placed spirally around a core. Stranded rope steel wire patterns have different layers that cross each other to form an even stronger cable or rope. Stranded ropes contain one of three types of core: a fiber core, a wire strand core, or a wire rope core.
- Other common categories of ropes include running ropes, hoist wire, stationary ropes, track ropes, and a product known as a wire rope sling.
- Wire Rope Sling
- Wire rope slings provide an added level of security to a manufacturing production application. Wire rope slings are made from improved plow steel wire ropes that, apart from offering added security, also provide superior return loop slings. Plow steel wire ropes improve the life of a mechanism by shielding the rope at its connection points. The key objective of wire rope slings is to enhance the safety of an application while increasing its capacity and performance. Rope slings are also available in various sling termination options, such as hook type, chokers, and thimbles.
Common Types of Slings
Permaloc Rope Sling
The eye in this rope sling is made using the Flemish Splice method. Just like a typical sling, a Permaloc rope sling improves safety and provides reverse strength meaning that the uprightness of the eye does not depend on the sleeves of the metal or alloy. Additionally, permaloc rope slings offer an abrasion resistance feature that makes them long lasting.
Permaloc Bridle Sling
These slings have all the features that most other slings offer. However, compared to their counterparts, Permaloc bridle slings provide better load control, wire rope resistant crushing, robust hooks and links that work for a longer duration, and help save on maintenance requirements.
Grommets and endless slings are also available to manufacturers. With their movable legs, these slings offer unmatchable load stability and balance, which, ultimately, improve safety.
Wire Rope Applications
Manufacturers produce wire rope for many different reasons; from cranes to playground swings, wire ropes have something for everyone. Among the many applications of wire rope are hoisting, hauling, tie down, cargo control, baling, rigging, anchoring, mooring, and towing. They can also serve as fencing, guardrails, and cable railing, among other products.
Some of the industries that make use of wire rope include industrial manufacturing, construction, marine, gas and oil, mining, healthcare, consumer goods, and transportation. Others include the fitness industry, which uses plastic coated cable products in weight machines, the theater industry, which uses black powder coated cables for stage rigging, the recreation industry, which uses plastic coated cables for outdoor playground equipment, and the electronics industry, which uses miniature wire rope for many types of electronic equipment and communications devices.
Wire Rope Materials
Wire ropes are typically made from cold drawn steel wire, stainless steel wire, or galvanized wire. They may also be made from a wide variety of less popular metals, including aluminum, nickel alloy, bronze, copper, and titanium. However, nearly all wire ropes, including control cables, are made from strands of cold drawn carbon steel wires. Stainless steel rope and cables are subbed in for highly corrosive environments. Galvanized cables and galvanized wire rope are popular for their increased strength and durability; these qualities are important to specialized ropes like galvanized aircraft cable.
A core may be composed of metal, fiber or impregnated fiber materials depending on the intended application. Cores may also be another strand of wire called an independent wire rope core (IWRC).
Standards and Specifications of Wire Rope
Wire rope, depending on its application, is subject to many standard requirements. Among the most common of these are the standards detailed by OSHA, ASTM International, and ISO. Per your application and industry, you’ll likely have others you need to consider. To get a full list, talk to your service provider.
Safety Factor for Wire Rope
To determine the safety factor, which is a margin of security against risks, the first step involves knowing the type of load that the rope will be subjected to. The load must consider the shock loads and blowing wind effects. The safety factor is characterized in ratios; typical are 4:1 and 5:1. If a ratio is 5:1, then the tensile strength of a wire rope must be five times of the load it will be subjected to. In some applications, the ratios can go up to 10:1.
By weighing all these factors carefully, the wire rope that you will buy will be safe to use and last considerably. For the best advice and guidance, though, don’t go it alone! Find a great wire rope supplier that you can trust. You’ll know you’ve found the right supplier for you when you talk to one that can not only fulfill your requirements, but shows that they are excited to go the extra mile for you. For a company like this, browse the list near the top of the page.
Things to Consider When Purchasing Wire Rope
As the cables play an integral role in the safety of many operations and structures, careful analysis of a wire rope and all of its capabilities and features is vital. Important qualities and physical specifications you must consider include wire rope diameter, breaking strength, resistance to corrosion, difficulty of flattening or crushing, bendability, and average lifespan.
Each of the aforementioned considerations should be compatible with the specific application for which the rope is intended as well as the environment in which such operations are undertaken. Temperature and corrosive environments often require specially coated wire ropes with increased durability.
Proper Care for Wire Rope
When you use your industrial wire rope, the first thing to remember is to not exceed your rope’s rated load and breaking strength. If you do not stay within these parameters, you risk causing your rope to weaken or even break.
Rust, kinks, fraying and even carefully performed splicing will all have an impact on the performance of wire ropes. To maintain the integrity of your wire rope assembly, you need to inspect them regularly and clean and lubricate them as needed. In addition, you need to store them out of the wet and cold as much as possible. Also wrap them up properly, so they are not kinked.
If you keep your wire ropes well-maintained, you can expect them to have a long and fruitful working life.
Accessories for Wire Rope
Important wire rope accessories include connections, fasteners, fittings, and hardware like wire rope clip and steel carabiner products.
Wire Rope Terms
- Breaking Strength
- A calculation of the load necessary to break a wire rope that is in tension.
- 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.
- 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.
- To coat with zinc for the protection of the wire, strand or rope from corrosion.
- 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.
- 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.
- 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.
- Marine Rigging
- Used on commercial and recreational boats for a variety of purposes. Cables of various sizes are used to secure masts, hoist sails, tie boats up next to a dock, and hold cargo in place during transport.
- Mechanical Cable Assemblies
- Heavy duty mechanical cable assemblies are used in a variety of industrial equipment applications to pull objects and bear large amounts of weight at any given time. Mechanical cable assemblies can also be used for much smaller applications like the brakes on a normal bicycle or the throttle pulley on a car.
- 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.
- Rigging Equipment
- Used on sail boats to secure masts and move sails as needed. Cables of various sizes are used on the rigging to stiffen the mast in the wind, hoist the sails, tie boats up next to a dock, and even hold cargo in place during transport.
- A pulley wheel with a channel, mounted in a frame, that guides or alters the direction of the cable or rope.
- 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.
- 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.
- A continual span of metal that has been cold drawn from a rod.
- Wire Braids
- It is composed of wire strands that are braided together. Wire braid is similar to stranded wire. The difference between the two is the fact that stranded wire features strands that are bundled together, rather than braided.
- Wire Rope Fittings
- Essential parts of cable assemblies, wire rope assemblies and wire rope slings that assist spliced or swaged rope ends in connecting to other cables and keeping cables and rope from unraveling.
- Wire Rope Cable Assemblies
- A wire rope cable assembly is a metallic rope consisting of bundles of twisted, spiraled, or bonded wires. While the terms wire rope and cable are often used interchangeably, cables are typically designated as smaller diameter wire ropes, specifically wire ropes with a diameter less than 3/8 inch. Therefore, wire rope cable assemblies are typically utilized for lighter duty applications.
- Wire Rope Lanyards
- Or cable assemblies, are cables which are composed of many spiraled bundles of wire. These cables are used to support hanging objects, connect objects, pull or lift objects, secure items, and much more.
- Wire Rope Wholesalers
- Wire rope wholesalers can sell an extensive range of wire rope and wire rope accessories at a very affordable rate as well as in bulk. Many of the additional wire rope equipment that wire rope wholesalers provide include: swivel eye pulleys, eye nuts, eye bolts, slip hooks, spring hooks, heavy duty clips, clevis hooks, turnbuckle hooks, anchor shackle pins, s hooks, rigging blocks, and much more. Wire rope fittings will generally improve the versatility of the wire and also prevent fraying.