types of wire rope breaks quotation
Like all industrial equipment, aircraft cables and wire ropes wear while in service, and will require replacement. Though the cycle life of each cable varies based on construction and application, factors such as load and pulley condition can actually reduce this lifespan by triggering wire breaks. Not all wire breaks look the same, and understanding these differences can help detect issues in your system before they damage additional cables, or put human lives in danger. Here is a quick guide to help you understand where wire breaks occur (crowns vs. valleys), and three common examples of wire breaks (tension, fatigue, and abrasion).
Wire breaks typically occur in two different locations on the outside of wire rope or aircraft cable. The first location is on the crowns of the strands, which are the highest points with the most surface area exposure. The second location is the valleys, or the spaces between the strands. Though crown breaks typically result from normal wear and tear, valley breaks are more suspicious and may indicate issues with the pulley system or wire rope itself.
Wires that have been worn to a knife-edge thinness are characteristic of abrasion breaks. Abrasion can occur from a number of different sources, but sheaves are the most common. Remember to check sheaves for signs of wear, damage, or deformity and replace as necessary.
If you notice one end of a broken wire is cupped, and the other end resembles a cone, your wire rope likely experienced a tension break. Tension breaks result from excessive loading, causing the wires to stretch beyond their limits until they snap. Once one wire break appears, others will continue to occur if the cable is not addressed.
Fatigue damage is usually represented by zig-zag breaks with square ends. Like abrasion breaks, fatigue breaks can be triggered by a broad range of factors, including incorrect pulley size and excessive vibration. Check for worn pulleys and slack in the system to prevent issues from exacerbating.
Once you have replaced your damaged pulleys, or removed sharp obstructions in your system, begin your quote for brand new wire rope at https://strandcore.com/contact/. Our wire rope craftsmen can help you select the ideal wire rope for your application, and oftentimes provide a better solution for your existing setup. Browse our selection ofwire rope and aircraft cableonline, and do not hesitate to contact our sales team at sales@sanlo.com if you have any questions.
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Wire ropes on vehicle lifting equipment come under a lot of strain during their life span. Fatigue related damage such as broken strands in the outer wires can be caused by numerous things. Typically these kinds of breaks are caused by the stress put on the parts of the rope continually running in or around pulleys and guides.
When a ramp is loaded and operated with a vehicle, the tension of the ropes increases causing extra stress to the outer core. If any of the outer wires our found to be broken or showing signs of wear, it is time to renew them.
Kinking of wire ropes is usually caused by poor manufacture of the layers winding process, or from pulleys becoming worn, causing the running surface to narrow and deform the ropes as they pass through. The usual signs of worn pulleys are small shards of steel filings around the base of the vehicle ramps upright posts.
Wire ropes that fail due to corrosion are usually caused by improper lubrication type or lack of regular maintenance. Corrosion is easily identified by the pitted surface or rust patches on the external wires of the rope. The extent of the damage to the interior core of the rope is very difficult to judge and due to this, corrosion is one of the most dangerous causes of rope deterioration.
Severe wear to a wire rope is identified as flat spots or signs of crushing in different points around the rope. These points are usually found in areas that constantly run around pulleys etc and can be a sign of slipping, overloading or narrowing of the ropes, causing damage to the running track of the pulleys. Other causes of wire rope wear, could be the bearings or sleeves inside the pulleys and pins becoming worn and causing the ropes to run at a slight angle to the pulley line.
Birdcage type damage to wire ropes can be caused by a multitude of scenarios. The most common is caused by the ropes twisting out of line, causing the internal core to break through the individual external wires. This can be caused by poor installation, or the fact that all the components the rope runs around or over are not aligned centrally.
If you require more information about wire ropes or to arrange for an engineer to visit your workshop to carry out a safety inspection, please get in touch with Straightset service.
Industrial machines generally have heavy loads to lift and pull. Whether it’s excavators or farm machinery, wire rope is the rope that is used. Industrial wire ropes typically range from 3/8” (9.5mm) to 2-1/2” (63.5mm) in diameter, and besides heavy machining applications, wire ropes also serve as support cables for large static structures such as stadium roofs and bridges. Manufacturing a wire rope begins with steel wire that is anywhere from .6 to 8 millimeters in diameter. The first step is to wind several of these wires together, into a strand. How many wires per strand depends on the application of the wire. Different applications require various levels of flexibility and strength.
Steel wires are used for wire ropes and are typically fashioned from a non-alloy carbon steel material. This metal has a carbon content of 0.5 to 0.95%, which makes it incredibly strong. As a result of its strength and durability, steel wires are able to support large tensile forces and can run over sheaves with small diameters.
Strands are created when wires of different layers cross each other. Parallel lay strands are some of the most commonly manufactured strands. The lay length of the wire strands is generally equal to the wires of any two layers that are parallel. This means that there is linear contact. Inner layer wires support the outer layer wires along the entire length of the strand.
In essence, spiral ropes are round strands that are assembled in layers of wires that are aligned in a spiral design. Spiral ropes are constructed so that they are non-rotating, which means that that there is practically no tension under the rope torque.
Stranded ropes are comprised of several different layers of strand that are laid in multiple spiraling layers around a core. A stranded rope core can come in three different types: fiber cores, wire strand cores, or independent wire rope cores. Fiber cores are the most flexible and elastic of the 3 variations, but are easily crushed. Wire strand cores are typically used for suspension and have a high tensile strength. Independent wire rope is the most durable in all types of environments.
Safety should be the top concern of anyone employed in rigging. When working a job where so many lives could be cut short due to carelessness, there is no excuse for laziness or distraction. Rigs should be inspected thoroughly for any potential areas of breakage. It is important for employees to gain a fluency in the causes of wire rope damage and failures so they can spot areas of weakness and fix them before they grow into a dangerous problem.
Corrosion issues in wire ropes are one of the most difficult causes of wire rope damage and failures to identify, which is why it is one of the most dangerous. Wire rope failures due to corrosion are typically the result of poor lubrication. You can measure some amount of the lubrication by looking at the pitted surface of every individual rope, but this tells us little of the damage done to the core. Since it is difficult to identify the full spectrum of corrosion, this break stands apart as mysterious and deadly.
Abrasion-caused failure occurs when the wire rope has been damaged by irregular contact with hoist sheaves and drums or when it awkwardly rubs against an object such as shelving or a crane girder. It is also often caused by poorly grooved drums and sheaves. You know the wire ropes have experienced abrasions when the wire ends are worn thin.
When hoist ropes go through repetitive bending over sheaves, cracks will eventually develop in the individual wires. Sections of the wire that move over the sheaves develop the worst fatigue. The damage can often be seen by the naked eye. Whenever one broken wire appears due to fatigue, more will follow. Since these issues are essentially the result of wear and tear on the rope wire, they are considered a normal part of operating a crane.
Wire rope is a machine! It is the workhorse that lifts the heavy loads on wire rope hoists. As a crane technician, there is an endless amount of information you should know about wire rope. The more you understand, the better resource you can be to your customers. Luckily, you don’t need to be the expert! There are others to help you out including, crane and hoist manufacturers, wire rope manufacturers, and other crane technicians. In this article, we will talk about how Demag designs wire rope hoists, selects the wire rope for models that you can buy today, and those you will still find in the field for inspections and repair.
In the world of wire rope, lay has many meanings and definitions. First, we will go through the directional meanings. Lay can refer to the direction in which the strands are twisted around the core of the wire rope. When left hand and right hand lay is referred to like this, it is describing whether the strands are twisted clockwise (left hand) or counter-clockwise (right hand) around the core. For a frame of reference, grab the wire rope in either hand with your thumb pointing up. When the strand appears as if going up to the left, this is a Left Hand lay rope. When it appears as though it is going up to the right, this is a Right Hand lay.
Lay can also refer to the cut of the groove corkscrew in the drum and the corkscrew can go to the left or right. The wire rope will start gathering on the left-hand side of the drum in the case of a left lay and the opposite for right lay. One way to determine this is to look at the drum from the end where the rope is clamped. The term lay can be used to describe the distance of a complete wrap of a strand once around the core. When conducting a wire rope inspection, knowing how to measure the lay is critical. It is measured by determining the distance starting on the outside wrapping the strand one complete time back to the same outside position. This measurement is used to determine the maximum number of broken wires allowed within a single lay and for the number of broken wires in the same strand in a lay. Always consult your inspection criteria bodies, like CMAA and HMI, for the most up-to-date standards.
Lay can also denote whether a rope is Regular Lay or Lang Lay. Regular lay and Lang lay rope are different types of wire rope and differ based on the wire orientation in the strand. Regular lay rope wire appears as though the outermost wire surface is aligned parallel with the centerline of the wire rope axis. Lang lay rope wires appears to be at a 45 degree angle with the wire rope centerline axis. Lang lay type of rope allows for more surface contact with the groove surface on the drum or sheave, increasing the support zone and decreasing the load by spreading it out over a larger area. It is more costly to manufacture, but it can be used in special cases where better wear life for the drum and sheaves is needed. Today, Regular Lay rope is commonly used unless there is a specific design need to use Lang Lay wire rope.
Countries and industries may have different standards or best practices for wire rope. In the USA, the wire rope industry recommends using a Right Hand (RH) lay rope on a Left Hand (LH) drum corkscrew and a Left Hand (LH) lay rope on a Right Hand (RH) drum corkscrew. This is recommended for good spooling of the rope, especially on a grooveless drum. In most cases, Demag designs their wire rope hoists in violation of this best practice, but for a major engineering reason that benefits the user and for additional safety.
Demag wire rope hoists are designed for RH rope on a RH drum and LH rope on a LH drum. This design creates straighter drops of wire rope down to the bottom block as using the same strand lay and corkscrew twists the strands tighter around the core. The straighter drop eliminates interference in a 4/1 reeving configuration as the rope crisscrosses during lifting. This becomes very apparent when the lift height is around the 70 foot range. To make sure that the hoist has positive spooling, the drum is designed with a partial groove and is equipped with a rope guide with pressure rollers or a ring that keeps the rope in the groove.
When it comes to hoists configured for 4/2 reeving with 2 attachment points for the same rope, only one side of the drum follows the best practice. Since there are 2 attachment points in 4/2 reeving, one drum corkscrew is RH and the other LH. Inherent from the reeving design, close to vertical lifting is achieved and crisscrossing interference is not a concern.
Due to wear on the drum and sheaves, we will never recommend changing the lay of the rope used on a hoist when the wire rope needs changed. The existing wire rope lay has already established wear patterns on the drum and sheave that could make changing the rope with a different lay dangerous. Being able to identify or find out what type of rope is used on a wire rope hoist is key to success when wire rope needs changed.
Wire rope is a complex machine, lifting the heaviest loads like space shuttles and precast concrete components. It does the heavy lifting when a load is being lifted by a crane and wire rope hoist. Having a good understanding of wire rope is essential for all crane technicians. Being able to understand what lay means and how to determine what kind of rope is on an existing hoist is just the beginning. Not only will this knowledge allow you to be a more effective technician for your customers, but you can promote safety in the industry.
Rope strength is a misunderstood metric. One boater will talk about tensile strength, while the other will talk about working load. Both of these are important measurements, and it’s worth learning how to measure and understand them. Each of these measurements has different uses, and here we’re going to give a brief overview of what’s what. Here’s all you need to know about rope strength.
Each type of line, natural fiber, synthetic and wire rope, have different breaking strengths and safe working loads. Natural breaking strength of manila line is the standard against which other lines are compared. Synthetic lines have been assigned “comparison factors” against which they are compared to manila line. The basic breaking strength factor for manila line is found by multiplying the square of the circumference of the line by 900 lbs.
When you purchase line you will buy it by its diameter. However, for purposes of the USCG license exams, all lines must be measured by circumference. To convert use the following formula.
As an example, if you had a piece of ½” manila line and wanted to find the breaking strength, you would first calculate the circumference. (.5 X 3.14 = 1.57) Then using the formula above:
To calculate the breaking strength of synthetic lines you need to add one more factor. As mentioned above, a comparison factor has been developed to compare the breaking strength of synthetics over manila. Since synthetics are stronger than manila an additional multiplication step is added to the formula above.
Using the example above, letÂ’s find the breaking strength of a piece of ½” nylon line. First, convert the diameter to the circumference as we did above and then write the formula including the extra comparison factor step.
Knots and splices will reduce the breaking strength of a line by as much as 50 to 60 percent. The weakest point in the line is the knot or slice. However, a splice is stronger than a knot.
Just being able to calculate breaking strength doesn’t give one a safety margin. The breaking strength formula was developed on the average breaking strength of a new line under laboratory conditions. Without straining the line until it parts, you don’t know if that particular piece of line was above average or below average. For more information, we have discussed the safe working load of ropes made of different materials in this article here.
It’s very important to understand the fundamental differences between the tensile strength of a rope, and a rope’s working load. Both terms refer to rope strength but they’re not the same measurement.
A rope’s tensile strength is the measure of a brand-new rope’s breaking point tested under strict laboratory-controlled conditions. These tests are done by incrementally increasing the load that a rope is expected to carry, until the rope breaks. Rather than adding weight to a line, the test is performed by wrapping the rope around two capstans that slowly turn the rope, adding increasing tension until the rope fails. This test will be repeated on numerous ropes, and an average will be taken. Note that all of these tests will use the ASTM test method D-6268.
The average number will be quoted as the rope’s tensile strength. However, a manufacturer may also test a rope’s minimum tensile strength. This number is often used instead. A rope’s minimum tensile strength is calculated in the same way, but it takes the average strength rating and reduces it by 20%.
A rope’s working load is a different measurement altogether. It’s determined by taking the tensile strength rating and dividing it accordingly, making a figure that’s more in-line with an appropriate maximum load, taking factors such as construction, weave, and rope longevity into the mix as well. A large number of variables will determine the maximum working load of a rope, including the age and condition of the rope too. It’s a complicated equation (as demonstrated above) and if math isn’t your strong point, it’s best left to professionals.
However, if you want to make an educated guess at the recommended working load of a rope, it usually falls between 15% and 25% of the line’s tensile strength rating. It’s a lotlower than you’d think. There are some exceptions, and different construction methods yield different results. For example, a Nylon rope braided with certain fibers may have a stronger working load than a rope twisted out of natural fibers.
For safety purposes, always refer to the information issued by your rope’s manufacturer, and pay close attention to the working load and don’t exceed it. Safety first! Always.
If you’re a regular sailor, climber, or arborist, or just have a keen interest in knot-tying, be warned! Every knot that you tie will reduce your rope’s overall tensile strength. Some knots aren’t particularly damaging, while others can be devastating. A good rule of thumb is to accept the fact that a tied knot will reduce your rope’s tensile strength by around 50%. That’s an extreme figure, sure, but when it comes to hauling critical loads, why take chances?
Knots are unavoidable: they’re useful, practical, and strong. Splices are the same. They both degrade a rope’s strength. They do this because a slight distortion of a rope will cause certain parts of the rope (namely the outer strands) to carry more weight than others (the inner strand). In some cases, the outer strands end up carrying all the weight while the inner strands carry none of it! This isn’t ideal, as you can imagine.
Some knots cause certain fibers to become compressed, and others stretched. When combined together, all of these issues can have a substantial effect on a rope’s ability to carry loads.
Naturally, it’s not always as drastic as strength loss of 50% or more. Some knots aren’t that damaging, some loads aren’t significant enough to cause stress, and some rope materials, such as polypropylene, Dyneema, and other modern fibers, are more resilient than others. Just keep in mind that any knots or splices will reduce your rope’s operations life span. And that’s before we talk about other factors such as the weather or your rope care regime…
Wire rope is constructed of multiple strands of wire that are twisted and braided together to form a spiral design or helix. Once the separate wires are shaped into a solid form, they become a single wire with greater strength because the individual wires equalize pressure and have greater flexibility than the individual strands.
To further enhance the strength of wire ropes, they are grouped and wound together to produce cables, which adds to their usefulness as a means of support, ability to lift, and give structural stability.
A key factor in wire rope is the lay of the strands, which can be regular or lang. With regular lay, or right and ordinary lay, the strands are wound from left to right with the wires laid in the opposite direction of the lay of the strands. With lang lay, the wires are wound in the same direction.
The structure and design of wire rope produces a final product that has superior strength, excellent strength flexibility, and the ability to handle constant bending stress as well as being weather resistant.
Wire rope is one of those products that has found a place in a wide variety of industries since it can be adapted and shaped to fit several applications. It can be found as a tow cable for boats and airplanes or in the movie industry as a harness for stunt artists. The varied uses of wire rope have made it an essential part of operations that require a rope with strength, endurance, and flexibility.
In the aerospace industry, wire ropes, or Bowden cables, connect pedals and levers in the airplane cockpit to send power to aircraft systems to control the airplane. The things that are controlled by wire ropes are propeller pitch, cowl flaps, and throttle. Wire ropes on aircraft are insulated to avoid vibrations.
Wire rope is extensively used in the auto industry for a wide variety of applications due to its versatility and strength. It is used for raising windows and opening and closing sunroofs. Other uses include steering wheels, cables, exhausts, springs, sunroofs, doors, and seat components. In the manufacturing process, wire rope is used to hoist vehicles, move large body parts, and on hoists and cranes.
The construction industry has a greatest reliance on wire rope because of the need to lift and lower heavy loads. Wire rope used in construction must have extremely high strength and exceptional performance for safety reasons and efficiency. Larger versions of wire rope are used for suspension bridges and supporting concrete columns.
The main use of wire rope in food processing is for lifting, moving loads, and other heavy tasks. Finished products or raw materials require being moved in storage units and processing centers. The strength and endurance of wire rope makes it possible to move these materials. Wire rope for food processing must be able to withstand regular chemical cleaning.
As with other industries, the oil and gas industry needs strong and reliable equipment for moving heavy equipment. In ocean drilling, machinery is dropped into the ocean using wire rope to securely hold devices to be dropped to extreme depths. Wire ropes are designed to withstand the extreme pressure and stress required. A further use of wire ropes for drilling operations is to maintain stability in the drilling lines. One of the unique features of oil rig wire rope is its length, which can exceed 10,000 feet.
A very common use for wire rope is mooring and towing of sea and freshwater boats and vessels. In the shipbuilding industry, wire rope is used to secure lifeboats as well as lower them into the water. On sailboats, wire rope is used to lift and lower sails. The benefit of using wire rope is its resistance to corrosion and rust caused by salt water and ocean mist.
The skiing industry, much like heavy equipment industries, uses wire rope to hold cars, lifts, or chairs to transport skiers up the mountain. This type of wire rope comes in several varieties depending on the size of the mountain. The benefits of wire rope for skiing is its dependability, guaranteed safety, and reliability. The main challenge of wire rope for use in sports is the weather conditions it must endure.
Since the beginnings of amusement parks, wire rope has been an essential part of attraction construction. It is used to bring roller coaster cars to the top of the ride, hold swings, and pull various vehicles through attractions. One of the main concerns of public amusement parks is safety since rides are filled with powerful machinery designed to operate continuously.
Making the dangerous and exciting shots in movies requires well planned safety precautions. One of the aspects of that planning is wire rope that is designed to protect performers when they are engaged in dangerous and life threatening shots. Dependable wire ropes are ideal since they have the flexibility, strength, endurance, and versatility to be adapted to any conditions.
In architecture and design, wire rope has been used for guard rails, balustrades, and roof construction. In innovative green buildings where plants grow along the surface of the building, the plants grow along specially designed vertical wire ropes that are capable of withstanding weather conditions.
A common use of wire rope is in railings, which are safe, durable, and provide a pleasing aesthetic appeal. The use of wire rope for railings provides protection without obstructing the view from a building. This aspect of wire rope is one of the reasons that it is used for large architectural projects since it blends into the structure without interiors with the architectural design.
The types of wire rope are determined by the number of wires in each strand and how many are in the rope, which is defined by a two number system with the first number being the number of wires and the second being the number of wires in each strand. For example, a 6x19 wire rope has 6 wires in 19 strands.
There are a wide variety of products that are produced using wire rope. The demand for wire rope products is due to its strength, durability, and reliability. Since the basic purpose of wire rope is to lift and move heavy materials and items, the most common type of wire rope product is the wire rope sling.
Though the construction of wire rope slings is very similar for all types, there are certain variations applied to slings to adjust them to fit different applications. Slings are configured in various ways to fit different types of loads. These changes are referred to as hitches.
Choker Hitch: In the choker configuration, one eye of the sling is attached to the lifting hook. The second eye is looped over the first sling eye to form a noose shape or choke. The load is placed in the choke loop.
Bridle Hitch: The multiple leg or bridle hitch style has more than one wire rope sling attached to equalize the load and control balance. They reduce load damage by using fixed points on the load and offer easier rigging when hooked into fixed lifting points. .
Single Part Wire Rope Sling: The eye for a single part wire rope sling is formed by looping the wire rope back on to the rope. The end of the rope is attached by a clamp or being woven by hand or mechanically into the rope body. Single part wire rope slings use a single wire rope to produce the sling.
Braided Wire Rope Sling: A braided wire rope sling is made by braiding wire ropes to form a sling. The increased number of strands enhances the strength of the sling and its load capacity. Braiding can be done with three to nine wire ropes.
Cable Laid Wire Rope Sling: Cable laid wire rope slings are made from combining several smaller wire ropes to form a flexible, easy to handle, and kink resistant sling.
Woven Eye Wire Rope Sling: For the woven eye version of a wire rope sling, the eye is formed by weaving the wire rope into itself after forming the loop. It is designed to reduce the chance of the sling catching or being hung up when lifting.
Thimble Wire Rope Sling: To add to the strength of wire rope slings and lessen the stress on a small area of the eye, a thimble, a U shaped piece into which the wire rope fits, is placed in the eye, which helps the sling to retain its natural shape. The thimble is positioned to prevent the hook or load from coming in contact with the wire rope.
Endless Wire Rope Sling:Endless wire rope slings are adaptable slings without a set wear point. They can be manufactured in a wide range of sizes and are used in applications where headroom may be a problem. Endless wire rope slings are made by splicing the ends of a piece of wire rope together or by tucking strand ends into the body to form a core with a tucked position the opposite of the core position. They are also referred to as grommet wire rope slings.
Coiled wire rope is made from bundles of small metal wires that are twisted into a coil. It comes in many varieties and is easy to store since it does not require a spool. Coiled wire rope is produced in coils. When it is not in use, it springs back into a coil, which makes it easy to handle.
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.
Push pull wire rope assemblies are used to send force and are used in the aircraft, exercise, medical, automotive, and office equipment industries. Unlike using a single heavy wire, push pull assemblies made with wire rope are stiffer and have a larger bend radii for smoother motion of the wire.
Wire rope assemblies include wire rope and various parts and components that have been added to the wire rope to enhance its function. The connectors for a wire rope assembly are designed to connect the assembly to hooks, equipment, or machines as well as other wire rope assemblies. The central part of a wire rope assembly is the wire rope, which determines the type and kind of work the assembly can perform.
Wire rope lanyards are a standard wire rope product that have a multitude of uses. They are produced using the same process that is used to produce wire rope with the same numbering categorizing system. Lanyards are used to hold fasteners, hardware, or components to prevent loss of an item or prevent injury.
As can be seen in the image below, lanyards come with a variety of connectors to specifically fit an application. Custom designed lanyards are designed for unusual and unique functions where a standard lanyard will not fit. The variety of connectors allows the lanyard to be easily connected.
Ends Fittings or Terminals: The nature of the end fitting depends on the function of the lanyard. All manufacturers have a wide assortment of end fittings to choose from. They include stamped eyes, ball ends, ball shanks, stops, sleeves, thimbles, threaded studs, and strap forks and eyes, to name a few. The image below has a few examples of end fittings terminals.
In many ways, wire rope is a form of machine with multiple moving parts. Normally, when we think of a machine, we imagine a device with a motor, drives, and gears. Wire rope does not have any of those components but does fit the definition of being a complex mechanism. It has moving parts that work together to move heavy materials and loads.
The main function of wire rope is to do heavy lifting, which is very dependent on wire rope slings. The type of sling is determined by the quality of the wire rope used to form them and whether several ropes have been braided or wound together.
Wire is the smallest part of wire rope but makes up the various strands. The composition of the wire can be steel, iron, stainless steel, copper, or other types of metal wires and are produced in different grades. The individual wires can be coated or bright, meaning uncoated.
Strands are sets of wires that are twisted together and are placed in a helical pattern around the core. The size of the wire determines its abrasive qualities with larger wires being more abrasive and less flexible than smaller ones.
The core is the center of the wire rope and serves as a support for the strands and helps the wire rope keep its position when it is under stress or bearing a load.
Lubrication is applied during the manufacturing process to reduce friction between the wires and strands as well as protection from corrosion and rust. The tight winding of the wires enhances the ability of the wire rope to retain the lubrication which is essential to its longevity.
The purpose of applying lubricant is to limit the friction between the cables to increase the useful life of the wire rope. In certain applications, such as space travel, lubricants can be hazardous and cause equipment to malfunction. In those instances, non-lubricated wire rope is used, which is referred to as dry wire rope or cable.
Of all of the products that are made from wire rope, slings are the most common and widely used. These looped wire ropes come in different varieties and grades depending on the type of wire used. Also, to enhance wire sling performance, several wire ropes may be wound together to form a sturdier and more reliable sling.
Flemish splicing is a method for repairing a wire rope and involves breaking the wire rope in half and tying it back together. In the Flemish method, the wire rope is tied back on itself and swaged down a sleeve over the unbroken wire rope to create the new eye.
Prior to placing the wire rope into the holding device used to shape the eye, a steel compression sleeve is placed on the rope, which will be used to secure and hold the eye.
Once the proper size is achieved, the unwound strands are rewound in the reverse order of their former positioning. If the wire rope has a right hand lay, it is rewound using a left hand lay. The opposite is true if the wire rope has a left hand lay, then it is rewound using a right hand lay. By using this technique, a friction mold is formed for the splicing of the sling.
Anti-rotational wire rope resists the forces of rotation by having opposing layers of helical stands. By winding the wire rope with oppositional strands, the wire rope is guaranteed to not unwind in clockwise or counterclockwise directions. The key to anti-rotational wire rope is to ensure that the outer diameter is static.
In the manufacture of anti-rotational wire rope, counter stranded filaments have vacant spaces between them. To make the wire rope anti-rotational, it is tightly twisted in the counterclockwise direction, which tightens the spaces between the filaments. If the wire rope is turned in a counterclockwise direction, the strands tighten around each other creating a spring force.
The tails and stray wires of the wire rope have to be straightened and properly formed before applying the compression sleeve. Once the sleeve has been placed, it is carefully checked to be sure that it is accurately engaged.
Prior to placing the wire rope sling in the swaging die, the die has to be thoroughly lubricated. Once the die is set, the wire rope‘s compression sleeve and the wire rope are compressed using several hundred thousand pounds of force. The swaging process alters the dimensions of the wire rope and compression sleeve to form a tight connection for the correct diameter for the sling connection. As force is applied, the compression sleeve is turned so that pressure is evenly applied.
There are several types of metal wires that are used to produce wire rope, which include steel, stainless steel, galvanized, aluminum, nickel alloy, bronze, copper, and titanium. Carbon steel is the most common type of wire rope material.
Wire ropes are made using uncoated bright wire, which is high-carbon steel. The type of steel depends on the requirements of the wire and its tensile strength and its fatigue and wear resistance.
Galvanized wire rope is treated with zinc to prevent corrosion and can be used in harsh conditions and environments. It is a cost effective alternative to stainless steel but does not have the same corrosion resistance. Galvanized wire rope is stronger than stainless steel of the same grade and size. Vinyl coated galvanized wire rope is easy to handle and flexible.
Stainless steel wire rope is corrosion and rust resistant. It is available in types 316 and 304 with 316 having greater corrosion resistance. Stainless steel wire rope can be used for marine applications, acidic environments, and other demanding conditions. It is produced with the appropriate tolerances and composition to meet the needs of the application.
Multiple strands of copper are braided into a round hollow shape, which is pressed into the desired width and thickness. Copper wire rope has exceptional flexibility, an exceptional life span and can be used as part of electrical components.
Bronze wire rope inhibits sparking and is corrosion resistant. It is made from preformed wire to ensure that it maintains its shape and does not unravel when cut. Bronze wire rope is abrasion resistant and very flexible with a crush resistant core.
Inconel wire can be used in applications that reach temperatures as high as 2000° F and is oxidation and corrosion resistant. It is non-magnetic and has excellent resistance to chloride based corrosion cracking. Inconel wire rope can be used with nuclear generators and chemical and food processing.
Titanium wire rope comes in several grades with grade two being 99% pure. It is easily formable and weldable. Titanium wire rope is commonly used in chemical processing and marine hardware.
For wire rope to perform properly, it needs to have proper care. Wire rope is an essential tool necessary to perform a wire range of lifting and moving jobs. It is important that it be handled, treated, installed, stored, and treated correctly to prolong its life and perform to the highest standards.
Seizing should be completed on both ends of the wire rope, which will protect it from loosening. If this is done improperly, the wire rope can become distorted. Wire rope that is properly seized evenly distributes the load.
Wire rope is stored on reels or coils and has to be carefully handled when it is being removed. To ensure excellent performance, the wire rope should not be dropped during removal. If the reel or coil is dropped or damaged, it can make handling the wire rope difficult and cumbersome. As the wire rope is removed from the reel, check to see that the reel is rotating as the wire is removed.
Wire rope is depended on for heavy lifting and is trusted to keep a load and people safe. As with all heavy duty equipment, wire rope must have a regular inspection schedule and be visually assessed during use.
Broken Strands – An easy way to check for broken strands is to run a cloth over the length of the wire. Broken strands that are found in critical areas, such as parts that pass through pulleys or sections that are regularly flexed, rubbed, or constantly worked must be replaced and repaired.
Internal wear – This can be tested by flexing the wire rope, which indicates if the interior has deteriorated, experienced fatigue, or become distorted.
For wire rope to perform at the highest level, it has to be stored in a well ventilated environment that is dry, covered, and not in contact with the floor. The avoidance of high moisture or damp conditions is an absolute necessity. While the wire rope is in storage, it should be moved regularly to keep the lubricant from wearing off.
Though lubricant is applied during the manufacturing of wire rope, it wears off during use. Lubrication is the key to the performance of wire rope because it helps prevent abrasion as the wires rub against one another. Relubrication should be applied after the original lubricant has worn off.
Wire rope is a tool and must be cleaned regularly as with any form of machinery. This can be accomplished with different types of petroleum solvents and a wire brush. Mechanical methods of cleaning can include compressed air or a steam cleaner. Once the cleaning process is completed, the wire rope should be lubricated for protection.
There are several substances that can harm a wire rope. They include salt water, brine, acid, various gasses, and humidity. To avoid the intrusion of these negative effects, when a job is completed and the wire rope is to be stored, it should be cleaned, lubricated, and placed in proper storage.
When wire rope is being removed from a spool or being spooled, the operation must be performed smoothly with the spool rotating at a constant speed and rhythm. This will help prevent kinking or binding.
When a wire rope shows a reduction in diameter, has broken wires, kinks, nodes, flattened surfaces, out of place outer wires, damage from heat exposure, corrosion damage, or the formation of unexpected loops, it should be removed and replaced or be repaired.
Wire rope is regulated by the Occupational Safety and Health Administration (OSHA) as part of the regulations for cranes and derricks in construction as part of 29 CFR 1926.1413, which went into effect on November 8, 2010.
The inspection of wire ropes is on three levels: shift, monthly, and annually. Shift and monthly inspections can be completed by an approved operator, while annual inspection must be completed by certified personnel.
As with the shift and monthly inspections, the annual inspection follows the guidelines for the shift inspection. This inspection must be completed by certified personnel. The entire surface of the wire rope has to be inspected, with attention to:
Annual inspections can be excused if it is not possible due to the wire ropes setup or configuration or the location of the work site. It must be completed within six months. If any deficiencies are found, the wire rope must be repaired or removed. For some deficiencies, it is possible to keep the wire rope in use but have them regularly monitored.
Wire rope is a form of metal tool that is constructed of multiple strands of wire that are twisted and braided together to form a spiral design or helix.
To further enhance the strength of wire rope, they are grouped and wound together to produce cables, which adds to their usefulness as a means of support, ability to lift, and give structural stability.
The types of wire rope are determined by the number of wires in each strand and how many are in the rope, which is defined by a two number system with the first number being the number of wires and the second being the number of wires in each strand.
Wire rope is a collection of metal strands that have been twisted and wound to form the shape of a helix with the purpose of supporting and lifting heavy loads and performing tasks that are too rigorous for standard wire. On shipping docks, rigging, and load bearing equipment, wire rope is attached to swivels, shackles, or hooks to lift a load in a controlled, even, and efficient manner.
The uses for wire rope include adding support to suspension bridges, lifting elevators, and serving as additional reinforcement for towers. The design of wire rope, with its multiple strands wrapped around a stable core, provides strength, flexibility, and ease of handling for applications that have bending stress.
Individual designs of wire rope involve different materials, wire, and strand configurations as a means for supporting and assisting in the completion of lifting or supportive applications.
The term wire rope encompasses a wide range of mechanical tools that are made to perform heavy and extreme lifting jobs. Wire rope is a complicated and complex tool with multiple moving parts capable of moving in unison. A 6 by 25 wire rope has 150 outer strands that move as one in an intricate pattern supported by a flexible core.
An essential part of the design of wire rope is the required clearance between the strands to give each stand the freedom to move and adjust when the rope bends. It is this unique feature that differentiates wire rope from solid wire and other forms of cable.
The basic element of wire rope is wire that is used to configure, shape, and form the rope. Typically, steel, stainless steel, and galvanized wires are the first choice with aluminum, nickel alloy, bronze, copper, and titanium being second possibilities. The choice of wire is dependent on the type of work the wire is going to be used to perform with strength, flexibility, and abrasion resistance being the major determining factors.
Stainless steel wire rope has all of the basic qualities of galvanized and general wire rope with the added benefits of corrosion and rust resistance; this makes it the ideal choice for harsh and stressful conditions.
Steel wire rope is classified as general purpose wire rope and comes in a wide variety of sizes, diameters, and strengths. It is the most common type of wire rope and is used for several industrial, manufacturing, and construction applications.
Before going further into the discussion of how wire rope is made, it is important to understand the numbers used to describe each type. All wire ropes have a core around which wires are wound. The various styles of cores vary according to the construction and design of the requirements of the wire rope that is being produced.
Wire rope is classified by the number of strands it has as well as the number of wires in each strand. The most common classification is a seven wire rope that has one strand in the center and six around its circumference. This type of wire rope is lightweight with a very simple construction. The majority of wire ropes are more complex and intricate with multiple intertwining strands and wires.
What must be understood about wire rope is that it has a complicated configuration. It is actually wires wrapped around wires to form bundles that are wrapped around other bundles. In the case of a seven wire wire rope, the core has bundles of wires wound around it; this can be seen in the image below.
The first step in wire rope creation is the production of wire strands where wires are wound around a single core wire. The number of wires included in the strand is dependent on the specified strength, flexibility, and size requirements of the rope. Once the strand is completed, it is straightened before being moved to wire rope construction.
Like wire ropes, strands have different patterns; patterns are the arrangements of the wires and their diameters. Though most strands have a core, there are strand patterns that have three or four wires without a core that are referred to as centerless strands. The design of each strand pattern is meant to enhance the strength of the wire rope and improve its performance.
For a multiple layer strand, the layers of wire are placed over one another in successive order. The placement of the wires on top of each other must be such that they fit smoothly and evenly.
The Warrington pattern is like the multiple layer pattern with one variation. Like the multiple layer pattern, the inner wires and the core are the same and have the same diameter. The difference is in the outer layer, which has wires of alternating sizes of large and small with larger diameter wires laying in the valleys of the inner wires.
All of the wires of a filler pattern are the same size. What makes this pattern unique is the insertion of small wires in the valleys of the inner wires to fill the gap between the inner and outer layer.
The flattened strand pattern is also known as the triangular strand, which can be triangular or oval. Three round wires form the core. The outer flattened surface has a greater sectional metallic area; this makes this pattern stronger and longer lasting.
The core of a wire rope runs through the center of the rope and can be composed of a variety of materials, which include synthetic fibers, natural fibers, a single strand, or another wire rope. The core supports the wound strands, helps maintain their position, is an effective lubricant carrier, and provides support.
Wire ropes with fiber cores are restricted to light loads and are not used in severe, harsh, or stressful conditions. Polypropylene and nylon are types of synthetic fiber cores and can be used in conditions where there is exposure to chemicals.
Cores made of wire are classified as independent wire cores. The core of a wire rope with a wire core is actually a wire rope with another wire rope serving as the core, as can be seen in the diagram below. These types of wire ropes are used where the rope will be exposed to exceptional resistance and crushing.
A strand, or wire strand core, is exactly like the rest of the strands of the wire rope with wires of the same diameter and size as the other strands.
The choice of core and creation of the strands are the simplest yet most essential parts of wire rope construction. Wire rope lays, the method used to wind the strands, is more complex and involves several choices.
Lay is a term used to describe three of the main characteristics of wire rope: direction, relationship, and linear distance. The strands can be wrapped around the core going right or left. Right or left refers to the direction of the strands wrapped around the core and the wires within the strands. The linear distance is how far a strand moves when it is making a revolution around the core.
In a regular lay, the wires and strands spiral in opposite directions. With a right hand regular lay, the wires spiral to the left and the strands to the right. In the left hand regular lay, the wires spiral to the right and the strands to the left. This type of lay is easy to handle but wears out quickly because the crown wires are in contact with the bearing surface.
In the Lang, or Albert, lay, the wires and strands spiral in the same direction with right hand lay being the most common. The wires in a Lang lay appear to run parallel to the center line of the rope. The difficulty with Lang lay wire ropes is handling since they tend to kink, twist, and crush.
Wire rope is an exceptionally strong tool that has been configured and designed to withstand the stress placed upon it through rigorous and continual use. In most applications, wire rope has to endure extreme stress and strain. It is for these reasons that coatings have been developed to protect wire rope from abrasions, corrosion, UV rays, and harmful and damaging chemicals.
Three main types of coatings are used to protect wire rope: polyvinyl chloride (PVC), polypropylene, and nylon. Of the three types, PVC is the most popular.
PVC is popular because it is multifunctional, extremely flexible, and general purpose as well as low cost. It has an operating temperature between -30° F (-35° C) and 180° F (80° C) with a hardness of 90 on the durometer.
In cases where there are severe and hazardous working conditions, polypropylene is the recommended choice since it is capable of protecting wire rope against corrosion and chemical leaching. Additionally, it is resistant to impact damage and abrasion. Polypropylene is a tough, rigid, and crystalline thermoplastic that is made from a propene monomer and is resilient as well as inexpensive.
Nylon is exceptionally abrasion resistant, which makes it ideal for use in cold environments. It is not as flexible as PVC but has excellent protection against corrosion and impact. It has excellent chemical resistance at temperatures between -65° F (-54° C) and 230° F (110° C) and is available in a wide assortment of colors, or it can be transparent.
Braided wires are electrical conductors made up of small wires that are braided together to form a round tubular braid. The braiding and configuration of braided wire makes them very sturdy such that they do not break when flexed or bent. Braided wires are widely used as conductors, are commonly made from copper due to copper"s exceptional conductivity, and can be bare or coated depending on the application.
Braided wire can be round and tubular or flat. Round tubular braids fit in most spaces where flat braided wire will not. Flat braided wire begins as round braided wire which is flattened on a capstan. They are exceptionally strong and designed for medical and aircraft applications.
Metals used to make wire rope are various grades of stainless steel, bright steel, and galvanized steel. Though the majority of wire rope manufacturers use these three metals, other metals such as copper, aluminum, bronze, and monel are also used on a limited basis.
The most important aspect of wire rope is the wire and the metal from which it is made. The strength and resilience of wire rope is highly dependent on the quality of metal used to make it, and these are essential factors to be considered when purchasing it.
Bright steel wire does not have a coating and is rotation resistant, (designed to not rotate when lifting a load). It is drawn from hot rolled rods that are put through a die to match its specific dimensional tolerances, mechanical properties, and finish. Bright wire is used as a single line in conditions that require a rope that will resist cabling.
Galvanized steel has a zinc coating for corrosion resistance and has the same strength and durability as bright steel. Environmental conditions determine the use of galvanized steel. In mildly severe and slightly harsh conditions, galvanized steel wire is an economical replacement for stainless steel.
In the manufacturing process, galvanized wire goes through the process of galvanization, a method of coating steel wire with a protective and rust resistant metal. Galvanized wire is exceptionally strong, rust resistant, and flexible enough to meet the needs of a variety of applications.
Stainless steel does not have the same strength and endurance as bright steel or galvanized steel but has the many benefits commonly associated with stainless steel, such as resistance to stains, wear, rust, and corrosion. More expensive than the other two metals, stainless steel has the added benefit of lasting longer and providing exceptional performance.
Wire rope made from copper is mostly used for electrical applications due to its exceptional electrical characteristics. The benefits of copper wire rope are its durability, flexibility, and resilience compared to standard copper wire. The strength of copper wire rope is seen in its use in applications where there are vibrations and shaking.
The wire rope lubrication process begins during its fabrication and continues during its use. Lubrication of wire rope is designed to lower the amount of friction it endures and provide corrosion protection. Continued lubrication increases the lifespan of wire rope by preventing it from drying up, rusting, and breaking.
The types of lubricants for wire rope are penetrating or coating with coatings covering and sealing the outside of the rope. Penetrating lubricants go deep into the rope and seep into the core where they evaporate to form a thick coating or film.
The application of the lubricant is dependent on the type of core. Fiber cores absorb the lubricant and serve as a reservoir that retains the lubricant for an extended period of time. With metal cores, the lubricant is applied as the wire is twisted into strands to give complete saturation and coverage of the wires.
Petrolatum compounds are translucent and provide excellent corrosion and water resistance. They tend to drip off at high temperatures but keep their consistency in cold conditions. Petrolatum is a mixture of hydrocarbons from the distillation of petroleum that belong to the methane family of hydrocarbons. It can be used in semi-solid or liquid form and forms a jelly in its semi-solid form.
Asphaltic compounds are a mineral based oil combined with bitumen to create a tacky, high viscosity lubricant with an undiluted viscosity. As a lubricant, asphaltic compounds create an oil film that separates the mating surfaces and are applied as a spray. Once applied, the meshing of surfaces causes the solvent to flash; this leaves a viscous coating of lubricant.
There are several types of greases that are used as wire rope lubricating agents and are made up of oil, a thickener, and additives. The essential components are the base oil and additives, which influence the behavior of the grease. The thickener holds the base oil and additives together. The amount of base oil in a grease is between 70% and 95% with an additive of 10%.
The additive in grease enhances the positive properties of the oil and suppresses the negative properties. Common additives are oxidation and rust inhibitors as well as pressure, wear, and friction reducing agents.
Of the many choices for lubricants, vegetable oil is the easiest to use and penetrates the deepest. The design of the additives for vegetable oils gives them the necessary qualities required to penetrate deep into a wire rope. The exceptional penetration provides protection against wear and corrosion. Since vegetable oil is a fluid, it helps in washing the wire rope to remove external abrasive contaminants.
Wire rope is widely used in machines, structures, and varied lifting applications. Its type, size, and requirements are determined by how it will be used. Regardless of its use, wire rope guarantees exceptional strength and provides high quality and excellent performance.
The lifting of heavy loads for centuries involved the use of hemp rope or chains, neither of which was a guaranteed or substantial method. Early in the 18th Century, between 1824 and 1838, Wilhelm Albert, a German mining engineer, combined the twisting of hemp and strength of chains to create today‘s wire rope.
The most common use of wire rope is as a part of a crane hoist wherein it is attached to the hook of the hoist and wrapped around a grooved drum. The tensile strength and durability of wire rope makes an ideal tool for lifting and keeping loads secure. Though it is used in several industries, it is very popular for production environments wherein materials need to be lifted quickly and efficiently.
In addition to its many lifting applications, the strength and stability of wire rope is useful in other applications, especially in the aerospace industry. Pedals, levers, and connectors in the cockpit of an aircraft are connected with wire rope. The wires provide for the passage of power between systems and mechanisms; this allows control of the aircraft. Wire rope is used to control propeller pitch, cowl flaps, and the throttle. It also assists in lowering and minimizing vibrations.
Tires are reinforced with wire rope to increase their durability and strength. All automotive production environments make use of wire ropes for supplying materials, moving heaving loads, and positioning equipment. Wire rope can be found in the production of steering wheels, cables, exhausts, springs, sunroofs, doors, and seating components.
As surprising as it may seem, the place that wire rope has the greatest use is in the home, where its strength, long life, endurance, and resilience provide guaranteed protection and performance. The main reason wire ropes are so popular for home use is cost.
Inexpensive, easy to obtain, easy to install, and easy to maintain, wire ropes provide an additional method for performing home repairs and structural support. Their excellent flexibility and sturdiness combined with their invisibility has made wire rope an ideal solution to several home maintenance issues. It is used to support staircases, fences, decks, and hang plants.
The search and production of crude oil has relied on wire ropes for centuries to lift drill bits, insert shafts, and support oil rigs on land and the water. When equipment, machinery, and tools have to be lowered into the depths of the earth and sea, wire ropes are the tool that the oil industry relies on to do the job.
Many of the tasks of oil production require tools that are capable of enduring severe and harsh conditions. Wire ropes have to withstand enormous pressure, extraordinary stress, and a wide range of temperatures. The use of wire rope includes maintaining oil rig stability and moorings for offshore rigs.
Wire rope has long been a standard component for the transportation industry, from the cable cars of San Francisco to the lift chairs for ski resorts. For many years, cable cars have relied on heavy duty cables (wire ropes) to be pulled by a central motor from multiple locations. It is a method of transportation that has existed for centuries.
In Europe, funiculars use cables that hang from a support to move cars up and down a mountain with cables moving in opposite directions. The word funicular is from the French word funiculaire, meaning railway by cable. The terms wire rope and cable are used interchangeably when discussed by professionals. The first part of funicular, or funiculaire, is from the Latin word "funis," meaning rope.
The major use for wire ropes in the food and beverage industries is as a means for lifting and moving heavy loads. Wine barrels and containers full of ingredients are lifted and placed through use of cranes and wire ropes. They are also part of conveyor systems that move products from one station to another.
From the beginnings of amusement rides up to the present, wire ropes have been an essential part of attraction construction and safety. They pull cars on roller coasters, hold cabins that swing, and move carriages through haunted houses. The main concern of amusement parks is safety. The strength, stability, and guaranteed performance of wire ropes ensures that people who attend amusement parks will have a good time and stay safe.
The rigging used to complete the stunts in modern movies depends on wire rope for safety. Much like in amusement rides, wire ropes protect performers from injury and harm as they hang above a scene or carry out an impossible move.
The live theater industry uses wire ropes to raise and lower curtains, support overhead rigging, and hold backdrops and scenery pieces. During a production, rapid and efficient movement is a necessity that is facilitated by the use of wire ropes.
Wire rope is a tool that we tend to envision as indestructible, unable to succumb to any form of damage. Though it is exceptionally sturdy and strong as well as capable of enduri