This article takes an in depth look at wire rope.
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Wire rope is made up of multiple strands of wire twisted and braided together into a spiral or helix design. When these individual wires are combined into a solid form, they create a single, stronger wire. The combined strands distribute pressure evenly and offer greater flexibility than the individual wires alone.
To further increase the strength of wire ropes, they are grouped and wound together to form cables. This process enhances their utility, making them more effective for support, lifting, and providing structural stability.
A key factor in wire rope construction is the lay of the strands, which can be either regular or lang. In regular lay, also known as right or ordinary lay, the strands are wound from left to right, with the wires laid in the opposite direction of the strand's lay. In contrast, with lang lay, the wires are wound in the same direction as the strand's lay.
The structure and design of wire rope result in a final product with superior strength, exceptional flexibility, and the capacity to withstand constant bending stress. Additionally, wire rope is weather-resistant, making it highly durable in various conditions.
Wire rope is a versatile product used across a wide range of industries due to its adaptability and ability to be shaped for various applications. It is used as tow cables for boats and airplanes and as harnesses for stunt artists in the movie industry. The diverse applications of wire rope make it an essential tool in operations requiring strength, endurance, and flexibility.
In the aerospace industry, wire ropes, also known as Bowden cables, are used to connect pedals and levers in the airplane cockpit, transmitting power to various aircraft systems for controlling the plane. These cables control functions such as propeller pitch, cowl flaps, and throttle. To prevent vibrations, wire ropes on aircraft are insulated.
Wire rope is widely utilized in the auto industry for numerous applications due to its versatility and strength. It is employed for raising windows, opening and closing sunroofs, and is also found in steering systems, exhausts, springs, doors, and seat components. During the manufacturing process, wire rope is used to hoist vehicles, move large body parts, and is integral to the operation of hoists and cranes.
The construction industry heavily relies on wire rope due to its essential role in lifting and lowering heavy loads. For safety and efficiency, wire rope used in construction must exhibit extremely high strength and exceptional performance. Larger versions of wire rope are employed in suspension bridges and for supporting concrete columns.
In food processing, wire rope is primarily used for lifting, moving loads, and handling other heavy tasks. It is essential for transporting finished products and raw materials within storage units and processing centers. The strength and durability of wire rope enable it to manage these tasks effectively. Additionally, wire rope used in food processing must be resistant to regular chemical cleaning.
In the oil and gas industry, strong and reliable equipment is crucial for handling heavy loads. During ocean drilling, wire rope is used to lower machinery into the ocean, securely anchoring devices at extreme depths. These wire ropes are engineered to endure the intense pressure and stress involved. Additionally, wire ropes play a role in maintaining stability in drilling lines. Notably, wire ropes used in oil rigs can be exceptionally long, with lengths exceeding 10,000 feet.
Wire rope is widely used for mooring and towing sea and freshwater boats and vessels. In the shipbuilding industry, it is essential for securing and lowering lifeboats into the water. On sailboats, wire rope is used to lift and lower sails. Its key advantage is its resistance to corrosion and rust, which is caused by saltwater and ocean mist.
In the skiing industry, wire rope is used to support cars, lifts, or chairs that transport skiers up the mountain. The type of wire rope used varies depending on the size of the mountain. The advantages of using wire rope in skiing include its dependability, guaranteed safety, and reliability. However, a key challenge is ensuring the wire rope can withstand the harsh weather conditions it encounters.
Since the early days of amusement parks, wire rope has been crucial in constructing attractions. It is used to lift roller coaster cars to the top of rides, support swings, and pull vehicles through various attractions. Safety is a major concern for public amusement parks, given the powerful machinery and continuous operation required for rides.
Creating thrilling and dangerous movie scenes requires meticulous safety planning, including the use of wire rope to protect performers. Wire rope designed for these purposes must be dependable, offering the flexibility, strength, endurance, and versatility needed to adapt to various conditions and ensure safety during high-risk stunts.
In architecture and design, wire rope is used in various applications such as guardrails, balustrades, and roof construction. In innovative green buildings, wire rope supports vertical gardens by allowing plants to grow along specially designed ropes that can endure different 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 classified based on the number of wires in each strand and the total number of strands in the rope. This classification follows a two-number system: the first number represents the total number of wires, while the second number indicates the number of wires in each strand. For example, a 6x19 wire rope consists of 6 strands, each containing 19 wires.
The wire shown is a 7x7 stainless steel wire rope made from grade 302 stainless steel. As depicted in the diagram, it consists of seven wires and seven strands.
A wide variety of products are made using wire rope, driven by its strength, durability, and reliability. One of the most common wire rope products is the wire rope sling, which is primarily used for lifting and moving heavy materials and items.
While the basic construction of wire rope slings is similar across all types, there are variations tailored to specific applications. These variations, known as hitches, adjust the sling configuration to accommodate different types of loads.
Vertical Hitch: A vertical hitch involves attaching one eye of the wire rope to the hook and the other eye to the load.
Choker Hitch: In the choker configuration, one eye of the sling is attached to the lifting hook, while the second eye is looped over the first sling eye to create a noose or choke shape. The load is then placed within this choke loop.
Basket Hitch: The basket hitch is formed when both eyes of the sling are looped over the lifting hook, creating a sling that supports the load from both sides.
Bridle Hitch: The multiple leg or bridle hitch style involves more than one wire rope sling, which helps to equalize the load and maintain balance. This configuration minimizes load damage by utilizing fixed points on the load and facilitates easier rigging when connected to fixed lifting points.
Single Part Wire Rope Sling: In a single-part wire rope sling, the eye is created by looping the wire rope back onto itself. The end of the rope is secured using a clamp or by weaving it manually or mechanically into the rope body. This type of sling utilizes a single wire rope to form the complete sling.
Braided Wire Rope Sling: A braided wire rope sling is created by braiding multiple wire ropes together to form the sling. This process increases the strength and load capacity of the sling due to the greater number of strands involved. Braiding can be accomplished with three to nine wire ropes.
Cable Laid Wire Rope Sling: Cable laid wire rope slings are constructed by combining several smaller wire ropes to create a flexible, easy-to-handle, and kink-resistant sling.
Woven Eye Wire Rope Sling: In the woven eye version of a wire rope sling, the eye is created by weaving the wire rope into itself after forming the loop. This design helps reduce the likelihood of the sling catching or getting hung up during lifting.
Thimble Wire Rope Sling: To enhance the strength of wire rope slings and reduce stress on a small area of the eye, a thimble—a U-shaped piece that fits the wire rope— is placed in the eye. This helps the sling maintain its natural shape and prevents the hook or load from coming into contact with the wire rope.
Endless Wire Rope Sling:Endless wire rope slings, also known as grommet wire rope slings, are versatile slings without a fixed wear point. They can be made in various sizes and are useful in applications with limited headroom. These slings are created by splicing the ends of a piece of wire rope together or by tucking the strand ends into the body to form a core with the tucked position opposite to the core.
Coiled wire rope is created from bundles of small metal wires twisted into a coil. Available in various types, it is easy to store because it does not need a spool. Coiled wire rope is manufactured in coils and, when not in use, naturally springs back into its coiled shape, making it simple 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 consist of the wire rope itself along with various added components that enhance its functionality. These assemblies include connectors designed to link the rope to hooks, equipment, machines, or other wire rope assemblies. The central element of a wire rope assembly is the wire rope, which defines the type and extent of work the assembly can perform.
Wire rope assemblies are utilized for:
Wire rope lanyards are a versatile wire rope product manufactured using the same process and numbering system as wire rope. They are designed to secure fasteners, hardware, or components, helping to prevent loss or reduce the risk of injury.
As shown in the image below, lanyards are available with a range of connectors tailored to specific applications. Custom-designed lanyards are created for unique or specialized functions where standard lanyards may not be suitable. The variety of connectors ensures easy and secure attachment.
When deciding to purchase a lanyard, consider the following factors:
In many respects, wire rope functions like a machine with multiple moving parts. Although it lacks traditional components like motors, drives, and gears, wire rope fits the definition of a complex mechanism due to its intricate design. Its various elements work in unison to handle and transport heavy materials and loads.
The primary function of wire rope is heavy lifting, which relies significantly on wire rope slings. The type of sling used depends on the quality of the wire rope and whether multiple ropes have been braided or wound together.
The components of wire rope include the wire itself, a core, strands, and lubricant.
Wire is the fundamental component of wire rope, forming the strands. It can be made from steel, iron, stainless steel, copper, or other metals and comes in various grades. Wires may be coated or left bright (uncoated).
Strands are groups of wires twisted together and arranged in a helical pattern around the core. The size of the wires affects their abrasive qualities, with larger wires being more abrasive and less flexible compared to smaller ones.
The core is the central component of the wire rope, providing support for the strands and maintaining the rope's shape under stress or when bearing a load.
Lubrication is applied during manufacturing to minimize friction between the wires and strands, and to protect against corrosion and rust. The tight winding of the wires helps the wire rope retain this lubrication, which is crucial for its durability and longevity.
Lubricant is applied to wire ropes to reduce friction between the cables, thereby extending their lifespan. However, in specific applications, such as space travel, where lubricants can pose risks or cause equipment malfunctions, non-lubricated wire ropes—known as dry wire ropes or cables—are used instead.
Among the various products made from wire rope, slings are the most prevalent and widely used. These looped wire ropes come in different varieties and grades based on the type of wire used. To enhance performance, multiple wire ropes can be wound together, creating a sturdier and more reliable sling.
For processing and delivery, wire rope is spooled. The production of wire rope slings starts with unspooling this wire rope.
The wire rope is cut to the required length to create the sling.
Flemish splicing is a technique used to repair wire rope. It involves cutting the rope in half and then rejoining it. In this method, the wire rope is doubled back on itself, and a sleeve is swaged over the unbroken section to form a new eye.
Before inserting the wire rope into the holding device for shaping the eye, a steel compression sleeve is placed onto the rope. This sleeve is used to secure and hold the eye in place.
To create the correct eye size, the rope is unwound to the number of lays needed for the specific eye configuration.
Once the correct size is reached, the unwound strands are rewound in the reverse order of their original arrangement. If the wire rope has a right-hand lay, it is rewound using a left-hand lay, and vice versa. This technique creates a friction mold necessary for splicing the sling.
Anti-rotational wire rope is designed to resist rotational forces by incorporating opposing layers of helical strands. This construction prevents the rope from unwinding in either clockwise or counterclockwise directions. The effectiveness of anti-rotational wire rope relies on maintaining a static outer diameter.
In the production of anti-rotational wire rope, the filaments are counter-stranded with intentional gaps between them. To achieve anti-rotational properties, the rope is tightly twisted counterclockwise, closing these gaps and creating a spring force when the rope is rotated in that direction. This design ensures that the strands tighten around each other, preventing unwinding.
Before applying the compression sleeve, the tails and stray wires of the wire rope must be straightened and properly aligned. After placing the sleeve, it is crucial to verify that it is correctly positioned and fully engaged to ensure a secure and effective splice.
Before inserting the wire rope sling into the swaging die, ensure that the die is thoroughly lubricated. Once the die is prepared, the wire rope's compression sleeve and the wire rope are subjected to several hundred thousand pounds of pressure. This swaging process modifies the dimensions of both the wire rope and the compression sleeve to create a tight, precise connection, ensuring the correct diameter for the sling. During compression, the sleeve is rotated to ensure even application of pressure.
The final step in manufacturing a wire rope sling is to test it to verify that it meets its load specifications and performs reliably under the intended conditions.
What are the different types of metal wires used to produce wire rope?
Wire ropes are made from uncoated bright wire, which is high-carbon steel. The specific type of steel used depends on the wire’s requirements for tensile strength, fatigue resistance, 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 known for its corrosion and rust resistance, making it suitable for challenging environments. It is available in two main types: 316 and 304, with 316 offering superior corrosion resistance. This type of wire rope is ideal for marine applications, acidic conditions, and other demanding environments. It is manufactured to precise tolerances and composition to meet the specific requirements of its intended use.
Copper wire rope is crafted by braiding multiple strands of copper into a round hollow shape, which is then pressed to achieve the desired width and thickness. Known for its exceptional flexibility and durability, copper wire rope is often utilized in electrical components and applications requiring reliable, long-lasting performance.
Bronze wire rope is designed to inhibit sparking and resist corrosion. It is manufactured from preformed wire to maintain its shape and prevent unraveling when cut. This type of wire rope offers excellent abrasion resistance, flexibility, and features a crush-resistant core.
Inconel wire is suitable for applications with temperatures up to 2000°F and offers resistance to oxidation and corrosion. It is non-magnetic and highly resistant to chloride-based corrosion cracking. Inconel wire rope is commonly used in nuclear generators as well as in chemical and food processing industries.
Titanium wire rope is available in various grades, with Grade 2 being 99% pure. It is known for its excellent formability and weldability. Titanium wire rope is widely used in chemical processing and marine hardware applications.
To ensure optimal performance, wire rope requires proper care. As an essential tool for various lifting and moving tasks, it is crucial to handle, treat, install, store, and maintain it correctly to extend its lifespan and ensure it performs at its best.
Seizing should be applied to both ends of the wire rope to prevent it from loosening. Improper seizing can lead to distortion of the wire rope. Properly seized wire rope ensures an even distribution of the load.
Wire rope should be stored on reels or coils and handled with care during removal. To maintain its performance, avoid dropping the wire rope. If the reel or coil is dropped or damaged, handling the wire rope can become challenging. Ensure that the reel rotates smoothly as the wire is being removed.
Wire rope is crucial for heavy lifting and ensuring the safety of both loads and people. Like all heavy-duty equipment, it must be regularly inspected and visually assessed during use to maintain its reliability and safety.
What to Check for During a Visual Assessment:
To ensure optimal performance, wire rope should be stored in a well-ventilated, dry, and covered environment, keeping it off the floor. It’s essential to avoid high moisture or damp conditions. While in storage, the wire rope should be moved periodically to prevent the lubricant from wearing off.
Although lubricant is applied during the manufacturing process, it diminishes with use. Regular lubrication is crucial for maintaining wire rope performance, as it prevents abrasion from the wires rubbing against each other. Relubrication should be done after the initial lubricant has worn off to ensure continued effective operation.
Wire rope, like any machinery, needs regular cleaning to maintain its effectiveness. This can be done using petroleum solvents and a wire brush. Mechanical cleaning methods, such as compressed air or a steam cleaner, can also be employed. After cleaning, it's essential to apply lubrication to protect the wire rope and ensure its longevity.
Wire ropes can be damaged by substances such as salt water, brine, acids, gases, and humidity. To prevent damage, clean and lubricate the wire rope after use and store it properly in a dry, covered environment.
When removing or spooling wire rope, ensure the operation is smooth and that the spool rotates steadily at a constant speed. This practice helps to prevent kinking and binding.
If a wire rope exhibits reduced diameter, broken wires, kinks, nodes, flattened surfaces, displaced outer wires, heat damage, corrosion, or unexpected loops, it should be removed and either repaired or replaced.
Wire rope is regulated by the Occupational Safety and Health Administration (OSHA) under the regulations for cranes and derricks in construction, specifically in 29 CFR 1926.1413, which has been in effect since November 8, 2010.
Wire rope inspections occur at three levels: shift, monthly, and annually. Shift and monthly inspections can be carried out by an approved operator, whereas the annual inspection must be performed by certified personnel.
Shift inspections are conducted at the start of each shift and involve a visual check for the following factors:
Monthly inspections follow the same guidelines as shift inspections, with the addition of:
As with the shift and monthly inspections, the annual inspection follows the same guidelines but must be completed by certified personnel. This inspection requires a thorough examination of the entire surface of the wire rope, with particular attention to:
Annual inspections can be waived if the wire rope's setup, configuration, or work site location makes it impossible to perform. However, the inspection must be completed within six months. If any deficiencies are discovered, the wire rope must be repaired or removed. In some cases, if the deficiencies do not compromise safety, the wire rope may continue to be used but must be monitored regularly.
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