What Is Wire Rope? Understanding the Specifications and ...

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

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

• Strength
• Flexibility
• Abrasion resistance
• Crushing resistance
• Fatigue resistance
• Corrosion resistance
• Rotation resistance

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

A Wire Rope Is a Machine with Many Moving Parts

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

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

Understanding and accepting the “machine idea” gives a rope user a greater respect for rope, and enables them to obtain better performance and longer useful life from rope applications. Anyone who uses a rope can use it more efficiently and effectively when they fully understand the machine concept.

Components of Wire Rope

There are four basic components that make up the design of a finished wire rope:

1. Wires made from metal that form a singular strand
2. Multi-wire strands laid around a core in a helical pattern
3. A fiber or steel core
4. Lubrication

Wire

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

The wires themselves can be coated but are most commonly available in a “bright” or uncoated finish.

Strands

Strands of wire rope consist of two or more wires arranged and twisted in a specific arrangement. The individual strands are then laid in a helical pattern around the core of the rope.

Strands made of larger diameter wires are more resistant to abrasion, while strands made of smaller diameter wires are more flexible.

Core

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

Lubrication

Lubrication is applied during the manufacturing process and penetrates all the way to the core. Wire rope lubrication has two primary benefits:

1. Reduces friction as the individual wires and strands move over each other
2. Provides corrosion protection and lubrication in the core, inside wires, and outside surface

Wire Rope Construction

The following terms help to define the construction and properties of wire rope:

• Length
• Size
• Preformed or Non-Preformed
• Direction and Type of Lay
• Finish of Wires
• Grade of Rope
• Type of Core

Length

The total number of feet (cut to size) when wrapped around the spool and delivered.

Size

This is the specified nominal diameter of the wire rope and can be specified in inches or millimeters.

Strand Patterns

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

• Single Layer – The most common example is a 7 wire strand with a single-wire center and six wires of the same diameter around it.
• Filler Wire – Two layers of uniform-size wire around a center with the inner layer having half the number of wires as the outer layer. Small filler wires, equal to the number in the inner layer, are laid in valleys of the inner wire.
• Seale – Two layers of wires around a center with the same number of wires in each layer. All wires in each layer are the same diameter. The large outer wires rest in the valleys between the smaller inner wires.
• Warrington – Two layers of wires around a center with one diameter of wire in the inner layer, and two diameters of wire alternating large and small in the outer later. The larger outer-layer wires rest in the valleys, and the smaller ones on the crowns of the inner layer.
• Combination – A combination strand is constructed using any combination of two or more of the patterns listed above.

Preformed or Non-Preformed

On a preformed wire rope, the strands and wires are formed during the manufacturing process to the helical shape that they will take in a finished wire rope.

Preformed rope can be advantageous in certain applications where it needs to spool more uniformly on a drum, needs greater flexibility, or requires more fatigue-resistance when bending.

Direction and Type of Lay

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

• Regular Lay – The wires line up with the axis of the rope. The direction of the wire lay in the strand is opposite to the direction of the strand lay. Regular lay ropes are more resistant to crushing forces, are more naturally rotation-resistant, and also spool better in a drum than lang lay ropes.
• Lang Lay – The wires form an angle with the axis of the rope. The wire lay and strand lay around the core in the same direction. Lang Lay ropes have a greater fatigue-resistance and are more resistant to abrasion.
• Alternate Lay – The wire rope consists of alternating regular lay and lang lay strands—used mainly for special applications.

Finish of Wires

Zinc coated (galvanized), zinc/aluminum alloy coated (mischmetal), stainless steel, or unfinished steel (“bright”).

Grade of Rope

The strength of wire rope is broken down into different grades, including:

• Improved Plow Steel (IPS)
• Extra Improved Plow Steel (EIPS) is 15% stronger than IPS
• Extra Extra Improved Plow Steel (EEIPS) is 10% stronger than EIPS

The plow steel strength curve forms the basis for calculating the strength of most steel rope wires.

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Type of Core

Wire rope cores are designated as:

• Fiber Core (FC)
• Independent Wire Rope Core (IWRC)
• Wire Strand Core (WSC)

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

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

Based on what we’ve learned above, this wire rope description would provide the user with the following information:

1″ 6 x 25 FW EIP RRL IWRC

• Diameter = 1″
• Number of Strands = 6
• Number of Wires Per Strand = 25
• Strand Pattern = Filler wire
• Grade = Extra Improved Plow Steel
• Direction and Lay = Right Regular Lay
• Core Type = Independent Wire Rope Core

Different Types of Wire Rope

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

The table below shows some of the most common wire rope configurations arranged in specific classifications.

Besides the general classifications of wire rope, there are other types of wire rope that are special construction and designed for special lifting applications.

Rotation Resistant Wire Rope

Some types of wire rope, especially lang lay wire rope, are more susceptible to rotation when under load. Rotation resistant wire rope is designed to resist twisting, spinning, or rotating and can be used in a single line or multi-part system.

Special care must be taken when handling, unreeling, and installing rotation resistant wire rope. Improper handling or spooling can introduce twist into the rope which can cause uncontrolled rotation.

Compacted Strand Wire Rope

Compacted strand wire rope is manufactured using strands that have been compacted, reducing the outer diameter of the entire strand, by means of passing through a die or rollers. This process occurs prior to closing of the rope.

This process flattens the surface of the outer wires in the strand, but also increases the density of the strand. This results in a smoother outer surface and increases the strength compared to comparable round wire rope (comparing same diameter and classification), while also helping to extend the surface life due to increased wear resistance.

Compacted / Swaged Wire Rope

A swaged wire rope differs from a compacted strand wire rope, in that a swaged wire rope’s diameter is compacted, or reduced, by a rotary swager machine after the wire rope has been closed. A swaged wire rope can be manufactured using round or compacted strands.

The advantages of a swaged wire rope are that they are more resistant to wear, have better crushing resistance, and high strength compared to a round strand wire rope of equal diameter and classification. However, a swaged wire rope may have less bending fatigue resistance.

Plastic Coated Wire Rope

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

Plastic Impregnated (PI) Wire Rope

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

Plastic Coated or Plastic Filled IWRC Wire Rope

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

Wrapping it Up

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

• Strength
• Flexibility
• Abrasion resistance
• Crushing resistance
• Fatigue resistance
• Corrosion resistance
• Rotation resistance

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

At Mazzella Companies, we offer all different kinds of wire rope from all of the leading manufacturers. We sell the highest-quality domestic and non-domestic rigging products because product quality and operating safety go hand-in-hand. We have one of the largest and most complete inventories of both domestic and non-domestic rigging and lifting products to suit your lifting needs.

Galvanised steel wire rope is ideal for long-term outdoor use, prioritizing corrosion resistance, While Ungalvanized steel wire rope is better suited for less demanding environments where corrosion isn’t a concern. In this article, I’ll highlight the key differences, advantages, common specifications, and guide you on how to choose the right option.

What is Galvanised Steel Wire Rope and Ungalvanized Steel Wire Rope?

Galvanised Steel Wire Rope:

• A Galvanised Steel Wire Rope refers to a wire rope that has undergone a galvanization process, typically involving hot-dip galvanizing or electro-galvanizing, where a protective layer of zinc is applied to the steel wires. This zinc coating provides corrosion resistance, significantly enhancing the rope’s durability when exposed to harsh environments, especially moisture, salts, and chemicals. The coating acts as a sacrificial anode, protecting the underlying steel from rust and oxidation.
• Galvanised ropes are typically used in marine, offshore, construction, and other outdoor applications where prolonged exposure to corrosive conditions is expected. The rope’s construction can vary (e.g., 6×19, 7×19, 1×19) depending on the required flexibility, strength, and resistance to wear.

Ungalvanized Steel Wire Rope:

• Ungalvanized Steel Wire Rope refers to a wire rope made of plain steel, carbon steel, or stainless steel, without any protective coating like zinc. As such, it lacks the inherent corrosion resistance found in galvanised ropes, making it susceptible to rust and degradation in humid or corrosive environments.
• While ungalvanized ropes are often used in controlled, dry indoor environments or for applications where external corrosion is not a major concern, their limited resistance to external elements means they are not suitable for prolonged outdoor or harsh conditions unless further treatments are applied (e.g., lubrication or protective coatings). The construction of ungalvanized ropes, such as 7×7, 7×19, and 1×19, remains the same as galvanised ropes, but the lack of galvanization reduces their service life when exposed to weathering, abrasion, and chemical attack.
  
  

What Is the Difference Between Galvanised Wire Rope and Ungalvanized Wire Rope?

Corrosion Resistance:

• Galvanised ropes offer superior resistance to rust and corrosion due to the zinc coating.
• Ungalvanized ropes are more susceptible to rusting and degradation when exposed to moisture or harsh environments.

Durability and Lifespan:

• Galvanised ropes generally last longer, especially in outdoor or marine environments.
• Ungalvanized ropes wear out faster when exposed to the elements.

Wire Rope Procurement Cost：

• Galvanised ropes tend to be more expensive due to the additional coating process.
• Ungalvanized ropes are cheaper upfront but may require more maintenance and replacement over time.

Appearance:

• Galvanised ropes have a silver or greyish finish due to the zinc coating.
• Ungalvanized ropes have a natural steel color, usually a darker or rust-colored finish over time if exposed to moisture.
  
  

What Is the Most used Galvanised Steel Wire Rope Construction?

Galvanised steel wire ropes is widely used in various industries due to its corrosion resistance, especially in outdoor and harsh environments. The most common and widely used structural types in everyday applications are as follows:

7×7 Construction：

• Description: 7 strands, each containing 7 wires twisted together.
• Applications: This construction provides a good balance between strength and flexibility, making it suitable for general-purpose lifting, rigging, and hoisting applications.
• Common Industries:
• Construction: Used for lifting and hoisting heavy loads, cranes, and rigging applications.
• Marine: Employed for docking, mooring, and towing operations.
• Logistics & Transportation: Used in material handling, loading, and unloading systems

7×19 Construction：

• Description: 7 strands, each containing 19 wires twisted together, offering higher flexibility than 7×7.
• Applications: This structure is used in applications that require greater flexibility and dynamic performance, such as winching, marine applications, and elevator ropes.
• Common Industries:
• Marine: For anchor lines, mooring, towing, and other marine lifting operations.
• Construction: Frequently used for cranes and hoists where flexibility is important.
• Entertainment & Stage Rigging: For suspending heavy loads such as lighting rigs or stage equipment.

6×19 and 6×37 Construction：

• Description: 6 strands, with 19 or 37 wires per strand, offering a mix of strength, flexibility, and abrasion resistance.
• Applications: Ideal for heavy-duty lifting, hoisting, and marine applications, where high strength and durability are required.
• Common Industries:
• Marine: For mooring lines, offshore drilling, and marine cranes.
• Oil & Gas: Used on offshore platforms for lifting, rigging, and material handling.
• Construction: Heavy lifting equipment, like tower cranes and hoists.

1×19 Construction：

• Description: 1 strand with 19 wires twisted together, offering high strength and rigidity with limited flexibility.
• Applications: Typically used in rigid lifting applications where strength is more important than flexibility, such as in elevators and static hoisting.
• Common Industries:
• Construction: For high-strength applications, such as elevator cables or static hoists.
• Mining: Used in mining hoists and equipment requiring high rigidity.
  
  

What Is the Most used Ungalvanized Steel Wire Rope Construction?

The most commonly used Ungalvanized Steel Wire Rope construction is 7×19. This construction provides excellent flexibility and strength, making it ideal for applications where high flexibility is required, such as winching, marine operations, and elevator ropes. It’s widely used in environments where corrosion resistance is not a primary concern or where additional protective coatings are applied post-installation.

For more galvanized steel wire rope manufacturerinformation, please contact us. We will provide professional answers.

7×7 Class：

• Description: 7 strands, each containing 7 wires twisted together, offering a balance of strength and flexibility.
• Applications: General-purpose lifting, hoisting, and rigging in indoor or low-exposure environments, such as in factories, warehouses, and material handling.

7×19 Class：

• Description: 7 strands, each containing 19 wires twisted together, providing greater flexibility than 7×7.
• Applications: Used in winching, marine applications, elevator ropes, and dynamic lifting. Common in entertainment rigging and suspension systems.

1×19 Class:

• Description: 1 strand with 19 wires, offering high strength and rigidity, with limited flexibility.
• Applications: Static lifting, hoisting, and elevator cables, especially in construction and mining applications that require rigidity over flexibility.

6×19 Class:

• Description: 6 strands, each with 19 wires twisted together, offering a combination of strength and flexibility.
• Applications: Used for heavy-duty lifting, crane ropes, and hoisting in construction and industrial environments.

6×37 Class:

• Description: 6 strands, each with 37 wires, providing excellent flexibility and abrasion resistance.
• Applications: Common in heavy-duty applications, marine operations, winching, and rigging in construction and oil & gas industries.

8×7 Class:

• Description: 8 strands, each with 7 wires twisted together.
• Applications: Primarily used in hoisting and lifting applications where strength and medium flexibility are required. Suitable for indoor material handling and light rigging.

8×19 Class:

• Description: 8 strands, each containing 19 wires, offering good flexibility and strength.
• Applications: Used for lifting and hoisting in applications that require high flexibility and load-bearing capacity, such as elevator ropes and marine lifting.

8×37 Class:

• Description: 8 strands, each with 37 wires twisted together, providing high flexibility and strength.
• Applications: Suitable for heavy-duty lifting and dynamic loading in industrial and marine environments, such as cranes, winches, and towing operations.
  
  

How to Choose Between Galvanised and Ungalvanized Steel Wire Rope?

1.Environmental Considerations:

• If the rope will be exposed to moisture, chemicals, or extreme weather, galvanised ropes are a better choice due to their corrosion resistance.
• Ungalvanized ropes may be suitable for indoor, dry environments where rust is not a major concern.

2.Budget vs. Durability:

• Consider the cost of the rope versus how long it will last in your specific application. Galvanised ropes are an investment for long-term durability.

3.Required Strength and Flexibility:

• Depending on the application, the structure of the rope (e.g., 7×7 or 7×19) may matter more than whether it is galvanised or not.

4.Maintenance Considerations:

• Galvanised ropes require less maintenance because of their corrosion resistance.
• Ungalvanized ropes need more frequent inspection and potential replacement in corrosive environments.
  
  

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