Understanding the basics of wire rope will help guide you on how to choose the right wire rope for your job. Application, required strength, and environmental conditions all play a factor in determining the type of wire rope that is best for you.
But when it comes to buying wire rope, the various numbers and abbreviations that describe the different types of wire rope can be confusing. EIPS wire rope, 6X19 IWRC wire rope, and lang lay wire rope are just some of the many variations available. But what does it all mean?
These wire rope basics will help you understand the differences among types of wire so you can buy with confidence.
Displayed as inch or fractional inch measurements, the size indicates the diameter of the rope. Industry standards measure the rope at its widest point. A wide range of sizes are available from 1/8” wire rope to 2-1/2” wire rope. Thicker sized wire rope has a higher break strength. For example, our Wire Rope has a 15,100 lb. break strength while our Wire Rope has a 228,000 lb. break strength.
Wire rope is composed of individual wires that are twisted to form strands, which twist again to form a rope construction.
7/16" stainless steel wire rope: 6 x 19 construction
The numbers indicate its construction. For example: in wire rope, as shown above the first number is the number of strands (6); the second number is how many wires make up one strand (19).
Numbers may also be followed by a letter combination such as FW or WS which indicates how the outside layer is constructed.
This refers to the twisting direction of the wires and strands during the construction of the rope.
When it comes to wire rope basics, regular lay also refers to right lay or ordinary lay. This indicates that the strands pass from left to right across the rope and the wires in the rope lay in opposite direction to the lay of the strands. This type of construction is the most common and offers the widest range of applications for the rope.
This term indicates that the wires twist in the same direction as the strands. These ropes are generally more flexible and have increased wearing surface per wire than right lay ropes. Because the outside wires lie at an angle to the rope’s axis, internal stress is reduced making it more resistant to fatigue from bending. This type of rope is often used in construction, excavating, and mining applications.
Refers to what makes up the center of the wire rope.
Fiber cores are made of vegetable (sisal, etc.) or synthetic (polypropylene, etc.) fiber and offer more elasticity.
Independent wire rope cores offer more support to the outer strands and have a higher resistance to crushing and heat. Independent wire rope core also has less stretch and more strength.
Refers to the grade of steel used. Classifications include:
IPS= improved plowed steel.
EIPS = extra improved plowed steel (approximately 10% stronger than IPS).
EEIPS= extra extra improved plowed steel (approximately 10% stronger than the EIPS).
GIPS= galvanized improved plowed steel; galvanized wires add corrosion resistance.
DGEIP= drawn galvanized improved plow steel; galvanized for corrosion resistance. Drawn wires generally have a higher break load than GIPS.
6 x 37 EIPS IWRC 3/8" galvanized wire rope
This last tip on wire rope basics refers to the protective coating applied to the rope.
Made with uncoated wires manufactured from high carbon steel.
Provides extra corrosion resistance.
Highly resistant to corrosion and is commonly used in marine applications.
3/4" bright wire rope: 8 x 19 EIPS IWRC
Many of our customers use our rope and our wire rope clips to create rope assemblies. Check out of video blog on Wire Rope Clips to Wire Rope Assemblies to learn more.
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.
Wire rope is a preferred lifting device for many reasons. Its unique design consists of multiple steel wires that form individual strands laid in a helical pattern around a core. This structure provides strength, flexibility, and the ability to handle bending stresses. Different configurations of the material, wire, and strand structure will provide different benefits for the specific lifting application, including:
However, selecting the proper wire rope for your lifting application requires some careful thought. Our goal is to help you understand the components of a wire rope, the construction of wire rope, and the different types of wire rope and what they might be used for. This will allow you to select the best performing and longest-lasting wire rope for the job at hand.
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.
There are four basic components that make up the design of a finished wire rope:
Wires are the smallest component of wire rope and they make up the individual strands in the rope. Wires can be made from a variety of metal materials including steel, iron, stainless steel, monel, and bronze. The wires can be manufactured in a variety of grades that relate to the strength, resistance to wear, fatigue resistance, corrosion resistance, and curve of the wire rope.
The wires themselves can be coated but are most commonly available in a “bright” or uncoated finish.
Strands of wire rope consist of two or more wires arranged and twisted in a specific arrangement. The individual strands are then laid in a helical pattern around the core of the rope.
Strands made of larger diameter wires are more resistant to abrasion, while strands made of smaller diameter wires are more flexible.
The core of a wire rope runs through the center of the rope and supports the strands and helps to maintain their relative position under loading and bending stresses. Cores can be made from a number of different materials including natural or synthetic fibers and steel.
Lubrication is applied during the manufacturing process and penetrates all the way to the core. Wire rope lubrication has two primary benefits:
The following terms help to define the construction and properties of wire rope:
The total number of feet (cut to size) when wrapped around the spool and delivered.
This is the specified nominal diameter of the wire rope and can be specified in inches or millimeters.
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.
On a preformed wire rope, the strands and wires are formed during the manufacturing process to the helical shape that they will take in a finished wire rope.
Preformed rope can be advantageous in certain applications where it needs to spool more uniformly on a drum, needs greater flexibility, or requires more fatigue-resistance when bending.
Direction and type of lay refer to the way the wires are laid to form a strand (either right or left) and how the strands are laid around the core (regular lay, lang lay, or alternate lay).
Zinc coated (galvanized), zinc/aluminum alloy coated (mischmetal), stainless steel, or unfinished steel (“bright”).
The strength of wire rope is broken down into different grades, including:
The plow steel strength curve forms the basis for calculating the strength of most steel rope wires.
Wire rope cores are designated as:
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:
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.
ClassificationOuter StrandsWires / Strand6 x763–146 x 19615–266 x 36627–496 x 61650–746 x 91675–1097 x 19715–267 x 36727–498 x 783–148 x 19815–268 x 36827–498 x 61850–74Besides the general classifications of wire rope, there are other types of wire rope that are special construction and designed for special lifting applications.
Some types of wire rope, especially lang lay wire rope, are more susceptible to rotation when under load. Rotation resistant wire rope is designed to resist twisting, spinning, or rotating and can be used in a single line or multi-part system.
Special care must be taken when handling, unreeling, and installing rotation resistant wire rope. Improper handling or spooling can introduce twist into the rope which can cause uncontrolled rotation.
Compacted strand wire rope is manufactured using strands that have been compacted, reducing the outer diameter of the entire strand, by means of passing through a die or rollers. This process occurs prior to closing of the rope.
This process flattens the surface of the outer wires in the strand, but also increases the density of the strand. This results in a smoother outer surface and increases the strength compared to comparable round wire rope (comparing same diameter and classification), while also helping to extend the surface life due to increased wear resistance.
A swaged wire rope differs from a compacted strand wire rope, in that a swaged wire rope’s diameter is compacted, or reduced, by a rotary swager machine after the wire rope has been closed. A swaged wire rope can be manufactured using round or compacted strands.
The advantages of a swaged wire rope are that they are more resistant to wear, have better crushing resistance, and high strength compared to a round strand wire rope of equal diameter and classification. However, a swaged wire rope may have less bending fatigue resistance.
A plastic coating can be applied to the exterior surface of a wire rope to provide protection against abrasion, wear, and other environmental factors that may cause corrosion. However, because you can’t see the individual strands and wires underneath the plastic coating, they can be difficult to inspect.
Plastic filled wire ropes are impregnated with a matrix of plastic where the internal spaces between the strands and wires are filled. Plastic filling helps to improve bending fatigue by reducing the wear internally and externally. Plastic filled wire ropes are used for demanding lifting applications.
This type of wire rope uses an Independent Wire Rope Core (IWRC) that is either filled with plastic or coated in plastic to reduce internal wear and increase bending fatigue life.
Remember, wire rope is a complex piece of mechanical machinery. There are a number of different specifications and properties that can affect the performance and service life of wire rope. Consider the following when specifying the best type of wire rope for your lifting application:
When you select a piece of rope that is resistant to one property, you will most likely have a trade-off that affects another property. For example, a fiber core rope will be more flexible, but may have less crushing resistance. A rope with larger diameter wires will be more abrasion resistant, but will offer less fatigue resistance.
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.
If you’re looking for a standard or custom specified wire rope for your lifting project, contact a Lifting Specialist at a Mazzella Companies location near you.
We stock well over 2,000,000 feet of wire rope in our various locations … ready for immediate delivery! We provide wire rope assemblies, and manufacture bridge cables, crane cables, steel mill cables, and thousands of OEM assemblies.
We can also manufacture assemblies with standard or custom end fittings. Special testing and tolerance requirements are also available.
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We can produce any assembly to fit your specifications precisely.
When ordering, many factors must be considered, including but not limited to:
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