wire rope bending stiffness brands

... kPSI the more brittle the wire is but the better it retains its shape. The high kPSI wire is good for making straight electrodes that need to penetrate through tissue. The low kPSI is a softer more flexible ...

1. IWSC (Independent Wire Strand Core):The core consists of a strand made of the same material as the outside strands of the wirerope. These strands are combined in configurations such as 3x7, 7x7 and 7x19. This structure can be used universally as a mechanical element and features excellent axial rigidity and bending flexibility.

2. IWRC (Independent Wire Rope Core):The core consists of a wire rope, around which the outside strands are twisted. The core wire rope and strands are combined in configurations such as {(7x7)+(1x19)x8} and others. This structure is used for mechanical elements that require high flexibility. As durability in the original form is low due to easy deformation under contact stress, these types are usually coated with a synthetic resin such as nylon.

In order to ensure the highest quality, we draw our own wire material in-house. Besides regular SS304 and SS316, Asahi also has its proprietary WHT (high-tensile strength) stainless-steel. We also work with tungsten and nitinol.

6x36 is a flexible general engineering wire rope readily available in galvanised, ungalvanised and marine grade stainless steel. The wire rope has an equal lay construction (warrington seale) and achieves a superior breaking load to the 6x19 construction range. The construction has been designed to give a flexible rope with a good fatigue life. A 6x36 wire rope is available with either FC (fibre core) or IWRC (independent wire rope core) and is used for a wide range of applications, examples of which are shown below:

Manufacturing companies choose to use Dyneema rope over steel wire rope for heavy lifting applications such as heavy lift slings, crane rope, and other rigging operations because Dyneema rope:

Dyneema fiber rope is made from Ultra-High Molecular Weight Polyethylene (UHMWPE) fiber. Dyneema 12 strand rope is a common Dyneema fibered rope used for heavy-duty rigging applications. USA Rope & Recovery manufactures several different types of Dyneema fiber rope including the popular 12 Strand, and 24 Strand ropes, as well as others. No matter the application, USA Rope provides strong, durable, and efficient rope for the marine, arborist, nautical, off-roading, and other manufacturing industries.

More times than not, Dyneema fiber rope and steel wire rope are compared by most manufacturing companies–likeThe Rigging Company–for certain maritime, mooring, and towing rope applications. Pound for pound, Dyneema fiber rope is up to 15 times stronger than steel and up to 40% stronger than aramid fibers–otherwise known as Kevlar rope. The high-performance strength and low weight of Dyneema rope ensures that it is safer to use than steel wire rope. Ideally, Manufacturing companies want a rope that can withstand tremendous weight while being light enough to move, use, and work with when needed. Traditionally, steel wire rope is used for heavy-duty maritime, rigging, and mooring rope applications. Although steel wire rope is known for being used for heavy-duty rigging, the disadvantage is the serious risks that come from its heavy-weight and uneven breakage behavior. When a steel wire rope breaks, the combination of the enormous energy and incredible force causes unpredictable recoil. This unpredictable recoil comes from how wire rope is coiled. Essentially, wire rope is several strands of metal wire twisted into a helix, forming a composite rope. When breakage occurs, the helix formed rope unravels, creating a snaking behavior which can cause sharp edges of the broken strands to release at a dangerous force. The lack of strength compared to Dyneema rope shows that steel wire rope is more susceptible to breaking. This can increase risk factors for manufacturing companies that use steel wire rope for rigging, mooring, and heavy duty lifting.

For example, when comparing a ⅜ inch 12 Strand Dyneema rope to a ⅜ inch steel wire rope, the 12 strand Dyneema rope is significantly stronger and presents safer breaking characteristics. The ⅜ inch steel wire rope withstands a load of 14,478 pounds. As the video shows, even in the event of a partial rupture, the steel wire ropes higher mass and recoil provides a greater risk over 12 Strand Dyneema rope. With a ⅜ inch 12 Strand Dyneema rope, it can withstand 18,857 pounds. With the Dyneema fibers low mass and recoil, it reduces the risks for manufacturing companies using rigging rope for heavy-duty lifting applications.

Dyneema is 7 times lighter than steel wire rope at the same strength. In the event of a break, the recoil force is considerably less. Furthermore, the different construction of a Dyneema rope shows a linear recoil without any snaking behavior. This is due to the fact that Dyneema rope is manufactured from UHMWPE, which is comprised of extremely long chains of polyethylene oriented in the same direction, resulting in an overlapping effect. The overlapping of the UHMWPE increases the bond of the chains and thereby strengthens the Dyneema fiber. Dyneema rope offers durable characteristics that can withstand an immense amount of strength while having very little weight to the rope. Because Dyneema fiber is lighter and has a lesser impact when breakage occurs, choosing Dyneema rope over steel wire rope is the safer choice for manufacturing companies working with heavy lifting and below the hook rigging applications for the industrial, nautical, and arborist industries.

When choosing the best rope for any maritime, mooring, towing, or heavy-duty lifting application, choose a rope that can withstand extremely heavy loads and has a long enough lifetime to handle external factors in the nautical, industrial, or arborist industry. In order to decide which rope is best for the job, there are four main challenges that rigging, heavy-duty lifting, mooring, and towing ropes need to overcome:

Dyneema rope is the only high modulus synthetic fiber that has been scientifically engineered–from Ultra-High Molecular Weight Polyethylene (UHMWPE)–to overcome all four of these challenges. Dyneema is the world’s strongest fiber producing ropes that are 15 times stronger than steel wire ropes of the same weight and has become one the most trusted fiber ropes over generic HMPE ropes and steel cable wire ropes for all rigging, maritime, mooring, and towing rope applications.

Manufacturing companies that work with maritime and mooring applications need a durable rigging rope to withstand the constant pulling that comes from the rope running through fairleads and over capstans. Also, in heavy-duty lifting and towing applications, ropes come in contact with rough surfaces such as chocks and the vessel’s deck. These applications can potentially provide severe abrasions to the ropes and degrade the exposed fibers, eventually breaking them. Choosing a Dyneema fibered rope provides manufacturers with a durable, lightweight rope that carries an abrasion lifetime that is four times longer than steel wire rope and rope made with regular HMPE and polyester. With Dyneema’s extended abrasion lifetime, manufacturers are choosing Dyneema rope over steel wire rope for all mooring, towing, maritime, and heavy-duty lifting applications throughout the nautical, arborist, and industrial industries.

Bending fatigue occurs every time a rope flexes under tension. For heavy-duty lifting applications, rope experiences potential bending-fatigue every time something needs to be moved. For example, when a steel beam manufacturer has completed a 15-ton custom-made beam for a military-grade application, the finished product needs to be moved onto a truck for shipment. Rigging ropes are then attached to a crane to then lift, move and place the steel beam from the warehouse to the truck. This can wear out the rope. Another example is when the rope runs over fairleads and pedestals in maritime and mooring applications. This stresses the fiber both inside and outside of the rope causing bending fatigue and decreases the useful life of the rope. Certain conditions in towing and mooring applications can also lead to compression fatigue. This happens when ropes become slack during services and the fibers compress. Due to the molecular properties (UHMWPE) engineered to make Dyneema fiber– and its extremely long chains of polyethylene oriented in the same direction–threats of compression and bending fatigue are far less over other synthetic fibers and steel wire ropes.

In all rigging applications, synthetic ropes elongate when over a long period of time when loaded in higher temperatures–commonly referred to as creep. Creep is irreversible and when combined with abrasions or other risks, it can lead to rope failure. With regular HMPE rope, in heavy-duty lifting and towing applications where high loads and high temperatures are constantly a factor, the creep process can accelerate. This can be a major risk for ropes made from generic HMPE. In contrast, Dyneema rope has up to four times longer creep lifetime. When comparing Dyneema fiber to Spectra, another synthetic fiber rope, under 122 degrees Fahrenheit and 600 MPa load, Dyneema rope has a significantly longer creep lifetime than Spectra fiber rope.

eAfter comparing Dyneema rope to steel wire rope–a ⅜ inch 12 Strand Dyneema rope to a ⅜ inch steel wire rope–there is a guarantee that Dyneema rope is 15 times stronger and better at dealing with abrasions over steel wire rope. For manufacturing companies, Dyneema rope is also considered to be superior to Nylon rope due to Dyneema fiber having low ability to stretch, is UV resistant, and possesses an immense amount of strength. USA Rope properly manufactures Dyneema fibered ropes that are synthetically engineered to uphold incredible weight while enduring constant friction for application uses involving heavy-duty lifting, crane rope support, and below the hook rigging.

Understanding that Dyneema fiber rope is better used for manufacturing companies over steel wire rope, USA Rope & Recovery works hard to manufacture the highest quality rope by using top-of-the-line supplies from across the USA. Dedicating time and effort to finding the next best and technologically advanced products in the market is our main goal at USA Rope in order to help our customers gain the best competitive advantage in their respective field. USA Rope & Recovery also manufactures additional ropes including Spectra, Nylon, Polyester, Polypro, and Kevlar (Aramid) fiber ropes. No matter the application, USA Rope is a leader in custom rope manufacturing for industries including nautical, industrial, arborist, and marine.

In general, running rigging should be replaced whenever it shows visible signs of damage – core hemorrhaged through the cover, several broken strands close together, “rot” from UV exposure, or green and stiff from disuse. There’s a rule of thumb, but it varies rigger to rigger. The Rule of thumb says to replace all rigging hardware every 5-10 years. However, depending on how much everyday usage, weight, and environmental factors the rigging ropes take on can make the rule of thumb shorter or longer.

Wire rope is also known by many other names, such as: wire, multi-strand wire, flexible wire, cable, cord, steelcord, etc. but it is essentially a collection of small filaments wound around each other in a manner that largely retains its shape when bent, crushed and/or tensioned.

It is a system for significantly increasing the strength and flexibility of steel wire and is used in almost every important application we see around us. For example: suspension bridges, tyres, brake and accelerator cables (in cars), high-pressure flexible pipes, lifting and rigging cables, electrical conductors, etc. and it comes in many different forms. Fig 2 shows just a very small sample of available designs.

With minor variations, the generally accepted method for designating a wire rope construction in the industry is by describing it numerically. For example:

Whilst "IWRC" wire ropes offer a slightly greater tensile capacity (≈7%) than those with fabric or polymer fillers, the additional strength does not come from the tensile capacity of the core filaments but from improved dimensional stability under load. And whilst they are also much more resistant to crushing, they are stiffer than fibre core ropes and therefore not recommended for applications where tension occurs under bending.

Warrington (Fig 1) is a parallel lay construction with an outer layer comprising wires of alternating large and small diameters, each outer layer having twice the number of wires as the layer immediately beneath. The benefit of this design is to increase packing and therefore strength density, however, unless the different diameter filaments are of the same strength (unlikely), this construction is limited by the strength of the weakest filaments.

Seale (Figs 1 & 2 6x36) is also a parallel lay construction but with the same number of wires in each wire layer. All the wires in any layer are the same diameter. This is an alternative to the Warrington construction, with similar benefits and disadvantages.

Regular lay constructions are used much more widely (than Lang lay) because they have excellent structural stability and less tendency to unwrap under tension (see Rotating vs Non-Rotating below). However, because it has a knobbly (undulating) surface it will wear both itself and any surface over which it is run much more quickly than Lang lay wire rope.

Lang lay constructions have a flatter surface than regular lay constructions giving them better resistance to wear and bending fatigue, especially when made from flattened (elliptical) filaments. They are, however, much less structurally stable and subject to birdcaging if the wire rope is over-bent or twisted against its wrapped direction.

"Regular Lay", multi-strand constructions are normally subject to slightly less rotation under tension (than Lang lay) due to the opposite helical direction of the filaments (within the strands) and the strands (within the rope), however, you can improve their rotation characteristics still further by;

Fillers (Fig 2) may be fabric, polymer or even smaller diameter filaments (e.g. 6x36). Whilst they contribute little to the tensile strength of wire rope, they can significantly; improve performance under bending (fabric and polymer cores only), reduce axial growth, reduce rotation in rotation-resistant constructions, improve structural stability and increase fatigue life.

There is little point in having a central core manufactured from the same material as the filaments as it will be the first to break. If you need a metal core, this should be of a material with lower axial stiffness than the strand that surrounds it.

This filler material should not be included in strength (tensile capacity) calculations, but must be included in those for axial stiffness (extension). If it is ignored, your calculations will reveal excessive extension as the wire rope collapses.

Suspension bridges tend to be constructed from densely packed, single strand plain "Wire Rope" constructions using large diameter galvanised filaments. Little heed is paid to rotational resistance as strength is paramount and once tensioned, they should remain in that loading condition for their design life.

Lifting & winching normally require wire ropes of good flexibility and fatigue resistance. Therefore they tend to be similar to 6x36 but with fibre core instead of the IWRC in Fig 2

Remote operating cables such as hand-brakes and accelerators on cars normally only work in tension so they need to be strong but not necessarily stiff (as they are fully contained in reinforced outer sheaths). These tend to be manufactured from large diameter "TyreCord" or small diameter single-strand "Wire Rope".

Axial stiffness is the linear relationship between axial strain and force that allows us to predict the condition of any material or structure when exposed to a specified tensile force. However, it works only with materials and structures that obey Hooke"s law.

Wire rope does not obey Hooke"s law. Therefore, you cannot accurately predict how much it will stretch for any specified force. This unpredictability applies to any section removed from the same manufactured length of cord and even between cords produced to the same specification but by different manufacturers.

CalQlata has decided that the accuracy of axial stiffness (EA) of wire rope falls outside its own levels of acceptability and therefore does not include it in the wire rope calculator. The extension calculated in the Wire Rope calculator (δLᵀ) is based upon the effect of axial tension on packing density. It is therefore important that core material is not ignored when using the calculator to evaluate this characteristic.

Torsional stiffness is the linear relationship that allows us to predict the rotation of any material or structure when exposed to a torque. However, it works only with materials and structures that obey Hooke"s law.

Wire rope does not obey Hooke"s law. Therefore, you cannot accurately predict how much it will twist for any specified torque. This unpredictability applies to any section removed from the same manufactured length of cord and even between cords produced to the same specification but by different manufacturers.

CalQlata has decided that the accuracy of torsional stiffness (GJ) of wire rope falls outside its own levels of acceptability and therefore does not include it in the wire rope calculator.

1) No wire rope calculator, whether dedicated or generic, will accurately predict the properties of any single construction under a wide range of loading conditions

2) No wire rope calculator, whether dedicated or generic, will accurately predict any single property for a range of constructions under a wide range of loading conditions

The only wire rope that can be reliably analysed is that which is used for suspension bridges, because; it comprises a single strand, is very densely packed, has negligible twist, contains filaments of only one diameter, is never subjected to minimum bending and every filament is individually tensioned.

There is a very good reason why manufacturers do not present calculated performance data for construction or design proposals, because even they cannot accurately predict such properties and quite rightly rely on, and publish, test data.

During his time working in the industry, the wire rope calculator"s creator has seen, created and abandoned numerous mathematical models both simple and complex. He has gradually developed his own simplified calculation principle based upon his own experience that still provides him with consistently reliable results of reasonable accuracy.

The purpose of CalQlata"s wire rope calculator is to provide its user with the ability to obtain a reasonable approximation for a generic construction, after which, accurate test data should be sought from the manufacturer for the user"s preferred construction.

The calculation principle in the wire rope calculator is based upon changes in the properties of the wire rope that occur with variations in packing density under tension

Bearing in mind the above limitations CalQlata can provide the following assistance when generating (manipulating) the wire rope calculator"s input data and interpreting its output

Alternatively, for wire rope with multiple filament diameters, you need to find an equivalent diameter with the following proviso; you must enter the minimum filament yield stress (SMYS)

It is expected that apart from fillers, all the material in the wire rope will be identical and therefore have the same density, i.e. using different materials will result in less than "best" performance. However, if such a construction is proposed, you can calculate an equivalent density as follows:

It is expected that apart from fillers, all the material in the wire rope will be identical and therefore have the same tensile modulus, i.e. using different materials will result in less than "best" performance. However, if such a construction is proposed, you should enter the highest tensile modulus.

The wire rope calculator simply adds together the total area of all the filaments and multiplies them by the SMYS entered, which represents a theoretical maximum breaking load that would exist if this load is equally shared across all of the filaments and the lay angles have been arranged to eliminate localised (point) loads between adjacent filaments.

If the wire rope has been properly constructed it is likely that its actual break load will be greater than 80% of this theoretical value. However, given the vagaries of wire rope construction, the actual break load can vary considerably dependent upon a number of factors. CalQlata suggest that the following factors may be used to define the anticipated break load of any given construction:

The axial stiffness and strain under load will be affected by this value, hence the reason why the most reliable (predictable) constructions tend to be minimum [number of] strands and single filament diameter. The Warrington and Seale constructions and combinations thereof tend to provide the highest packing density (but lowest flexibility) and there is little to be gained from using these constructions in more than single stranded wire rope as the benefit of high-packing density will be lost with no gain in flexibility.

The anticipated second moment of area of the wire rope at tension "T" due to deformation but insignificant flattening as it is assumed the wire rope will be bent over a formed (shaped) sheave or roller.

The anticipated tensile modulus of the wire rope at tension "T" due to deformation but insignificant flattening as it is assumed the wire rope will be bent over a formed (shaped) sheave or roller.

It is not advisable to induce this bend radius in operation due to uncertainties associated with wire rope construction, especially for dynamic applications. CalQlata suggests that a similar approach to that used for the break load (Fb) above also be applied here, i.e.:

A change in diameter will occur in all wire rope, irrespective of construction, until packing density has reached a limiting value. The value provided in the wire rope calculator is that which would be expected if the construction remains intact at the applied tension "T"

Unreliability of this value increases with complexity in wire rope due to its longitudinal variability and the increased likelihood of premature failure.

The accuracy of this data will range from about ±1% for wire rope with a single strand and a single filament diameter, up to about ±15% for constructions of similar complexity to OTR cord

A change in length of any wire rope will occur due to the fact that the packing density increases with tension. This is not, however, a linear relationship.

This can be an unreliable value as illustrated by tests carried out (by the author) on two pieces of wire rope supplied by the same well-known manufacturer both of which were cut from the same length, varied in tensile capacity by only 1.5%, but the tensile modulus (and strain at break) varied by 34%. Whilst this was an extreme case, significant variations have been seen in wire rope manufactured by a number of manufacturers.

Whilst the wire rope calculator does not calculate axial stiffness (see Calculation Limitations 9) above), CalQlata can suggest the following rule-of-thumb that will provide reasonable results for most constructions at the applied tension "T":

Whilst the wire rope calculator does not calculate bending stiffness (see Calculation Limitations 8) above), CalQlata can suggest the following rule-of-thumb that will provide reasonable results for most constructions at the applied tension "T":

Low complexity means single strand and single wire diameter. Medium complexity means multi-strand and single wire diameter. High complexity means multi-strand and multiple wire diameters.

pre-working – loaded to 50% of breaking load and then rested for 24 hours (this causes the rope to bed down so that its elastic behaviour is more consistent and repeatable)