wire rope bending stiffness pricelist

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)

... 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 ...

The paper concerns the different forms of rope bending stiffness. The characteristic of elastic stiffness and "tribo-stiffness" are discussed. A survey is presented of the methods used to determine these two forms of bending stiffness. The influence of the type of core on bending stiffness is also addressed. Stiffness data for several types of wire ropes are presented.

The South Africa market size for steel wire rope reached a value of more than USD 10.75 million in 2021. The South Africa steel wire rope market is expected to grow at a CAGR of 2.60% between 2023 and 2028, reaching a value of USD 12.68 million by 2027.

Steel wire rope is a strong and durable rope used for fastening, securing, and positioning equipment because of its characteristics such as rigidity, toughness, and strength. Steel wire rope’s bending fatigue resistance is increased by adding a layer of plastic between outer strand, through an independent wire rope core (IWRC), and by increasing the area of contact between the sheave and steel wire rope.

Focus on bringing on new advancements and various other experimentation to South Africa by the key players is contributing to the growth of the South Africa steel wire rope market.

Increasing use of steel wire rope in mining, and oil and gas offshore transportation has largely contributed to the market growth. Ropes required at offshore need to be able to withstand extreme environmental conditions and which is why steel wire rope is used.

Corrosion resistance is one of the key trends that is increasing the demand for steel wire ropes. It increases the cost-effectiveness of the steel wire ropes as the non-corrosive nature keeps the wire intact, particularly in vital installations, and further enhances durability.

Based on type of lay, the South Africa steel wire rope market can be segmented into regular lay, lang lay and alternate lay. On the basis of strand pattern, the market can be divided into single layer, filler wire, Warrington, and combination. By coating type, the market is categorised into vinyl, zinc, nylon, and PVC, among others. Based on application, the market is divided into oil and gas, heavy machinery, mining, marine, general engineering, and construction, among others.

The comprehensive EMR report provides an in-depth assessment of the market based on the Porter"s five forces model along with giving a SWOT analysis. The report gives a detailed analysis of the following key players in the South Africa steel wire rope market, covering their competitive landscape and latest developments like mergers, acquisitions, investments, and expansion plans.

The strands in regular lay flows in the opposite direction due to which they have higher stability and greater resistance to crushing. These characteristics have resulted in regular lay type occupying a significant segment of the South Africa steel wire rope market.

The flow of the strands in lang lay are in same direction which makes pulling, lifting, pushing, and hoisting of objects easier. Lang lay steel wire ropes are also abrasion resistant and have superior tolerance to fatigue.

Alternate lay is a combination of lang lay and regular lay. It contains three strands of lang lay and other three of ordinary lay along, resulting in a combination of properties of both the lay types. Alternate lay steel wire ropes are typically used for special applications.

Different applications of steel wire ropes can benefit from different coating materials. Nylon is usually applied as a coating in order to prevent damage and corrosion of the steel wire rope. Meanwhile, vinyl and PVC are used as a coating for galvanised steel wire rope and stainless steel.

PVC is used for resistance from water and harsh weather conditions. PVC is widely adopted by individuals because it is cost-effective too. Nylon is tough when compared to other coatings which is why is used for various load running application. Nylon is considered for the largest market share holder in the South Africa steel wire rope market due to its toughness and damage protection capabilities.

Rope Constructions Company was established in 1919 with its headquarter in Johannesburg, South Africa. They provide quality steel wire ropes, rigging gear, lifting equipment, and anchoring equipment to their consumer markets.

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.

US Producer Price Index: Metals and Metal Products: Ferrous Wire Rope, Cable, Forms Strand is at a current level of 374.05, up from 373.69 last month and up from 316.95 one year ago. This is a change of 0.09% from last month and 18.02% from one year ago.