what is the minimum bending radius of wire rope in stock

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To obtain reasonable service life from your aircraft cable or wire rope, you must choose the optimal diameter of rope and sheave for your application. In general, the larger the size of the drum or pulley with respect to the wire diameter, the longer the service life. The opposite is also true: in general, the smaller the size of the drum or pulley with respect to your wire rope, the shorter the service life. Keep these relationships between cable, rope, and pulleys in mind when specifying the competence you use in your application.

The tables below provide the minimum recommended pulley diameter as well as the approximate bend radius of the rope. You"ll notice that the calculation is approximately half of the minimum recommended pulley tread diameter. Whether running fully over the sheave or drum, or some fraction thereof, check your design against the recommendations to better understand the service life you can expect in relation to the other factors involved.

Thinking about it and looking again at the info. from loosco above, it also depends on what you want the bend for. Their info. is for rope use over pulleys (a "moving" application), but if you look at wire rope slings (let us call them a "static" application), there is no way they are made to those sizes.

Bend radius is the minimum radius a pipe, cable, wire, sheet, cable, tube or hose can bend without damaging it (including kinking). The smaller the radius, the greater is the flexibility of the material. The minimum bend radius is the radius below which an object should not be bent.

Factors which influence the minimum bending radius include the cable size, the cable construction, the conductor type and the sheathing and insulation types used. The bending radius is normally expressed as a factor of the overall dimension of the cable for example, 6D or 6x the outer diameter of the cable.

According to Table 1, the minimum bend radius is found to be six times the cable’s overall diameter. The overall diameter of the cable is given as 2.08 inches in the product catalog. Multiplying 2.08 inches by six, we get 12.48 inches.

The minimum bend radius will vary depending on the specific fiber cable. However, in general, the minimum bend radius should not be less than ten times the outer diameter (OD) of the fiber cable. Thus a 3 mm cable should not have any bends less than 30mm in radius.

We recommend a minimum bend radius of 1t for all sheet metal parts. Thus the smallest radius of any bend in a sheet should be at least equal to the thickness of the sheet. For example, if the thickness of the sheet is 1 mm, the minimum bend radius should be 1 mm.

However, in general, the minimum bend radius should not be less than ten times the outer diameter (OD) of the fiber cable. Thus a 3 mm cable should not have any bends less than 30mm in radius. Telcordia recommends a minimum 38 mm bend radius for 3 mm patch cords.

thick, grade 350 and 400 may have a minimum bend radius of 2.5 times the material thickness when transverse bending, while longitudinal bending may require a minimum bend radius that’s 3.75 times the material thickness. And between 0.8 and 2 in.

Flange length must be at least 4 times the material thickness. It is recommended to use the same radii across all bends, and flange length must be at least 4 times the material thickness.

The minimum bend radius A typical value for a cable under no load conditions, or “unloaded,” is 10 times the cable’s outside diameter. When a cable is under tensile load or “loaded,” the minimum bend radius is usually 15 times the cable’s outside diameter. Learn more: Fibre cable and pulling eyes.

The normal recommendation for fiber optic cable bend radius is the minimum bend radius under tension during pulling is 20 times the diameter of the cable. When not under tension (after installation), the minimum recommended long term bend radius is 10 times the cable diameter.

Bend radius is the minimum radius a pipe, cable, wire, sheet, cable, tube or hose can bend without damaging it (including kinking). The smaller the radius, the greater is the flexibility of the material. The minimum bend radius is the radius below which an object should not be bent.

Recommended Bend Radius Rope Diameter Minimum Recommended Pulley Tread Diamete Approximate Bend Radius .009″ 3/8″ 3/16″ .014″ 5/8″ 5/16″ .018″ 13/16″ 13/32″ .024″ 1″ 1/2″

Answer: SHD-GC is a shielded mining cable. According to Table 1, the minimum bend radius is found to be six times the cable’s overall diameter. The overall diameter of the cable is given as 2.08 inches in the product catalog. Multiplying 2.08 inches by six, we get 12.48 inches.

For cable connectors such as ferrules or clamps, holding the cable in place may also flex the cable beyond its recommended bend radius. In addition, pulling the cable at an improper angle in relation to the connector may cause damage. Questions?

Depending upon your application, please consider that Carl Stahl Sava Industries offers customers a rich and detailed guide for your cable selection needs. Please take a moment to get familiar with the cables you require to satisfy your unique application circumstances.

Carl Stahl Sava Industries uses 95% 304 Stainless Steel in making cable, with the balance being 302 Stainless Steel. This is for standard catalog cables and many others for Sava customers. While Sava does use 316 on occasion and upon request, it is far less common. 302/304 is prevalent in the US, while 316 is common in Europe, Japan and other countries. 316 has slightly less tensile strength and on average about 90% of the strength of 302/304 SS. In order of increased corrosion resistance: 302, 304 and most corrosion resistant, 316.

Nylon should be used in applications over pulleys in all cases where possible. It is designed to be integrated into the cable when applied as it is pressurized into the cable stranding. Nylon has excellent adhesion to the cable. Vinyl is used for basic applications outdoors and when coating will not be used over pulleys. It is the least expensive option for coating, available in many colors and has UV inhibitors ideal for outdoor use. Vinyl has limited adhesion to the cable. FEP is a clear color (also available in colors upon request) extrusion that is vacuum formed to the cable, so it has very limited adhesion. It should not be used over pulleys, as it will quickly delaminate and come off the cable. FEP has excellent corrosion resistance to many chemicals and can be used in many environments as a result. FEP has a very low coefficient of friction as well, so it is slippery on the surface.

The smallest stainless steel cable diameter is .006” (Sava P/N 2006, SS .006” 1X7), while the largest is 3/8” (Sava P/N 2375, SS 3/8” 7X19 and Sava P/N 3375, GAC 3/8” 7X19).

Yes. Carl Stahl Sava Industries extrudes the coatings at our manufacturing facility in Riverdale, NJ. Please let us know what your application requires are and we may have the material and/or color available.

No. Carl Stahl Sava Industries is a manufacturer of mechanical cable and cable assemblies. However, some of the cable assemblies are used in electromechanical applications.

Yes. Depending on size and quantity, Sava can accommodate your metric requirements. However, generally all of our sizes are in inches. Contact Sava to discuss your production requirements.

Yes. Carl Stahl Sava Industries has a proven, standard operating procedure to test all of our cable for breaking strength, diameter and material, ensuring that all industry standards are met. Cable assemblies are manufactured and tested, as a first stage, in process inspection as well as final inspection, promising that the breaking strengths and dimensions are consistent throughout the manufacturing run.

Two kinds of stretch occur in cable: constructional stretch and elastic stretch. They are due to two different causes. To learn more about cable stretch, visit the Cable Expertise portion of our website.

When strand and cable are made, the load at the closing head is light. Therefore, there are small clearances between the wires and strands, and between the strand and the core. The application of initial load causes wires and strands to seat properly, and a slight overall elongation of the strand or cable accompanies this section. The amount of constructional stretch is not constant for all cables, as it depends on such variables as type of construction, length of lay and other factors, including the load applied.

Elastic stretch is the actual elongation of the wires of a strand or a cable. This is caused by the application of a load, up to the yield point of the metal, and the stretch is approximately proportional to the load applied. When the load is released, strand or cable subjected to elastic stretch returns to its approximate original length, providing the stretch has not reached the yield point of the metal.

Yes. Cable does have a tendency to stretch, depending upon the load being applied. Proof loading each cable assembly serves two purposes. First, it ensures the efficiency of the assemblies; and second, it prestresses the cable, removing some of the constructional stretch. Proof loading is generally done at 60% of rated breaking strength. The removal of constructional stretch means that frequent adjustments are not necessary to maintain proper tension in a control system. After assemblies are proof loaded, subsequent handling should be held to a minimum, otherwise the prestressing effect will be partially removed. If stretch is critical in your application, Sava suggests contacting our engineering department for further information.

Carl Stahl Sava Industries can electrocut the bare cable, which is a system to fuse the ends of the wires together. When this is not possible, it is recommended to use Sava cable cutter C07, C09 or C12, which encircles the bare cable, keeping the wires together before cutting through it. Other cable cutters are scissor-like and induce fraying before the cable is even cut. The cable can also be stress relieved or preformed. Coated cable can be mechanically cut with the Sava cable cutters mentioned above or using standard cable cutters.

Stress relieving is a process in which the bare cable is passed through a certain temperature to reduce the fraying when mechanically cut. This process also helps to keep the cable straighter when laying flat and assists in minimizing the residual oils from the wire drawing process. Cable assemblies can also be vapor degreased and/or ultrasonically cleaned to further remove any residual oils from the above process. These methods have been used widely in medical applications.

The bend radius is the radius at which a cable can be bent without damaging it (including kinking). The smaller the radius, the greater the required flexibility of the material. A frequently asked question in this context is: how much can we bend a cable without damaging it or impairing its function? The answer depends mainly on the particular cable being considered. There are several industry standards, such as IEEE 1185, ICEA S-75-381, ICEA S-66-524 or ICEA S-68-516, which provide minimal bend radii for many different cable types.

The minimum bend radius is the radius below which an object cannot be bent. In many installations, cable carriers are used, so the question arises: how do we select the bend radius of a cable or a cable carrier?

When deciding on a cable management system, there are several ways to extend the service life of the cable. One of the most important factors is the selection of the right bend radius for the cable carrier. It is important that the radius (except, perhaps, in space constrained applications) is greater than the recommended minimum bend radius of the cables. One of the key factors in long service life and operational reliability is choosing the right radius for the cable carrier. All cable carriers have several bend radii to choose from and each manufacturer proposes a minimum bend radius . The radius chosen for the cable carrier depends on the cable with the largest diameter.General rules and recommendations for selecting the radius

Do not exceed the manufacturer"s recommended minimum radius - but the maximum radius is optimal. Basically, cables with flexible specifications that move must be supported so that the connection points are not mechanically stressed and a sharp bend is avoided. If this is achieved by a loop, the cable must be provided with a bend radius of at least 10 times the diameter of the cable. The larger the radius, the less stress is exerted on the cables, which ensures a longer service life. It should be noted that the minimum bend radius is partially based on a temperature range for the bending. Particular care should be taken when the ambient temperature reaches or exceeds this temperature for the cable.

This is especially true for cryogenic applications where thermoplastic cables tend to stiffen when exposed to cold. Rigid cables can increase the radius of the cable carrier and lead to mechanical errors. It is recommended to use a cable with a PUR or TPE jacket at low temperature and/or to consult the manufacturer for recommendations on bend radii. For space constrained applications, the cable carrier radius must be less than the recommended minimum bend radius for the filling pack. This is not ideal, but if it cannot be avoided, cables designed specifically for low bend radius installations should be used. The igus chainflex range includes load-bearing control cables, servo and motor cables or robot cables as well as encoder cables, bus cables and data cables, which can be safely used in demanding environments and are characterised by their very long service life.

The use of rope for any purpose results in friction, bending and tension. All rope, hardware, sheaves rollers, capstans, cleats, as well as knots are, in varying degrees, damaging to ropes. It’s important to understand that rope is a moving, working, strength member and even under the most ideal conditions will lose strength due to use in any application. Maximizing the safety of rope performance is directly related to how strength loss is managed and making sure ropes are retired from service before a dangerous situation is created. Ropes are serious working tools and used properly will give consistent and reliable service. The cost of rope replacement is extremely small when compared to the physical damage or personnel injury that can result from using a worn out rope.

There are basically three steps to consider in providing the longest possible service life for ropes, the safest conditions and long range economy: Selection, Usage and Inspection.

Selecting a rope involves evaluating a combination of factors. Some of these factors are straight forward, like comparing rope specifications. Others are less qualitative, like color preference or how a rope feels while handling. Cutting corners, reducing design factors, sizes or strengths on an initial purchase creates unnecessary replacements, potentially dangerous conditions and increased long term costs. Fiber and construction being equal, a larger rope will outlast a smaller rope, because of greater surface wear distribution. By the same token, a stronger rope will outlast a weaker one, because it will be used at a lower percentage of its break strength and corresponding Work Load Limit with less chance of overstressing. The following factors should be considered in your rope selection: Strength, Elongation, Firmness, Construction and Abrasion.

When given a choice between ropes, select the strongest of any given size. A load of 200 pounds represents 2% of the strength of a rope with a 10,000 Lbs. breaking strength. The same load represents 4% of the strength of a rope that has a 5,000 Lbs. breaking strength. The weaker rope will work harder and as a result will have to be retired sooner. Braided ropes are stronger than twisted ropes that are the same size and fiber type.

Please note that the listed break strengths are average break strengths and do not consider conditions such as sustained loads or shock loading. Listed break strengths are attained under laboratory conditions. Remember also that break strength is not the same as the Work Load Limit.

It is well accepted that ropes with lower elongation under load will give you better control. However, ropes with lower elongation that are shock loaded, like a lowering line, can fail without warning even though the rope appears to be in good shape. Low elongating ropes should be selected with the highest possible strength. Both twisted ropes and braided ropes are suitable for rigging. Size for size, braided rope has higher strength and lower stretch than a twisted rope of similar fiber. See page 390 for additional information on rope elongation.

Select ropes that are firm and hold their shape during use. Soft or mushy ropes will snag easily and abrade quickly causing accelerated strength loss.

Rope construction plays an important role in resistance to normal wear and abrasion. Braided ropes have a basically round, smooth construction that tends to flatten out somewhat over the bearing surface. Flattening distributes wear over a much greater area, as opposed to the crowns of a three strand or to a lesser degree, an eight strand rope.

All rope will be severely damaged if subjected to rough surfaces or damaging edges. All rope must be protected against damaging or abrasive surfaces. Wire rope will score and gouge chocks and bitts creating cutting edges that can damage synthetic ropes. Chocks, bitts, drums and other surfaces must be kept in good condition and free of burrs and rust. Weld beads on repaired capstans, fairleads, etc., are equally damaging, unless dressed down smoothly. Pulleys must be free to rotate and should be of proper size to avoid

Avoid using a rope that shows signs of aging and wear. If in doubt, do not use the rope. Damaged rope must be destroyed to prevent any future use. No visual inspection can be guaranteed to accurately and precisely determine the residual strength of the rope. When fibers show wear in any area, the damaged area must be removed and the rope should be re-spliced or replaced. Check regularly for frayed or broken strands. Pulled strands should be rethreaded into the rope if possible. A pulled strand can snag on a foreign object during usage. Both outer and inner rope fibers may contribute to the strength of the rope. When either is worn the rope is naturally weakened. Open the strand of the rope and inspect for powdered fiber, which is one sign of internal wear. A heavily used rope will often become compacted or hard, which indicates reduced strength. The rope should be discarded and made unusable if this condition is detected. See pages 395 and 396 for additional inspection information.

New rope tensile strength is based upon tests of new and unused spliced rope of standard construction in accordance with Samson testing methods, which conform to Cordage Institute, ASTM and OCIMF test procedures. It can be expected that strengths will decrease as soon as a rope is put into use. Because of the wide range of rope use, changes in rope conditions, exposure to the many factors affecting rope behavior and the possibility of risk to life and property, it is impossible to cover all aspects of proper rope applications or to make generalized statements as to Work Load Limits.

Work Load Limits are the load that a rope in good condition with appropriate splices in non-critical applications is subjected to during normal activity. They are normally expressed as a percentage of new rope strength and should not exceed 20% of the stated break strength. Thus, your maximum Work Load Limit would be 1/5 or 20% of the stated break strength.

A point to remember is that a rope may be severely overloaded or shock loaded in use without breaking. Damage and strength loss may have occurred without any visible indication. The next time the rope is used under normal Work Loads and conditions, the acquired weakness can cause it to break.

Normal Work Load Limits do not cover dynamic conditions such as shock loads or sustained loads, nor do they apply where life, limb or property are involved. In these cases a stronger rope must be used and/or a higher design factor applied.

Normal Work Load Limits are not applicable when rope is subjected to dynamic loading. Whenever a load is picked up, stopped, moved or swung there is increased force due to dynamic loading. The more rapidly or suddenly such actions occur, the greater the increase in the dynamic loading. In extreme cases, the force put on the rope may be two, three or many more times the normal Work Load involved. Examples of dynamic loading would be: towing applications, picking up a load on a slack line or using a rope to stop a falling object. Dynamic loading affects low elongation ropes like polyester to a greater degree than higher elongation, nylon ropes. Dynamic loading is also magnified on shorter length ropes when compared to longer rope lengths. Therefore, in all such applications, normal Work Load Limits do not apply.

IMPORTANT NOTE: Many industries are subject to state and federal regulations for Work Load Limits that supersede those of the manufacturer. It is the responsibility of the user to be aware of and adhere to those laws and regulations.

Work Load Limits as described do not apply when ropes have been subjected to shock loading. Whenever a load is picked up, stopped, moved or swung, there is an increased force due to dynamic loading. The more rapidly or suddenly such actions occur, the greater this increase in force will be. The load must be handled slowly and smoothly to minimize dynamic effects. In extreme cases, the force put on the rope may be two, three or even more times the normal Work Load involved. Examples of shock loading are picking up a tow on a slack line or using a rope to stop a falling object. Therefore, in all applications such as towing lines, life lines, safety lines, climbing ropes, etc., design factors must reflect the added risks involved. Users should be aware that dynamic effects are greater on a low elongation rope such as manila than on a high-elongation rope such as nylon and greater on a shorter rope than on a longer one.

The shock load that occurs on a winch line when a 5,000 Lbs. object is lifted vertically with a sudden jerk may translate the 5,000 Lbs. of weight into 30,000 Lbs. of dynamic force, which could cause the line to break. Where shock loads, sustained loads or where life, limb or valuable property is involved, it is recommended that a much higher design factor than 5 be used.

Remember, shock loads are simply a sudden change in tension, from a state of relaxation or low load to one of high load. The further an object falls, the greater the impact. Synthetic fibers have a memory and retain the effects of being overloaded or shock loaded. Ropes that have been shock loaded can fail at a later time, when used within Work Load Limits.

Polyester fibers are least affected by UV exposure, while Nylon is more susceptible. With both nylon or polyester, the degree of susceptibility to UV damage is dependent on the type of fiber, length of exposure and the protection afforded by various treatments and inhibitors, i.e., Samthane coating.

When a wire rope is bent around any sheave or other object there is a loss of strength due to this bending action. As the D/d ratio becomes smaller this loss of strength becomes greater and the rope becomes less efficient. This curve relates the efficiency of a rope diameter to different D/d ratios. This curve is based on static loads and applies to 6-strand class 6×19 and 6×37 wire rope.

The LOOP of an eye & eye sling has nearly DOUBLE the strength of its body. For this reason the D/d ratio in the LOOP is just half as critical as opposed to when the sling is used in BASKET hitch.

In most cases the shackle or hook over which the sling is placed will have a sufficient D/d ratio. On the other hand, do not place too LARGE an object into the sling eye as this will result in splitting forces affecting the sling splice and sling safety. The object (a shackle, a crane hook, a steel bar, etc.) you place into the sling eye must not be larger than 1/2 of the sling eye length.

When a sling is used in a BASKET- or CHOKER HITCH with D/d ratios smaller than listed in the capacity tables, the rated capacities (or WLLs) must be decreased.

For example: The BASKET and CHOKER hitch capacities listed (in all Standards and Regulations) for 6-strand ropes are based on a minimum D/d ratio of 25:1.

An object you place into a 1" diameter 6-strand wire rope sling using a basket- or choker hitch must have a minimum diameter of 25". If the object is smaller than the listed 25:1 D/d ratio the capacity (or WLL) must be decreased. Table A) illustrates the percentage of decrease to be expected.

Note: The minimum D/d ratio for GATOR-FLEX® and for TRI-FLEX® slings is just 5:1. If you need to lift small objects and don’t want your sling to kink or bend permanently use these types.

If the object lifted with a 6-strand wire rope sling in a basket hitch is at least 25 x larger than the sling diameter (D/d 25:1) the basket capacity need not to be adjusted.

It is better to use a larger shackle or a Wide Body shackle type. If the shackle or object has at least 5x the sling diameter (D/d 5:1) the basket sling capacity must still be reduced by about 25%.

Load Hooks must have sufficient thickness to ensure proper sling D/d ratio, particularly when using slings in an inverted basket hitch; that is the sling BODY is placed into the hook and the sling EYES are facing downwards.

Endless (or Grommet) slings DO NOT HAVE A LOOP which has double the strength of the sling body. Prior to EVERY lift, YOU, the user, has to determine if the D/d ratio is equal or higher than the ones listed in the capacity tables.

Source:RP 2SM, Design, Manufacture, Installation, and Maintenance of Synthetic Fiber Ropes for Offshore Mooring, First Edition, July 2014. Global Standards

Bergen Cable is known for its high-quality wire rope and cable assembly products, unmatched technical expertise, and superior customer service. The company doesn’t just manufacture top quality products; it also works hard to ensure that its customers are educated on proper wire rope application and maintenance, and the effects of bending. With that in mind, Bergen Cable has posted helpful information on its website.

Most wire ropes are subject to bending around sheaves or drums, which means that they are also subject to the effects of bending — loss of strength and fatigue.

Loss of strength:The bending of a wire rope is accompanied by a readjustment in the positions of the strands and wires, and results in actual bending of the wires. Repetitive flexing of the wires develops bending loads, which sets up points of stress concentration. Eventually, the individual strands and wires will be unable to adjust themselves to their changed position when the rope is bent.

Fatigue:This effect appears in the form of small cracks in the wires at these over-stressed points. These cracks propagate under repeated stress cycles, until the remaining sound metal is inadequate to withstand the bending load. This results in broken wires showing no apparent contraction of cross section.

It is important to understand that there is a relationship between the size of the individual outer wires of a wire rope and the size of the sheave or drum about which it operates. Therefore, sheaves and drums smaller than 200 times the diameter of the outer wires will cause permanent set in a heavily loaded rope. It’s recommended to use sheaves and drums with diameters 800 times the diameter of the outer wires in the rope for heavily loaded fast-moving ropes.

It’s impossible, however, to give a definite minimum size of sheave or drum about which a wire rope will operate with satisfactory results, because there are other factors affecting the useful life of the rope. For example, if the loads are light or the speed slow, smaller sheaves and drums can be used without causing early fatigue of the wires. Reverse bends, where a rope is bent in one direction and then in the opposite direction, cause excessive fatigue and should be avoided whenever possible. In instances where a reverse bend is necessary, however, larger sheaves are required.

Factors which influence the minimum bending radius include the cable size, the cable construction, the conductor type and the sheathing and insulation types used.

The relevant standards determine a minimum bending radius so as to protect the integrity and performance of the cable. Where the cable bending radius has been exceeded - whether through winding onto drums with a barrel diameter too small for the cable or during installation - the cable can show kinking or other sheath damage as an indication of other possible problems. Where it is suspected the cable bend radius has been exceeded it is recommended that testing, such as the sheath integrity test conducted by The Cable Lab, be undertaken prior to further install to determine if the cable performance has been impeded.

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:

"0.43+6x0.37+6x(0.37+6x0.33) HT" refers to a seven strand construction: a single central strand (one central filament diameter 0.43mm and 6 planetary filaments of diameter 0.37mm) and 6 planetary strands (one central filament of diameter 0.37mm and 6 planetary filaments of diameter 0.33mm) all manufactured from high-tensile steel"

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.

Tyrecord generally comprises a single strand of less than 1.5mm in diameter and normally contains about 12 filaments all of the same diameter between 0.15mm and 0.25mm, but designs and configurations can vary considerably dependent upon manufacturer and tyre design requirements. This design tends to be the most flexible of all constructions.

OTR is more or less a complicated tyrecord construction (see above) up to 4.5mm in diameter containing around 100 filaments of a similar size to tyrecord, albeit towards the larger end of the size range (0.2mm to 0.25mm).

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;

Whilst there are very distinct non-rotating constructions such as 19x7 and rotation-resistant designs such as 19x19, new ideas are evolving all the time and each manufacturer will have its own design preferences.

"Lang lay" and single strand (e.g. Fig 2 1x7) constructions will always try to straighten (unwrap) under tension. There are a number of things that could be done to minimise this problem, such as a) to c) above and/or;

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

Hosecord is suitable for HPHT flexible pipes as lateral flexibility is generally considered less important than minimal longitudinal growth or maximum tensile strength (per unit cross-sectional area).

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

3) Unless additional heat treatment or material modification is performed during the manufacturing (drawing) process, the smaller the filament diameter the greater will be its SMYS

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:

Accuracy is expected to be within ±0.1% of the calculated value for good quality manufacturing but variations in manufactured filament diameter can, in extreme cases, reduce this to ±1%

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":

Where: θ = the "absolute" sum of the average filament lay angle and the average strand lay angle⁽²⁾. Note; the angle of twist (θ) will reduce as tension approaches break load.

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.

If the filament lay angle and the strand lay angle are in opposite directions, as with Regular Lay constructions, you must add the angles together as positives; i.e. -12° + 23° = 35°

MINIMUM BEND RADIUSDuring installation, cables are bent or flexed in various environmental Cable multipliers are determined by industry standards and varyconditions. Cables are often bent around a curve in conduits or depending on the cable type. Table 1 provides a general guide on cableunderground ducts. Cables are also bent when pulling a cable around multipliers for various cable types. Please note that the multiplier maya sheave, which is a pulley set up in a manhole to help ease a cable change depending on the cable type and industry standard. For morearound a curve. information, see 2014 NEC Articles 300.34, 330.24 and 336 as wellCables are composed of different components that may become IEEE 1185, ICEA S-75-381, ICEA S-66-524 and ICEA S-68-516.compromised if bent too far and stress is placed on the cable. For Cable Type Minimum Bend Radius as aexample, while bending a medium-voltage cable consisting of a copper Multiple of Overall Cable Diametertape shield, the cable may form cracks in the outer jacket. To prevent Single or multiple conductor cables Eight times the overall cable diameter1cable damage, cable standards such as The National Electrical Code without metallic shielding, >1,000 V(NEC) and the Insulated Cable Engineers Association (ICEA) formed Single conductor cables with shielding 12 times the overall cable diameter1requirements for minimum bend radius. >1,000 VThe minimum bend radius is the smallest allowed radius the cable is Multiconductor cables with 12 times the individual conductorallowed to be bent around. Figure 1 shows a cable with an outer diameter individually shielded conductors diameter or seven times the overall >1,000 V cable diameter — whichever is greater1of 2 inches being bent around a radius of 12 inches. Portable (mining) cables Six times for cables rated 5000 volts or less, eight times for cables rated over 5,000 volt2 Interlocked armor or corrugated Seven times overall cable diameter3 sheath (Type MC) cables 1 2014 NEC Section 300.34 Conductor Bend Radius 2 ICEA S-75-381 Portable and Power Feeder Cables for Use in Mines and Similar Applications 3 2014 NEC Section 330.24 Bending Radius

Example: What is the minimum bend radius of a 1/0, 5 kV, SHD-GC cable? Answer: SHD-GC is a shielded mining cable. According to Table 1,Figure 1: Minimum Bend Radius the minimum bend radius is found to be six times the cable’s overallThe minimum bend radius is based on the diameter of the cable and the diameter. The overall diameter of the cable is given as 2.08 inches in thetype of cable. The following formula is used: product catalog. Multiplying 2.08 inches by six, we get 12.48 inches. The minimum bending radius for this SHD-GC cable is approximately 12.5Minimum bend radius = cable outer diameter X cable multiplier inches. This cable can be safely bent around a diameter of 25 inches.

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