what is breaking strength of wire rope factory

Rope strength is a misunderstood metric. One boater will talk about tensile strength, while the other will talk about working load. Both of these are important measurements, and it’s worth learning how to measure and understand them. Each of these measurements has different uses, and here we’re going to give a brief overview of what’s what. Here’s all you need to know about rope strength.

Each type of line, natural fiber, synthetic and wire rope, have different breaking strengths and safe working loads. Natural breaking strength of manila line is the standard against which other lines are compared. Synthetic lines have been assigned “comparison factors” against which they are compared to manila line. The basic breaking strength factor for manila line is found by multiplying the square of the circumference of the line by 900 lbs.

When you purchase line you will buy it by its diameter. However, for purposes of the USCG license exams, all lines must be measured by circumference. To convert use the following formula.

As an example, if you had a piece of ½” manila line and wanted to find the breaking strength, you would first calculate the circumference. (.5 X 3.14 = 1.57) Then using the formula above:

To calculate the breaking strength of synthetic lines you need to add one more factor. As mentioned above, a comparison factor has been developed to compare the breaking strength of synthetics over manila. Since synthetics are stronger than manila an additional multiplication step is added to the formula above.

Using the example above, letÂ’s find the breaking strength of a piece of ½” nylon line. First, convert the diameter to the circumference as we did above and then write the formula including the extra comparison factor step.

Knots and splices will reduce the breaking strength of a line by as much as 50 to 60 percent. The weakest point in the line is the knot or slice. However, a splice is stronger than a knot.

Just being able to calculate breaking strength doesn’t give one a safety margin. The breaking strength formula was developed on the average breaking strength of a new line under laboratory conditions. Without straining the line until it parts, you don’t know if that particular piece of line was above average or below average. For more information, we have discussed the safe working load of ropes made of different materials in this article here.

It’s very important to understand the fundamental differences between the tensile strength of a rope, and a rope’s working load. Both terms refer to rope strength but they’re not the same measurement.

A rope’s tensile strength is the measure of a brand-new rope’s breaking point tested under strict laboratory-controlled conditions. These tests are done by incrementally increasing the load that a rope is expected to carry, until the rope breaks. Rather than adding weight to a line, the test is performed by wrapping the rope around two capstans that slowly turn the rope, adding increasing tension until the rope fails. This test will be repeated on numerous ropes, and an average will be taken. Note that all of these tests will use the ASTM test method D-6268.

The average number will be quoted as the rope’s tensile strength. However, a manufacturer may also test a rope’s minimum tensile strength. This number is often used instead. A rope’s minimum tensile strength is calculated in the same way, but it takes the average strength rating and reduces it by 20%.

A rope’s working load is a different measurement altogether. It’s determined by taking the tensile strength rating and dividing it accordingly, making a figure that’s more in-line with an appropriate maximum load, taking factors such as construction, weave, and rope longevity into the mix as well. A large number of variables will determine the maximum working load of a rope, including the age and condition of the rope too. It’s a complicated equation (as demonstrated above) and if math isn’t your strong point, it’s best left to professionals.

However, if you want to make an educated guess at the recommended working load of a rope, it usually falls between 15% and 25% of the line’s tensile strength rating. It’s a lotlower than you’d think. There are some exceptions, and different construction methods yield different results. For example, a Nylon rope braided with certain fibers may have a stronger working load than a rope twisted out of natural fibers.

For safety purposes, always refer to the information issued by your rope’s manufacturer, and pay close attention to the working load and don’t exceed it. Safety first! Always.

If you’re a regular sailor, climber, or arborist, or just have a keen interest in knot-tying, be warned! Every knot that you tie will reduce your rope’s overall tensile strength. Some knots aren’t particularly damaging, while others can be devastating. A good rule of thumb is to accept the fact that a tied knot will reduce your rope’s tensile strength by around 50%. That’s an extreme figure, sure, but when it comes to hauling critical loads, why take chances?

Knots are unavoidable: they’re useful, practical, and strong. Splices are the same. They both degrade a rope’s strength. They do this because a slight distortion of a rope will cause certain parts of the rope (namely the outer strands) to carry more weight than others (the inner strand). In some cases, the outer strands end up carrying all the weight while the inner strands carry none of it! This isn’t ideal, as you can imagine.

Some knots cause certain fibers to become compressed, and others stretched. When combined together, all of these issues can have a substantial effect on a rope’s ability to carry loads.

Naturally, it’s not always as drastic as strength loss of 50% or more. Some knots aren’t that damaging, some loads aren’t significant enough to cause stress, and some rope materials, such as polypropylene, Dyneema, and other modern fibers, are more resilient than others. Just keep in mind that any knots or splices will reduce your rope’s operations life span. And that’s before we talk about other factors such as the weather or your rope care regime…

As a wire rope is used, the outer wires wear through abrasion and so the rope suffers loss of cross-sectional area – this obviously reduces the breaking strength of the wire rope. Resistance to abrasive wear is therefore an important property of a wire rope.

Abrasion resistance is directly related to the design of the rope, in particular the design of the strands of the rope. In general, ropes with fewer larger wires will be more abrasion resistant than a similar rope made up of smaller wires – a 6 x 19 rope will therefore be more abrasion resistant than a 6 x 36 rope.

In a later article in this technical series we will discuss fatigue resistance in great detail but for the purposes of this discussion, we must recognise that a cyclic stress reversal occurs when a body is subjected to alternating tensile and compressive loads.

In a drilling operation, wire ropes run through sheaves constantly and so are constantly subjected to alternating tensile and compressive loads – i.e. cyclic stress reversals.

Figure 1 illustrates a wire rope bending over a sheave. It is clear that the outer parts of the rope running over the sheave are in tension and the inner parts of the rope running over the sheave are in compression and as the rope moves over the sheave these stresses reverse.

It should be obvious that the smaller the diameter of the sheave the greater the magnitude (amplitude) of the stress reversal and so the more rapidly fatigue will occur in the rope.

Wire ropes experience external forces that will tend to alter or distort the shape of the rope. Crushing prevents wires and strands moving easily over one another during normal operation and this can lead to accelerated wear and reduced rope life.

Wire ropes are essential for safety purposes on construction sites and industrial workplaces. They are used to secure and transport extremely heavy pieces of equipment – so they must be strong enough to withstand substantial loads. This is why the wire rope safety factor is crucial.

You may have heard that it is always recommended to use wire ropes or slings with a higher breaking strength than the actual load. For instance, say that you need to move 50,000 lbs. with an overhead crane. You should generally use equipment with a working load limit that is rated for weight at least five times higher – or 250,000 lbs. in this case.

This recommendation is all thanks to the wire rope safety factor. This calculation is designed to help you determine important numbers, such as the minimum breaking strength and the working load limit of a wire rope.

The safety factor is a measurement of how strong of a force a wire rope can withstand before it breaks. It is commonly stated as a ratio, such as 5:1. This means that the wire rope can hold five times their Safe Work Load (SWL) before it will break.

So, if a 5:1 wire rope’s SWL is 10,000 lbs., the safety factor is 50,000 lbs. However, you would never want to place a load near 50,000 lbs. for wire rope safety reasons.

The safety factor rating of a wire rope is the calculation of the Minimum Break Strength (MBS) or the Minimum Breaking Load (MBL) compared to the highest absolute maximum load limit. It is crucial to use a wire rope with a high ratio to account for factors that could influence the weight of the load.

The Safe Working Load (SWL) is a measurement that is required by law to be clearly marked on all lifting devices – including hoists, lifting machines, and tackles. However, this is not visibly listed on wire ropes, so it is important to understand what this term means and how to calculate it.

The safe working load will change depending on the diameter of the wire rope and its weight per foot. Of course, the smaller the wire rope is, the lower its SWL will be. The SWL also changes depending on the safety factor ratio.

The margin of safety for wire ropes accounts for any unexpected extra loads to ensure the utmost safety for everyone involved. Every year there aredue to overhead crane accidents. Many of these deaths occur when a heavy load is dropped because the weight load limit was not properly calculated and the wire rope broke or slipped.

The margin of safety is a hazard control calculation that essentially accounts for worst-case scenarios. For instance, what if a strong gust of wind were to blow while a crane was lifting a load? Or what if the brakes slipped and the load dropped several feet unexpectedly? This is certainly a wire rope safety factor that must be considered.

Themargin of safety(also referred to as the factor of safety) measures the ultimate load or stress divided by theallowablestress. This helps to account for the applied tensile forces and stress thatcouldbe applied to the rope, causing it to inch closer to the breaking strength limit.

A proof test must be conducted on a wire rope or any other piece of rigging equipment before it is used for the first time.that a sample of a wire rope must be tested to ensure that it can safely hold one-fifth of the breaking load limit. The proof test ensures that the wire rope is not defective and can withstand the minimum weight load limit.

First, the wire rope and other lifting accessories (such as hooks or slings) are set up as needed for the particular task. Then weight or force is slowly added until it reaches the maximum allowable working load limit.

Some wire rope distributors will conduct proof loading tests before you purchase them. Be sure to investigate the criteria of these tests before purchasing, as some testing factors may need to be changed depending on your requirements.

When purchasing wire ropes for overhead lifting or other heavy-duty applications, understanding the safety dynamics and limits is critical. These terms can get confusing, but all of thesefactors serve an important purpose.

Our company has served as a wire rope distributor and industrial hardware supplier for many years. We know all there is to know about safety factors. We will help you find the exact wire ropes that will meet your requirements, no matter what project you have in mind.

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A similar rope to 6x7 but the fibre core is replaced by a wire strand, resulting in a greater resistance to crushing and added strength, lacks flexibility on larger diameter ropes.

This rope is widely used for General Purpose Engineering, It has good strength and flexibility with reasonably good resistance to abrasion and crushing.

The wires of wire rope are made of high-carbon steel. These carbon steel wires come in various grades. Wire ropes are usually made of Extra Improved Plow Steel (EIPS) or Extra Extra Improved Plow Steel (EEIPS) which roughly equivalents to a wire tensile strength of 1960N/mm² and 2160N/mm².

The fill factor measures the metallic cross section of a rope and compares this with the circumscribed area given by the rope diameter. Traditional rope constructions ‘fill’ the rope diameter only up to about 58% with steel. Python® and Compac® wire rope ‘fill’ the rope diameter up to 80% with steel. That is an metallic increase of about 38% which results in a similar increase in rope strength.

It turns out that there is little margin of safety with steel cable equipped winches. Why is this? Unlike the lifting industry, the recreational pulling industry is unregulated, consequently winch manufacturers typically equip winches with steel cables with minimum breaking strengths that are very close to the max winch capacities. The lifting industry requires a 5:1 safety factor due to the overhead dangers. The pulling industry does not. In fact many steel equipped winches possess a safety factor of less than 1.5!

Take for instance common 5/16 steel cable supplied on most winches up to 10K capacities. The working load limit (WLL) on common 5/16 steel cable is only 2000 pounds. The minimum breaking strength is approximately 10K pounds. So in many cases a 10K winch can be supplied with a steel cable with a minimum breaking strength of 10K. Take a look at the steel cable writeup from our friend Tyler at Roundforge (Roundforge.com) for more comprehensive data on steel cable types and classes.

One of the reasons that cable failures are relatively infrequent is mostly due to vehicle recoveries being in the 4-5k pulling load range, well below the cable breaking strength. Also, often times steel cables can possess ultimate strengths above the minimum breaking loads. So what’s the takeaway here? Due to the little margin of safety in steel cables, make sure you properly maintain the cable and be on the lookout for weakening factors like kinks, broken wires etc., and when possible use a snatch block to reduce the cable load.

Picture supplied by our friend James Pickard. James snapped his steel cable while using the UltraHook. The UltraHook possesses a breaking strength of 31,000 pounds(hook opening) to 48,000 pounds(shackle pin mount). Engineering facts matter.

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Although Westech Rigging Supply strives to manufacture and sell the highest quality rigging and safety gear, use of the gear is dangerous if not used correctly by competent trained professionals. Westech Rigging Supply disclaims any liability resulting from the misuse of its rigging and safety gear. Please take a moment to more thoroughly review our disclaimer.

Westech Rigging Supply rigging and safety gear is only intended to be used by competent trained professionals. Misuse of the rigging and safety gear can result in serious injury up to and including loss of life. As such, Westech Rigging Supply disclaims liability for any misuse or incorrect product selection by our customers.

Rigging and safety gear purchased from Westech Rigging Supply should be used in strict accordance with all industry and OSHA standards. At no time should rigging or safety gear be used beyond its certified load ratings (aka Working Load Limits). Normal wear and tear should be expected with use of rigging and safety gear; therefore, all gear should be thoroughly inspected before each and every use. Worn or unsafe rigging and safety gear should never be used.

Galvanized wire rope is categorized by number of strands in its construction. We supply most of them but we concentrate on the two major categories of galvanized (and ungalvanized or bright) wire rope. These “classes” are referred to as 6x19 and 6x36. Within each category of galvanized wire rope there are different “constructions” illustrated in the tables below.

Wire rope, galvanized and ungalvanized is used for many kinds of projects and applications. No matter the application galvanized wire rope must be used properly to insure the safest working conditions. All of our galvanized wire rope is manufactured to meet or exceed Federal Specification RRW-410 and is mill certified.

All of these general purpose wire ropes are available in full reels, custom cut sizes or as part of a custom made wire rope sling. Contact us today for more information.

Galvanized wire rope also comes in different strength categories (IPS and EIPS) and different cores (FC or fiber core and IWRC or independent wire rope core). Relevant data for each is listed in the table below.

Wire rope and cable are each considered a “machine”. The configuration and method of manufacture combined with the proper selection of material when designed for a specific purpose enables a wire rope or cable to transmit forces, motion and energy in some predetermined manner and to some desired end.

Two or more wires concentrically laid around a center wire is called a strand. It may consist of one or more layers. Typically, the number of wires in a strand is 7, 19 or 37. A group of strands laid around a core would be called a cable or wire rope. In terms of product designation, 7 strands with 19 wires in each strand would be a 7×19 cable: 7 strands with 7 wires in each strand would be a 7×7 cable.

Materials Different applications for wire rope present varying demands for strength, abrasion and corrosion resistance. In order to meet these requirements, wire rope is produced in a number of different materials.

Stainless Steel This is used where corrosion is a prime factor and the cost increase warrants its use. The 18% chromium, 8% nickel alloy known as type 302 is the most common grade accepted due to both corrosion resistance and high strength. Other types frequently used in wire rope are 304, 305, 316 and 321, each having its specific advantage over the other. Type 305 is used where non-magnetic properties are required, however, there is a slight loss of strength.

Galvanized Carbon Steel This is used where strength is a prime factor and corrosion resistance is not great enough to require the use of stainless steel. The lower cost is usually a consideration in the selection of galvanized carbon steel. Wires used in these wire ropes are individually coated with a layer of zinc which offers a good measure of protection from corrosive elements.

Cable Construction The greater the number of wires in a strand or cable of a given diameter, the more flexibility it has. A 1×7 or a 1×19 strand, having 7 and 19 wires respectively, is used principally as a fixed member, as a straight linkage, or where flexing is minimal.

Cables designed with 3×7, 7×7 and 7×19 construction provide for increasing degrees of flexibility but decreased abrasion resistance. These designs would be incorporated where continuous flexing is a requirement.

Selecting Wire Rope When selecting a wire rope to give the best service, there are four requirements which should be given consideration. A proper choice is made by correctly estimating the relative importance of these requirements and selecting a rope which has the qualities best suited to withstand the effects of continued use. The rope should possess:Strength sufficient to take care of the maximum load that may be applied, with a proper safety factor.

Strength Wire rope in service is subjected to several kinds of stresses. The stresses most frequently encountered are direct tension, stress due to acceleration, stress due to sudden or shock loads, stress due to bending, and stress resulting from several forces acting at one time. For the most part, these stresses can be converted into terms of simple tension, and a rope of approximately the correct strength can be chosen. As the strength of a wire rope is determined by its, size, grade and construction, these three factors should be considered.

Safety Factors The safety factor is the ratio of the strength of the rope to the working load. A wire rope with a strength of 10,000 pounds and a total working load of 2,000 pounds would be operating with a safety factor of five.

It is not possible to set safety factors for the various types of wire rope using equipment, as this factor can vary with conditions on individual units of equipment.

The proper safety factor depends not only on the loads applied, but also on the speed of operation, shock load applied, the type of fittings used for securing the rope ends, the acceleration and deceleration, the length of rope, the number, size and location of sheaves and drums, the factors causing abrasion and corrosion and the facilities for inspection.

Fatigue Fatigue failure of the wires in a wire rope is the result of the propagation of small cracks under repeated applications of bending loads. It occurs when ropes operate over comparatively small sheaves or drums. The repeated bending of the individual wires, as the rope bends when passing over the sheaves or drums, and the straightening of the individual wires, as the rope leaves the sheaves or drums, causing fatigue. The effect of fatigue on wires is illustrated by bending a wire repeatedly back and forth until it breaks.

The best means of preventing early fatigue of wire ropes is to use sheaves and drums of adequate size. To increase the resistance to fatigue, a rope of more flexible construction should be used, as increased flexibility is secured through the use of smaller wires.

Abrasive Wear The ability of a wire rope to withstand abrasion is determined by the size, the carbon and manganese content, the heat treatment of the outer wires and the construction of the rope. The larger outer wires of the less flexible constructions are better able to withstand abrasion than the finer outer wires of the more flexible ropes. The higher carbon and manganese content and the heat treatment used in producing wire for the stronger ropes, make the higher grade ropes better able to withstand abrasive wear than the lower grade ropes.

Effects of Bending All wire ropes, except stationary ropes used as guys or supports, are subjected to bending around sheaves or drums. The service obtained from wire ropes is, to a large extent, dependent upon the proper choice and location of the sheaves and drums about which it operates.

A wire rope may be considered a machine in which the individual elements (wires and strands) slide upon each other when the rope is bent. Therefore, as a prerequisite to the satisfactory operation of wire rope over sheaves and drums, the rope must be properly lubricated.

Loss of strength due to bending is caused by the inability of the individual strands and wires to adjust themselves to their changed position when the rope is bent. Tests made by the National Institute of Standards and Technology show that the rope strength decreases in a marked degree as the sheave diameter grows smaller with respect to the diameter of the rope. The loss of strength due to bending wire ropes over the sheaves found in common use will not exceed 6% and will usually be about 4%.

The bending of a wire rope is accompanied by 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, even though well within the elastic limit of the wires, set up points of stress concentration.

The fatigue effect of bending appears in the form of small cracks in the wires at these over-stressed foci. 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.

Experience has established the fact that from the service view-point, a very definite relationship exists between the size of the individual outer wires of a wire rope and the size of the sheave or drum about which it operates. Sheaves and drums smaller than 200 times the diameter of the outer wires will cause permanent set in a heavily loaded rope. Good practice requires the use of sheaves and drums with diameters 800 times the diameter of the outer wires in the rope for heavily loaded fast-moving ropes.

It is impossible to give a definite minimum size of sheave or drum about which a wire rope will operate with satisfactory results, because of the other factors affecting the useful life of the rope. If the loads are light or the speed slow, smaller sheaves and drums can be used without causing early fatigue of the wires than if the loads are heavy or the speed is fast. 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. When a reverse bend is necessary larger sheaves are required than would be the case if the rope were bent in one direction only.

Stretch of Wire Rope The stretch of a wire rope under load is the result of two components: the structural stretch and the elastic stretch. Structural stretch of wire rope is caused by the lengthening of the rope lay, compression of the core and adjustment of the wires and strands to the load placed upon the wire rope. The elastic stretch is caused by elongation of the wires.

The structural stretch varies with the size of core, the lengths of lays and the construction of the rope. This stretch also varies with the loads imposed and the amount of bending to which the rope is subjected. For estimating this stretch the value of one-half percent, or .005 times the length of the rope under load, gives an approximate figure. If loads are light, one-quarter percent or .0025 times the rope length may be used. With heavy loads, this stretch may approach one percent, or .01 times the rope length.

The elastic stretch of a wire rope is directly proportional to the load and the length of rope under load, and inversely proportional to the metallic area and modulus of elasticity. This applies only to loads that do not exceed the elastic limit of a wire rope. The elastic limit of stainless steel wire rope is approximately 60% of its breaking strength and for galvanized ropes it is approximately 50%.

Preformed Wire Ropes Preformed ropes differ from the standard, or non-preformed ropes, in that the individual wires in the strands and the strands in the rope are preformed, or pre-shaped to their proper shape before they are assembled in the finished rope.

This, in turn, results in preformed wire ropes having the following characteristics:They can be cut without the seizings necessary to retain the rope structure of non-preformed ropes.

They are substantially free from liveliness and twisting tendencies. This makes installation and handling easier, and lessens the likelihood of damage to the rope from kinking or fouling. Preforming permits the more general use of Lang lay and wire core constructions.

Removal of internal stresses increase resistance to fatigue from bending. This results in increased service where ability to withstand bending is the important requirement. It also permits the use of ropes with larger outer wires, when increased wear resistance is desired.

Outer wires will wear thinner before breaking, and broken wire ends will not protrude from the rope to injure worker’s hands, to nick and distort adjacent wires, or to wear sheaves and drums. Because of the fact that broken wire ends do not porcupine, they are not as noticeable as they are in non-preformed ropes. This necessitates the use of greater care when inspecting worn preformed ropes, to determine their true condition.

Depending on the application, wire rope strength is determined on a case-by-case basis. 304 Stainless steel cable, for example, may not suit applications where excessive heat is present. Conversely, tungsten, the strong metal known on earth, will perform exceptionally well under extreme heat. Accordingly, the question isn’t necessarily, “what is the strongest wire rope?”, but rather, “what do you need to accomplish with mechanical cable?”

As discussed, mechanical engineers consider the material, diameter and the quantity of filaments that comprise the wire rope or miniature cable. So, these characteristics, taken in the aggregate, inform the choice of cable and its strength benefits.

304 stainless steel is among the strongest, and most popular materials used in the manufacturing of mechanical cable. While other grades of stainless steel prevail in wire rope and miniature cable making, 304, in the USA in particular, is extremely common.

Stainless steel cable is used in virtually all markets that use mechanical cable to achieve motion. Whether in endoscopic medical instruments, or an air-defense system, or even an implantable hip joint system, stainless steel is a staple. However, tungsten mechanical cable, common in the growing surgical robotics space, has swiftly supplanted stainless steel as the go-to ultrafine cable material.

Empirically, tungsten is the stronger material as compared with stainless steel alternatives. Pound for pound, tungsten, on the periodic table known as wolfram or simply W, is the strongest metal on earth. Thus, again speaking scientifically, it trumps stainless steel. But, for instance, in applications where tungsten properties aren’t as desirable, stainless steel will outperform the presumably stronger alloy. Say, the application is going to be implanted into a human’s hip joint. In this case, the non-corrosive properties of stainless steel, combined with its strength offering, makes it the ideal cable material for this surgical application. Furthermore, choosing stainless steel in this case promises a more cost-effective cable product because tungsten is dramatically more expensive.

However, if the tensile strength required of the application exceeds that of what stainless steel can yield, in a given diameter, say in the appendages of a surgical robot, tungsten is the stronger candidate. Tungsten will not compromise strength along tight turns, where miniature pulleys are required. But, if stainless steel were used to make tight radii, around extremely small pulleys, the material’s springiness may resist a given radius and perhaps compromise flexibility and subsequently lifecycle.

When determining if the cable is strong enough for the application, the filament diameter, along with the cable’s overall outer diameter (OD), contribute as well.

All mechanical cables comprise stranded wires. The larger the diameter of these wires, contributes greatly to the tensile strength achieved. So, in simplest terms, a tungsten surgical robotics cable, made from 201 wires, but at a diameter of .0005”, would not possess the strength of the same cable made from .0007” wires.

And while the difference between a single 7 and a 5 appears marginal, the difference in strength - going from .0005” to .0007” is dramatic. What’s more, adding larger diameter wires, even in constructions with fewer total wires in the cable strand, may yield more strength that more wires, albeit smaller ones, in comparably sized cable. So a 1x7 cable, which comprises seven total wires, at an outer diameter (OD) of .016” will actually yield more tensile strength that a 3x3, which comprises nine total wires, at an OD of .017”.

When two, or even 10 cables, are made from the same alloy, say tungsten, for instance, the quantity of wires, the design of construction of the mechanical cable, as well as the diameter of completed strand, all coalesce to determine strength.

Counterintuitive as it seems, adding more tungsten wires to a miniature cable, for instance, constructed in extremely small diameters, does not necessarily yield the engineer a stronger cable. Because adding ultrafine tungsten wires also adds flexibility to the completed cable, the engineer may accept some strength limitations in favor of significant improvement in malleability. While this is not always so, adding larger, but fewers filaments, provides the engineer a more rigid cable, but one more flexible around tight radii.

Strength of the mechanical cable, as is likely becoming clearer, is therefore not entirely determined by the size of the wires, nor the wire material, but the total sum of these and other variables.

When determining how much weight your mechanical cable can handle, engineers recommend using approximately 60 percent of the cable’s breaking strength. If the mechanical cable breaking strength is 100 pounds, for example, engineers would only use the cable to support 60 lbs. The higher the rated strength of the cable, the more force engineers can apply to it.

When it comes to choosing the right wire rope, you need to ensure you choose the materials best suited to meet your application’s needs, while also being sensitive to budget. This requires working with the right stainless steel wire supplier that meets ISO 9001 requirements. Stainless steel wire rope manufacturers like Carl Stahl Sava Industries know that it is cost-effective, strong, durable, corrosion-resistant, and heat resistant. This makes stainless steel among the more popular cable rope materials that Sava works with precisely due to its wide range of applications and affordability.

Stainless steel wire rope suppliers often recommend it over other cable construction materials because of its cost-effectiveness. But what’s interesting about stainless steel stranded wire is that its affordability, as compared with more expensive alternatives like tungsten for example is rooted in its low maintenance, longevity, availability and ease of use and installation. Therefore the material’s mechanical malleability, including its lifespan, combined with how readily available it is, makes stainless steel ideal in many use cases.

As a stainless steel wire rope supplier & manufacturerSava typically works with industry-standard stainless steel, such as 303, 304 and 316 stainless steel. However, we can work with any stainless steel a customer needs,and through our stainless steel wire fabrication process we provide a product other wire rope manufacturers, suppliers, and stainless steel wire rope factories cannot. We are a wire rope supplier of over-the-counter stainless steel cable and manufacture an entire family of cable fittings to create your custom cable assembly.

Another reason stainless steel is an industry-standard is because of stainless steel wire rope’sstrength and durability. It is an exceptionally strong wire.

For example, Grade 301 and 304 stainless steel possesses a tensile strength of up to 1300 MPa in strip and wire forms. Galvanized steel, with a tensile strength of up to 550 MPa, comparatively, makes stainless steel remarkably strong.

Consequently, stainless steel has a long lifespan, although not as long as tungsten due to the latter’s tolerance of more intense temperatures. Even so, stainless steel is effective in a wide range of applications over many cycles, making it ideal across many applications.

As mentioned, tungsten is preferable in extremely hot environments that require a long life span, because it heats up quickly but dissipates the heat equally as fast. However, stainless steel can perform at these same levels of extreme heat and at a lower cost, but over less cycles. But that it doesn’t last as long as tungsten under extreme conditions doesn’t rule it out. For instance, if you have an operation that needs a high lifecycle, but it’s not being used as frequently, stainless steel mechanical cable might be perfect. If cycles are less frequent, then it’s possible stainless steel will last as long as the application requires and again, under the same hostile temperatures that gives tungsten all the glory.

So, while tungsten certainly has its benefits, stainless steel mechanical cable is a strong alternative that will provide similar, if not the same, results for most applications.

Another feature that makes stainless steel cable advantageous is that it’s easy to work with, compared to other materials. It is very easily formed, especially in the small-diameter wires inside the cable as well. What’s more, stainless steel mechanical cable is also easy to lay into the appropriate shape when stranded.

When the stainless steel cable is manufactured with a nitinol core, the results possess seemingly magical easy-to-use properties. Known as a memory alloy, nitinol “remembers,” so-to-speak, the shape it was in, allowing the stainless steel cable housing the nitinol core wire to traverse winding and twisting pathways like arteries and other narrow vessels. In such surgical applications, this nitinol core wire is the center of the stranded cable otherwise comprised of stainless steel. So when paired with nitinol, stainless steel cable becomes a flexible, memory-based solution for a wide array of medical devices that use medical cable assemblies, and medical grade stainless steel wire. But as nitinol is not used to comprise the entire stranded cable used in these elegant medical devices, stainless steel remains the best material to work with when bending is critical, but cost is equally important.

If your application requires sensitivity to corrosion, such as weather or water, salt or otherwise, stainless steel cable is an excellent choice. The material’s tolerance of harsh environmental conditions ensures the cable can take a beating over a long period of time by moisture. Comparatively speaking, galvanized steel, another steel cable Sava manufacturers, is vulnerable to applications where corrosive variables are present, like marine or submerged saltwater uses.

If you are looking for a stainless steel cable supplier and manufacturer, our USA based manufacturing team can help you decide which stainless steel wire rope is right for your application. Visit our contact page to get in touch with a Sava team member and inquire about your stainless steel wire rope options!

Wire rope strength is normally refered to as minimum breaking force or minimum breaking load. The minimum breaking load of any given rope diameter can be increased in two basic ways;

1. An increase in the tensile strength of the wire used to manufacture the rope will increase the minimum breaking load of the final rope. Typical tensile grades of wire used for crane rope manufacture are 1770N/mm2, 1960N/mm2 and 2160N/mm2.

2. Additionally it is possible to increase the steel fill factor of the wire rope. Fill factor means the ratio between the sum of the nominal cross sectional areas of all the wires in the rope and the circumscribed area of the rope based on its nominal diameter. More simply it measures the metallic cross sectional area of the rope.

It is possible to marginally increase the fill factor by varying the construction i.e. adding smaller filler wires. More effectively the individual strands of the rope can be compacted.

The resultant rope has a very high steel fill factor and consequently a relatively high minimum breaking load for any given diameter when compared with a conventional rope.

The high breaking load to diameter relationship offered by compacted ropes can allow crane manufacturers to optimise the design of crane components such as winding drums and sheaves whilst still complying with international crane design standards.

Lower stress levels which occur when crane operators replace a conventional rope with an identical diameter of high strength compacted rope can lead to more ‘comfortable’ operation and longer rope life. Diameter

Correct and consistent wire rope diameter is critical to performance on a modern crane, and a rope which is too large or too small, for the drum and sheaves in which it is operating can cause premature rope failure.

It is not only important to select a rope which has the correct nominal diameter according to the original equipment operating manual, but it is also important that the diameter of the rope is consistent throughout its entire length. Inconsistency in diameter, particularly short lengths where the rope is oversize, can cause premature localised wire breaks and short rope life.

Wire rope strength is normally refered to as minimum breaking force or minimum breaking load. The minimum breaking load of any given rope diameter can be increased in two basic ways;

Bend fatigue resistance is the ability of the wire rope to withstand repeated bending under constant or fluctuating loads. As the load increases in any reeving system so the rate of fatigue will increase. As bending radii decrease in a reeving system so the rate of fatigue will increase.

The compacted strand has very favourable internal and external contact conditions when compared with the point contact of round wires within a conventional strand.

The smooth surface of compacted rope offers a wider bearing surface to the sheave or drum groove. Increased fill factor, lowering internal stress levels, combined with improved internal and external contact conditions lead to longer rope life.

Laboratory fatigue testing indicates that it is possible to achieve up to two times normal rope life when comparing compacted rope with a conventional rope of equivalent construction.

Each wire rope construction will have an inherent torque characteristic where both ends of the rope are secured and an applied force will generate torque at the fixing points. Each wire rope construction will have an inherent turn characteristic where one end of the rope is free to rotate and an applied force will cause the free end of the rope to turn.

The torque or turn generated will depend upon the magnitude of the force applied and also upon the construction of the wire rope selected.In terms of resistance to rotation wire ropes can be divided into three basic catgories.

Single layer ropes have a much greater tendency to rotate under load than the two or three layer ropes which are often referred to as rotation resistant. Similarly the three layer rope will have less tendency to rotate when compared with the two layer rope.

Both the two layer and three layer ropes depend on torsional balance between the outer and inner layers to create rotational stability. With correct rope selection rotation should not cause a problem in service provided that the rope has been correctly balanced in design and manufacture.

Before selecting a rotation resistant rope, consideration should be given to a single layer construction. If the application/duty in question does not require the rope to resist rotation then it is possible that a single layer rope can represent a more robust and more effective solution.

Safety note – Single layer Langs lay ropes (where the direction of strand lay is the same as the direction of rope lay) have exceptionally bad rotational characteristics and must only be used in applications where both ends of the rope are securely fixed.

In multi-layer coiling situations where crushing of lower layers particularly at crossover point is unavoidable. Carl Stahl UK would recommend the use of compacted rope. The high steel fill factor, which is a feature of the compaction process, will offer greater resistance to crushing than an equivalent conventional rope.

Larger external wires can provide greater resistance to wear and abrasion therefore a 6×19 construction might be selected in preference to a 6×36 construction in a situation in which wear and abrasion rather than bend fatigue are the principle cause of rope deterioration.

The smooth surface of the compacted rope offers a wider bearing surface to the sheave or drum groove resulting in improved resistance to wear and abrasion.

Abrasive wear can occur between the rope and any ancillary equipment such as sheaves and the surface of the winding drum but probably the most significant cause of abrasive wear on cranes takes place between adjacent laps of rope where the rope moves on and off the winding drum.

Selection of a compacted rope with its smooth external surface and very good contact condition will minimise abrasive wear between the rope and ancillary equipment and also between adjacent laps of rope.

Laboratory bend fatigue tests show the significant effect which high performance manufacturing lubricant and in-service lubrication has on rope life. In-service lubrication with a suitable lubricant should be carried out wherever possible however the best opportunity to introduce lubricant into the rope is during manufacture.