steel wire rope breaking strength brands

Wire rope manufacturers produce their products in order to provide a high load capacity, versatile alternative to weaker ropes like manila rope or hemp rope. Wire rope products are used for a wide variety of motion transmission applications, among them: lifting, baling, tie down, hoisting, hauling, towing, mooring, anchoring, rigging, cargo control, guidance and counterbalance. They can also be used as railing, fencing and guardrailing.

Wire rope is a must-have for many heavy duty industrial applications. From mining to forestry to marine and beyond, there’s wire rope for almost every job. Some of the many industries in which wire rope is popular include: construction, agriculture, marine, industrial manufacturing, fitness, sports and recreation (plastic coated cables for outdoor playground equipment and sports equipment), electronics, theater (black powder coated cables for stage rigging), mining, gas and oil, transportation, security, healthcare and consumer goods.

Wire rope as we know it was invented just under 200 years ago, between 1831 and 1834. At that time, the goal was to create a rope strong enough to support work in the mines of the Harz Mountains. Invented by Wilhelm Albert, a German mining engineer, this wire rope consisted on four three-stranded wires. It was much stronger than older rope varieties, such as manila rope, hemp rope and metal chain rope.

While studying at Freiburg School of Mines, a man named L.D.B. Gordon visited the mines in the Harz Mountains, where he met Albert. After he left, Gordon wrote to his friend Robert Stirling Newall, urging him to create a machine for manufacturing wire ropes. Newall, of Dundee, Scotland, did just that, designing a wire rope machine that made wire ropes with four strands, consisting of four wires each. After Gordon returned to Dundee, he and Newall, along with Charles Liddell, formed R.S. Newall and Company. In 1840, Newall received a patent for “certain improvements in wire rope and the machinery for making such rope.”

In 1841, an American manufacturer named John A. Roebling began producing wire rope for suspension bridges. Soon after, another set of Americans, Josiah White and Erskine Hazard, started incorporating wire rope into coal mining and railroad projects, forming Lehigh Coal & Navigation Company (LC&N Co.). In 1848, wire rope from their wire rope factory in Mauch Chunk, Pennsylvania provided the lift cables needed to complete the Ashley Planes Project. This project sought to improve the performance and appearance of the freight railroad that ran through Ashley, Pennsylvania, by adding lift cables. This increased tourism and increased the railroad’s coal capacity. Before, cars took almost four hours to return; after, they took less than 20 minutes.

Wire rope likewise changed the landscape (again) in Germany, in 1874, when an engineering firm called Adolf Bleichert & Co. used wire rope to build Bi-cable aerial tramways. These allowed them to mine the Ruhr Valley. Several years later, they also used wire rope to build tramways for the German Imperial Army and the Wehrmacht. These tramways were wildly successful, opening up roads in Germany and all over Europe and the USA.

Since the 1800s, manufacturers and engineers have found ways to improve wire rope, through stronger materials and material treatments, such as galvanization, and different rope configurations. Today, wire rope makes possible many heavy industrial processes. It has become a necessity of the modern world.

Strands are made by tightly twisting or braiding individual wire together. One strand could have anywhere between two and several dozen wire filaments depending on the necessary strength, flexibility, and weight capacity.

One of the most dynamic elements of wire cables is the inner core. The strands are wrapped around the core, and it can be made of different metals, fibers, or even impregnated fiber materials. For heavy applications, cores are often made of a different strand of wire called an independent wire rope core (IWRC). An IWRC has a considerable amount of flexibility and it is still very strong. In fact, at least 7.5% of the strength increase in a wire rope can be attributed to an IWRC.

While they sometimes use other metals, like aluminum, nickel, copper, titanium, and even bronze for some applications, manufacturers primarily produce wire rope from steel. This is because steel is very strong and stretchable. Among the most common types they use are: galvanized wire, bright wire, stainless steel and cold drawn steel.

Of the wire rope steels, cold drawn carbon steel wire is most popular, although stainless steel wire rope is sometimes employed as well. Stainless steel rope is most popular for its anti-corrosive properties. Bright wire rope, a type of ungalvanized steel wire rope, is also popular. For added strength and durability, galvanized steel wire rope/galvanized steel cables are a very popular choice. Galvanized aircraft cable, for example, is always a must in aerospace.

When choosing or designing a custom wire rope for your application, suppliers consider factors such as: the environment in which the rope will function, required rust resistance, required flexibility, temperature resistance, required breaking strength and wire rope diameter. To accommodate your needs, manufacturers can do special things like: make your rope rotation resistant, color code your rope, or add a corrosion resistant coating. For instance, sometimes they specially treat and coat a cable with plastic or some other compound for added protection. This is particularly important to prevent fraying if the wire rope is often in motion on a pulley.

Manufacturers and distributors identify the differences in wire cable by listing the number of strands and the amount of wires per strand so that anyone that orders understand the strength of the cable. Sometimes they are also categorized by their length or pitch. Common examples of this include: 6 x 19, 6 x 25, 19 x 7, 7 x 19, 7 x 7, 6 x 26 and 6 x 36.

More complex wire rope identification codes connote information like core type, weight limit and more. Any additional hardware like connectors, fasteners, pulleys and fittings are usually listed in the same area to show varying strengths and degrees of fray prevention.

Cable wire rope is a heavy-duty wire rope. To give it its high strength, manufacturers construct it using several individual filaments that are twisted in strands and helically wrapped around the core. A very common example of cable wire rope is steel cable.

Spiral rope is made up an assemblage of wires with round or curved strands. The assemblage features at least one outer layer cord pointed in the opposite direction of the wire. The big advantage of spiral ropes is the fact that they block moisture, water and pollutants from entering the interior of the rope.

Similarly, stranded rope steel wire is made up of an assemblage of spirally wound strands. Unlike spiral rope, though, its wire patterns have crisscrossing layers. These layers create an exceptionally strong rope. Stranded rope may have one of three core material types: wire rope, wire strand or fiber.

Wire rope chain, like all chains, is made up of a series of links. Because it is not solid, wire rope chain is quite flexible. At the same time, it is prone to mechanical failure.

Wire rope slings are made from improved plow wire steel, a strong steel wire that offers superior return loop slings and better security. The plow wire steel also shields rope at its connection points, which extends its working life. Wire rope slings, in general, provide their applications with increased safety, capacity and performance. Wire rope sling is a rope category that encompasses a wide range of sub-products, such as permaloc rope sling, permaloc bridle slings and endless slings. These and other wire rope slings may be accompanied by a wide variety of sling terminations, such as thimbles, chokers and hooks.

Wire rope offers its user many advantages. First, design of even distribution of weight among strands makes it ideal for lifting extremely heavy loads. Second, wire rope is extremely durable and, when matched properly to the application, can withstand great stress and elements like corrosion and abrasion. In addition, it is very versatile. Its many iterations and the ways in which the rope can treated means that users can get rope custom fit for virtually any application.

Depending on the type of wire rope with which you are working and your application, you may want to invest in different accessories. Among these accessories are: wire rope clips, steel carabiners, fittings, fasteners and connections.

To ensure that your wire rope quality remains high, you must regularly inspect them for wear and degradation. The right wire rope should be selected for a particular use. Watch out for performance-impacting damage like: rust, fraying and kinks. To make sure that they stay in tip-top shape, you should also clean and lubricate them as needed. Check for this need as a part of your regular inspection.

Rope care is about more than inspection. It’s also about making an effort to use and store them properly every time you use them. For example, never exceed your rope’s rated load and breaking strength. Doing so will not only cause the weakening of your cable, but it may even cause immediate breakage. In addition, always store your wire rope cable in a dry and warm area, away from those elements that could cause premature rusting or other damage. Finally, always carefully wind your wire rope when you’re done with it, so as to avoid kinks. If you follow all these tips and treat your wire rope assemblies well, they will reward you with a long and productive service life.

Always make sure that you purchase wire rope that matches your industry and regional standards. Some of the most widely referenced standards organizations for wire rope include: ISO, ASTM International and OSHA. Talk over your specifications and application with your wire rope supplier to figure out what’s best for you.

If you’re in the market for a wire rope or a wire rope assembly, the best way to know you’re getting something that will both perform well and be safe if by working with a vetted professional. Find one among the list we’ve provided on this page. Check out their profiles to get an idea of the services and products they offer. Pick out three or four to whom you’d like to speak, and reach out. Talk to them about your specifications, standard requirements and budget. Ask about lead times and delivery options. Once you’ve spoken with all of them, compare and contrast their answers. You’ll know you’ve found the one when you talk to a wire rope company that is willing to go above and beyond for your satisfaction.

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.

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…

The 6 x 19 classification of wire ropes includes standard 6 strand, round strand ropes with 16 through 26 wires per strand. The 6 x 36 classification of wire ropes includes standard 6 strand, round strand ropes with 27 through 49 wires per strand. Although their operating characteristics vary, all have the same weight per foot and the same nominal strength, size for size.

While the 6 x 19 ropes give primary emphasis to abrasion resistance in varying degrees, the 6 x 36 ropes are important for their fatigue resistance. This fatigue resistance is made possible by the greater number of small wires per strand.

Although there are exceptions for special applications, the constructions in 6 x 36 classification are primarily designed to be the most efficient for each rope diameter. As the rope size increases, for instance, a large number of wires can be used to achieve required fatigue resistance, and still those wires will be large enough to offer adequate resistance to abrasion.

In this construction, each strand has nine outer wires over nine smaller inner wires over one large center wire. A comparison of cross-sections shows that these outside wires are larger than those of the 6 x 25FW or 6 x 26WS. Therefore, its resistance to abrasion is increased, but its fatigue resistance is decreased. This is a good rope to withstand abrasion or crushing on the drum.

To most wire rope users, 6 x 19 means 6 x 25 filler wire. It is the most common rope in the 6 x 19 classification. This rope has a good balance between both abrasion resistance and fatigue resistance in relation to other ropes.

This construction has better resistance to abrasion than a 6 x 25FW. It also features a compact construction with solid support for the wires; hence, it has a high resistance to crushing. Its number and relative size of the inner wires add to the stability of the strand and gives it a fatigue resistance comparable to a 6 x 25FW.

A standard 6 x 26WS construction provides the best rope for a wide range of applications. In general, we recommend the use of a 6 x 26WS in any application where a 6 x 25FW is used.

In most rope sizes, only one 6 x 36 classification rope is made. These constructions were selected to provide fatigue resistance without having wires that are too small.

The greater number of wires in the 6 x 36 classification makes these ropes more susceptible to crushing. This can be minimized, however, by specifying an Independent Wire Rope Core (IWRC) and by using well-designed sheaves, grooved drums and proper operating techniques.

Rotation-resistant ropes can frequently provide the best and most economical service in specific applications when you choose, handle and use them properly.

Contra-helically laid, rotation-resistant ropes are different from standard ropes because they"re designed to reduce rope torque. Modes of failure and wear for rotation-resistant ropes can differ from those for standard rope constructions. The very nature of these ropes requires special handling, selection and usage not encountered with standard constructions. They are susceptible to kinking, crushing and unbalancing in the form of "core pops" and "birdcages" Use extreme care to avoid operational practices that can possibly lead to these conditions.

Rotation-resistant ropes should not be used with swivels that allow rope rotation -- or in single part lifts where the load can rotate. Rotation will cause a reduction in strength, unequal loading in the rope and possible rope unbalance. If any significant change in diameter is found in a short length of a rotation-resistant rope, the rope needs to be replaced.

These ropes should be replaced when you see two randomly distributed crown wire breaks in six rope diameters -- or four randomly distributed crown wire breaks in 30 rope diameters.

Because rotation-resistant ropes are special, there are separate design, maintenance, inspection and removal criteria established for them by applicable industry regulations and standards.

In an application where a single-part hoist rope is used to lift a free load -- or where rotation-resistant properties are essential for rope performance -- the 19 x 7 can be used. Its rotation-resistant characteristic is achieved by laying six strands around a core strand in one direction, then laying 12 strands around the first operation in the opposite direction. Thus, when the rope is in tension, opposing rotational forces are created between the inner and outer layers.

In addition, frequent and regular inspection for broken wires is critical when using this rope. Due to its design, the 19 x 7 construction has a relatively low reserve strength. This can result in short service life between the point in time when the broken wire removal criteria are met and when actual rope failure occurs.

In a multi-part wire rope system where the blocks have a tendency to twist -- or for a single-part hoist line that doesn"t require the degree of rotation-resistant properties found in a 19 x 7 rope -- the 8 x 25 Resistwist rope has found successful application. The rotation-resistant characteristic is achieved by laying the eight outer strands around an independent wire rope core so these strands are in the opposite direction to the lay of the core. Thus, when the rope is in tension, opposing rotational forces are created between the core and the outer strands.

Though not as rotation-resistant, the 8 x 25 Rotation Resistant rope is more stable than a 19 x 7 rope. It also has increased resistance to bending fatigue and crushing. This is achieved through the use of eight-strand construction with an independent wire rope core.

Like any application where an installation"s rope type is changed, the 8 x 25 Rotation Resistant rope should be substituted only after carefully comparing specifications and strength requirements.