wire rope eye splice strength brands

Engineering wire rope slings for your application is a highly specialized field – with exacting standards – that we gladly live by. A Union sling can meet or exceed the most exacting specifications. We apply thorough design and production controls – including an extensive ISO-controlled process. And our traceability process tracks every component through completion of the assembly and into the field.

A mechanical-spliced wire rope sling is constructed when eyes are formed using the Flemish eye splice. Ends are then secured by pressing a metal sleeve over the ends of the strands of the splice. Pull is directly along the centerline of rope and eye. This splicing method gives the most efficient use of rope capacity and proves to be economical.

Engineering wire rope slings for your application is a highly specialized field – with exacting standards – that we gladly live by. A Union sling can meet or exceed the most exacting specifications. We apply thorough design and production controls – including an extensive ISO-controlled process. And our traceability process tracks every component through completion of the assembly and into the field.

A hand-spliced wire rope sling is constructed when the end of a single wire rope is bent back along the rope to form the eye. These strands are then hand tucked into the body of the rope in what is called a tapered and concealed splice. This splice makes a sling that is easily pulled through narrow spaces and there are no rough ends to snag hands. Slings with rope bodies larger than 1 ½” diameter are made only with Burnt End splices in which ends of the strands are left exposed and cut off with a torch. These may also be cut shorter and served for smoothness. Both types of hand splices have the same rated capacity.

Strong & economical, Wire rope cable slings are versatile & long lasting. More durable than nylon slings, wire slings have higher temperature limits. Mechanically spliced eyes offer an efficiency rating of 95% the strength of the cable. Each sling comes tagged with rated capacities.

XTremaloop is a quick softline link where speed of connection is matched by improved safety and ease of handling in heavy duty environments. No hardware is needed for the XTremaloop connection enabling single hand handling. It uses a simple knot/eye connection. Where a shackle is used, there is no need to open the shackle, the XTremaloop feeds through any smooth strongpoint to complete the connection.

The XTremaloop connection is made from a twelve-strand HMPE (High Modulus Polyethylene) rope. It has an unmatched weight-to-strength ratio. Compared to a steel wire sling of the same length and capacity, it will match the breaking strength at only 15% of the weight.

XTremaloop can be used in, for example, surface and deep mining operations including tow lines and winch lines or almost any man-handled wire rope application where reduced weight and speed of connection will be of benefit.

A light thimble can distort under high load. Cheap wire thimbles often have sharp edges, and even well-polished examples can open the weave or chafe at strands, or seriously damage a splice if they shift.

At the heart of the problem is stretch. Nylon double braid rope stretches about 12 percent for every 20 percent of breaking strength; 3-strand rope stretches about 15 percent and climbing ropes stretch about 18 percent. Because each leg of the eye carries only half of the load, the stretch at 20 percent of breaking strength should be only 6 percent, but we must add to that some construction stretch, since it takes time for a splice to settle in. As a result of all the stretch, even factory-installed thimbles become loose at high load.

Even when a thimble is very well-fitted and tightly seized-as good and any we have seen-and stretched to the normal working load (10 percent breaking strength), it becomes quite loose. Any side load or binding could allow the thimble to shift its position. We were sent images of a bridle on a Jordan Series Drogue (a drag device used to slow the boat in a storm), and the bridle was severely chafed by a thimble that shifted. Had it failed, the consequences would have been serious. A closed thimble or a webbing sleeve is a safer choices for this application. We’ve seen similar near failures resulting from open-style thimbles in mooring applications as well.

Wear. A mooring line around a rusty shackle is a perfect case for a thimble. Abrasion is aggressive, and a nice thick layer of steel offers the best protection. But what about eyes attached to polished stainless shackles? Unless they are under extreme load and simultaneously sawing back-and-forth across the shackle pin, ring, or other load-bearing attachment point, there will be virtually no apparent wear.

Any rope is weakened when loaded around a small radius. The fibers on the outside carry more load than those on the inside, which may actually be slack, doing no work at all. This effect can be mitigated by changing the ratio of the rope diameter (D) to the diameter of the shackle pin (d) or other attachment point.

For determining block size, D/d ratios of at least 8 are recommended to cope with the loads and the greater potential for chafe. But depending on the application, the loads, and type of line used, the D/d ratio for an eye-splice can be as little as 1:1 without risking failure. The following discussion of D/d ratios applies only to spliced eyes in a splice, in which each leg carries only 50 percent of the load.

Wire rope. Wire rope is the extreme case, requiring a 20:1 D/d ratio. Wire does not stretch, and is subject to fatigue if repeatedly bent, and thus a thimble is required to increase the radius. Since wire rope does not stretch much, and because the cable is also steel, the thimble should stay put and would do little harm if an edge did chafe the cable.

Nylon. Fibers that stretch (nylon) do not suffer extreme strength reduction around a tight radius, because the fibers naturally share the load better. When the ratio of the rope diameter (D) to diameter of the pin (d) or shackle is 1:1, nylon is the strongest of all common rope constructions.

When the D:d ratio = 1 with these ropes, the strength of the eye is undiminished. It is true that each leg of the eye is weakened 50 percent, but because each leg only carries 50 percent of the load, the strength of the eye is undiminished, and the splice is usually the first to fail.

In the case of nylon, some increase in diameter may be desirable for lines that are routinely loaded over their working load limit (9 percent of breaking strength). Factory-added spinning lubricants help resist chafe but don’t last. This protection be partially restored in used ropes by treating them with certain water repellent coatings (see Winter Sailing Tips for Die-Hards, Practical Sailor, December 2016).

High molecular polyethylene (HMPE): Slippery HMPE fibers (such as Dyneema) share the load better, since they can easily slip over each other. Like nylon, when the D:d ratio = 1, the strength of the eye is undiminished. Because the line diameter and the pin diameter are generally about equal strength in applications that use Dyneema, no thimble is required. Heat-set Dyneema, used for standing rigging, is a special case, and should have a thimble or ring.

Polyester: What about polyester, so common in running rigging? In most cases it is oversized for stretch and hand, and thus will be working so far below its working load limit (20 percent of breaking strength) it is irrelevant.

The bottom line is that during our entire break-testing program of Dyneema, nylon, and polyester eye splices, we never saw a failure over the pin (see Sewn Splices Follow Up, PS June 2016). We saw failures within the splice, at the end of the splice, in the throat, and even in the center of the rope, but never at the pin.

Traditional and often cheap, lighter-duty open thimbles distort under load and have sharp edges. Even strong, well-polished versions can shift and damage rope. Occasionally the splices are tightly lashed in place, but this is like treating the symptoms rather than the cause.

Either welded or cast in an elliptical shape, these present no sharp edges that can damage a rope or sail. However, they do increase the throat angle (the angle formed by the two legs of the spliced eye) slightly and can fall out if poorly fitted or highly strained.

Traditionally used on large mooring hawsers because of the challenges in fitting other thimble types to large stiff lines, these have become popular with Dyneema winch cables. Their ability to maintain strength even after being distorted is a great asset.

In many cases, this may be all the protection you need. The thick nylon tubular webbing pads over sharp corners, increases the D/d ratio slightly, and easily manages any abrasion that can occur between a polished pin and the rope.

It also has advantages that no other thimble design can match: they cannot slip out of position, damage the rope, or scratch the deck. They are lighter, cost practically nothing, install in seconds, and are suitable for knotted loops as well. Perhaps the only downsides are that they are still unfamiliar to many sailors, and the appearance is decidedly non-traditional.

Made from very densely woven nylon, this well-proven chafe gear lasts at least 10 times longer than a typical polyester rope cover. For additional wear, coat with Maxijacket.

Often covers are available, either from high modulus line covers that have been stripped by racers, or salvaged sections of lines that have seen little wear (the portion of a halyard that lived inside the mast is often very good). A larger size can be slid over the eye. A cover is particularly useful for knotted lines, where it can also reinforce the knot.

This thin but incredibly durable covering proved virtually wear-proof in prior testing (UV, Chafe Protection, March 2105 Practical Sailor ). The only down side is the ends are difficult to melt, and tucking it in is impractical in a splice. Thus, a neat job requires advanced skills.

We’re not fond of wire rope thimbles for tough jobs. Although they have a long, generally successful history, we’ve seen too many cases where the thimble itself did serious damage. A sailmakers thimble is one answer. There are no sharp edges and they do not distort under high load.

For very high load, larger lines, and even knotted eyes, captive thimbles offer a more expensive but dependable solution. That would be our choice for a mooring pendant, combination rope-chain rode (splicing direct to the chain is even better), Jordan Series Drogue, or sea anchor. But for most running rigging jobs, either no thimble or a webbing chafe sleeve is the best answer.

The Mazzella 6 x25 IWRC (independent wire rope core) single-leg wire rope sling has eye-and-eye endings and a mechanical splice for lifting loads with vertical, choker, or basket configurations in industrial applications. The 6 x 25 IWRC construction contains six strands of wire rope with 25 wires per strand wrapped around a separate 7 X 7 wire rope, which has seven strands with seven wires per strand, in the center of the sling. This construction provides a balance between abrasion resistance and fatigue resistance, or resistance to the weakening that results from too much bending. The wire rope construction is flexible and has more abrasion and heat resistance than a web sling. This eye-and-eye sling has an eye, or loop, on both ends, and can be used with vertical, choker, and basket lifting configurations. The eyes are secured with a mechanical (also called Flemish) splice that is stronger than a hand splice. This sling has a minimum D/d ratio of 25 and meets American Society of Mechanical Engineers (ASME) specification B30.9 and Occupational Safety and Health Administration (OSHA) specification 1910.184.

Slings are used to lift heavy objects for industrial applications. Types of slings include web slings, wire rope slings, chain slings, and mesh slings. The appropriate type of sling for an application depends on the strength-to-weight ratio, flexibility and resistance to bending, resistance to abrasion and cutting, resistance to crushing, resistance to stretching, and resistance to high temperatures and other environmental stressors. Slings have one, two, three, or four legs; or a continuous loop of webbing or wire rope. Legs are support branches that extend from a single point at the top of the sling to the item being lifted so the weight of the load is distributed evenly among the branches. Slings have eyes (loops) or alloy steel fittings on the ends.

A vertical lifting configuration connects a crane hook directly to a load with a single, vertical sling, usually by means of a hook. In a choker configuration, the sling wraps entirely around the load, and one loop passes through the other to form a slip noose, or choker. In a basket configuration, the sling passes under the load and both ends of the sling connect to the crane hook. Load capacity is the maximum weight to be lifted in a vertical configuration. The capacity in a choker configuration is approximately equal to the vertical capacity times 0.8. The capacity in a basket configuration, with sling ends at a 90-degree angle, is approximately equal to twice the vertical capacity. Load capacity in a basket configuration decreases if the angle of the sling is less than 90 degrees. For example, a sling with a capacity of 2,000 lb. in a vertical configuration will have an approximate capacity of (2,000)(0.8)=1,600 lb. in a choker configuration and an approximate capacity of (2,000)(2)=4,000 lb. in a basket configuration, if the sling ends are at a 90-degree angle to the load. A wire rope sling"s capacity in a basket configuration applies only when the configuration meets the sling"s minimum D/d ratio, which is the ratio of the diameter of the rope"s curve around the load (D) to the diameter of the sling (d). If the minimum D/d ratio is not met, the capacity of the sling is decreased.

Amsteel is a samthane coated, non-rotational, 12-strand single braid that is known for its low stretch and high strength. It has a similar strength to wire rope with 1/7th of the weight. In addition, the product is flexible, lightweight, durable, resists flex-fatigue, & abrasion-resistant.

They are not the same thing but are often confused. As an example, the average strength of 1/4” Amsteel is 7400 pounds, while Amsteel Blue is 8600 pounds. Samson’s Amsteel is made from Dyneema SK60. Amsteel Blue is made from Dyneema SK75. What is being sold by cottage vendors today is usually Amsteel Blue, even if they don’t always call it that.

It depends. The 7/64 commonly used for whoopie slings, has only eight strands, but diameters beyond that have twelve. The Samson documentation invariably lists Amsteel Blue as a (class 2)12-strand product, but that documentation often does not include the 7/64 size because it is too small for the marine and industrial use that Samson caters to. Class I ropes are manufactured from polyolefin, nylon and or polyester fiber. Class II ropes (including Amsteel) are manufactured from high-modulus fiber, such as Dyneema Composite Fabrics.

Amsteel is defined by Samson as a “high-modulus polyethylene” rope. The high-modulus part means that Amsteel has “low elasticity elongation” or in other words, it doesn’t stretch much. However, this also means that this type of rope doesn’t like to be shock-loaded, so ease into the hammock! Safe working loads do not apply to shock loading.

Samson specifies that a fid is equal to the diameter of the rope x 21, and that an effective bury for Class 2 rope should be three and a half fids. The diameter of Amsteel 7/64 is 0.11 inches, so for this rope, one fid is equal to 2.31 inches. So the recommended bury would be about 8 inches. Bury = fid x 3.5 = 2.31 x 3.5 = 8.01 inches Note that the length of the bury is dependent on the diameter of the rope. Counter-intuitively, the smaller the diameter of the rope, the shorter the bury needs to be. For example, a whoopie made with 1.75 mm Zing-it would only need five inches of bury (if following Samson specs), while one made with 1/8 inch Amsteel would need nine inches.

The eye of the whoopie sling is usually made with a locked Brummell, which does not require stitching. The eye made in a variation of the “utility constrictor rope” (UCR), does require lock stitches (I like UCRs better than whoopies).

“Tough-Lock™” and “Cable-Flex™” slings are uniquely constructed unlike various return wire loop types. Note that our five step manufacturing process, commonly referred to as a “Flemish” splice, results in 100% breaking strength promoting additional safety! Further testing proved increased efficiency and greater work load limits.

All “Tough-Lock™” slings adhere and comply with current specifications of OSHA, ASME B30.9c-2000 Wire Rope Technical, and Associated Wire Rope Fabricators

Slings feature a taper and concealed splice closure of the loop eye allowing the rigger to pull the sling free under the load – CAUTION, these slings are rated lower in work load limits, refer to capacity chart.

Lift-All Permaloc slings are made using the Flemish Eye splice technique to form the eyes. Unlike the simple return loop method that places 100% of its strength on the swaged sleeve, Permaloc slings have reserve strength should the sleeve become damaged in use.

Many yachts have oversized lines within their rigging, which are expensive and unnecessary. Professional sailors and regatta participants are well aware of the advantages of spliced lines and use them to cut down on weight and save money.

A line that has been spliced can easily hold double the load than one which has simply been tied in a knot. However, an incorrect splice or knot can reduce the tensile strength of a rope by up to 75%!

The strength of a splice is based on friction and the phenomenon of self-locking and can only be completely maintained if a splice is done by a professional.

Yale Cordage began in 1950 with a belief in how synthetic material and high quality braiding techniques could transform the cordage industry. Our continued commitment is to remain grounded in this objective – to provide innovative end-user solutions through superior approaches to the design, manufacture, and fabrication of synthetic rope and rope systems.

We are constantly improving the safety and productivity of our products and pledge to provide exceptional customer service and products that work as hard as we do – up in space, down to the deep seafloor, and everywhere in between. A rope industry leader in expertise and innovation – Yale is passion for the pursuit of better performance.