High-quality wire rope rigging is important for the safety of workers. It lasts and makes it easier for on-site personnel to do their jobs.
Originally, companies used wire rope in the aerospace industry to hoist cranes. As a result, you may also hear people call wire rope aircraft cable.
There are several kinds of wire rope. Figuring out the right types of wire rope isn’t always straightforward. Because of these choices, it may prove confusing to figure out which one is the best for your application. However, you can make sense out of all your options with a few key pieces of information.
For a guide to the different types of wire rope and which is best, read on.
Types of Wire Rope
Manufacturers classify wire rope by the number of wires in each strand. They’re also classified by the strands in the entire rope.
These classifications have led to a two-number identification system. For instance, you might hear a wire rope called 7×19.
The first number represents the number of strands in the wire rope. The second number, however, represents the number of wires in each strand. If you were to unravel one of the strands of the rope, you’d see 19 separate wires.
As an aside, the second number does represent the number of wires in a rope strand—in theory. However, this specification is more of a way to identify a class or range of wire rope.
In other words, this part of the classification isn’t an exact measurement. Nevertheless, it’s important.
Wire cables that are the same core, grade, and size have similar strengths and characteristics. They also have a similar per foot weight.
Strongest Type of Wire Rope
Companies use certain wire rope types more frequently. Most often, you’ll find that they use 1×19, 7×7, and 7×19 wire rope.
1×19 wire rope is stiff and does not flex or bend. You’ll typically see companies use this kind of wire rope for running a straight line. For example, you may see electric utility companies use it as a guy wire to add stability to freestanding poles.
Meanwhile, a company might use a 7×7 cable for rigging, towing, or manoeuvring heavy objects. In general, companies will use a 7 x 7 wire cable when they need flexibility. This kind of wire rope is ideal for making slight bends.
For heavier applications, a company might use a 7×19 wire rope. For example, a company might use this kind of wire rope for a pulley system.
Understanding Types of Wire Rope Breaks
On job sites, you should inspect wire rope regularly. As wire rope ages or experiences increased use, you should inspect it with more frequency.
During the inspection, there are a few things that you should observe. For instance, you should keep an eye out for fatigue failure.
This kind of wire break will occur when you subject it to heavy loads over small pulleys. When this happens, you’ll see breaks in the valleys of the strands called strand nicking.
When strand nicking occurs, you may notice a section of strand missing from the rope. Strand nicking happens when rope strands rub against one another.
This kind of wear is normal for wire rope. However, heavy loads can increase the presence of this kind of damage.
Another form of wire rope damage that you might observe is called a birdcage. A birdcage break will form when a wire rope is suddenly relieved of tension.
A birdcage is a wire rope break that occurs when the wires do not return to their original position. In this instance, you’ll need to replace your wire rope immediately.
You might also notice changes in the shape of the wire rope. This type of damage may happen when workers pull down a loop in a slackline. If you look closely, you’ll see the distortion of the individual strands.
Types of Wire Rope Slings
There are many kinds of wire rope slings. Each sling has a variety of uses.
Most often, companies will use a single-part wire sling. A single-part wire sling might have a single-leg or four-leg spreader. It might also have a hand or a mechanical splice termination.
A company may also make use of a socket rope assembly sling. With this kind of sling, companies pour or press sockets on to both ends of the assembly. You’d typically use this type of sling for a permanent installation.
Sometimes, an application calls for a braided rope sling. A company will make this kind of sling by continuously braiding several ropes together into a single wire rope. You’d use this kind of wire rope for an application that requires flexibility and high load capacity.
A galvanized cable-laid sling is another commonly used wire rope sling. For this kind of sling, companies combine seven smaller groups of wire rope.
Finally, some applications call for a stainless steel wire rope sling. This kind of sling works well for outdoor applications. For example, a company might use this for an outdoor installation rather than a standard single-part sling.
The Right Wire Rope for the Job
There are many different characteristics of wire rope that affect its performance capability. As a result, it’s important to understand each rope’s different characteristics.
No one wire rope is suitable for all jobs. All wire ropes offer trade-offs and characteristics.
For example, you cannot purchase wire rope with both increased fatigue and abrasion resistance. You might increase fatigue resistance by choosing a rope with more wires. However, it will have less abrasion resistance because it has more small outer wires.
When choosing wire rope, it’s important to select wire with the appropriate minimum breaking force (MBF) for your application. It’s also important to choose a wire rope with suitable fatigue resistance.
Crushing resistance is another important measure of wire rope. It’s the amount of crushing pressure that a wire rope can withstand while maintaining its shape.
You must also consider resistance to metal loss and deformation. This characteristic is based on how much metal wears away from the outer wires of the rope. When deformation occurs, the shape of the outer wires will change.
Finally, you must consider the resistance to rotation of a wire rope. When you use wire rope, you subject it to torque.
The torque of your application will cause wire strands to straighten out over time. If you choose a wire rope that cannot withstand the torque of your common applications, however, the rope may allow your load to rotate.
Stay Sharp, Learn More About Your World!
Now you know more about the different types of wire rope. Hopefully, you’ll find it easier to choose the right equipment for your next job.
Every day, engineers develop new and exciting products and technology. It can prove tough staying informed about the best goods and services that can improve your business or life.
Image Credits: Carl Stahl Sava Industries, Inc.