Select the Perfect Rope Based on Construction, Performance & Material
Everything you need to know about rope. Performance is a design, not an accident. Rope is a tool. Like any other tool, it is important to use the right rope for the job at hand. To help you choose the right rope, Novatec Braids developed the following Guide To Rope. It provides a simple overview of the major factors that influence rope construction and performance.
When it comes to designing a rope, there are an infinite number of data points that may be considered. This is the science behind the creation of high-performance rope. Success requires understanding the characteristics of each component in a rope. It demands knowing how each component will performs when combined to construct a rope. Paying attention to these details is how Novatec Braids helps customers design and build ropes that provide the best possible performance for their application.
If you would like more information about any of these factors, please e-mail our customer service department with your questions. Our Customer Service Manager will quickly respond with the information you need.
Novatec Braid’s Guide To Rope:
Twisted vs Braided
Solid Braid Ropes
Yarns – Polyester, Nylon, Aramid and Natural fibers
Flexibility
Splicing Characteristics
Uniform Tension Control
Elongation
Importance of Specific Gravity
SEAGUARD® Finish
Abrasion Resistance
Urethane Coatings
Impact of UV Light
Impact of Saltwater
Mildew and Rope
Dielectric Properties
Rope Rotation
Chemical Resistance
Rope Torque
Dynamic and Static Characteristics
When to retire a rope
Twisted vs. Braided
Ropes are commonly built in one of two ways. They are either twisted or braided. Twisting is the oldest and simplest way to make rope. It also is the way individual filaments are gathered together into fibers, which then become strands of a rope. Twisted ropes are easy to manufacture, relatively inexpensive, and disposable. Because they are inexpensive, twisted ropes are often used in settings where strength, durability and reliability aren’t factors. Twine on a bale of hay is a good example of a twisted rope at work. It is used once and then thrown away.
Braided ropes, on the other hand, are the workhorses of the rope world. By braiding fibers together into strands and strands into rope, it is possible to overcome the shortcomings of twisting. The process also adds incredible strength to the product. A well-made braided rope features fibers that are aligned in a single direction and overlap in a way that behaves like a Chinese finger-lock. The result? The more pull exerted on the rope, the more the braiding locks each fiber into place. This creates strength, durability and reliability.
Solid Braid Ropes
Solid braids are a variant of braided rope that provide high abrasion resistance, relatively high strength and relatively low stretch. They also are remarkably easy to handle.
Yarn
Yarn is the basic component of rope. It can be an organic product, such as jute, a petroleum-based fiber, such as polyester, or a hybrid product combining a fiber with another element, such as a metal wire. When it is time to begin turning the raw yarn into rope, the first step is to twist individual yarns in different directions (s and z twists). High performance ropes have individual yarn strands twisted to a specific number of twists per inch (TPI). Then, when the strands are braided into rope, every yarn strand is perfectly aligned with the direction of the rope. The most common materials used in the construction of rope include: Polyester, Nylon, Aramid and Natural fibers.
Polyester
Polyester has a number of characteristics that make it well suited for use in rope. It is relatively strong, and stretches little. It can take a good deal of abrasion, and handles a variety of weather conditions very well. It doesn’t shrink after getting wet. Temperature has little impact on its flexibility.
Nylon
Nylon is another fiber well suited for making rope. Unlike polyester, nylon can stretch a great deal, which allows it to absorb energy. When wet, nylon fibers can lose approximately 15% of their strength. They also shrink after being wet. Nylon fiber handles a variety of weather conditions very well and is abrasion resistant. Temperature has little impact on its flexibility.
Polypropylene
Polypropylene’s major advantage is that it absorbs little water and doesn’t shrink after becoming wet. It offers about 60% of the strength available from either nylon or polyester fibers. It stretches little. Polypropylene does not have the abrasion resistance of nylon or polyester, nor is it as tolerant of weather conditions. Temperature has little impact on polypropylene’s flexibility. Polypropylene ropes should not be used where there is a lot of friction, due to a low melting point, which can lead to abrasion and fusion of fibers.
Aramid
Aramid is another artificial fiber used in NOVABRAID™ product. Commonly known by the names Twaron or Kevlar™, Aramid fibers stretches very little and are extremely strong. They are neither abrasion nor UV resistant.
Flexibility
Every rope needs a degree of flexibility. Flexibility is affected by the relationship of the core and cover. The core of a rope is what contribute strength to the product, and should always be covered. The sleeve has to cover the core in a way that prevents it from popping out (herniating) between plies of the sleeve.
Splicing Characteristics
Often when people join two pieces of rope, they simply knot them together. While this is a common method of joining ropes, it creates a weaker rope. Splicing is the best means of joining two pieces of rope. Done correctly, the new rope retains between 90% and 95% of an individual rope’s strength. The process of splicing literally reweaves the two ropes into one, continuous rope. As a safety precaution, always inspect splices on a regular basis.
Uniform Tension Control
Rope is a bundle of braided fibers under tension. If those fibers aren’t under the same degree of tension, their strength can’t be equally used. During rope making’s winding stage, the tension on each individual strand must be kept equal. This, in turn, keeps the tension throughout the rope equal. The result is a rope with uniform tension and strength along its entire length. Uniform tension is important because it allows a rope to perform at its maximum ability. Changing the tension, like changing a braid angle, changes the performance characteristics of a rope.
Elongation
Elongation, as defined by the Cordage Institute is the deformation in the direction of a load caused by a tensile force. Elongation may be expressed in units of length or calculated as a percentage of the original specimen length. It may be measured at any load or at the maximum load.
Importance of Specific Gravity
According to the Cordage Institute, Specific Gravity is the ratio of the mass of material to the mass of an equal volume of water at 4 degrees Celsius. The range for ropes is dependent to some extent on the liquid used as the immersant because of possible rope fibers swelling and absorption. If a rope needs to be buoyant and not absorb water, its specific gravity must be below 1.0 specific gravity. Ropes with a specific gravity less than 1.0 will float. Anything greater than 1.0 will absorb water and sink. The distance it sinks depends upon the specific gravity of that rope. For example, a rope with specific gravity of 1.38 will sink deeper than a rope with a 1.10 specific gravity.
SEAGUARD Finish
SeaGard is a patented marine overlay finish produced by Allied Signal which improves the wet abrasion resistance of both nylon and polyester fibers. Applied in the fiber making process, SeaGard won’t wear off or wear out. It adds wet performance without sacrificing other mechanical properties. Ropes built with SeaGard treated fibers exhibit superior wet and dry abrasion resistance. These improvements have been verified by Cordage Institute tests.
Abrasion Resistance
Abrasion resistance refers to an individual fiber or rope’s ability to withstand wear associated with rubbing against itself or another surface.
Urethane Coatings
Urethane is applied to rope as a seal to prevent the absorption of water and foreign elements.
Impact of UV Light
Prolonged exposure to sunlight’s ultraviolet rays can weaken and damage a rope. Polypropylene and polyethylene fibers are especially susceptible to UV damage. You can tell when UV degradation has taken place by discoloration of the rope, splintering and the presence of slivers on the surface of the rope.
Impact of Saltwater
Salt will harm a rope, affecting both its life and efficiency. The best method for removing salt from a rope is to soak it in fresh water.
Mildew and Rope
Mildew develops on damp and wet ropes. Over time, mildew will rot and deteriorate a rope.
Dielectric Properties
Dielectric properties refers to the electrical conductivity of a rope.
Rope Rotation
When force is applied to a rope, it produces a twisting or rotating motion on the rope. The continuous rotating or twisting of a rope will eventually cause it to weaken and make it difficult to work with.
Chemical Resistance
Chemicals will damage a rope. Natural fiber ropes are especially susceptible to damage by chemicals.
Rope Torque
As defined by the Cordage Institute, torque is a force or combination of forces producing a twisting or rotating motion. When applied to rope, the term torque refers to the character which tends to make it turn on itself as a result of twisting.
Dynamic and Static Characteristics
Dynamic Rope: Examples of a dynamic rope are NOVABRAID™ Dock and Anchor Lines, which provide stretch when needed, absorbing and dissipating energy (like a rubber band) by as much as 10% (this means a 10 foot rope will stretch one foot). Static Rope: is designed to provide very little stretch, and used in applications like construction and arborist work. Depending upon the construction of a static rope, it will stretch a maximum of 1-2%.
When To Retire A Rope
When fibers show wear in any given area, a rope should be replace. In some cases, the section of worn rope can be replaced with new rope, but there is little guarantee that it will retain its original strength.