Bungee Cords
A bungee cord is a rope that is composed of two or more elastic strands coated with a woven fabric. It has hooks that are placed on both ends. A bungee cord is also known as shock cord and elastic cord...
High Strength Ropes: Types and Materials
Introduction
This article takes an in depth look at high strength ropes.
This will cover topics such as:
- What are High Strength Ropes?
- Materials Used for High Strength Ropes
- Types of High Strength Ropes
- Types of Fiber
- And Much More…
Chapter 1: What are High Strength Ropes?
High Strength Rope is strands, fibers, piles and yarn joined together to form a strong and a large structure. These strands or fibers are either twisted or braided to produce high tensile strength rope that is stronger and more resilient. High strength ropes are also used for lifting and dragging purposes. Ropes were used by mankind since prehistoric times for different purposes such as tugging, hunting, climbing, securing things, fastening, and carrying things. In ancient times, natural fibers were used to construct ropes. In the 1950s, synthetic fibers started to be used in rope making. There are two types of high strength rope. These are natural and synthetic rope.
Natural Ropes
Natural ropes are crafted from environmentally friendly materials that do not produce harmful byproducts during manufacturing. Common natural fibers used include cotton, hemp, and sisal. When natural fibers are combined with synthetic fibers, the resulting rope is stronger and more durable. Although natural fiber ropes are robust in use, they can be susceptible to damage from water, mildew, mold, or UV light. They are resistant to high heat but can burn when exposed to open flames. Natural fiber ropes may shrink when wet and not return to their original size or shape, which can limit their applications. However, their non-slip characteristics make them effective for securing objects.
Synthetic Fiber Ropes
Synthetic fiber rope is made from synthetic or manmade materials such as nylon, polyester, polypropylene and multiple other synthetic materials. Synthetic ropes are stronger and last longer than that of natural fiber. Their average life span is about 30% more than that of natural fiber rope. Wet environments can’t cause damage to these ropes. Another beneficial aspect is that they are not prone to damage from mildews, UV light, or mold, making them useful in an open atmosphere. Synthetic ropes do not perform well when exposed to heat because it will melt these ropes. They are not environmentally safe because of harmful by-products emitted in the atmosphere during the production process. But they are strong and can be used easily for lifting or towing purposes.
Construction of High Strength Ropes
High strength ropes are available in various construction types, defined by their twisting or braiding patterns. These ropes are categorized and named based on their specific construction methods. Each style of rope construction is detailed below:
Single Braid 12 Strand Rope
Single braid 12 strand ropes are made of HMPE with a high strength to weight ratio and better break strength than wire rope. It is made by interlocking braids, which makes the rope very strong. Single braid 12 strand rope is a good choice for heavy pressure or weight to be pulled or lifted. The braiding process involves braiding twelve strands of HMPE fiber using a complex pattern of over and under braiding that securely interlocks the fibers. For best results and prevention of failure, single braid 12 strand ropes are jacketed with an elastomer for greater protection.
Plaited Rope
Also known as square braid rope, this type is coarser compared to other twisted ropes. It consists of approximately four sets of strands, which are twisted and interwoven to create a braided structure. These ropes are highly flexible and strong, making them easy to knot. However, a drawback is that all the strands are exposed to the environment because they are twisted around a central core, making them susceptible to damage.
Twisted Rope
Twisted rope, often referred to as laid rope, is ideal for applications requiring splicing. It is constructed by twisting strands together in the same direction. Typically, three of these strands are twisted in opposite directions to form a braided structure, enhancing grip strength. These ropes tend to be less flexible and are prone to kinking if not handled properly. They are commonly used for dock lines and towing operations.
Double Braided Rope
Double braided rope is an excellent option when strength and durability are required. It is constructed by coiling double braided strands around a double braided core, offering enhanced stability and flexibility. This type of rope is abrasion-resistant, making it ideal for marine environments but less suitable for manufacturing sites. Double braided ropes are highly resilient and resistant to kinking, with their high strength derived from the protective double braiding surrounding the core.
Hollow Ropes
Hollow ropes are empty or hollow from the inside and can be spliced easily. It is a lightweight synthetic rope that can be used for ski towing and anchor lines because these are water resistant.
Diamond- Braid Rope
Diamond braid ropes are crafted by meticulously braiding fibers around an inner core to create a firm and rigid structure. This precise and tight braiding results in a higher cost compared to other rope types, but it also provides a durable and attractive finish. These ropes are known for their durability, roundness, and firmness, making them suitable for demanding conditions. Additionally, diamond braided ropes are easily spliced, which makes them compatible with other types of ropes.
Jacketed Rope
Jacketed rope features a protective covering that shields the rope from abrasion and UV damage. This tough outer layer, made from synthetic materials such as urethane elastomers and thermoplastic elastomers (TPE), acts as a barrier against friction and environmental effects. The jacket is applied as a resin layer with a specific thickness and can also be color-coded for easy identification.
Jacketed ropes are particularly useful for outdoor applications, as they help prevent the rapid degradation of rope fibers due to exposure to the elements.
Leading Manufacturers and Suppliers
Chapter 2: What materials are used to make HEPA vacuum cleaners?
Various materials are used in the production of high strength ropes, with several popular options highlighted here:
- Aramid
- HMPE
- VECTRAN
- PBO
- Polyester
- Polypropylene
- Nylon
- PEEK
- Polyethylene
These are the materials commonly used in the production of high strength ropes. Each material is further classified into various types, which will be covered in detail in this chapter.
Aramid Fiber
Aramid, also known as poly(para-phenylene terephthalamide), is a high-strength fiber with minimal stretch, notable for its resistance to high temperatures and creep. It is one of the earliest and most effective fibers used in rope manufacturing, with examples including Technora, Twaron, and Kevlar. While aramid fibers are strong, they have limited abrasion and UV resistance and are often wrapped in additional materials like polyester for protection. Meta-aramids (such as Nomex and Teijinconex) offer excellent heat and abrasion resistance, but para-aramids generally provide greater strength than meta-aramids.
HMPE Fiber
High modulus polyethylene (HMPE) ropes are among the strongest available and come in various grades. HMPE fibers feature long molecular chains, making these ropes exceptionally durable and stronger than steel, with high impact resistance. HMPE ropes have a strength-to-weight ratio that is eight times greater than that of high-strength steel, making them one of the most popular rope fibers worldwide.
VECTRAN Material
VECTRAN, known as aromatic liquid crystal polyester, is a high-strength material with low stretch properties similar to aramids and notable resistance to heat.
PBO or Zylon
Zylon, commercially known as PBO (poly(p-phenylene-2,6-benzobisoxazole)), is a recently introduced material in the rope industry. It is an exceptionally strong fiber with minimal stretch and excellent high-temperature resistance. Like aramids, Zylon requires protection from UV light and abrasions.
Polyester in Rope
Polyester is one of the most effective synthetic materials used in the rope industry, offering exceptional resistance to water, UV light, and abrasion. These attributes make polyester an excellent choice for reinforcing other materials and enhancing their durability. Polyester has a density of 1.38, a melting point of 260°C, and a breaking extension of 12%.
Nylon or Polyamide
Nylon, or polyamide, is a synthetic material known for its superior strength when dry compared to polyester. However, when wet, nylon can lose up to 10% of its strength. While it offers good abrasion and UV resistance, its notable feature is its stretchability. Nylon can stretch up to 30%, making it ideal for applications requiring pressure resistance. Its relative density is 1.14, and it has a melting point of 220°C.
Polypropylene Material
Polypropylene is a lightweight material with a density of 0.91, allowing it to float on water. It offers moderate resistance to UV light and abrasion. Although its breaking extension is similar to polyester, polypropylene is generally weaker. It is highly resistant to chemicals and has a melting point of 170°C.
Polyethylene Material
Polyethylene shares many characteristics with polypropylene, but it offers slightly better UV resistance. With a relative density of 0.97 and a melting point of 165°C, polyethylene is a comparable yet distinct option.
PEEK
PEEK, or polyetheretherketone, is a polymer from the ketone family known for its outstanding dimensional and thermal stability. It is highly resistant to severe chemical and abrasive conditions. Zyex PEEK fiber, in particular, is renowned for its exceptional durability under high temperatures, chemicals, and heat.
Types of Fibers
Various types of ropes are manufactured from these high-strength fibers and find application across numerous fields. Examples of high-strength fiber products include Kevlar, Twaron, Technora, Dyneema, Spectra, Polyester, and Nylon. These will be explored in detail here.
Aramid Fibers (Kevlar, Technora, Twaron)
Due to their strength, stiffness, hardness, and thermal stability, aramid fibers are the best option for many purposes. Kevlar rope is known for its low shock resistance properties. If kevlar ropes are subjected to shock, they are easily damaged. It is for this reason that Kevlar ropes are normally jacketed since they break down rapidly when exposed to shock and the elements.
Chemical Structure of Kevlar (Aramids)
Kever’s chemical structure reveals it as a polar molecule with a lengthy crystalline formation that significantly contributes to its strength. While this polarity allows Kevlar to bond with substances like epoxy and water, these bonds can sometimes be detrimental. For instance, water can easily wet Kevlar, potentially affecting its performance.
Physical Properties of Kevlar
Kevlar fibers are interconnected, and their strong bonding capacity with other molecules imparts aramids with distinct properties. The physical characteristics of Kevlar include:
- High resistance to cut makes it suitable to use as protective clothing.
- They have a high chemical resistance though chlorine can affect Kevlar.
- Aramids have a high tensile strength i.e. 2920 MPa.
- Kevlar is flame resistant and hence is self extinguishing.
- The critical temperature of aramids is 400°F and decomposes at 800°F.
- Low temperatures cannot affect aramids because of the low thermal shrinkage property.
- The specific gravity of Kevlar is 1.44
- High stiffness
- Kevlar can absorb moisture easily.
- Subjected to UV radiations.
- Electrical conductivity is not a feature of Kevlar.
- Kevlar can be easily damaged by shock loads.
- It has a low elongation break i.e. 1.5-4.5 %.
- Kevlar exhibits excellent dimensional stability.
Chemical Properties of Kevlar
- Kevlar ropes are resistant to organic solvents.
- Degrades quickly in strong acids and bases.
- Chlorine can damage Kevlar rope quickly and should not be used as bleach for this rope.
- Oxy clean is a safe option but never use hydrogen peroxide as bleach.
Aramid Rope Uses
Kevlar ropes are lightweight and resistant to chemicals, making them an excellent alternative to steel cables. However, they are susceptible to UV degradation, necessitating a protective cover. Typically, the core is composed of aramid rope, while the outer layer is made of UV-resistant material like polyester. Kevlar ropes are extensively used in boating applications. Despite their strengths, they are not ideal for climbing due to their vulnerability to shock loads, which can cause sudden breakage. They are, however, effectively used in winches, suspension bridges in Scotland, and guy wires for hydro towers. Their high heat resistance also makes them a viable substitute for asbestos in various applications.
Aramid Advantages
- Aramids have high strength, toughness and rigidity.
- They have an excellent resistance to heat, burning or thermal degradation.
- They are non conductive but can conduct electricity when wet.
- Aramids are chemically stable ropes but cannot stand strong acids or bases.
- Kevlar ropes are low stretch.
- They are difficult to cut.
Disadvantages of Aramids
- Aramids cannot float in water.
- They are polar molecules and thus they attract water towards them.
- Quite expensive material.
- Kevlar ropes can be easily damaged by shock loads and do not give warnings before and can break down easily after 1000th use.
- Properties of compression are quite poor for these ropes.
- Technora and Kevlar ropes require special attachment sites to maintain strength.
- Knots in these ropes can damage them.
High Modulus Polyethylene (HMPE) Dyneema, Spectra
High modulus polyethylene, often referred to as high-performance polyethylene (HPPE), is known in the sailing and boating industries under the names Spectra and Dyneema.
Chemical Structure of HMPE
HMPE's chemical structure features long molecular chains with no additional groups, which prevents other molecules from interacting with it chemically. This configuration results in a robust material that can stretch easily. HMPE does not attract water, chemicals, or microorganisms, thus remaining dry and non-sticky. The manufacturing of Dyneema and Spectra involves a process known as gel spinning.
Physical Properties of HMPE
High modulus polyethylene stands out due to its distinctive chemical structure, which imparts various unique properties. These include:
- HMPE does not attract water so it is hydrophobic and repels water.
- Dyneema and Spectra have stronger ropes and do not weaken when they are wet.
- HMPE feels too slippery to handle.
- It is a self lubricating rope fiber.
- Its melting point is about 144 to 152°C.
- HPPE can easily float on water due to its low density of 0.95.
- Under continuous load polyethylene creeps quickly.
- It is very strong, as strong as hardened steel.
- Low coefficient of friction is a property of HMPE and it is as slippery as Teflon.
- Polyethylene is very resistant to abrasions and UV radiations.
- It has low elasticity and cannot be stretched much.
Chemical Properties of HMPE
- HMPE chemical structure shows long chains of molecules and it does not contain any chemical group attached to it therefore they are not chemically active.
- It repels water, but certain oxidizing agents can attack these molecules.
Uses of HMPE
HMPE is a robust, lightweight fiber that can float on water. It offers excellent resistance to abrasion, chemicals, and UV light. This fiber is utilized in high-performance sails and rigging for yachting. Additionally, high modulus polyethylene is employed in body armor, vehicles, cut-resistant gloves, climbing gear, fishing lines, paragliding equipment, spear lines, bow strings, parachute suspension lines, and various other applications. Spectra, a type of HMPE, is also used for towing and winching, particularly in marine environments due to its buoyancy.
Advantages of UHMWPE
- They are high strength and low weight
- UV and abrasion resistant
- Light enough to float on water
- HMPE are low conductors of electricity
- They are smooth and slippery, as self lubricating material.
- Vibration damping and a low stretch
- They are chemically inactive but sometimes strong oxidizing agents can react to them.
- Transparent to radar is also a property of HMPE.
Disadvantages of UHMWPE
- It has a lower melting point of 144 to 152°C
- Needs a lower boiling point of less than 80°C
- It can creep easily due to consistent shock load.
- It is so slippery in nature and cannot bear knots.
- Low friction can distort and twist the rope layers.
- It is 4-5 times more expensive than polyester.
- HMPE is so slippery in nature, making it difficult to cut smoothly.
Polyester Fiber
Terylene, Dacron, and Trevira are commercial names for polyester fiber. Polyester fibers are favored for boat lines and sailing due to their durability, flexibility, and cost-effectiveness. These fibers are very thin, with a diameter of 0.023 mm, and are typically white. It is generally challenging to differentiate between nylon and polyester.
Physical Properties of Polyester
- Polyester does not float and has a specific gravity of 1.38.
- Polyester fiber is strong, durable and rigid.
- Polyester is non stretchy material and has a low creep under load.
- Polyester is good at retaining its strength when it is wet.
- Melting point of polyester is 240°C.
- UV resistance of polyester is better and only loses by 10% if used for outdoor purposes. Therefore, it is considered best for outdoor use.
- It exhibits excellent abrasion resistance.
- Polyester is a non- conductor of electricity.
Chemical Properties of Polyester
- Polyester fiber exhibits a good resistance to strong acids and alkalis at room temperature, but if the temperature is increased then resistance will be decreased.
- Polyester fibers are good in showing resistance to petroleum based solvents such as bleach. If soaked in bleach for a while it will deteriorate.
Advantages of Polyester
- Polyester is widely available and a well priced fiber.
- A good resistance to UV radiations making it an excellent choice for outdoor applications.
- Exhibit good chemical resistance but only at room temperature.
- Polyester is typically a hard, rigid and strongest fiber in the market.
- Polyester’s strength doesn’t wear off when it gets wet.
- Low stretch and can bear loads
Disadvantages of Polyester
- Polyester is not designed to float on water.
- Polyester is low stretch and rigid, which makes it unable to work in blocks
- If there is a jerking factor in loads then it is not a good choice. It can be used as protective layering instead.
Application of Polyester
Polyester is an excellent synthetic fiber for various applications where other fibers might fail due to its superior UV and abrasion resistance and its stiffness. It is extensively used in making sheets, sailing boats, and ropes for mooring or winch lines. Unlike other fibers that melt at high temperatures, polyester has a high melting point, making it suitable for such conditions. It functions well as a shock absorber and is effective on blocks and capstans where low creep is crucial. Additionally, polyester is used in protective layers for other fibers like aramids, allowing them to endure longer in outdoor environments without significant wear.
Nylon Fiber
Nylon, also known as polyamide, is a synthetic fiber that can be molded, spun, and machined. It is widely utilized in various fields and applications. The physical and chemical properties of nylon are outlined below.
Physical Properties of Nylon
- Nylon is strong and durable
- It has excellent abrasion resistance.
- Nylon can be stretched a lot before breaking down making it an excellent shock absorber.
- Nylon has a specific gravity of 1.13. Nylon does not float.
- Nylon melts at high temperatures rather than burning. If it burns it will emit cyanide.
- Nylon has a good strength to weight ratio.
- Infrared light can pass through nylon, meaning it is transparent to infrared light.
- Nylon has a maximum temperature of 99°C and a minimum temperature of -70°C.
- Melting point of nylon is 420°C, with a tensile strength of 5800 psi
- Nylon has a good UV resistance.
- In dry form nylon is an electrical insulator but its properties change when it is wet.
Chemical Properties of Nylon
- Nylon is resistant to oils, alcohols and formaldehyde.
- Nylon has poor resistance to phenols, alkalis, iodine, chlorine and acids
- Nylon cannot be degraded easily because of its great resistance to insects, animals, fungi and rot.
- Nylon cannot burn but if it burns it will emit cyanide, which is a highly poisonous gas.
Advantages of Nylon
- Nylon is strong and abrasion resistant.
- It does not melt easily thus showing high heat resistance.
- Nylon can be made from lustrous, semi lustrous and dull material.
- It can be dyed and can be found in many colors.
- Polyamides are good at UV resistance.
- It is a quite inexpensive material.
- It is resistant to solvents, acids and bases.
- Nylon is highly elastic and can be stretched up to 40%.
- It is made soft and feels pleasant to handle.
Disadvantages of Nylon
- Nylon does not float and sinks in water.
- If it burns, nylon will emit a highly poisonous gas called cyanide.
- It is too stretchy and is not suitable for places where dimensional stability is needed.
- Nylon loses strength when it is wet and repeated cycles can cause it to emit internal heat at a higher pace which resultantly degrades its performance.
Uses of Nylon
Nylon is employed in dock lines because it can be dyed in various colors, allowing fishermen to enhance the aesthetic appeal of their docks. Nylon nano filaments have been utilized in fishing lines for many years. Most yacht anchor lines are made of nylon, and paracord, a nylon string, is used in parachute suspension.
Zylon Fiber (Meta- Aramid)
Zylon is currently one of the best synthetic fibers on the market, offering high tensile strength and rigidity. Its tensile strength is 1.6 times greater than that of Kevlar. Zylon is used in a variety of applications, ranging from tennis racquets to construction projects.
Physical Properties of Zylon
- Zylon is the rigid and strongest synthetic fiber of all.
- Tensile strength of zylon is 1.6 times higher than that of Kevlar.
- Zylon has a high flame and heat resistance.
- Chemical bonding of zylon gives maximum strength to this fiber.
- This material can be modified into any form and any product.
- Zylon is found in a variety of media such as filament, chopped fiber, spun yarns and many more.
- Zylon fiber can be recycled and reused over time.
Chemical Properties of Zylon
- Zylon has an excellent strength to weight ratio.
- Zylon chemical properties are even better than that of carbons and aramids.
- It has outstanding dimensional stability which means it cannot creep easily.
- It has a very good resistance to many organic solvents.
Uses of Zylon
Zylon is extensively used in the production of protective clothing due to its heat-resistant properties. It is also utilized in the protective coating of certain wires and in cement for reinforcement purposes. In the sports industry, Zylon is found in bike tires, tennis racquets, snowboards, yacht ropes, and more. Additionally, it is used in cable cover material for welding machines.
Advantages of Zylon
- Highly rigid and stronger material.
- High tensile strength 1.6 times more than Kevlar.
- Highly resistant to heat and organic solvents.
- It cannot creep easily due to its strong dimensional stability.
- It can be reused and recycled by the respinning method.
- It is considered as the world strongest material that is made synthetically.
Disadvantages of Zylon
- Zylon is highly sensitive to light and its tensile strength can be decreased upon exposure to light.
- It is a highly expensive material to manufacture.
Nomex Fiber
Like Kevlar, Nomex is an aromatic polyamide. However, Nomex, a Meta-Aramid, differs from Para-Aramids in its molecular linkage. The chemical bonding in Nomex is zigzag in composition, resulting in lower tensile strength and rigidity compared to Para-Aramids. Nomex is an elongated fiber that is best utilized in making yarns.
Physical Properties of Nomex Fiber
- Nomex is a flame resistant fiber.
- UV resistance of Nomex is exceptional.
- It is heat and abrasion resistant.
- Breaking tenacity of Nomex is 5.0g/d.
- Specific gravity of Nomex is 1.38.
Chemical Properties of Nomex
- Nomex has a good resistance to acids and alkalis.
- It also exhibits excellent resistance to organic solvents.
- But strength loss drops in acid like hydro-sulphuric acid.
- It has good resistance to alkalis at room temperature but degrades quickly at a high temperature.
Uses of Nomex
Nomex fiber is well-known for its use in protective gear for firefighters, pilot crews, and in industries where protection from flames and electricity is crucial. Cement and asphalt factories also use Nomex filter media. Gear made from Nomex provides protection against flames, electrical currents, and various other hazards.
Advantages of Nomex
- Highly resistant to UV, heat and abrasions.
- It is a strong and durable material.
- High resistance to acids and alkalis.
- Low shrinkage properties
- Helps in yielding good protective clothing.
- Nomex is a soft and lightweight material.
Disadvantages of Nomex
- It is resistant to acids and alkalis at room temperature but degrades at high temperatures.
- It is an expensive material.
- Its strength drops in strong acids.
Chapter 3: What should you look for when buying high-strength rope?
Selecting high strength rope is comparable to choosing an essential piece of equipment and requires careful thought. These ropes are critical for industrial use, such as in slings or pulley systems, and must be robust enough to handle significant stress while moving or lifting loads. When chosen with precision, high strength ropes ensure safety and efficiency in all lifting operations.
Key Considerations for Purchasing High Strength Rope
- Material - An essential factor in choosing the correct rope for an application is knowing the material used to manufacture it. For high strength ropes, natural materials are normally avoided since they do not have the necessary breaking strength to handle heavy loads. A factor that makes natural materials attractive is their lower cost and easy availability.
High strength applications typically utilize synthetic materials, sometimes with protective jackets, that offer the necessary breaking strength, resilience, and durability to manage substantial loads while ensuring longevity. For example, certain grades of nylon start with a breaking strength of around 1000 lbs, whereas other synthetic materials can support loads in the thousands of pounds.
HMPE is one of the most commonly used materials for ropes due to its exceptional strength-to-weight ratio, which is comparable to steel. In configurations like double braid and 12-stranded braid, HMPE stands out as the strongest option available. A 12-stranded braided HMPE rope with a 48 mm diameter has a breaking strength of 165 tons and an impressive operational lifespan of 4000 hours.
- Strength - The strength of a rope is calculated by determining its breaking point, which is the point at which a rope will break. Natural rope materials have breaking points between 300 to 600 pounds while synthetic materials have breaking points well over 1000 pounds.
While the breaking strength is a valuable measure of a rope's durability, it is not always straightforward to predict due to various influencing factors. Often, employing double-braided or 12-stranded braided ropes can help achieve a reliable safety margin for the breaking point.
- Diameter - The factors that determine the selection of the diameter of a high strength rope are maneuverability, handling, comfort, and safety. For most high strength rope applications, thicker rope is chosen for its strength and the equal distribution of pressure. As rope gets thicker, it becomes less flexible and more difficult to handle.
In most high-strength rope uses, larger diameters are favored, particularly in lifting scenarios where load capacity is crucial. When selecting rope for pulleys, flexibility and pliability become important, as the rope must navigate smoothly through the pulley system. Double-braided or 12-stranded braided HMPE ropes are excellent options for these applications, as they offer the required strength while maintaining smaller diameters.
- Length - Of the selection factors, the length of the rope is the easiest one since it is determined by the application. Slings and harnesses do not have to be long but must be very strong. The length of towing or pulling ropes are determined by their application and the weight of the load to be moved. In all cases, the strength and diameter are the primary factors since they are the main ingredients in determining how much a rope can move.
Conclusion
- High strength ropes are used in making the best kind of ropes in the market.
- Ropes are constructed in many shapes such as braided, plaited, hollow and many more.
- Different types of material are used in rope making such as aramids, polypropylene, polyethylene, PBO, polyester, etc.
- All the fibers have different and specific qualities which distinguish them from each other.
- Zylon is the best fiber for rope manufacturing.
