This article will take an in-depth look at shock, bungee, and elastic cords.
The article will bring more detail on topics such as:
This chapter will discuss bungee cords, shock cords, elastic cords and their manufacturing.
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.
Usually, the elastic material is rubber and is bound by a fabric sheath. As it is elastic in nature, the bungee cord is used in a wide range of applications. It is commonly used to tie down the luggage on the outside of the vehicle.
The elastic strands of the bungee cord are made of rubber, can be natural, synthetic, or even a configuration of both. It’s all dependent on the use of a bungee cord. The outer woven sheath can be made of any material such as polypropylene, cotton, or nylon. These materials are helpful in protecting the outer sheath and provide an extra stretch to the cord.
The raw material that is used for making a bungee cord is rubber, either synthetic or natural. Natural rubber, also known as latex rubber, is typically a good choice because it has good tensile strength and exceptional extensibility. It also has the ability to return back to its original shape. These properties make natural rubber an excellent material for bungee cords. Latex rubber has a minimum resistance to sunlight and air. It means that ultraviolet radiation can damage natural rubber.
On the other hand, synthetic rubber shows better resistance to sunlight and air. But synthetic rubber such as neoprene shows less tensile strength and flexibility than natural rubber. Due to these reasons, natural rubber is used most of the time for military specifications. Natural rubber is used for bungee jumping also.
The coat of the bungee cord is a fabric covering that is made of cotton or nylon yarn. This yarn is braided in construction. The coating of fabric is different, and it is according to the rope’s intended use. The bungee cords that are used commercially have a single layer of nylon covering. A single layer of nylon gives more resistance to abrasions and also has high tensile strength. However, if the bungee cord is used for military purposes and bungee jumping, then it has two layers of cotton covering. Some specially designed bungee ropes have a natural rubber covering, and this is braided in construction.
The design of bungee rope is determined by its application. For standard commercial bungee rope, a diameter from 0.25 inch to 0.62 inch is available. For military purposes, a diameter of 0.25 inch to 0.87 inches is available. Bungee cord used for jumping purposes is 0.62 inches in diameter.
Bungee cords are designed to stretch to specific lengths, with a particular amount of elongation. The elongation of bungee rope is determined by comparing it with the length of unstretched length. For example, if a bungee cord can stretch to twice its original length, it is said to have an elongation of 100%.
The manufacturing process of bungee cord has the following steps:
The first step of the manufacturing process is extracting rubber, either natural or synthetic. The rubber is then shaped into long ribbons. The dimensions of the rubber ribbon are 0.09inch to 0.12 inch in thickness, 0.25 inch in width and up-to 100 ft long. The rubber is then placed into the extruder, which consists of a heated cylinder. There are two ends in the extruder, from one end of the cylinder the rubber moves under pressure, and it is forced out through the other small hole of the extruder. The hole, from which the pressed rubber is forced out, is in the form of the desired shape. After this, the cooling process is done and the rubber is shipped to the manufacturers.
The tensile strength and the diameter of the bungee rope are determined by the number of strands and ribbons that are placed in the cord. For the braiding process, these strands are unwound from the coils evenly. Sometimes, due to hot weather there are certain chances for the strands to stick to each other. To avoid such circumstances, these rubber strands are coated with finely powdered talc or soapstone. This coating process is continuous and ends with the end of the unwinding process.
The next step is the braiding of the rubber strands. This process is done in a machine called a braider. The free ends of the rubber strands are put manually in the braider. On entering, these rubber strands are gently squeezed with the help of rollers and other devices that are placed in the braider. On the output end, there is another roller or take up reel that pulls the strands through the machine.
The rubber strands are kept under tension and slightly stretched with the help of adjusted speed and pressure. This stretch and tension help reduce the diameter of the rubber strands and allow the fabric covering to be wounded tightly. The braider weaves the yarn on the stretched rubber strand and covers the rubber while it is passing through the machine. The covering must be tightly woven, so that no dirt can enter the yarn gaps when the cord is fully extended. If there is a need for two or more coverings of the yarn, then it is done one after another. The outer yarn covering can be colored or color coded as required by the client.
When the bungee cord is manufactured, it is ready to be shipped. The cord is cut to the required length, coiled and then placed in a cardboard box. These cords are also placed in dark plastic bags to protect them from sunlight, air, and ultraviolet radiation.
The manufacturer does not attach the end fittings of the bungee cord. The end fittings are done according to the requirement. For bungee cords, used for luggage and equipment tie down, it is first cut down into the required length. After cutting it, both ends of the cord are doubled and coiled by a stiff wire. A wire coiler machine does this coiling. After coiling, a J shaped hook is placed at the end to make it secure. For bungee cord that is used for jumping, a stretched cord is wound tightly by a strong and waxed string known as whipping. The ends of the bungee cord are bent around a non-metallic eye. Some other endings are to sew the cord to the woven fabric webbing.
The quality control of bungee cord is dependent on the following factors, which should be checked using:
Visual inspection of the cord means looking for any defect in the cord which is clearly visible such as defects in rubber, wrong coloring, gaps in a woven sheath or broken cord.
Testing of the bungee cord is very important to look for its tensile strength, load capacity, and extension rate. It should be done for all sorts of bungee cord, either commercial or for military purposes. These factors can be checked easily by attaching loads to the cord.
Some companies make their own bungee cord and give color accordingly. But the bungee cords that are used in the military have special colors and these colors show their date of manufacture. These cords become less efficient with age, and it is recommended to ship these cords within six months of its manufacture. Some colors such as green, yellow, red and blue are given to the cord according to its manufacture date and are revised now with some changes. However, it is believed that the colors of the commercial bungee cords are just for decorative purposes.
A shock cord is a cord that is made from top quality rubber core and a polyester cover, which makes it compact, durable, and stable. Shock cords are suitable for many different applications that include tethering tools to your harness and tying down gear.
The polyester material used to make the outer cover of shock cords is extremely abrasion-resistant, which totally protects the inner rubber core. Shock cords are similar to bungee cords in almost every way except that, bungee cords usually come with a bungee cord hook. A shock cord can also be used in the military field to absorb shocks of large cargo, parachutes, and bungee jumping.
The features of shock codes include:
Elastic cords are smaller cords with a smaller diameter as compared to shock/bungee cords. They are best utilized for smaller crafts that include making jewelry such as necklaces and bracelets. They are used in the making of headbands, lanyards, or signs for decorating a classroom, dorm room, or living space.
There are also smaller shock cords, but larger shock cords can be used for tying down tarps, tents, and objects in the bed of a trailer or truck. A shock cord may not be suitable for use when securing a load depending on the load and height of the items in transport. Both shock cords and elastic cords can be used in numerous DIY projects, such as organizing utensils in the kitchen, bundling up toys, and holding up things in a fixed place like a bike in a garage.
Elastic cords may be similar to shock cords in the sense of the materials they are made from, but shock cords have longer stretches or elongations than elastic cords. The typical elongation of a shock cord is 100% or it can stretch to twice its original length, while the typical elongation of elastic cords is 50% or they can stretch to one and half times their original length.
This chapter will discuss the different types of bungee cords, shock cords, and elastic cords.
The types of bungee cords, which are also categorized as shock cords, include:
These types of bungee cords have lengths that can be altered depending on the application requirements. They usually come with a maximum length of 32 inches (including the hook) and they can be adjusted down to a length of 10 inches. They provide flexibility for household and light-duty jobs.
Adjustable bungee cords have lighter tension as compared to heavy-duty cords, so they can be stretched easily to fit a variety of tasks. Each cord has a thickness of 8 mm with a hook on both ends. The hooks are made from metal and they are covered in a non-scratch coating that protects them from scrapes. These types of bungee cords are affordable and useful picks for everyday tasks. The tasks include household storage, securing gear, and hiking backpack.
These types of bungee cords are designed with a comfortable plastic finger hole for safe handling. The cord can be stretched without the cord slipping because of the allowance given by the finger grip. This is a safety concern that is common with bungee cords.
The hooks have strong metal cores and plastic coatings that prevent scratches. These cords usually come in lengths that are 32 to 48 inches. The material used to make these cords is UV-resistant, latex blend, and cross-woven rubber designed to not become thin or brittle with use over time. These bungee cords are tough and suit indoor and outdoor uses in different climates. For easy storage and portability, these cords have a zippered carrying case.
These types of bungee cords come in lengths ranging from 7 to 70 inches. The premium rubber core is surrounded by an abrasion resistant cover for long lasting use. Their hooks are adjustable and are reinforced by fiber.
The hooks are also UV stabilized and include a finger grip for safe handling. The hooks have a patented locking design that is easy to adjust. To adjust the hooks, no ties, knots, or mechanical ratchets are required; they are just slid to the length desired, and then the cord is pulled to lock it into position. The length can also be changed while the bungee cord is in use. These types of bungee cords are suitable for application indoors or outdoors.
These types of bungee cords are made to withstand tough conditions. The cover of the cord is made from high-grade Dacron polyester sheath.
This sheath is resistant to ultraviolet radiation, moisture, oils, chemicals and abrasion. This Dacron polyester is a synthetic fiber of low stretch and high strength. This sheathing allows good performance of the cord during prolonged use outdoors. The safety standards are met by this cord.
The rubber core of these types of bungee cords is premium grade and long-lasting. The woven outer sheath is resistant to ultraviolet radiation to withstand outdoor conditions and repeated use. They usually come in 10 inch lengths with dichromate steel hooks that resist warping under tension. The cords are available in a broad range of bright and eye-catching colors.
They combine visibility and utility to fit a variety of household jobs. They are used around the home for everyday jobs like securing, organizing, and performing other small tasks. Indoors, they are utilized for storage like organizing a workshop or garage. Because the bungee cords are able to resist ultra violet radiation, they can be utilized outdoors for securing a tarp, camping, and many other applications.
These types of bungee cords feature two steel carabiner hooks that have a wide-mouth design. They are much stronger compared to conventional bungee cord hooks and establish secure attachments.
The hook and latches are kept in place by the spring loaded closure, once attached. This functions to prevent the accidental release of the hooks, making this bungee cord a particularly safe pick. The base of the hook features a molded grip, which increases strength and security to the user. These types of bungee cords come in 48 inch lengths and are designed to withstand ultra violet rays and weather damage. They are composed of premium rubber that remains elastic for repeated use. These types of bungee cords are used for home, recreational, and work use when a reliable hook is required.
The types of elastic cords include:
This cord has an elastic core. The polyester used to coat this cord is found in a wide variety of colors. This type of elastic cord is used for hair accessories and other applications in which the cord remains visible in the finished design. This cord cannot be used for long lasting jewelry.
This type of elastic cord is found in a variety of colors but not a lot of sizes. The most common sizes available are 0.5mm and 0.7mm, which suit smaller beads. Unlike stretch magic, stretch floss is constructed by multiple strands of stretchy material woven together. This will increase its elasticity and make it easier to knot than single strand cords.
This is the most common elastic code that is rubbery, round, and made up of a single strand. These types of cords are perfectly used with large beads. Stretch magic can be slightly more difficult to knot tightly compared with other types of elastic cords. But this type of elastic cord is reliable. These cords can be kept tied by using a surgeon’s knot, with an extra half knot.
This chapter will discuss the uses and benefits of bungee/shock/elastic cords.
The different uses of bungee cords are:
A bungee cord can be used to hang up canning rings. This is a convenient way of storing your canning rings as it keeps them out of the way. This is a much better way of storing them since they can be easily accessed, rather than storing them in the bottom of a dark drawer.
Bungee cords can be used for making a temporary holder for paper towels. Usually short bungee cords suit this application. The cord is just slid through the center of the roll and then hooked into something that is sturdy at both ends. This is a convenient way for keeping paper towels handy for camping or at outdoor parties.
A bungee cord can be used to make a handy strap for a mat. The center of the cord is held along the center of the mat. Both ends of the cord are pulled around the mat, and hooked to the section held against the mat. The mat is kept rolled up, which creates a great carrying handle.
A bungee cord can be used to hang a baby’s favorite toys to entertain the baby. The bungee cord is stringed up between the handles in the back seat. The baby toys are hanging from it. It acts as a toy mobile that is perfect for the car.
When groceries are loaded into a car, they can spill out of the bags when you hit bumps. Using a bungee cord, you can easily secure your groceries from being spilled out of the bags. By feeding the bungee cord through both handles of each bag and then securing the cord around the headrest of the car seat on which the groceries are sitting, you can prevent them from spilling out.
Trash bags can slip down into garbage cans. This problem can be fixed through a bungee cord. By putting the trash bag in place and wrapping a bungee cord around the rim of the trash can, and then hooking the cord to itself, the trash bag can be kept in place.
Using wire shelving is a great way to add extra storage in a room. But the shelves can’t typically be filled too much because things might topple right off the edges. This is when a bungee cord comes into play. The bungee cord can be stringed across the front end to prevent the items from toppling off the edges. This way, more items can be kept on the shelf without having to worry about them falling off.
A bungee cord can be a great way of adding another layer to your curtains without the installation of additional hardware. The bungee cord is slid through the top of the curtain and hooked into the curtain rod at either end. This way, you can easily add a layer of blackout curtains behind your existing curtains. This helps to block more light in a bedroom.
To save a lot of space in the kitchen, backing sheets are stored vertically. This is when bungee cords come into play to create a simple storage solution that is vertical for the baking sheets. A few bungee cords are strung up vertically between shelves, and then the baking sheets are slid between the cords.
However, these drawbacks of bungee/shock/elastic cords are outweighed by the advantages.
Bungee cords, shock cords, and elastic cords may be constructed from the same materials but have differences in their elasticity and applications. Bungee cords are more suitable for outdoor use in which great strength is required, whereas elastic cords cannot withstand too much tension. Shock cords are not suited for applications requiring great strength. They do suit applications that require medium strength compared to bungee and elastic cords. Elastic cords have a small diameter and are best suitable for small crafts such as jewelry making. Lastly it is important to make careful considerations when purchasing bungee, shock, or elastic cords.
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