GL Metal
Location:  Home  /  Blog  /  How Extension Springs Are Used in Engineering

How Extension Springs Are Used in Engineering

Views:233 Author:Site Editor Publish Time:2022-09-30 11:58:29 Orgin:Site

Although springs have a deceptively simple appearance, they are an essential design component for various engineering applications. An extension spring is a way to go if you need to store energy or create a barrier to a force acting in one direction. Engineers in the medical, electrical, manufacturing, and farming industries will find this especially helpful for various reasons.

If you want to design a component that can reliably provide the desired outcome under specific conditions, evaluating the principal function of a tension spring is beneficial.

What are extension springs?


As their name implies, extension springs (tension springs) are springs that can be altered by stretching to expand their length. These springs get into tension as their length is increased. The ends of most extension springs feature a hook or an eye for easy attachment, and the spring exerts a pulling force when the parts are separated.

In contrast to compression springs, which need to be supported along their length, extension springs remain under tension the entire time. Most extension springs on the market are coiled springs made from steel wire.

How do extension springs work?


Coil springs used in extensions are firmly twisted, leaving no space between the coils. When you apply tension to an extension spring, the coils unwind, allowing the spring to stretch. A coil's ability to resist this force allows it to store mechanical energy. When the tension is removed, the spring returns to its original form with no space.


How are extension springs used in engineering?


Controlling Movement


One of the most obvious applications of springs is regulating lateral motion, like opening and closing a door. Tension springs are versatile enough to be employed either to initiate an opening or closing motion or to reduce the impact of such a motion when an external force induces it, which means the spring can be tailored to meet the system's overall requirement for force over a given distance with relative ease. 

Since the extension spring stores energy instead of deflecting it, the forces at play are always important to consider. This concept is also responsible for the spring's bouncing action. While this has its uses, maintaining tight control over the system's moving elements necessitates a means of counteracting it.

Circuit breakers and switches


Engineers can take advantage of the many properties of extension springs beyond their use in common applications. You can implement tension spring technology in circuit breakers and switches. Since springs can store energy, you can use them as vibration dampers.

Accordingly, just like locking pliers, you can employ extension springs to secure a mechanical component, which is functionally comparable to a diaphragm valve, which uses a network of tension springs to regulate an opening in proportion to the magnitude of the force applied to it, operates.

Using an extension spring for this purpose has the distinct advantage of not needing any external power, which can be scarce in times of crisis.

Farm Machinery


Heavy-duty extension springs are used in farm machinery because of the tremendous pulling force required. You can use extension springs on your farm to their full ability, whether tractors or combine harvesters. Moving big objects around your farm and plowing fields are all examples of hard labor on your farm that extension springs can help you with.

Although hook and loop extension springs are the most common in heavy machinery, other types exist. When problems arise with your farm equipment, like rusty springs, it's time to get a new set as soon as possible; therefore, you must visit a reliable company to find replacements.

Taking Accurate Measurements


The extension spring is also frequently employed by engineers in the measurement of system-wide force magnitudes. Using a tension spring, you can primarily do one of two things to measure these dynamic forces: To that end, the springs can be designed to generate a target quantity of pulling force according to a specified extension rate. You can then figure out how much force is being applied to the spring by how far it is stretched.

Take Away


Extension springs last for quite some time. Although they come in various materials, the most common ones are composed of hard metals like stainless steel. There is no need to worry about them breaking down on you at an inconvenient moment, as tension springs have a very long lifespan, even when subjected to a constant tension strain. It would help if you seek advice from a professional spring manufacturer before you decide which extension spring best fits your application.

Everything about Extension Springs
Everything about Extension Springs
time: 2023-08-08 09:43:33

An extension spring, also known as an expansion or tension spring, is a helical-shaped spring that stretches or elongates under load applied on either end of the device. An extension spring is an important component that is utilized in a wide range of devices and mechanisms. This comprehensive article explores everything you need to know about extension springs.

extension springs.png

The Design and Working Mechanism of Extension Springs

An extension spring features a helical shape made from closely coiled metal wire. This type of spring is typically a close wound, meaning the diameter of the wire is the same as that of the spring pitch. As such, the spring coils touch each other when the spring is in a resting state.

The spring offers resistance when a force is applied through extending or stretching. It returns to its original state when the force is withdrawn. Extension springs have hooks or hoops at either end, where components are attached.

There are two key mechanisms at work at these ends. More tension is present at the attachment ends of the spring than the spring’s loops (coils). When the device is under a tension load that elongates the spring, it absorbs and stores energy.

When the force from the load is relaxed or removed, the energy is converted into kinetic energy, which makes the attached components return to their original positions.

An extension spring is designed to work opposite to the way a compression spring works. Both types of springs are designed for the same purpose - to store mechanical energy. The difference is that an extension spring does so by stretching, while a compression spring achieves the same by being squashed down.

Another feature of extension springs is no spacing between the individual coils. The tightly wound coils rest alongside one another when at rest and have initial tension.

Through the transfer of force, the coils are pulled apart and return to their closed state once the extending force is removed. The design of extension springs makes them excellent devices for absorbing and storing energy and resisting pulling forces.


Types of Extension Springs

While all extension springs have the same basic design and working mechanisms, there are several variances in the devices, including:


1. Stock Extension Springs

This type is a basic version of the extension spring design with typically helical metal coils wound together with loops or hooks at either end. You can easily attach stock extension springs to other components to make a force transfer and load bearing mechanism.


2. Precision Extension Springs

These are extension springs produced under tight and strict tolerances and are made from particularly high-quality materials. The physical dimensions of precision extension springs are more exact, with the devices designed to support specific amounts of load.

In heavy cycles and some dynamic applications such as prototyping, equipment repair, and maintenance, precision springs can extend the life cycles of important equipment and mechanisms.


3. Custom Extension Springs

Many manufacturers design and produce extension springs based on customer specifications. These may include specific sizes, materials, load requirements, metal gauges, and finishes.

Custom extension springs are crucial for various highly specific applications. In such cases, the stock configurations may be challenging or unfeasible to work with, either due to demanding environments or space restrictions.


4. Heavy-duty Extension Springs

These are high quality springs constructed from thicker metal widths and have significantly wider spring diameters. They are capable of supporting much higher load weights compared to standard extension springs.

The springs employed in mechanical industrial applications are usually heavy-duty extension springs.


5. Drawbar Extension Springs

A drawbar extension spring features a metal loop that goes through the middle of the spring, referred to as a drawbar. The loads attached to either end of the spring are connected to the drawbar. The spring is a mix of extension and compression spring mechanisms in one piece of hardware.

This unique assembly enables the main spring to compress when force is applied to extend the drawbar. It simultaneously provides a fixed stopping point, which prevents hyperextension (overstretching).

In case of a spring failure, the drawbar takes over the load bearing function. This type of extension spring is used to provide additional safety to potentially dangerous load bearing mechanisms such as platforms, heavy doors, and suspended seats. The drawbar holds the components until you can replace or repair the assembly.


6. Constant Force Extension Springs

This is a type of extension spring consisting of flat metal stripping. The spring is formed into a tight coil that lengthens and straightens in a linear manner when it is deflected. The spring's attempt to return to its original coiled form provides the return force.


Materials Used to Make Extension Springs

Manufacturers use a variety of materials to produce extension springs. The material used is largely determined by the intended application. The performance of an extension spring is highly dependent on the type of material used to construct the device.

Manufacturers consider several factors when determining the materials for spring production. These factors include spring parameters, operating temperatures, and corrosion resistance. Below is an overview of the material used to manufacture extension springs:


1. Carbon Steel

Carbon steel contains a percentage of carbon that gives the steel exceptional strength. It also allows manufacturers to heat-treat the material for extra hardness and durability.

Manufacturers may alloy carbon steel with various elements or materials to imbue with the material with additional useful properties. The alloys also increase the operating temperatures of the springs. These alloys may include nickel, chromium, silicon, manganese, vanadium, and molybdenum.


2. Stainless Steel

Stainless steel is widely used to manufacture extension springs. It is cost-effective, highly corrosion resistant, and has magnetic properties. The various types of steel used to manufacture extension springs include stainless steel 17-7 PH, 316, 304, and 302.


3. Copper Alloys

Copper alloys are used in the manufacture of extension springs since they provide electrical conductivity and excellent corrosion resistance. Extension springs made from copper alloys are used in extreme temperature, marine, chemical process, and electric spring applications. Types of copper alloys include phosphor bronze, brass (zinc copper), beryllium copper, and nickel copper alloys.


4. Nickel Alloys

Nickel is a highly versatile material that can be alloyed with many metals. Nickel is used in spring production for its high heat resistance. Extension springs made from nickel alloys are strong, highly durable, and reliable.

Nickel alloys used in spring production include nickel chromium iron alloy, nickel chromium molybdenum alloy, nickel cobalt chromium, and Hastelloy. The extension springs function well in chemical environments.


5. Plastic Composite

Plastic composite is used to produce extension springs with great thermal properties and chemical resistance. The most common type of plastic composite used is Ultem.


How Manufacturers Produce Extension Springs

The production process of extension springs takes into account a number of factors regarding specifications and parameters.

Careful consideration of these factors ensures a manufacturer design and produces effective, high-quality extension springs. Among the most important parameters, include:

 Material used

 Free length - The length of the spring when it is at rest (length of the inner surface of the spring ends).

 Wire diameter - The width of the metal wire used to construct the spring coil.

 Coil diameter - The total width of the extension spring when at rest, excluding the wire diameter.

Spring rate - The amount of force (pounds) required to extend the spring by an inch. Aspects such as spring material and wire diameter influence the spring rate.

Maximum extended length - The furthest distance an extension spring can stretch before it deforms or fails.

Maximum load - The weight or amount of stress the spring can handle at full extension.

Spring pitch - The distance between the centers of the wires in adjacent spring coils. The spring pitch is equal to the wire diameter in closely wound coils.

Initial tension - The force needed to overcome the standard pitch of the extension spring at rest.

Other factors that manufacturers consider are initial spring tension the spring can handle, the type of spring ends, and more.


The Manufacturing Process

The manufacturing process for extension springs is relatively simple and straightforward. While there may be variations depending on the type of spring being made, the process involves three main steps - winding, heat treatment, and finishing.

Winding is the first step, where manufacturers feed the spring wire into a mechanical machine known as a Computer Numerical Control (CNC) spring coiler.

The machine straightens the wire and molds it into the helical spring shape. The spring coiler features several tooling heads that form different spring shapes.

Following the formation of the extension spring, manufacturers feed it to an oven, heating it at a set temperature for a specific period of time. The heat treatment process depends on the type of material and extension spring. The spring is then cooled down in preparation for the finishing process.

The final step involves coating and finishing. Manufacturers coat the springs in layers of material, which enhance some of its physical and chemical properties. These include durability, corrosion resistance, and heat resistance.

The common coating processes include powder coating, plating, and shot peening. There is a variety of finishes for extension springs, including:

Zinc galvanization - Manufacturers coat the extension springs with a galvanized zinc layer to help prevent corrosion.

Black oxide – A cost-effective spring finish that affords extension springs a durable corrosion-resistant finish.

Passivation - A process whereby manufacturers coat the extension springs with a layer of nitride or oxide. It improves the spring’s corrosion resistance.

Gold Iridite coating – This coating improves the durability and conductivity of extension springs.


Extension Spring Ends

Loads or sources of force are attached to the ends of extension springs via a wide variety of spring ends. Manufacturers carefully consider the type of spring end to ensure the device can handle mechanical stress.

They design the spring hooks or loops based on the intended application. The most common types of extension spring ends include crossover loops and machine loops. Other types include:

Double twisted loop

Full twisted loop

 Half loop open

 Rectangular hook


Raised hook

Offset hook


Applications of Extension Springs

Extension springs are a widely used type of spring. They are applied in a wide range of industries to support the function of numerous products used in everyday life. The various applications include:

Garage doors - Extension springs are attached to the sides or top of garage doors to help in the opening and closing mechanism. The spring helps minimize the strength used to lift and close garage doors.

Toys - Toy manufacturers utilize extension springs to produce toys that require projectile motion or throwing actions like cars and shooting toys.

Medical devices - A wide variety of medical devices, such as surgical lights, stretchers, and surgical instruments, employ extension springs.

Firearms - The magazine springs in firearms use extension springs to push rounds or cartridges into the firearm's magazine. The spring provides the force needed to push the rounds into the firing chamber. It enables fast feeding of cartridges. These springs are typically made of high carbon steel to withstand continuous cycles without sacrificing strength. In addition, the recoil spring used to absorb recoil shock in firearms is an extension spring.

Window and door screens - Window and door screens snap back to their original closed positions by using extension springs. When a force is applied by opening the screen, the spring extends outwards and pulls the screen to its original position. When you close the window or door screen, the spring snaps back to its original state, keeping the screen shut.

Extension springs are also used in home appliances such as washing machines, foldout furniture like sofa beds and foldable tables, upholstery, and DIY tools.


Safety Considerations for Extension Springs

An extension spring is unique in that its failure is likely to be more catastrophic compared to other types of springs.

When you compare an extension spring and a compression spring of similar material and size, the safe working stress of the extension spring is about ¾ of the load, while the compression spring can safely handle 100 percent of the load weight.

Further, while the stretch on the spring may be able to handle the working load, the spring ends are considerably weaker than the spring coils. As such, this is where the stress points will be concentrated.

High stress can snap or wrap the spring ends. For this reason, the application of an extension spring must account for these aspects. Exceeding the load capabilities of the springs often reduces their usable life cycles significantly.

All in all, extension springs are important devices designed to offer support to a range of consumer products, systems, and machinery. As such, it is important to source high-quality springs from reputable manufacturers.

GL Metal is one of the leading manufacturers and suppliers of quality extension springs. We use high-grade materials and refined production processes to produce best-in-class metal products.

Extension vs. Compression Springs: What's the Difference?
Extension vs. Compression Springs: What's the Difference?
time: 2022-07-29 11:38:25

Springs are one of the most commonly used parts in a moving or stationary machine. However, did you know there are different types of springs? Well, there are two main types of springs; extension and compression springs.

Both are made of different materials, including cold-drawn steel, copper, titanium, and stainless steel. These materials determine the cost and use of the springs.

We have prepared a detailed review of the difference between these two springs to help you make a sound decision while shopping or looking for a spring to integrate into your machine.

Let's delve in!


How are Extension and Compression Springs Used?


Also known as tension springs, the primary function of these springs is to either bring pieces together or compress them. The criterion of functionality integrated into these springs ensures optimal functionality of the compressed or extended parts.

Extension springs can be used in a wide range of industries, including oil, rail, gas, and agriculture. They are quite popular in the medical industry and are mostly used in surgical lights and stretchers. Compression springs are used in industries such as automobiles and electrical.

Application of Compression Springs 


One of the most commonly used applications of a compression spring is in a spring-operated ballpoint pen. When the head is squeezed to remove the nib, the internal spring compresses and stores energy.

When the head is squeezed again to bring in the nib, this energy is released when the spring returns to its original form.

Such springs are also commonly utilized in mechanically controlled cam-follower devices, certain valves, and other applications. The trampoline has several extension springs that give the appropriate rebounding force based on its size.

When someone jumps on it, the spring stretches and stores energy in it. They then immediately release the energy by shortening their length and resuming their previous form.

Application of Extension Springs


To fit specific functions, extension springs are designed with a variety of hook or loop end configurations. Extended twist loops, headed inserts, expanded eyes, hooks, crossover center loops, rectangular ends, teardrop-shaped ends, and reduced eyes are examples of extension spring ends.

Extension springs vary by extended length, body length, maximum load, and loop or hook length. These springs are found in a wide range of products, such as garage doors, tools, washing machines, and toys.

Because of their size range, extension springs are useful in many applications, including medical equipment and off-road gear. They are commonly used in the following applications:

· Vice-grip pliers

· Car exteriors and interiors

· Washing devices

· Toys

· Garage door assemblies

· Carburetors

· Farm machinery

Difference Between Extension and Compression Spring


Extension Springs


Also known as tension springs, they are used in products such as brakes, levers, catches, trampolines, and many other applications. They work by absorbing and storing energy, which is also used to resist pulling forces.

The springs are placed on both sides of a component, and whenever they separate, the spring attempts to bring them back together.

The initial tension is what defines how firmly the spring is designed. If you are working with a heavy load, it is recommended to go with a stronger and wider extension spring. 

Simply put, these springs are designed to give an equivalent force to operating components that entails stretching to operate. As a result, they are made of materials that are quite strong and durable.

Compression Spring


Technically, a compression spring is designed to shorten the length under the action or length of external force. As compared to extension springs, compression springs are designed to compress when subjected to a load.

Compression springs are made of coiled metal that is quite similar to an extension spring. If you closely look at the two springs, you'll realize that the extension spring has a broader and wider coil.

The compression extension springs are also made of a thin strip of a coiled piece of metal, while the extension spring is made of a wider strip of a coiled piece of metal. Their criterion of functionality is also different from that of extension springs. You will note that extension springs lengthen under stress while compression springs shorten.

How to choose the Correct Spring Ends


Spring End


The spring ends are a distinguishing feature of springs. The spring ends will determine the spring to choose for a certain application or task needed. Some spring ends are hooked or looped, whereas others are closed, straight, or open. 

Resistance to Magnetic Forces


Will your spring work in a magnetic field? If so, you might need to get a spring made of non-magnetic materials, especially if the parts around it are magnetic. It will help prevent vibration when placed in a piece of equipment or instrument.

Spring Application


A spring will, of course, have to execute a specified duty or function. As a result, various springs are utilized for different applications; thus, choosing the proper one is critical. If you require springs for a mattress, for example, compression springs are more likely to be chosen than other varieties.

Resistance to Extreme Temperatures


This is the defining feature of springs. Many industries, especially automotive and aerospace, rely on the ability to work in severe cold or heat.

If your springs must perform in a tough environment, the first step in the spring design is to select a sturdy material that will not weaken or break in low or high temperatures. Inconel carbon, for example, can operate ideally at temperatures as high as 870oC.

Get Your Ideal Springs Today!


Choosing the ideal spring for your project can prove to be a daunting task. However, that does not mean that you cannot get your desired option.

If you put the above factors into consideration the next time you are shopping for spring, there is no doubt that you will experience exceptional results.

Contact us for the latest springs in the market. Let us ensure you get the best springsand we will offer cutom springs for your desired project.

Common Uses For Extension Springs
Common Uses For Extension Springs
time: 2022-07-07 11:19:07

Even if you weren't sure of the specific name, you've all encountered extension springs previously. The ability to give resistance to a more significant force to modify tension is provided by these coiled wire springs, which have two sides to make it simple to link them to another component.

You can accommodate numerous applications for extension springs through customization. They are helpful small components with many applications if given the necessary design features.


Typical Applications for Extension Springs

You can design extension springs with various loops or hook ends for particular tasks. In addition to rectangular endpoints and teardrop-shaped endings, extension spring ends come with threaded inserts, crossover center loops, hooks, expanded eyes, and reduced eyes.

For customized extension spring functions and fits, alter the hook length and the separation between the spring body. You can use extension springs for various things in daily life, from the vehicles that transport you daily to the agricultural equipment that generates food.

There is always a requirement for an extension of some kind because extension springs have various sizes and forms with multiple hooks and eyes to latch onto both sides. The springs are broadly applied in the automobile sector, farm equipment, electronics, toys, and a wide variety of other products.



A lot of toys in the past used extension springs. You can use the springs in various toys, particularly those with a shooting or throwing component. However, the small springs and the objects they discharged were considered dangerous for children. Pinball machines and wind-up toys are two examples of incredibly secure and well-liked toys that use extension springs.

Washing Machines


When it comes to mechanical extension spring uses, a washing machine is perhaps among the last items you might think of, but they play a crucial role in the equipment. Your washing machine's drum starts spinning as you turn it on, agitating the clothing and starting the washing cycle. The spinning drum would beat against the walls of the machine without extension springs, tossing it around the room and creating loud noise as you do your clothes.

Farm Machinery


Due to the force and strength needed to pull, farm machinery uses heavy-duty extension springs. Although "farm machinery" is used broadly, many vehicles utilized on farms will use extension springs. You can use the extension spring to its fullest extent on everything from tractors to combined harvesters. 

People plough fields, move heavy items around the farm, or even trailers tow large goods. While machinery often uses hook or loop-style heavy-duty extension springs, numerous varieties are available. If they notice any problems, like deflated tires or rusted springs, it's time for a change. Farm equipment needs to be updated and safe at all times.

Springs in Trampolines


As a result of the usage of extension springs, trampolines are particularly well-liked. They powerfully illustrate how you can use extension springs in the garden. The trampoline's base is fastened to the steel frame by thousands of hook-end extension springs. It is more flexible because of the number of springs used to hold the ground.

For instance, the trampoline's rebound wouldn't be as agile if it had half the amount of springs and solid connectors. The trampoline's springs are in their coiled state while at rest. 

The trampoline's bouncy quality is caused by the abundance of extension springs at its bottom. Thanks to these extension springs, people can jump without exertion by bouncing back to the trampoline. The trampoline bounces more when it has additional extension springs.



A pram is a common means of transportation for small infants and kids. The pram, or rather perambulator initially named, has been made employing extension springs from its inception: the first Coach Where the expensive strollers were built, Silver Cross. As you rock the baby to sleep in the pram, the springs create the suspension effect.

The springs increased the pram's flexibility and made it easier to maneuver. It's a somewhat big pram, but it was widely used until recently. It isn't easy to get in some of the front doors due to the tiny houses being built today together with pram size.

The first suspension strollers served as the model for all subsequent models. The suspension impact is still present in most modern strollers but to a lesser extent.

Garage Doors


The garage doors also feature extension springs. They support lowering and raising the door since they connect the edges of the doors. Those extension springs reduce the potential force needed to lift and close such doors.



The Chest Expander is the piece of exercise gear most often found with extension springs. A line of extension springs lined up side by side and attached to a metal or plastic handle at each end make up the chest expander's mechanism.

When using the chest expander, draw both handles simultaneously to extend the springs to the desired length. As you let go of the strain, the springs will exert all their force to return to their initial position. It functions by exerting energy on the muscles to pull and resist.

Medical equipment


The functioning of springs has been a staple of medicine for millennia. You can employ extension springs in a wide range of medical equipment. Some of these tools include stretchers, operating lights, and several small handheld devices.

Take away


If you need extension springs for your industry's purposes, you should buy them from professionals. Extension springs store potential energy and provide resistance since they have an object attached to each end. The initial tension of the spring controls how tightly the wind its coils are.

Extension springs differ by extended length, body length, maximum load, hook/loop length, and much more in addition to tension. Additionally, you can choose the loop's location, the distance between its ends, the finish, the material, and a lot more.

You can construct a spring-appropriate for various applications and environments by modifying its multiple properties. Some skilled engineers from Foshan GL Metal can assist you in choosing the right specs for any spring purchase. Contact their staffs to get started designing a set of springs right away.