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Helical Springs
Integrated into a wide range of mechanical systems, helical springs store applied forces and motion through the elastic deformation of their namesake coiled wire shape. They encompass three primary spring subtypes, each denoted by the directions of load and motion they are designed to accommodate: compression, extension, and torsion.
What Are Helical Springs?
Helical springs are mechanical springs in which the wire is wound into a coil shape. The geometry of this coiled shape determines how the spring responds when loaded. For example, compression springs shorten in length under an applied compressive (pushing) force. Extension springs elongate in length under an applied tensile (pulling) force, and torsion springs twist into a tighter coil under an applied torque (rotational force).
How Do Helical Springs Work?
In simplest terms, helical springs function by deforming elastically when subjected to an applied load. The subtypes of helical coil springs are differentiated by the direction of the applied loading they are designed to accommodate: compression springs resist pushing forces (compression), extension springs resist pulling forces (tension), and torsion springs resist twisting forces (torsion).
No matter the subtype, elastic deformation is the mechanism by which helical springs store mechanical energy and release it as the load is removed, returning to their original length and shape.
Key Design Characteristics of Helical Springs
Helical springs are versatile mechanical components defined by standard geometric and performance specifications. These design characteristics dictate how the spring fits into your assembly and how it responds to applied loads.
Carefully evaluate the following universally recognized attributes to ensure proper form and function of your coil spring in its intended application:
- Spring subtype: Defines the direction of the load the spring is designed to accommodate (compression, extension, or torsion).
- Wire diameter: The thickness of the metal wire that forms the helical coils.
- Outside diameter: The width of the formed helical coils, as measured from their outer surfaces.
- Free length: The total overall length of the spring when no load is applied.
Number of coils: The total count of helical coils that make up the spring body. - Spring rate: The measurement of the spring's stiffness, defined as the force required to deform the spring by a designated unit of length or degree of angular rotation.
With a grasp of these properties, you can determine the spring's load capacity and deflection profile for your application and ultimately select a helical coil spring that ensures optimal, long-lasting performance.
Explore Our Helical Springs Range
Century Spring is proud to offer thousands of in-stock helical compression springs in every spring type in an expansive selection of materials and sizes available to ship today. You can browse by outer diameter, wire size, spring rate, material, surface finish, and more.
Download the spring CAD to see how your spring will fit your application before purchasing!
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Custom Helical Springs
If you can’t find the conical spring you need in our expansive catalog, we offer custom conical spring solutions with many configurable options for conical springs.
We bring decades of design and manufacturing expertise to your project because we routinely design custom helical springs for our partners across numerous industries. We have brought thousands of custom spring solutions to market that operate reliably in the most demanding applications and industries.
You can start by browsing our selection of stock helical springs to better understand the customization options available for custom development projects.
Custom Helical Spring Manufacturing Capabilities
We proudly offer state-of-the-art manufacturing equipment to deliver high volumes of custom helical coil springs in various materials, surface finishes, and end types. We have cutting-edge CNC compression self-monitoring and coiling machinery to manufacture custom sizes, wire diameters, and spring lengths to fit any design envelope. We also provide complete prototyping and tooling assistance services.
We are ready to partner with you in all stages of development, from initial concept to procurement, to help you develop helical springs that will withstand the most demanding environments.
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Helical Spring Information & Resources
Helical Spring Types
Because of their versatility, helical springs are employed in countless machine designs across numerous industries and product categories. Here are a few of the highlights grouped by spring type.
Helical Coil Compression Springs
Helical compression springs are designed to resist compressive forces, meaning the coils are compressed together under an applied compressive load, storing compressive energy. Conical springs are a type of helical coil compression spring with coils that decrease in diameter from one end to the other in a consistent gradient, giving the springs a cone shape.
Helical Coil compression springs are present in medical devices such as surgical tools and orthopedic devices, even in medical implants such as implantable drug delivery systems.
They can be found in critical aerospace safety systems, the most recognizable being aircraft landing gear shock absorbing and suspension systems. Finally, helical coil compression springs are integrated into many household consumer products, such as mattresses, door locks, and air conditioners.
Helical Coil Extension Springs
Helical extension springs are designed to resist tension forces. They are similar to helical compression springs, except their coils are wound tightly together because the coils are pulled apart under an applied load. As the coils separate, they store energy and create a resisting force that acts opposite the direction of the spring extension.
Helical coil extension springs are integrated into aerospace applications such as door mechanisms and actuated systems, where a tension force is needed to open or close bay doors. Helical coil extension springs are common in diagnostic medical devices such as stretchers, surgical lifts, and certain surgical equipment.
Helical Coil Torsion Springs
Helical torsion springs are engineered to resist twisting forces, as the name suggests. They are tightly wound wire coils that unwind elastically under an applied torsion. The torsion spring stores energy by resisting forces that try to twist the spring coil into a tighter wind.
Helical Coil Torsion springs are found in dozens of safety-critical aerospace components, including aerodynamic control surfaces that control the plane’s flight.
Some great household consumer product examples of torsion springs include the simple torsion spring in wooden clothes pins or torsion spring brackets designed to hold recessed ceiling lighting into mounting fixtures. One great household product with a torsion spring is garage doors, which feature large torsion springs that enable the heavy door to be lifted open by hand.
For more information on how our springs can fit into your application, check out our industry pages:
How to Select a Helical Spring
Generally, critical geometric properties such as Free Length, Wire Diameter, Outer diameter (OD), and Spring Rate define a helical coil spring.
Other important compression spring design characteristics are Spring Pitch, Total Number of Coils, and Solid Spring Length.
Other important extension spring design characteristics are the spring's Maximum Deflection and Maximum Load Capacity.
When shopping for torsion springs, it’s essential to consider the angle between the legs, the torsion spring’s Inner Diameter (ID), and the Leg Length.
After you have evaluated the working load your spring will withstand, you can shop for helical springs by Spring Rate to calculate the spring displacement in your application. Then, you can determine how the spring will fit within your machine design during loading conditions.
These properties will help you determine the fit and function of your helical spring in your application.
If you have further questions about helical springs, we have compiled three standalone spring selection guides featuring detailed design and selection information on our stock compression, extension, and torsion springs. These guides feature all the critical design and sizing information you need to select a helical spring.
How to Select a Torsion SpringHow to Select a Compression SpringHow to Select an Extension SpringHow to Select a Disc SpringHow to Select a Die SpringHow to Select a Tapered Spring
How to Measure a Helical Spring
Using calipers to measure the following locations, you can obtain relevant dimensional properties of a helical coil spring.
Hold the spring on the outer surfaces between your fingers and use calipers to measure the outside of the coil to measure the compression spring's Outside Diameter (OD).
Use your calipers to measure the wire that forms the helical shape of the spring. This is called the Wire Diameter. You should measure the wire diameter at both ends of the spring to be sure of the measurement.
Place the entire length of the uncompressed spring between your calipers to measure the Free Length of the spring.
Place the spring flat on its side and count the total number of coils on the spring. Be sure to include fractions of coils in your total count. This number is called the Number of Coils.
To measure an extension spring’s Length inside Hooks (LIH), place the outer jaws of your calipers on the exterior of a helical coil extension spring’s hooks on each end so that the calipers envelop the entire spring. Record this value and then subtract from it two times the spring’s Wire Diameter, as measured previously. This measurement will determine whether a given spring fits your application.
Count the total number of coils on a torsion spring to determine the torsion spring’s Leg Configuration, which is the angle between the legs at the ends of the spring where the load is applied. It is defined by the number of coils on the spring, so you can determine the leg configuration by counting the coils on your torsion spring. For example, a spring with five coils is a zero-degree spring, a spring with 5.25 coils is a 90-degree spring, and one with 5.75 coils is a 170-degree spring.
Explore More Dimensional Measurement Guides
How to Measure Extension SpringsHow to Measure Compression SpringsHow to Measure Torsion Springs
FAQs About Helical Springs
What is a helical spring used for?
Helical springs are used in a broad range of mechanical systems to store mechanical energy and effectively manage force under repeated load cycling. Because of their versatile design, these springs are seamlessly integrated into countless machine components across aerospace, automotive, medical, and consumer products.
When selecting a helical spring for your design, the subtype—whether compression, extension, or torsion—is chosen based on the direction of the applied load the mechanism must accommodate.
What is the difference between a helical spring and a coil spring?
The terms "coil spring" and "helical spring" are frequently used interchangeably, as both terms simply describe springs that are fabricated from rigid metal wire wound into a coiled, spiral, or helical (i.e., corkscrew) pattern.
While they refer to the same type of mechanical component, "helical spring" is the more precise engineering term for the broad class of springs that encompasses three primary subtypes, differentiated by the direction of the load they are designed to accommodate: compression springs, extension springs, and torsion springs.
What materials are used in helical springs?
Helical springs are most commonly fabricated from various steel alloys, usually high-carbon or alloy steels; the ideal choice of steel depends on the application's specific mechanical and environmental requirements.
When a mechanism requires protection against moisture or harsh chemicals, stainless steel is generally the preferred material because it provides excellent natural corrosion resistance without additional surface treatments. Conversely, in extreme operating environments, advanced superalloys, such as Inconel®, may be used because they maintain strength and reliability in corrosive environments and exceptionally high temperatures.
How do I measure a helical spring?
You may use a pair of calipers to measure a helical spring’s Outer Diameter (OD), Wire Diameter, and Free Length. In addition to these linear dimensions, you can determine the total Number of Coils by carefully counting them along the length of the spring. Because different helical coil spring types have unique geometries and end types, refer to our dedicated measurement guides for each subtype for additional details.
How to measure a torsion spring
How to measure a compression spring
How to measure an extension spring
What is an example of a helical spring?
Helical springs can be found in everyday mechanical products across all three of their primary subtypes: compression, extension, and torsion. Small compression springs are used inside most ballpoint pens to provide their signature “click” retraction capability, while recreational trampolines rely on dozens of perimeter extension springs to provide the return force that propels the jumper into the air. Simple examples of torsion springs include the simple spring mechanism in a clothespin and the large, heavy-duty torsion springs that allow residential garage doors to be lifted open by hand.
What does "helical" mean?
“Helical" describes a shape that follows a helix; in springs, the helix is formed by a wire wound in a continuous spiral or corkscrew around a single central axis. The wire thickness and the number of coils determine physical spring dimensions such as free length and the number of active coils, which in turn dictate the spring’s mechanical properties, such as spring rate (stiffness).
Why Choose Century Spring
Our Commitment to Quality and Service
Century Spring is a quality-first, ISO 9001 and AS9100D certified, industry-leading spring supplier specializing in stock and custom springs. We are the most trusted name in spring manufacturing, offering products and expertise to serve every corner of the helical spring markets.
Our dedicated custom spring development and customer support teams help you navigate critical design criteria such as size, material, surface finish, and end type to find your application's optimal spring solution.
Our experienced product engineers, knowledgeable product quality team, and skilled manufacturing personnel always deliver the highest quality products to you faster than our domestic and international competitors. Our springs are always made in the USA.
We offer rapid delivery on over 40,000+ in-stock designs available to ship today. We are committed to getting products to you as quickly as possible because we understand your design scheduling constraints.
Visit us today to discover how our commitment to quality and customer satisfaction vastly improves your product design process.
Innovation and Customization in Spring Manufacturing
We bring extensive design for manufacturability (DFM) expertise to your project. We also have dedicated, high-speed machines that can quickly scale high-quality spring production processes to large part volumes.
We also have cutting-edge computational equipment simulation and testing techniques, such as CNC compression self-monitoring and coiling machinery. These capabilities enable us to deliver durable, reliable products across many custom sizes and styles. Our manufacturing services also include complete prototyping and tooling assistance.
Our team will work directly with you to create, refine, and optimize spring designs to fit specific tolerance, performance, and use case conditions. We are ready to partner with you to solve your most pressing design challenges.
Get In Touch
Contact Information
Contact us directly today, and let our experts resolve all your technical and sales questions. We can also guide you to one of our in-stock helical springs that will fit your application and load profile.
If you need immediate assistance, you can always reach us at our dedicated phone line to speak directly with our team: 800-237-5225.
Request a Quote and Consultation
We can also help you evaluate custom helical springs and determine whether a custom design suits your application better.
Simply Request a Custom Quotation so we can partner with you to customize a spring design for your unique application.
Once we hear from you, our design team will follow up with a quote for a custom solution and be happy to answer any follow-up questions you may have.