Minimal compressed height
The closed height equals only the strip width, allowing extremely compact installations where a helical spring would not fit.
Volute springs
Los muelles de voluta (Buffer Springs, Puffer Federn, muelles de tope o muelles cónicos de fleje) son resortes de compresión fabricados enrollando un fleje de acero en espiral cónica, de modo que la altura comprimida es igual al ancho del fleje.
Compressed height
= strip width
F/s curve
progressive · linear → exp.
Max. load
up to 500 kN
01
What are volute springs?
Conical compression springs made from a rectangular-section steel strip, coiled in a spiral around a mandrel so that each coil overlaps the next, forming a cone.
Unlike a conventional helical spring, volute springs compress to a height equal to the width of the starting strip, regardless of the number of coils or the spring's travel.
This geometry gives them a unique structural advantage: more force and travel per unit volume than any leaf spring, helical spring or torsion bar of equivalent dimensions (Floyd, Bournelis & Clark, Aerospace Mechanisms Symposium, NASA Ames, 2016).
02
Technical characteristics of volute springs
These are the design parameters and standard manufacturing ranges. Values marked "non-standard" are assessed case by case by Surisa's engineering team.
| Parameter | Value |
|---|---|
| Construction | Rectangular-section steel strip coiled into a cone — each coil overlaps the next. |
| Standard Ø range | D: 6 – 250 mm · up to 500 mm in non-standard versions. |
| Strip thickness | From 1 mm up to ≈ 32 mm. |
| Maximum load | Up to 500 kN in large springs. |
| Spring rate | Progressive — linear in the initial phase, exponential once the coils first make contact. |
| Damping | By friction between coils in the standard version. Can be eliminated in the free-clearance version. |
| Standard material | Carbon spring steel · 50CrV · 60Si2Mn. Stainless steel on request. |
| Finishes | Phosphating · paint · nickel plating · chrome plating · dry-film lubricant. |
FIG · technical dimensions and F/L curve
- d
- Internal diameter
- D
- External diameter
- h
- Strip width
- b
- Strip thickness
- L₀
- Free height
03
Types of volute spring by coil configuration
Volute springs are made in two main configurations depending on the number and arrangement of the conical spirals. Both share the same progressive characteristic curve, but their typical use differs.
single
Single volute
A conical spiral with one larger end and one smaller end. It is the most common type in high-load industrial applications.
double
Double volute
Two facing conical spirals forming a cylinder with the largest diameter in the centre. Common in garden shears and light cutting tools.
FIG · single vs. double volute
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04
Mechanical behaviour · the progressive load-deflection curve
Unlike helical springs with a linear rate, volute springs show a response in two clearly distinct phases:
- 1. Linear phase The coils slide against one another under axial compression. The rate is approximately constant and predictable.
- 2. Exponential phase Once the largest-diameter coil contacts the base (initial bottoming load), each successive coil bottoms out in sequence. The rate rises exponentially until it reaches the final bottoming load (solid height), where the spring is fully compressed.
Why it matters
This progressive behaviour is especially valuable in shock absorbers: the spring reacts gently to small loads and with increasing firmness to larger ones, protecting both the machine and the workpiece.
FIG · F vs. s curve — volute spring
P1initial bottoming
The largest-diameter coil touches the base. The exponential phase begins.
P2final bottoming · solid
Solid height — all coils in contact. Full compression.
05
Advantages over conventional helical springs
The following set of advantages explains why, in shock-absorption applications in tight spaces, the volute spring has no direct substitute.
Lateral stability
The overlap of the coils acts as an internal radial guide, preventing buckling without the need for an external guide column — a critical advantage in tight spaces.
Progressive load
The variable rate absorbs impacts of varying energy better than a fixed-rate spring.
High force-to-volume ratio
More force and travel per unit volume than leaf springs, helical springs or torsion bars in the same installation space.
Resistance to lateral deflection
The conical geometry and the coil overlap provide a stability that conventional compression springs cannot match.
06
Industrial applications of volute springs
Their compact profile and progressive response have no direct equivalent, so they find use across very diverse sectors — from tooling to satellite deployments.
Tooling and stamping
Stops in dies · presses
A stop and damping element in cutting, bending and forming dies. They absorb the press's end-of-stroke impact, protecting the tooling.
Rail
Historic application · John Brown · 1848
The first railway buffer device using a volute spring was patented by John Brown in 1848. They remain a standard component in buffer assemblies between wagons today, thanks to their high energy absorption in a small space.
Automotive and military vehicles
M4 Sherman suspension · 1942 – 1957
The suspension system of the M4 Sherman tank used volute springs as its main suspension element. They are also used in horizontal and vertical suspensions of industrial vehicles.
Automation and transfer lines
End stops · feeding
Damping of abrupt movements at end stops, feeding systems and industrial handling.
Cutting and garden tools
Double volute · self-guiding
The double volute is a common component of garden shears and pruners, where self-guiding and compactness are decisive.
Aerospace and satellites
Lockheed Martin · LRA · −100 °C / +95 °C
Lockheed Martin used volute springs in the Launch Restraint Assemblies (LRA) of satellite deployments. Testing validated force-output stability after 10 thermal cycles between −100 °C and +95 °C and under random-vibration environments (Floyd et al., NASA AMS 2016).
07
End configuration · a critical technical detail
The configuration of the spring's ends has a direct impact on deployment behaviour and stability. For high-precision or aerospace applications, it is always advisable to specify closed ends with a dead coil on each side on the engineering drawing. That said, three variants can be distinguished:
| Configuration | Characteristics | Recommendation |
|---|---|---|
| Unaltered ends unaltered |
Rectangular tips on the inner/outer coil. Causes unstable deployment and high exponential friction as it approaches solid height. | Not recommended |
| Ground ends ground |
Removes the rectangular tips. Improves deployment stability, but friction build-up persists on the inner coil. | Limited use |
| Closed ends closed · dead coil |
A dead coil at each end. Stable deployment, no friction changes throughout the travel, reliable force measurement. | Recommended |
08
Available materials and finishes
— Standard materials
Carbon spring steel
General industrial use
Stainless steel
Corrosion · food · chemical
— Surface finishes
- Phosphating · paint Standard base protection
- Nickel plating · chrome plating Cutting and garden tools
- Dry-film lubricant Vacuum or extreme-temperature applications — prevents cold welding
09
Frequently asked questions
01 What is a volute spring and how does it differ from a helical spring?
A volute spring is a conical compression spring made from a steel strip coiled in a spiral, where each coil overlaps the next. Its fundamental difference from the helical spring is the compressed height: the volute spring compresses to the strip width (regardless of the number of coils), whereas the helical spring compresses to the number of coils multiplied by the wire diameter. This makes it possible to fit more travel and more force into a minimal axial space.
02 Why is the spring rate of a volute spring progressive and not linear?
As it compresses, the coils come into contact in sequence, starting with the largest-diameter coil (the least stiff). Each coil that touches the support plane stops being active, reducing the spring's active length and increasing its rate. The result is a load-deflection curve that goes from linear to exponential from the first coil contact (initial bottoming load), which makes the spring an ideal progressive absorber for impacts of varying energy.
03 In which industrial applications are volute springs used?
Volute springs are common in stamping dies and press tooling, railway buffers (in use since 1848), suspensions of industrial and military vehicles, end stops in automation, garden tools and, in custom versions, in satellite deployment systems and aerospace components where a minimal compressed profile is a design requirement.
04 When should I choose the version with free clearance between coils?
The standard version generates friction between coils as it compresses, which is useful for damping vibration but ill-suited to continuous high-frequency dynamic cycling (the accumulated friction artificially raises the measured force and causes premature wear). If the application involves repeated cyclic compression and extension, request the version with free space between coils, which eliminates contact and allows dynamic operation without friction or heat build-up.
05 What technical data do I need to order a custom volute spring?
To size or select a volute spring you need to know: external diameter (D), internal diameter (d), strip width (h), strip thickness (b), free height (L₀), required load and working stroke. With this data and the expected load curve, Surisa's engineers can recommend the right catalogue reference or work out the manufacture of a custom spring.
06 What special materials are available for harsh environments?
Standard volute springs are made from carbon spring steel (50CrV, 60Si2Mn). For applications with corrosion requirements, high temperature (above 180 °C), humid environments or vacuum, Surisa offers stainless steel versions and special finishes (dry-film lubricant, nickel plating). Contact the engineering team to assess the most suitable material for each specific application.
Let's talk about your project
Tell us about your use case and our engineering team will help you choose the optimal solution.