Torsion springs
Leg springs, also known as torsion springs, are used in the automotive industry, electrical engineering, and mechanical engineering. We offer the optimal manufacturing process to meet all your leg spring requirements.
We manufacture individual pieces in-house. For small batches, we use semi-automated production to combine the advantages of manual and large-scale manufacturing. For high-volume production, we rely on fully automated processes.
Our machinery includes a wide range of spring coiling machines for producing pre-formed leg springs with simple leg geometries, as well as CNC-controlled machining centers with up to 28 individually programmable axes for manufacturing complex spring and leg geometries.
We process wire diameters ranging from 0.20 mm to 5.00 mm. Depending on the geometry, design, and quantity, we can produce springs with wire diameters up to 16.00 mm.
Materials
Surface Treatment
Useful information
Formula symbols
Contact Person
Steel wire and strip steel for the production of technical springs are used across all areas of technology — particularly in electrical engineering, communications, medical technology, and the automotive industry.
The choice of material grade depends on the mechanical stress and the operating environment of the spring.
The following list provides a representative selection of the materials we primarily process. Thanks to our extensive inventory of raw materials, we are usually able to meet customer-specific requirements at short notice.
| Designation | Material Description | Load, Properties, Applications | Operating Temperature |
|---|---|---|---|
| DIN EN 10270-1 SM | Spring steel | Medium static or occasional dynamic load, compression, torsion or tension springs, bent parts | max. 80° |
| DIN EN 10270-1 SH | Spring steel | High static or low dynamic load, compression, torsion or tension springs, bent parts | max. 80° |
| DIN EN 10270-1 DH | Spring steel | High static or medium dynamic load, compression, torsion, shaped or tension springs, bent parts | max. 80° |
| DIN EN 10270-2 FDSiCr | Tempered spring steel | High static load, compression and leg springs | max. 130° |
| DIN EN 10270-2 TDSiCr | Tempered spring steel | High static load, medium fatigue strength, compression and leg springs | max. 130° |
| DIN EN 10270-2 VDSiCr | Tempered spring steel | High static and dynamic load, high fatigue strength, compression and leg springs | max. 130° |
| DIN EN 10270-3 1.4310 | (X10CrNi18-8) | Stainless material for use at higher temperatures | max. 250° |
| DIN EN 10270-3 1.4401 | (X5CrNiMo17-12-2) | Non-magnetic, more corrosion-resistant than 1.4310 | max. 250° |
| DIN EN 10270-3 1.4568 | (X7CrNiAl17-7) | Less corrosion-resistant than 1.4310, high mechanical strength | max. 300° |
| DIN EN 10270-3 1.4571 | (X6CrNiMoTi17-12-2) | Seawater resistant | max. 300° |
| DIN EN 1654 CuSn | Bronze | Non-magnetic, electrically conductive | |
| DIN EN 1654 CuZn | Brass | Non-magnetic | |
| DIN EN 1654 CuNiZn | Nickel silver | Corrosion-resistant and electrically conductive | |
| 2.4610 Hastelloy C-4 | (NiMo16Cr16Ti) | Highly corrosion-resistant; high operating temperature; seawater resistant | -200° to max. +400° |
| 2.4669 Inconel X-750 | (NiCr15Fe7Ti2Al) | Non-magnetic; high corrosion resistance; high operating temperature | max. 370° |
| DIN EN 10016-2 C9D | Wire | Bent parts | |
| DIN EN 10016-2 C10D | Wire | Bent parts |
Springs may experience relaxation at elevated temperatures. Alternative materials for special applications are available upon request.
The information provided above is for general guidance only and does not claim to be exhaustive.
Surface coatings can be applied to provide subsequent corrosion protection for springs. This is particularly necessary when, for technical or economic reasons, a non-corrosion-resistant material is used in the manufacturing of the spring. When stainless spring wire is used, additional corrosion protection is generally not required. In addition, other surface coatings may be applied to enhance the functional or aesthetic properties of the springs (e.g., anti-friction coatings, etc.).
Below is a selection of surface treatments we offer. If the treatment you require is not listed, please feel free to contact us.
| Surface Treatment | Note |
|---|---|
| Zinc Plating | Electrolytic zinc plating is the most commonly used and cost-effective method for providing corrosion protection for technical springs. |
| Zinc Plating with Passivation | Zinc plating followed by passivation is an economical method to achieve effective corrosion protection for technical springs. |
| Nickel Plating | Nickel plating is a decorative surface treatment that offers good sliding properties along with high corrosion resistance. |
| Chrome Plating | Chrome-plated parts are decorative and offer excellent resistance to heat and corrosion. |
| Pickling | Pickling removes chemically bonded impurities from the surface. |
| Copper Plating | Often used as a base layer for further surface treatments, but also applied for color marking of springs. |
| Bluing (Burnishing) | Forms an iron oxide layer, giving the part a deep black surface. When oiled, it provides corrosion protection. |
| Phosphating | Used for corrosion protection and as a base for paints or KTL coatings. Also serves as a primer for subsequent coatings. |
| Zinc Flake Coating | An environmentally friendly coating system that meets high corrosion protection requirements. It is chromium-free and contains no heavy metals. Additional properties include high temperature resistance and minimal hydrogen embrittlement. |
| Cathodic Dip Coating (KTL) | KTL is an immersion painting process that meets the highest quality standards in terms of corrosion protection and resistance to undercorrosion. |
| Powder Coating | Ideal when a scratch- and impact-resistant surface with high corrosion protection is required. |
| Gleitmo | Gleitmo is an air-drying lubricant coating. The lubricating component is specially processed PTFE. Operating temperature: -180°C to +250°C. Offers low friction, is non-greasy, non-staining, and suitable for food contact. |
| Tin Plating | Tin plating provides excellent solderability. |
| Silver and Gold | Highly glossy and premium surfaces for both decorative and technical applications. |
| Shot Peening | Increases the dynamic service life of technical springs but offers limited corrosion protection. |
| Tumbling/Vibratory Finishing | Removes punching and cutting burrs; offers limited corrosion protection. |
Materials
Our torsion springs are made from patented drawn spring steel wire EN 10270-1 types SM, SH, and DH (DIN 17223-1 / DIN EN 10270-1). The stainless steel springs are predominantly manufactured from spring steel wire EN 10270-3, material numbers 1.4310, 1.4401, and 1.4568 (DIN 17224 / DIN EN 10270-3).
Coil Direction
Torsion springs are usually wound either to the right or to the left. If no other information is provided, a right-hand wound spring is assumed. Double torsion springs combine both right-hand and left-hand wound elements in a single spring. It should be noted that, for manufacturing reasons, externally wound spring elements are preferable.
Right
Left
Double-leg springs with external spring elements are preferable.
Double-leg springs with internal spring elements should be avoided whenever possible.
Legs
The legs transmit the spring force or torque to the application. Their shape is defined by the user (customer). The required design can be realized through a variety of combinations and modifications of the standard. Adhering to standardized design principles, such as a minimum inner bending radius of at least twice the wire thickness or maintaining at least three times the wire thickness as straight length between bends, usually allows for more cost-effective production. However, we also routinely handle unusual applications and challenges. Please let us know your specific requirements, and our specialists will be happy to advise you.
Standardized leg shapes
Legs straight, tangential
Legs bent outwards
Legs bent inwards
Legs raised axially
Leg position based on windings (decimal places)
X,0, angle 180°
X,25, angle 90°
X,50, angle 0°
X,75, angle 270°
Surface
Torsion springs made of spring steel EN 10270-1 are lightly oiled after heat treatment. Torsion springs made of spring steel EN 10270-3 are not further treated after heat treatment, as surface protection is usually not required. However, if desired, a wide variety of surface coatings can be applied.
Spring Testing
Quality production is our primary goal. Springs are tested for compliance with tolerances on our production equipment according to sample plans and customer specifications. We can perform and document the test specifications required by the customer for all springs, including individual tests. Torque tests can be carried out using state-of-the-art equipment; however, due to varying influences from different test fixtures used by customers and suppliers, reproducibility can sometimes be unsatisfactory.
Based on this experience, geometrically based measurements have proven to be more accurate and reproducible. Reasonably toleranced and verified geometric specifications generally result in smaller torque variations than standardized tolerances would allow. Corresponding test reports are, of course, available.
Production Compensation
Production compensation is necessary during spring manufacturing to ensure compliance with the specified load cases.
| Specified Parameters | Production Compensation by |
|---|---|
| One torque and the corresponding angle of the loaded spring | Δ0 |
| One torque, the corresponding angle of the loaded spring, and delta 0 | n and d or n and De, Di, (D) |
| Two torques and the corresponding angles of the loaded spring | Δ0, n and d or Δ0, n and De, Di, (D) |
It should be noted that changing the wire diameter (d) to the nearest standardized gauge usually causes a significant step in the spring values. The number of turns (n) can only be specified in whole turns, with its influence being proportional to the total number of turns.
Calculation
The spring is designed according to customer requirements using modern software and the standard EN 13906-3:2014.
Tolerances
Unless otherwise specified, DIN 2194 Grade 2 is used as the tolerance basis.
Types of Load
Static load is constant over time.
Quasistatic load is variable over time, with higher stroke stresses but with load cycles <10,000. Dynamic use occurs when the load varies over time with load changes >10,000 and stroke stresses above 0.1 x fatigue strength stroke.
Geometric Dimensions
| Sign | Description | Unit |
|---|---|---|
| neu / alt | ||
| d | Wire diameter | mm |
| i | Inner diameter of spring body | mm |
| De / Da | Outer diameter of spring body | mm |
| m | Mean diameter of spring body (theoretical value, not suitable for measurement) | mm |
| δ0 | δ0 Leg angle in delivery condition | Grad ° |
| Ls1 / Ls2 | Leg length1 / 2 | mm |
| r1,r2,… rn | Inner bending radius for legs | mm |
| φ1 , φ2 ,… φn | Bending angle | Grad ° |
| Lk | Spring body length with coils touching | mm |
| Lk0 | Spring body length with pitch between coils | mm |
| a | Distance between coils | mm |
| n / if | Active coils | |
| nt / ig | Total number of coils (for torsion springs typically n=nt) |
Information on torques
| Sign | Description | unit |
|---|---|---|
| δ0 | Leg angle in delivery condition | Degrees ° |
| α1 | 1. rotation angle (preloaded) | Degrees ° |
| δ1 | Leg angle in installed position | Degrees ° |
| M1 | 1. torque (in installed position) | Nmm |
| α2 | 2. rotation angle | Degrees ° |
| δ2 | Leg angle in actuated position | Degrees ° |
| M2 | 2. torque in end position | Nmm |
| αn | Maximum allowable rotation | Degrees ° |
| δn | Leg angle at maximum rotation | Degrees ° |
| Mn | Maximum allowable torque | Nmm |
| αh | Deflection angle (working range) | Degrees ° |
Information on calculation and testing
| Sign | Description | unit |
|---|---|---|
| R1, R2, … | Lever arm of the spring force | mm2 |
| F1,F2… | Spring force assigned to lever arm and angle of rotation | N |
| w = D/d | Winding ratio | |
| Dd | Working mandrel diameter | mm |
| Dh | Working sleeve diameter | mm |
| Dp | Test mandrel diameter | mm |
| σ, σ1, σ2, … | Bending stresses corresponding to spring torque | N/mm2 |
| σq, σq1, σq2, … | Corrected bending stresses considering the stress correction factor q | N/mm2 |
| szul | Permissible bending stress | N/mm2 |
| sqh | Corrected stroke-related bending stress | N/mm2 |
| shzul | Permissible stroke-related bending stress | N/mm2 |
Standardized versions
Leg straight, tangential
Leg bent outwards
Leg bent inwards
Leg axially raised
Leg position depending on windings (decimal places)
| n / ig / if | delta0 | |
| X,0 | 180° |  |
| X,25 | 90° |  |
| X,5 | 0° |  |
| X,75 | 270° |  |
Contact Person
DOMINIC HIMMER
Operations management
24-Hour Service
FOR URGENT REQUESTS
*Available upon request