Compression springs
Also known as coil springs, they are used in a wide range of applications – from everyday items like ballpoint pens to medical devices such as hearing aids, as well as in measuring instruments and the automotive industry.
With modern CNC machines, we are capable of producing a wide variety of designs and shapes in wire diameters ranging from 0.20 mm to 9.00 mm. Our equipment is equipped with measuring, control, and sorting systems to ensure the highest quality standards. Additionally, our spring end grinding machines, shot blasting systems, and setting equipment allow us to cover the entire production process of compression springs in-house – from start to finish.
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 stress requirements and the spring’s operating environment. The following list provides a representative selection of the materials we primarily process. Thanks to our extensive raw material inventory, we can usually accommodate customer requests at short notice.
| Surface Treatment | Material Description | Load, Properties, Intended Use | Operating Temperature |
|---|---|---|---|
| DIN EN 10270-1 SM | Spring steel | Moderate static or infrequent dynamic stress; compression, torsion, or tension springs, bent parts | max. 80° |
| DIN EN 10270-1 SH | Spring steel | High static or low dynamic stress; compression, torsion, or tension springs, bent parts | max. 80° |
| DIN EN 10270-1 DH | Spring steel | High static or medium dynamic stress; compression, torsion, shaped or tension springs, bent parts | max. 80° |
| DIN EN 10270-2 FDSiCr | Oil-tempered spring steel | High static stress; compression and leg springs | max. 130° |
| DIN EN 10270-2 TDSiCr | Oil-tempered spring steel | High static stress, medium fatigue strength; compression and leg springs | max. 130° |
| DIN EN 10270-2 VDSiCr | Oil-tempered spring steel | High static and dynamic stress; high fatigue strength; compression and leg springs | max. 130° |
| DIN EN 10270-3 1.4310 | (X10CrNi18-8) | Stainless steel 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, highly stressable | 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, suitable for high temperatures, seawater-resistant | -200° to max. +400° |
| 2.4669 Inconel X-750 | (NiCr15Fe7Ti2Al) | Non-magnetic, high corrosion resistance, suitable for high temperatures | max. 370° |
| DIN EN 10016-2 C9D | Wire | Bent parts | |
| DIN EN 10016-2 C10D | Wire | Bent parts |
Springs are expected to experience relaxation at high temperatures. Materials for special applications are available upon request.
The above statements are indicative only and are not intended to be exhaustive.
Surface treatment of compression springs can be done in two ways:
Shot peening:
Shot peening increases the fatigue strength of compression springs by introducing compressive stresses that counteract the load on the spring.
Surface coating:
Surface coatings can be applied to provide corrosion protection, especially when a non-corrosion-resistant material is used for manufacturing the spring for technical or cost reasons. When stainless spring wires are used, additional corrosion protection is generally not required. Furthermore, other surface coatings can 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 surface treatment you need is not listed, please feel free to contact us.
| Surface Treatment | Note |
|---|---|
| Zinc Plating | Electrogalvanic zinc plating is the most commonly used and cost-effective method of corrosion protection for technical springs. |
| Zinc Plating with Passivation | Electrogalvanic zinc plating followed by passivation is a cost-effective method to achieve good corrosion protection for technical springs. |
| Nickel Plating | Nickel plating is a decorative surface treatment that also provides favorable sliding properties along with high corrosion resistance. |
| Chrome Plating | Chrome-plated parts are decorative and have good heat and corrosion resistance. |
| Pickling | Pickling removes chemically bound impurities from the surface. |
| Copper Plating | Copper plating is used as a base for subsequent surface treatments and also for color marking of springs. |
| Blackening (Bluing) | A layer of iron oxide forms on treated parts, giving a deep black surface. Oiling provides corrosion protection. |
| Phosphating | Phosphating serves as corrosion protection and as an adhesion base for paint and coatings, and as preparation for KTL coating. |
| Zinc Flake Coating | An environmentally friendly coating system that meets increasing corrosion resistance requirements. These coatings are chrome-free and free of heavy metals, with high temperature resistance and low hydrogen embrittlement. |
| KTL Coating | KTL is a dip-coating process that meets the highest quality requirements for corrosion protection and under-rust protection. |
| Powder Coating | Powder coating is suitable when a scratch- and impact-resistant surface with high corrosion protection is required. |
| Gleitmo | Gleitmo is an air-drying sliding lacquer. Its lubricating component is specially processed PTFE. Operating temperature range -180° to +250°C, allows low friction, does not stain or grease, and is suitable for food contact. |
| Tin Plating | The main advantage of tin plating is good solderability. |
| Silver and Gold | Silver and gold provide high-gloss, premium surfaces for decorative and technical purposes. |
| Shot Peening | Shot peening increases the dynamic lifespan of technical springs but offers no corrosion protection (only limited). |
| Trowalizing / Vibratory Finishing | This surface treatment removes stamping or cutting burrs but provides no corrosion protection (only limited). |
Material
Our compression springs are manufactured from patented drawn spring steel wire according to EN 10270-1 Types SM, SH, or DH. Stainless steel springs are predominantly made from spring steel wire per DIN EN 10270-3, Material Nos. 1.4310, 1.4401, and 1.4568.
Coil Direction
Compression springs are typically wound with a right-hand coil. Spring sets may include both right-hand and left-hand wound springs, with the outer spring usually wound right-hand.
Right
Left
Ground
Ground and polished
End Coils
The spring ends transfer the spring force to the connected component. They are designed to allow axial compression in almost any spring orientation. Ends that are ground perpendicular to the spring axis promote axial compression. However, grinding of spring ends should be avoided whenever possible for wire diameters below 1.00 mm or for coil ratios greater than 15. Since spring end grinding is a cost-intensive process, it should be avoided for economic reasons if feasible. The same applies to the application of an inner and/or outer chamfer.
Surface
Compression springs made from spring steel EN 10270-1 are lightly oiled after heat treatment. Compression springs made from spring steel EN 10270-3 do not receive additional surface treatment after heat treatment, as surface protection is usually not necessary. However, if desired, a wide variety of surface coatings can be applied. A selection of these is provided above.
Spring Testing
Ensuring quality is our top priority. Springs are tested on our production equipment for compliance with tolerances according to sampling plans and customer specifications. We can perform and document all tests according to the customer’s testing requirements, including individual testing. Appropriate test reports are provided as standard practice.
Production Compensation
Production compensation is necessary in spring manufacturing to guarantee that the specified load requirements are met.
| Prescribed sizes | Production compensation through |
|---|---|
| One spring force and the corresponding compressed length | L0 |
| One spring force, the corresponding compressed length, and free length (Lo) | n and d oder n and Da, Di, Dm |
| Two spring forces and the corresponding compressed lengths | L0, n and d or L0, n and Da, Di, D |
Spring Buckling
Compression springs may buckle if their length exceeds a critical limit. A stability check is essential in such cases. The buckling length is denoted by Lk, and the spring travel at which buckling begins is denoted by Sk. Springs that are not inherently resistant to buckling must be guided using sleeves and/or mandrels to maintain axial alignment.
Settling of Springs
Compression springs may experience settling during use, meaning that after being loaded, they no longer return to their original free length (L0).
This irreversible shortening can be significantly reduced through a process called pre-setting, which is available upon customer request.
Calculation
Spring calculations are carried out in accordance with customer specifications, using modern software tools and conforming to the standard EN 13906-1:2013.
Tolerances
Unless otherwise specified, tolerances are based on EN 15800, Grade 2.
Types of Stress
Static use: Time-variable stresses with fewer than 10,000 load cycles, typically involving higher loads.
Static use refers to time-variable stresses with higher stresses but with load cycles <10,000. Dynamic use refers to time-variable stresses with load cycles >10,000 and stresses exceeding 0.1 x the fatigue limit.
Geometric dimensioning
| Symbol | Description | Unit |
|---|---|---|
| d | Wire diameter | mm |
| D | Mean coil diameter of the spring | mm |
| De | Outer diameter of the spring | mm |
| Di | Inner diameter of the spring | mm |
| n | Number of active coils | |
| nt | Total number of coils | |
| L0 | Free length of the unloaded spring | mm |
| a0 | Clear spacing between coils in unloaded state | mm |
| m | Pitch of the spring – center to center distance in unloaded state | mm |
Information about Spring Forces
| Symbol | Description | Unit |
|---|---|---|
| L0 | Nominal length of the unloaded spring | mm |
| L1 | Nominal length in installed condition -corresponds to spring force F₁ | mm |
| L2 | Nominal length in actuated condition – corresponds to spring force F₂ | mm |
| Ln | Smallest permissible spring length -corresponds to spring force Fₙ | mm |
| s1 | Spring deflection corresponding to spring force F₁ | mm |
| s2 | Spring deflection corresponding to spring force F₂ | mm |
| sh | Spring deflection – travel between two positions | mm |
| F1 | Spring force corresponding to length L₁ (at room temperature 20°C) | N |
| F2 | Spring force corresponding to length L₂ (at room temperature 20°C) | N |
| Fn | Spring force corresponding to smallest length Lₙ | N |
| Fc th | Theoretical spring force at solid length (L_c) | N |
| R | Spring rate | N/mm |
Information on Calculation and Testing
| Symbol | Description | Unit |
|---|---|---|
| τκ1 | Corrected shear stress – related to spring force F₁ | N/mm2 |
| τκ2 | Corrected shear stress – related to spring force F₂ | N/mm2 |
| τν | Uncorrected shear stress – related to spring force Fₙ | N/mm2 |
| τc | uncorrected shear stress – assignment of block length (Lc) | N/mm2 |
| τkh | corrected stroke voltage – assignment to the stroke (sh) | N/mm2 |
| G | Shear modulus (material property) | N/mm2 |
| Dd | Mandrel diameter | mm |
| Dh | Sleeve diameter | mm |
| Ls | Settling length of the spring | mm |
| c | Block length | mm |
| e1 | Permissible deviation of the helix line from the vertical spring axis (unloaded spring) | mm |
| e2 | Permissible deviation of the parallelism of the ground bearing surface | mm |
Contact Person
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