Custom extension spring

Extension springs

The tension spring is a flexible and reliable spring that absorbs and returns forces under tensile loads. This makes it ideal for a wide range of applications, from fine mechanical systems to heavy industrial installations.

About our extension springs

As the name suggests, tension springs are loaded in tension. Under the influence of force, the spring elongates and returns to its original position as soon as the force is removed. This makes tension springs ideal for applications where tension and durable performance are key.

To make the spring functional, hooks or eyes are attached to the ends. These ensure flexibility and safety, making the tension spring easy to install in a wide range of systems, from small-scale mechanisms to robust industrial applications.

Applications of extension springs

From offshore to the agricultural sector: Tension springs are indispensable in sectors where reliability and precision are crucial. In mechanical engineering, they ensure controlled movements in automation lines and safety mechanisms. In the offshore and maritime sectors, they withstand harsh conditions such as corrosion and pressure, and are essential for valves and seals. In shut-off valves and pumps, tension springs guarantee constant force and accurate repetition in sealing systems. In agricultural engineering, they increase the robustness of agricultural machinery by absorbing shocks and keeping parts stable.

De Spiraal provides customised solutions that continue to perform, even in the harshest environments. For anyone wondering which tension spring do I need?, De Spiraal offers clear explanations and customised solutions that continue to perform, even in the harshest environments.

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Stainless steel extension spring for corrosion-resistant applications
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Trekveer met cilindrischExtension spring with Extension spring with cylindrical coil for uniform performance
Tailored extension spring

Technical specifications and capabilities

Extension springs provide controlled tension and retraction in mechanical systems: from locking mechanisms in machinery to braking action in vehicles and medical equipment. We manufacture extension springs in accordance with ISO 9001, precisely tuned for initial tension and spring constant, completely aligned with your technical design.

Custom Sizing & Configuration

With our extensive machinery, we produce extension springs that precisely fit your mechanical design:

  • Wire Diameters: From 0.10 mm for precision instruments to 20 mm for heavy industrial installations, produced (semi-)automatically.
  • Feasibility Check: During the quotation phase, we immediately assess the technical feasibility of your design. If certain parameters are not optimal, we always recommend a suitable alternative.
  • Loop Designs: We advise on the correct loop shape for your attachment and application
    • German and English Loops: for standard attachments and general applications, also suitable for dynamic loads.
    • Hook Loops and Plate Loops: for specific installation and attachment situations.
    • Double Loops and Spring Plugs: for applications with high installation requirements.

Finishing & Specialization: Based on the dynamic load and desired lifespan, we advise on the appropriate post-treatment;

  • Heat Treatment: Every extension spring undergoes heat treatment. This removes stresses from the material and ensures the spring fully develops its elastic properties.
  • Surface Treatment (upon request): From galvanizing to specialized coatings for corrosion resistance in demanding environments.

Material Selection & Environmental Factors

The lifespan of an extension spring depends on several factors, including material selection, environmental conditions, and the nature of the load. Based on factors such as corrosion resistance, ambient temperature, and application, we advise you on the correct choice:

Type: Spring steel
Material number: 1.1200
Characteristics: Known for its high elasticity and fatigue limit

Type: Stainless steel
Material number: 1.4310 / 1.4301 / 1.4401
Characteristics: Excellent corrosion resistance; ideal for the medical and food industries.

Type: Specials
Material number: Inconel / Hastelloy
Features: For extreme temperatures or aggressive chemical environments such as the offshore & maritime sector

If your material is not listed, or if you are unsure about the right choice for your application? Contact our team; we'd be happy to assist.

Co-Engineering: Optimize Your Extension Spring

Our engineers fine-tune wire diameter (d), outer diameter (Du) and number of coils (n) to ensure your spring transmits force exactly as desired. We also advise on loop position and material selection: from alloy to unladen length (Lbio), all tailored to your load and environment. For both single units and larger series.

Need immediate technical advice?

Call our specialists at +31 (0)74 291 45 08 or send an email to info@despiraal.nl. We'd be happy to process your specifications.

Frequently asked questions

What is the delivery time of tension springs?

For standard extension springs, the delivery time is usually 2 to 5 business days. Custom tension springs are usually delivered within 2 to 4 weeks, depending on complexity and numbers. Express delivery and prototyping are also possible in consultation.

What is a tension spring and when do you use it?

A tension spring is a coil spring that exerts force when stretched. Extension springs are used to pull parts together or to build up tension during extension, for example in ports, valves, switches and sports equipment.

What is the maximum force or extension of a tension spring?

The maximum strength and extension depend on the material, wire thickness and construction. We are happy to advise you on the optimal ratio between resilience, choice of materials and longevity for your application.

Are tension springs resistant to corrosion or heat?

Yes, we supply tension springs in corrosion-resistant materials such as stainless steel and heat-resistant alloys such as Inconel. Finishes such as galvanizing or passivating are also possible for extra protection.

Can you supply tension springs with specific hook shapes?

Yes, we design and produce custom tension springs with various hook ends, such as German eye, English eye, threaded eyes, hinged hooks or special end structures on request.

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