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Springs & Wire Forms

Custom Extension Springs Manufacturer

Custom-made extension springs tailored to your specific specifications. Discover Filame's deep expertise, production capabilities, sector expertise, materials and finishings.

The extension spring is generally intended to operate by extension and is therefore the opposite of the compression spring.

This is calculated as a compression spring possibly taking a prestressing force into account called initial tension. Extension springs are generally cylindrical in shape and can be differentiated by the variety of hooks that can be formed at their ends (English hooks, German hooks, elongated hooks, etc.).

Available in all dimensions and qualities from 0.1 to 8 mm in wire thickness in small, medium or large series. Extension springs are available only up to 20 mm in small and medium series.

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Use Filame’s interactive calculation tool to size and preview your spring. Compute rates, loads, Wahl stress corrections, and submit verified parameters for rapid quoting.

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Specifications

Technical Specifications

  • Wire thickness: 0.1 mm to 8 mm (standard), up to 20 mm (special small/medium series).
  • Hooks: English, German, elongated, and custom designs.
  • Materials: Carbon steel, stainless steel (1.4310, 1.4401), Inconel, and more.
  • Standards: Manufactured according to EN 13906-2.
Materials

Worked Steels

  • SM, SH, DH grade spring steel, ...
  • Pre-coated galvanised SM grade, galvanised SH grade, Bezinal © SM grade and Bezinal © SH grade steel
  • Oteva © silicon-chrome oil-tempered steel
  • Stainless steel 1.4310, 1.4310 HS, 1.4401, 1.4568, 1.4462, 17/7 PH
  • Low-carbon stainless steel 1.4301
  • 1.4441 implant grade stainless steel
  • Inconel 600, 625, 718, 750
  • Monel, Nimonic, Elgiloy …
Surface Treatment

Finishings

  • Pre-stressed shot peening
  • Oiling
  • Zinc plating
  • Cataphoresis
  • Teflon © coating
  • Geomet © coating
  • Passivation
  • Phosphate treatment
  • Colour coding
  • Marking
  • Ultrasonic cleaning
  • Unit packaging in sachets, etc.
Portfolio

Product samples

Sectors

Industries we serve

The Filame Group manufactures precision components for a wide range of industries. Discover the main sectors we serve:

We also serve many other sectors. For more details on all of our industry services, visit our Industries & customers page, or contact us for any custom requests.

Documentation

Technical Documentation

Download the following document to help you define your specifications :
Media

Video

FAQ

Questions & Answers

01 What is the difference between compression and extension springs ?
While compression springs operate by pushing, extension springs are designed to operate by pulling or extension, often incorporating initial tension in their design.
02 What types of hooks can Filame produce for extension springs ?
We can manufacture a wide variety of hooks, including English hooks, German hooks, elongated hooks, and custom configurations to suit your specific application.
03 What is the maximum wire thickness for extension springs ?
Filame standard production covers 0.1 mm to 8 mm wire thickness, but we can accommodate up to 20 mm for small and medium series.
04 Can Filame help with the design of extension springs ?
Yes, our engineering team can assist in calculating the necessary initial tension and spring rate to ensure the extension spring meets your mechanical requirements.
05 In which materials can extension springs be manufactured ?
We work with various materials, including high-grade spring steel (SM, SH, DH), stainless steel (1.4310, 1.4401), and high-performance alloys like Inconel 600, 625, and 718.
06 How does Filame ensure the quality and compliance of its products ?
Filame is ISO 9001 certified and operates in accordance with IATF 16949 requirements. We utilize advanced automated optical inspection (AOI) systems for 100% dimensional compliance and routinely provide full EN 10204 3.1 material certifications and PPAP Level 3 documentation.
07 Can Filame assist in the engineering, design, and prototyping phase ?
Yes. Our in-house engineering design studio collaborates directly with your R&D teams to co-design progressive dies and optimize part geometries for cost-efficient mass production. We also utilize advanced 3D printing to quickly manufacture prototypes, assembly jigs, and custom verification fixtures.
08 Which industries does Filame primarily manufacture components for ?
We manufacture high-precision components for demanding sectors worldwide, including the Automotive, Aerospace, Medical & Pharmaceutical, Defense, Nuclear, Civil Engineering, Construction, and Locksmith industries.
09 What manufacturing machinery does Filame utilize for production ?
Our state-of-the-art Nivelles facility features high-speed automatic mechanical presses (with multi-step progressive tooling), stand-alone mechanical presses, hydraulic presses, Bihler multi-slide machines, CNC 2D/3D wire formers, laser-cutting/punching machines, and automated welding robots.
10 What are Filame's shipping capabilities and delivery times across Europe ?
Headquartered in Nivelles, Belgium, at the geographic heart of Europe, Filame provides robust logistics with rapid shipping across all major European countries—including Germany, France, the Netherlands, Luxembourg, and beyond—with transit times typically between 24 and 48 hours once production is completed.
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