Extension Springs

Extension springs are helical wound coils, wrapped tightly together to create tension. Extension springs are designed to resist a pulling force, returning to a tightly wound coil when the force is removed. Custom extension springs from Springfield Spring & Stamping are manufactured on state-of-the-art CNC wire forming equipment (for example, the CNC Itaya Wire Former; the CNC Orimec MLS-10V). This allows us to offer a wide variety of custom extension spring options with various end types; our custom extension springs are available with machine, crossover, side, or extended end options.

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Specifications

Materials

The highest grades of spring wire are used in manufacturing Springfield Spring & Stamping products. “Spring steel” is a term that includes music wire, hard-drawn wire and oil-tempered wire. Alloy steels for stock extension springs are offered only in 300 series stainless steel. For custom extension springs, we offer several steel and metal options depending on your specifications.

 

Tolerances

Tolerances for extension spring rates depend upon the body-diameter to wire-diameter but are usually +/- 10% and +/- 5% on the diameter. The initial tension is much more difficult to control and is offered as a reference value only.

End Configuration

The hooks or loops may have an across center transition of the last coil before forming the hook or loop. The angle between hook/loop planes (end position) is random. If you need a specific end configuration on your custom extension spring, please contact our custom spring department directly.

Extension Spring FAQs

What material types are available for extension springs?

Extension springs can be made from any of the following materials:

  • Music Wire
  • Pre Tin-Coated Music Wire
  • Pre-Galvanized-Coated Wire
  • Hard Drawn MB
  • Oil Tempered
  • Stainless Steel
  • Phosphor Bronze
  • Beryllium Copper
  • Brass
What are possible end configurations for extension springs?

Possible end configurations include Machine, Crossover, Side, and Extended. We have the capabilities to specify end configurations based on your needs. 

What are wire diameter capabilities for extension springs?

Our wire diameter capabilities range from 0.008″ to 0.135″

Wire Diameter Min.

.008 in
.201 mm

Wire Diameter Max.

.135 in
3.4 mm
What file types are acceptable for submitting a drawing?

We utilize CADKEY Creator and can translate most of the common CAD files for use. Here is a complete list of file formats we can work with:

  • AutoCAD (DWG and DXF)
  • BMP
  • Bit Mapped Graphics
  • GIF
  • Graphics Interchange Format
  • IGES
  • JPG or JEPG
  • Joint Photographic Experts Group
  • PDF
  • TIFF
  • Tagged Image File Format
Do you have the capabilities for secondary finishes on extension springs?

Yes, all of our components can have additional processing based on the end application requirements. Some examples of secondary finishes for extension springs are as follows:

  • Black Oxide
  • Color Code
  • Gold Plating
  • Manganese Phosphate
  • Nickel Plating
  • Painting
  • Passivation
  • Phosphate w/ Oil
  • Powder Coated
  • Tin
  • Varnish
  • Zinc (Clear and Yellow)

Interested in a secondary process not listed above? Reach out to our team and we can discuss together. 

What spring and stamping manufacturing equipment do you have?

A complete list of our equipment is as follows:   

  • Itaya MX-10, MX-20, RX-20 CNC Spring Forming Machines
  • Primera Precision ZX-250 CNC Spring and Wire Formers
  • Vinston CCM-12-236 R, CMM-12-450 R Camless Multi-Axis Rotary Wire Spring Formers
  • Nilson Four Slide 4 Ton, 5 Ton, 7 Ton, and 20 Ton
  • Bihler MK3 – B20-01-0001 Servo-controlled Stamping and Forming Machine
  • Fenn-Torin FZ Series CNC Spring Coilers
  • Moyer CNC Spring Grinders
  • MicroStudio MC54-30 Automated Setting and Sorting Machine
  • Tool and Die fabrication. CNC Machining, Wire EDM
Do you provide secondary services such as PPAPs for extension springs?

Yes! Our team has experience conducting PPAPs. We also offer  Pre-Qualifying Engineering Cost Reduction Programs, Statistical Process Control (SPC), and Automotive FMEA. 

What volumes are available?

Our volumes range from a single piece prototype to production volumes in the millions to everything in between.  

Learn more about what critical to function means to us

It’s not just a stamping, it’s not just a wireform, it’s not just a spring. It HAS to work. You can’t risk your medical or defense product to not work every time. At Springfield Spring, we partner with your team to solve your most complex problems. Our products are tested and engineered to work every time as they’re supposed to function. We strive to make the best springs, stampings, wireforms and fourslide parts.