Springs

Spring forming shapes coiled or bent wire into elastic components that store and release energy, with performance driven by material, geometry, and heat treatment.

Overview

Spring manufacturing in wire forming produces compression, extension, and torsion springs by coiling or bending wire, then stress-relieving, heat treating, and often finishing (shot peen, plating, passivation). Key outputs are spring rate, free length, solid height, and force at working lengths—more critical than tight linear dimensions.

Choose springs when your part needs repeatable force, return motion, vibration isolation, or preload across many cycles. It scales well from prototypes to high volume using CNC spring coilers and dedicated tooling, with fast cycle times once set up.

Tradeoffs: performance is sensitive to wire diameter, coil diameter, number of active coils, and end conditions, so small geometric changes can shift force noticeably. Cosmetic perfection is limited (tool marks, minor set), and tolerances vary by feature; you’ll often control force at length rather than every dimension. Material and heat treat selection drive fatigue life, corrosion resistance, and temperature capability.

Common Materials

  • Music wire (ASTM A228)
  • Stainless 302
  • Stainless 17-7PH
  • Chrome silicon
  • Phosphor bronze
  • Inconel X-750

Tolerances

±0.005"

Applications

  • Compression springs for valves and regulators
  • Extension springs for latches and door mechanisms
  • Torsion springs for hinges and clips
  • Battery contact springs
  • Die springs for stamping tooling
  • Vibration isolation springs for small assemblies

When to Choose Springs

Pick spring forming when the requirement is force/deflection behavior, preload, or energy storage rather than a rigid structural feature. It’s a good fit for prototype through high-volume programs where repeatability, cost per piece, and fatigue life matter. Expect to validate with load testing at defined lengths and cycle life targets.

vs CNC machining

Choose springs when you need elastic behavior (spring rate and travel) that a machined solid part can’t provide efficiently. Spring forming delivers the required force with far less material and weight, and it scales to high volumes with low piece cost.

vs Stamping (flat springs)

Choose coiled wire springs when you need large deflection, higher travel per envelope, or axisymmetric behavior like compression/extension. Wire springs typically deliver higher energy storage for the same footprint, while stamped springs are better for very thin, planar geometries.

vs Plastic injection molding

Choose metal springs when you need stable spring rate across temperature, long fatigue life, or high force in a small package. Molded plastic flexures can work for low-force, integrated features, but wire springs hold performance better over cycles and environment.

vs Additive manufacturing (metal 3D printing)

Choose wire-formed springs when the geometry is a standard coil or torsion form and you need predictable fatigue performance at reasonable cost. 3D printing makes sense for unconventional lattice springs or integrated assemblies, but surface finish and variability can hurt fatigue life.

Design Considerations

  • Specify functional requirements first: spring rate, force at one or more lengths, maximum travel, and required cycle life
  • Call out end style and orientation (closed/ground ends, hooks/loops, leg angles) and include a reference drawing with free length and solid height
  • Control critical diameters and clearances: wire diameter, outside/inside diameter limits, and any mandrel or housing constraints
  • Define environment early: corrosion media, temperature range, and any magnetic constraints to drive material and finish selection
  • Include finishing requirements explicitly (stress relief/heat treat, shot peen, passivation, plating) and note hydrogen embrittlement risk for high-strength steels
  • Plan inspection around load testing at defined lengths and provide acceptable force tolerance bands rather than over-controlling every linear dimension