Design Considerations for Compression Springs

  • Free Height (Maximum and minimum length limits)
  • Material
  • Finish (bake enamel, electropolish, passivate, plate, plastic coat, powder coat, shot peen or stress relieve)
  • Wire Size
  • Ends (Can be open or closed; closed ends can be ground or square)
  • Number of Coils or Turns
  • Winding (Left Hand or Right Hand)
  • Diameters (Inside and outside limits)
  • Pitch Diameter
  • Index (Ratio of the mean diameter
    of the spring to the diameter of the wire)
  • Rate (The deflection is proportional to the load)
  • Frequency of Compression
  • Load (at deflected positions)
  • Stress (Stress occurs from torsion)
  • Solid Height (length of spring when fully compressed) **
  • Allowed Space (when space for spring usage is limited and solid height restraints are extreme, square or rectangular wires offer greater energy storage in less space)

** Be mindful if plating or coating is in the design finishing, as this will increase its total solid height.


Stress relieving or heat treating affects compression springs as follows:

  1. Reduction in initial tension
  2. Change in spring diameter