Spring Compression Rate

Written by Jerry Ratzlaff on . Posted in Fastener

The constant rate of force expelled by a compression spring per inch or millimeter of travel once a load or force is applied to push and compress the compression spring.

formula

\(k_s = \frac {Gd^4} {8D^{3N}} \)

Where:

\(k_s\) = spring constant

\(G\) = shear modulus of material

\(d\) = wire size (inches)

\(D\) = mean diameter (inches)

\(N\) = number of active coils

\(D/N\) = index correction

  •  \(G\) value for common spring materials
    • Copper = 6.5 x 10^6
    • Beryllium Copper = 6.9 x 10^6
    • Inconel = 11.5 x 10^6
    • Monel = 9.6 x 10^6
    • Music Wire = 11.5 x 10^6
    • Phospher Bronze = 5.9 x 10^6
    • Stainless Steel = 11.2 x 10^6