Spring Index

Written by Jerry Ratzlaff on . Posted in Fastener

spring compression 6Spring index, abbreviated as C, is the ratio between the spring and wire diameter for a helical spring.  This number tells how tight the springs coils are.  All wire sizes have a limit to the coil diameter being formed, too small there can be damage to the material.  A higher spring index has a smaller wire and a larger spring diameter.  A lower spring index has a larger wire and a smaller spring diameter.


Spring Index formulas

\(\large{ C = \frac{ D }{ d }  }\)   
\(\large{ C = \frac{ 2 \; r }{ d }  }\)  


\(\large{ C }\) = spring index

\(\large{ D }\) = spring diameter

\(\large{ r }\) = spring radius

\(\large{ d }\) = wire diameter


Tags: Equations for Spring