Spring Index

on . Posted in Fastener

spring compression 6Spring index, abbreviated as C, a dimensionless number, 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 formula

\( C =  D \;/\; d \)     (Spring Index)

\( D =  C \; d  \)

\( d =  D \;/\; C \)

Symbol English Metric
\( C \) = spring index \( dimensionless \)  
\( D \) = spring diameter \( in \) \( mm \)
\( d \) = wire diameter \( in \) \( mm \)

 

Spring Index formula

\( C =  2 \; r \;/\; d \)     (Spring Index)

\( r =  C \; d \;/\; 2 \)

\( d =  2 \; r \;/\; C \)

Symbol English Metric
\( C \) = spring index \( dimensionless \)  
\( r \) = spring radius \( in \) \( mm \)
\( d \) = wire diameter \( in \) \( mm \)

 

P D Logo 1 

Tags: Spring