Design of Helical Springs
The design of a helical compression spring involves the following considerations:
a) Modes of loading – i.e., whether the spring is subjected to static or infrequently varying load or alternating load.
b) The force deflection characteristic requirement for the given application.
c) Is there any space restriction.
d) Required life for springs subjected to alternating loads.
e) Environmental conditions such as corrosive atmosphere and temperature.
f) Economy desired.
Considering these factors the designer select the material and specify the wire size, spring diameter, number of turns spring rate, type of ends, free length and the surface condition.
A helical compression spring, that is too long compared to the mean coil diameter, acts as a flexible column and may buckle at comparatively low axial force.
Springs which cannot be designed buckle- proof must be guided in a sleeve or over an arbor. This is undesirable because the friction between the spring and the guide may damage the spring in the long run.
It is therefore preferable, if possible, to divide the spring into buckle proof component springs separated by intermediate platens which are guided over a arbor or in a sleeve.