It is necessary to check that relatively long compression springs are not are risk of buckling.  If buckling is a problem it is necessary to incorporate some method of guiding the spring by placing it in a hole or on a suitable rod.

A longitudinal spring which is subject to rapid cycling may be at risk of surging.  This is when the pulses of compression surge along the spring and back.  This could continue and magnify if the natural material frequency of the spring is near the frequency of repeated loading.

Just as a column will buckle when the load becomes too large a long compression spring may buckle when the deflection exceeds a certain value.   The critical deflection is given by the following equation.

Table showing α for different end conditions

Absolute stability occurs when C'₂ /λ_eff² is greater than unity. The condition for absolute stability is therefore.

For more detailed notes refer to Surging of Springs

The equation for the lowest natural frequency of a compression spring located between two flat plates is..

Forcing frequencies near the above lowest natural frequency and at whole multiples (2,4,6...) of this frequency.