Hydraulics & Pneumatics

For design and manufacturing engineers involved in buying or specifying fluid power components and systems.

Laser Focus World

Semiconductors, medical equipment, lasers, optics and aviation and aerospace.

CNC Machining Design Guide

Optimize your designs, reduce machining time, and lower your costs.

Design-2-Part

How OEM's can make their parts better, faster, and more efficient.

more free magazines
Compression spring bucking refers to when the spring deforms in a non-axial direction, as shown here,

Buckling is a very dangerous condition as the spring can no longer provide the intended force. Once buckling starts, the off-axis deformation typically continues rapidly until the spring fails. As a result, it is important to design compression springs such that their likeliness to buckle is minimized.

Buckling of compression springs is similar to buckling for vertical structural columns. When the free height of the spring (Lfree) is more than 4~5 times the nominal coil diameter D, the spring can buckle under a sufficiently heavy load.

The maximum allowable spring deflection Dmax that avoids buckling depends on the free length, the coil diameter, and the spring ends (pivot ball, ground & squared, etc.).

Buckling Thresholds
One quick method for checking for buckling is to compute the deflection to free height ratio (D/Lfree) and use the following chart to check if the ratio exceeds the maximum allowable value: