Compressions Springs are open-coil helical springs wound or constructed to oppose compression along the axis of wind. Helical Compression Springs are the most common metal spring configuration.
Generally, these coil compression springs are either placed over a rod or fitted inside a hole. When you put a load on a compression coil spring, making it shorter, it pushes back against the load and tries to get back to its original length.
The most common compression spring, the straight metal coil spring, has the same diameter for the entire length. Other configuration options for compression springs include concave, and convex types.
Ground ends provide flat planes and stability. Squareness influences how the axis force produced by the spring can be transferred to adjacent parts. Although open ends may be suitable in some applications, closed ends afford a greater degree of squareness.