Glossary

Axial retention is the ability of a part—such as a fastener, bearing, or insert—to resist forces that try to push or pull it along its central axis. In other words, it measures how well the component stays fixed in place in the direction of its length, even when subjected to tensile (pulling) or compressive (pushing) loads.

To understand it simply: imagine trying to pull a pressed-in nut, stud, or bearing straight out of the material it’s installed in. The force required to do that represents its axial retention strength. A component with high axial retention will stay firmly in place, while one with poor retention may loosen, shift, or fall out under load or vibration.

In mechanical fastening, axial retention is critical for parts like self-clinching nuts, rivets, inserts, and bearings that are installed into thin sheet metal, castings, or plastic. These components typically rely on mechanical interlocking, friction, or adhesive bonding to achieve retention. For example, a self-clinching nut achieves axial retention when the surrounding sheet metal cold-flows into an undercut groove around the nut’s body during installation. This interlock physically prevents the nut from being pulled back out along its axis.

Axial retention is distinct from torque resistance, which refers to a fastener’s ability to resist rotation. The two often work together: torque resistance prevents spinning, while axial retention prevents pull-out. Engineers quantify axial retention using pull-out or push-out tests, where a controlled force is applied to determine the load at which the fastener or component dislodges.