A clinch nut is a solid nut with a knurled or smooth shank or pilot projecting from one end. These shanks are inserted into preformed holes in sheet metal and spread, crimped, or rolled over, thus "clinching" them to the parent material. Clinch nuts provide multiple threads in materials too thin to be extruded or tapped.
Clinch nuts use various configurations of pilot holes including hex, D-shaped, round and rectangular. The nut shank must be soft enough to roll over or be clinched by a tool.