broadly defined, a self-clinching fastener is any device, usually threaded, that, when pressed into ductile metal, displaces the host material around the mounting hole, causing it to cold flow into a specially designed annular recess in the shank or pilot of the fastener. A serrated clinching ring, knurl, ribs, or hex head prevents the fastener from rotating in the host material once it has been properly inserted Thus, self-clinching fasteners become a permanent part of the panel, chassis, bracket, or other item into which they are installed.
They also have greater reliability and more holding power than extruded/tapped or stamped threads. They are used chiefly where good pullout and torque loads are required in sheet metal that is too thin to provide secure fastening by any other method. Even if the sheet is thick enough to sustain tapping, it may actually be more economical to use self-clinching fasteners with gaugeable threads. They can be installed during fabrication to eliminate loose hardware during final assembly . In fact, the use of self-clinching fasteners often will allow the use of a thinner sheet. Because of their compact design and low profile, they provide for a neat appearance, too.
As a rule, a self-clinching fastener should be specified whenever a component must be readily replaced and where "loose" nuts and hardware won't be accessible. If it appears that the attaching "nuts" and "screws" can't be reached after a chassis or cabinet is assembled, self-clinching fasteners can be installed during metal fabrication and can simplify and expedite component mounting and assembly operations, including those performed in the field.