Captive Nut

There are two basic styles of captive nuts. A type of nut, clamp nut or clamp nut, is a traditional type of nut that is fixed by a metal plate bracket clamped on the part to be connected. These are usually used to connect screws to sheet metal parts that are too thin to thread, and they can usually be connected, removed, and reused using simple manual tools.
The second type of external nut is a threaded insert. They are either pressed into holes in the material to be connected, or molded into them. In any case, a portion of the insert is usually knurled to effectively grasp the material supporting the insert. A variant, swaged nut, has a knurled part that can be swaged on the side of the soft metal hole to grip the nut more tightly. Press fit and swage fixed nuts are used for panels that are too thin to thread or soft materials that are too weak to thread. They are installed by pressing in with a hand press.