(2) Stud: A type of fastener that does not have a head and only has external threads on both ends. When connecting, one end must be screwed into the part with an internal threaded hole, and the other end must pass through the part with a through-hole, and then a nut must be screwed on, even if these two parts are tightly connected as a whole. This type of connection is called a bolted connection and is also a detachable connection. Mainly used in situations where one of the connected parts has a large thickness, requires a compact structure, or is not suitable for bolt connection due to frequent disassembly.

As shown in the following figure:

(3) Screw: It is also a type of fastener consisting of a head and a screw. It can be divided into three categories according to its purpose: steel structure screws, set screws, and special-purpose screws. Machine screws are mainly used for fastening connections between a part with a threaded hole and a part with a through-hole, without the need for nut fitting (this type of connection is called a screw connection, which is also a detachable connection; it can also be used in conjunction with a nut for fastening connections between two parts with through-hole). Tightening screws are mainly used to fix the relative position between two parts. Special purpose screws such as lifting ring screws are used for lifting parts.

As shown in the following figure:

(4) Nut: with internal threaded holes, generally in the shape of a flat hexagonal column, but also in the shape of a flat square column or a flat cylindrical shape, used in conjunction with bolts, screws or steel structural screws to fasten and connect two parts into a whole.

As shown in the following figure:

(5) Self tapping screw: Similar to a screw, but the thread on the screw is a specialized thread for self tapping screws. Used to fasten and connect two thin metal components into a single unit, small holes need to be pre made on the components. Due to the high hardness of these screws, they can be directly screwed into the holes of the components to form corresponding internal threads. This type of connection is also a detachable connection.

As shown in the following figure: