Narrow Standard Parts

Narrowly defined standard parts refer to standardized fasteners, which are actually a type of connecting piece (connection piece). However, due to the wide variety and extensive applications, they are generally considered a category in practical use, even abbreviated as standard parts. It typically includes the following 12 types of components:
1. Bolt: A type of fastener consisting of a head and a rod (a cylindrical body with external threads), which must be paired with a nut to fasten and connect two parts with through holes. This form of connection is called bolt connection. If the nut is unscrewed from the bolt, it can separate the two parts, so bolt connection is classified as a detachable connection.
2. Stud: A type of fastener that has no head and only has external threads at both ends. During connection, one end must be screwed into a part with an internal threaded hole, while the other end passes through a part with a through hole, and then a nut is screwed on, thus fastening the two parts into a single unit. This form of connection is called stud connection, which is also classified as a detachable connection. It is mainly used in situations where one of the connected parts is thick, requires a compact structure, or where frequent disassembly makes bolt connection unsuitable.
3. Screw: Also a type of fastener consisting of a head and a rod, which can be divided into three categories based on application: machine screws, set screws, and special-purpose screws. Machine screws are mainly used for fastening connections between a part with a set threaded hole and a part with a through hole, without the need for a nut (this form of connection is called screw connection, which is also a detachable connection; it can also be paired with a nut for fastening connections between two parts with through holes). Set screws are mainly used to fix the relative position between two parts. Special-purpose screws, such as lifting ring screws, are used for lifting components.
4. Nut: A fastener with an internal threaded hole, generally shaped like a flat hexagonal prism, but can also be flat square or flat cylindrical. It is paired with bolts, studs, or machine screws to fasten and connect two parts, making them a single unit.
5. Self-tapping screw: Similar to machine screws, but the threads on the rod are specially designed for self-tapping screws. It is used to fasten and connect two thin metal components, making them a single unit. A small hole needs to be pre-made in the components, and due to the high hardness of this screw, it can be directly screwed into the hole of the component, forming the corresponding internal thread. This form of connection is also classified as a detachable connection.
6. Wood screw: Also similar to machine screws, but the threads on the rod are specially designed for wood screws, allowing it to be directly screwed into wooden components (or parts) to fasten a metal (or non-metal) part with a through hole to a wooden component. This connection is also classified as a detachable connection.
7. Washer: A type of fastener shaped like a flat circular ring. It is placed between the supporting surface of a bolt, screw, or nut and the surface of the connected part, serving to increase the contact surface area of the connected parts, reduce unit area pressure, and protect the surface of the connected parts from damage; another type of elastic washer can also prevent the nut from loosening.
8. Retaining ring: Used in the grooves or holes of machines and equipment to prevent parts on the shaft or in the hole from moving laterally.
9. Pin: Mainly used for positioning parts, and some can also be used for connecting parts, fixing parts, transmitting power, or locking other fasteners.
10. Rivet: A type of fastener consisting of a head and a shank, used to fasten and connect two parts (or components) with through holes, making them a single unit. This form of connection is called rivet connection, abbreviated as riveting. It is classified as a non-detachable connection, as separating the two connected parts requires destroying the rivet on the parts.
11. Assembly and connection pair: An assembly refers to a type of fastener supplied in combination, such as a certain type of machine screw (or bolt, self-tapping screw) combined with flat washers (or spring washers, lock washers); a connection pair refers to a type of fastener supplied in combination, such as a special bolt, nut, and washer for high-strength large hexagon head bolt connection pairs used in steel structures.
12. Weld stud: A type of fastener consisting of a shank and a head (or no head), fixed to a part (or component) using welding methods, so that it can be connected to other parts.