What Are Fasteners? What Are The Types Of Fasteners

1、 What are fasteners

Fastener is the general name of a kind of mechanical parts used to fasten two or more parts (or components) into a whole. Fasteners are widely used in various industries, including energy, electronics, electrical appliances, machinery, chemical industry, metallurgy, mold, hydraulic and so on. In various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemical industry, instruments and supplies, you can see all kinds of fasteners. They are the most widely used mechanical basic parts. It is characterized by a wide variety of specifications, different performance and uses, and a high degree of standardization, serialization and generalization. Therefore, some people refer to a kind of fasteners with national standards as standard fasteners, or referred to as standard parts for short.

2、 What kinds of fasteners are included

Fasteners generally include the following 12 types of parts:

1. Bolt: a kind of fastener composed of head and screw (cylinder with external thread), which is used to connect two parts with through hole. This kind of connection is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.

2. Stud: a kind of fastener without head and with external thread at both ends. When connecting, one end must be screwed into the part with internal thread hole, and the other end must go through the part with through hole, and then screw on the nut, even if the two parts are tightly connected as a whole. This type of connection is called stud connection, which also belongs to detachable connection. It is mainly used in the occasions where one of the connected parts is thick and requires compact structure, or where bolt connection is not suitable due to frequent disassembly.

3. Screw: it is also a kind of fastener composed of head and screw. It can be divided into three categories according to its application: machine screw, set screw and special purpose screw. The machine screw is mainly used for the fastening connection between a part with a fixed threaded hole and a part with a through hole, which does not need nut matching (this connection form is called screw connection, which also belongs to detachable connection; It can also be used with nuts for fastening between two parts with through holes.) Set screw is mainly used to fix the relative position between two parts. Special purpose screws such as eyebolts are used for lifting parts.

4. Nut: with internal thread hole, the shape is generally shown as flat hexagonal column, or flat square column or flat cylindrical, with bolts, studs or machine screws, used to fasten and connect two parts, making it a whole.

5. Self tapping screw: similar to machine screw, but the screw thread is special for self tapping screw. It is used for fastening and connecting two thin metal components to make them into a whole. Small holes need to be made on the component in advance. Because of its high hardness, the screw can be directly screwed into the hole of the component to form a responsive internal thread in the component.

6. Wood screw: it is also similar to machine screw, but the screw thread on the screw is a special wood screw thread, which can be directly screwed into the wood component (or part), used to connect a metal (or non-metal) part with a through hole with a wood component. This kind of connection is also detachable.

7. Washer: a kind of fastener with flat circular shape. It is placed between the supporting surface of bolt, screw or nut and the surface of connecting parts, which can increase the contact surface area of connected parts, reduce the pressure per unit area and protect the surface of connected parts from damage; Another kind of elastic washer can also prevent the nut from loosening.

8. Retaining ring: it is installed in the shaft groove or shaft hole groove of machine and equipment, and plays the role of preventing the parts on the shaft or hole from moving left and right.

9. Pin: it is mainly used for positioning parts, some can also be used for connecting parts, fixing parts, transferring power or locking fasteners.

10. Rivet: a kind of fastener composed of head and nail rod, which is used to fasten and connect two parts (or components) with holes to make them a whole. This kind of connection is called rivet connection. It is a non detachable link. Because if the two parts connected together are separated, the rivets on the parts must be broken.

11. Assembly and connection pair: assembly is a kind of fastener supplied by combination, such as the combination of machine screw (or bolt, self supplied screw) and flat washer (or spring washer, lock washer); Connection pair refers to a kind of fastener that combines some special bolts, nuts and washers, such as high-strength large hexagon head bolt connection pair for steel structure.

12. Welding nail: heterogeneous fastener composed of nail rod and nail head (or no nail head), which connects other parts (or components) by welding, so as to connect with other parts.