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Classification Of Fasteners

Dec. 26. 2019

1. Fasteners are a general term for a class of mechanical parts used when two or more parts (or components) are fastened together as a whole. Also called standard parts on the market.

2. It usually includes the following 12 types of parts:

Bolts, studs, screws, nuts, self-tapping screws, wood screws, washers, retaining rings, pins, rivets, assemblies, and joints.

2.1) Bolt: A type of fastener consisting of a head and a screw (a cylinder with external threads), which need to cooperate with a nut to fasten two parts with through holes. This type of connection is called a bolted connection. If the nut is screwed down through bolt, the two parts can be separated again, so the bolt connection is a detachable connection.

2.2) Stud: There is no head, only a type of fastener with external threads at both ends. When connecting, one end must be screwed into the part with the internal threaded hole, the other end must be passed through the part with the through hole, and then the nut is screwed on, even if the two parts are tightly connected as a whole. This type of connection is called a stud connection and is also a detachable connection. It is mainly used in the case where one of the connected parts has a large thickness, requires a compact structure, or is not suitable for bolting because of frequent disassembly.

2.3) Screw: It is also a type of fastener consisting of the head and the screw. It can be divided into three categories according to its purpose: machine screws, set screws and special-purpose screws. The machine screw is mainly used for a tight connection between a part with a screw hole and a part with a through hole, and does not require a nut. (This type of connection is called a screw connection, which is also a detachable connection; Cooperate with the nut for fastening connection between two parts with through holes.) Set screws are mainly used to fix the relative position between the two parts. Special purpose screws such as eyebolts are used for lifting parts.

2.4) Nut: Carbon steel flange nut with internally threaded holes, generally in the shape of a flat hexagonal column, but also a rectangular or cylindrical shape, with bolts, studs or machine screws , Used to fasten two parts together to make them a whole.

Carbon Steel Flange Nut

Carbon Steel Flange Nut

2.5) Self-tapping screws: Similar to machine screws, but the threads on the screw are special threads for self-tapping screws. It is used to fasten two thin metal members into one piece. Small holes must be made in advance on the member. Because this screw has high hardness, it can be screwed directly into the hole of the member to make the member Form the corresponding internal thread. This form of connection is also a detachable connection.

2.6) Wood screw: It is similar to machine screw, but the screw on the screw is a special hex head wood screw. It can be screwed directly into the wooden member (or part) and used to put a through hole Metal (or non-metal) parts are fastened to a wooden member. This connection is also a detachable connection.

Hex Head Wood Screw

Hex Head Wood Screw

2.7) Washer: A type of fastener with a flat circular ring shape. It is placed between the support surface of the bolt, screw or nut and the surface of the connected part, which plays the role of increasing the contact surface area of the connected part, reducing the unit area pressure and protecting the surface of the connected part from being damaged; another type of elastic washer, It can also play a role in preventing the nut from loosening.

2.8) Retaining ring: It is installed in the shaft groove or hole groove of the machine or equipment and plays a role of preventing the parts on the shaft or hole from moving left and right.

2.9) Pins: mainly used for positioning parts, and some are also used for parts connection, fixing parts, transmitting power or locking other fasteners.

2.10) Rivets: A class of fasteners consisting of a head and a nail rod, used to fasten two parts (or components) with through-holes into one piece. This type of connection is called rivet connection, or riveting for short. Is a non-detachable connection. Because the two parts connected together must be separated, the rivets on the parts must be destroyed.

2.11) Assembly and connection pair: Assembly refers to a type of fasteners supplied in combination, such as the combination of a certain type of machine screws (or bolts, self-supplied screws) and flat washers (or spring washers, lock washers); Vice refers to a class of fasteners that are supplied with a combination of certain special bolts, nuts and washers, such as steel structures with high-strength large hexagon head bolts connected to the vice.

2.12) Welding nail: Due to the heterogeneous fastener consisting of a polished rod and a nail head (or no nail head), it is fixedly connected to one part (or component) by welding in order to connect with other parts.