What are the classifications of screw hardware ?

It generally refers to standard parts made of metal, which usually include the following 12 types of parts:

1. Bolts:

A type of fastener consisting of a head and a screw (a cylinder with an external thread), which needs to be matched with a nut to fasten and connect two parts with through holes. This form of connection is called a bolted 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:

There is no head, only a type of fastener with external threads on both ends. When connecting, one end of it must be screwed into the part with the internal threaded hole, the other end must pass through the part with the through hole, and then screw the nut, even if the two parts are tightly connected as a whole. This form of connection is called a stud connection, which is also a detachable connection. It is mainly used for occasions where one of the connected parts is thick, requires a compact structure, or is not suitable for bolt connection due to frequent disassembly.

3. Screws:

It is also a type of fastener composed of a head and a screw. It can be divided into three categories according to the purpose: machine screws, set screws and special purpose screws. Machine screws are mainly used for a fastened connection between a part with a fixed threaded hole and a part with a through hole, without nut matching (this connection form is called screw connection, which is also a detachable connection; it can also be Cooperate with the nut, it is used for the fast connection between two parts with through holes.) The set screw is mainly used to fix the relative position between the two parts. Special purpose screws, such as eyebolts, are used for hoisting parts.

4. Nut:

With internal threaded holes, the shape is generally flat hexagonal cylindrical shape, but also flat square cylindrical shape or flat cylindrical shape, with bolts, studs or machine screws, used to fasten and connect two parts, making them into one piece overall.

5. Self-tapping screws:

Similar to machine screws, but the thread on the screw is a special thread for self-tapping screws. It is used to fasten and connect two thin metal components to make them a whole. Small holes need to be made in advance on the components. Due to the high hardness of this kind of screw, it can be directly screwed into the hole of the component, so that the Form the corresponding internal thread. This form of connection is also a detachable connection.

6. Wood screws:

It is also similar to a machine screw, but the thread on the screw is a special thread for wood screws, which can be directly screwed into a wooden component (or part) to connect a metal (or non-metallic) part with a through hole to a wooden component. Tightly connected together. This connection is also a detachable connection.

7. Washers:

A class of fasteners in the shape of an oblate ring. It is placed between the supporting surface of the bolt, screw or nut and the surface of the connecting parts, which increases the contact surface area of the connected parts, reduces the pressure per unit area and protects the surface of the connected parts from damage; another type of elastic washer, It can also play a role in preventing the nut from loosening.

8. Retaining ring:

It is installed in the shaft groove or hole groove of the machine and equipment, and plays the role of preventing the parts on the shaft or the hole from moving left and right.

9. Pin:

It is mainly used for part positioning, and some can also be used to connect parts, fix parts, transmit power or lock other fasteners.

10. Rivets:

A type of fastener consisting of a head and a nail rod is used to fasten and connect two parts (or components) with through holes to make them a whole. This form of connection is called rivet connection, or riveting for short. It belongs to the non-detachable connection. Because to separate the two parts that are joined together, the rivets on the parts must be broken.

11. Assembly and connection pair:

Assembly refers to a type of fasteners supplied in combination, such as a combination of a certain machine screw (or bolt, self-supplied screw) and a flat washer (or a spring washer, a lock washer); the connecting pair refers to a special bolt, A class of fasteners supplied in combination with nuts and washers, such as high-strength hexagon head bolts for steel structures.

12. Welding nails:

A heterogeneous fastener composed of a nail rod and a nail head (or no nail head) is fixed and connected to a part (or component) by welding so as to be connected with other parts.

What is the reason for the rust of the screw?

1. When the electroplating factory is electroplating hardware screws, it is not dried, resulting in residual water vapor. Or condensation water is formed during packaging after drying. Lead to chemical reactions, resulting in undesirable occurrences, resulting in rust of hardware screws.

2. Long-term storage in a humid place, the hardware screws will be slowly corroded and oxidized, resulting in serious rust.

3. When electroplating hardware screws, the electroplating is poor, and the electroplating layer is too thin. cause rust. All in all, analyze the reasons from four aspects.

The four directions are:

1. Storage environment 2. Electroplating type 3. Preservation method 4. Use environment.

Improvement measures: In terms of storage environment: the hardware screws must be placed in a suitable environment, should not be too humid, should be ventilated, ventilated, and should not have too much moisture. There should be a bracket to hold the hardware screws away from the ground. In terms of electroplating types: electroplating colors with a longer salt spray test time should be selected. When electroplating, the electroplating should be done well, and the electroplating layer should not be too thin. The storage method is similar to the storage environment, and they should not be placed in a humid place. The use environment is similar. It cannot be placed in an environment with high salinity, acidity, high saltiness, high corrosion, high temperature and high humidity.