Threaded fasteners are mechanical parts with internal or external threads. They are generally used as fasteners to facilitate the assembly of multiple components. The most common threaded fasteners are screws, nuts and bolts. However, there are other threaded fasteners, such as cage nuts, threaded inserts, threaded rods, etc.
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| Types of | Features and applications |
| Bolted | Used to connect two thinner parts. A through hole is opened in the connected member. There is a gap between the rod and the hole of the ordinary bolt, the processing requirements of the through hole are low, the structure is simple, the assembly and disassembly is convenient, and the application is wide. Hinge hole bolts (GB / T 27) often use transitional fits such as H7 / m6, H7 / n6. This connection can accurately fix the relative position of the connected parts. It is suitable for bearing lateral load, but the machining accuracy of the hole is high. Drilling and reaming are often used. |
| Stud bolt connection | It is used in the case where one of the connected parts is thicker and is not suitable for bolting. The thicker connected parts have lower strength and need to be disassembled frequently. Threaded holes are machined on thick parts, light holes are machined on thin parts, bolts are screwed into the threaded holes, and the thin parts are pressed with nuts. When removing, you only need to unscrew the nuts without removing the studs. Prevents damage to threaded holes in large parts |
| Screw connection | The bolt (or screw) is directly screwed into the threaded hole of the connected component without a nut. The structure is simpler and more compact than stud bolts. For one of the two connected parts that is thicker, but does not need to be dismantled frequently to avoid damage to the threaded hole |
| Set screw connection | Use the threaded end screwed into the threaded hole of the part to bear against the surface of the other part or into the recess on the other part to fix the relative position of the two parts. This connection method has a simple structure, and some can change the position of the part in the circumferential or axial direction for adjustment, such as the fixing of an electrical switch knob |
| Countersunk head screws | It is used for occasions where the strength is not high and the thread diameter is less than 10mm. The head or part of the screw sinks into the connected part. This structure is mostly used in situations that require a flat outer surface, such as an instrument panel |
| Self-tapping screws | It is used for occasions where the connection strength is not high. But generally, the bottom hole should be made in advance. If self-drilling and self-tapping screws with a drill part are used, no need to prefabricate the bottom hole, used for non-ferrous metals, wood |
| Wood screw connection | Generally used for the connection of wooden structures. Depending on the hardness of the material and the length of the wood screws, the wooden parts may not be prefabricated or a certain size and depth of prefabricated holes may be made. |
| Self-tapping locking screw connection | The thread is an arc-shaped triangular interface. The screw is hardened on the surface and can be screwed into a pre-made hole of a metal material to be extruded to form an internal thread. The internal thread formed by extrusion improves the strength by more than 30% than that of cutting. The small tensile strength of the screw is 800 MPa. Self-tapping locking screws have low tightening torque and high locking performance, and have been widely used in household appliances, electrical and automotive industries |
| Fastener-assembly connection | The washers and external thread fasteners are produced and assembled by a standard factory. China issued 23 production standards for fastener assemblies in 1988. This connector is easy to use, saves time, and is safe and reliable. It is often used in places where fasteners are used to connect tightly, such as terminal blocks in electrical cabinets. |
