This type of fasteners, like screws, is used almost everywhere. It is even difficult to imagine how they could be replaced if necessary. Strong and sharp threads allow fasteners to be screwed quite easily into the surface of a material of various types and thicknesses. A screw is nothing more than a rod with a structural element and an external thread, in most cases it is used to connect various metal structures. All parts of this type are divided into mounting and installation, depending on the method of application.
Self-tapping screws are widely used, they are used in many industries, but these fasteners are most in demand in mechanical engineering. High build quality, low time costs, ease of use increase the demand for screws. They can be screwed into any, even hard-to-reach place, the use of a nut is optional. In addition, there is absolutely no need to make a hole, directly during assembly, it is formed independently.
In most cases the screw is self-tappingused to connect structures made of materials such as mild steel, aluminum and copper alloys, plastic. Based on the name, you should not think that the screw is able to cut the material that it connects. It can only cause plastic deformation by pressing into metal or plastic.
Standards GOST 1478-93 and GOST 2702-93 regulate the quality of products and production technology. Specifications for galvanized self-tapping screws with countersunk and semi- countersunk heads are in general terms. Phillips spherical head screws are also available. The self-tapping screw has quite a few types, in addition to those listed, they are also found with a shaped head, flange, star drive. True, the last three screws are not used in the Russian Federation, because there are no standards for them. Although in terms of build quality, they are much more progressive than standard screws.
Self-tapping screw belonging to one of the new types cannot be used in Russian production. The reason lies in the discrepancy between the thread sizes. The fact is that screw-shaped fasteners with a star-shaped drive, a shaped head and a flange, although they are more advanced than domestic ones, they have a completely different thread. In addition, they do not at all comply with the three standards currently in force that regulate product quality and production technology. The design and size of the screws also do not meet Russian standards.
International standard ISO 1478-2005 has already acquired a new form, involving the production and use of screws with a rounded end. Perhaps soon such a self-tapping screw will appear in Russia, and the relevant standards will also be adopted. It has long been planned to update all Russian standards in order to comply with international standards.
When choosing screws, it is necessary to build on the material of the structure to be fastened, its thickness, as well as the required hole depth. Depending on the type of coating, all self-tapping screws are divided into galvanized, galvanized and black.
