This type of fastener, such as screws, is used almost universally. It’s even hard to imagine how they could be replaced if necessary. Strong and sharp thread allows fasteners to easily screw into the surface of the 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 kind are divided into mounting and installation, depending on the method of application.
Self-tapping screws have a fairly wide application, they are used in many industries, but most of these fasteners are in demand in mechanical engineering. High build quality, low time, ease of use increase the demand for screws. They can be screwed into any, even inaccessible place, the use of a nut is optional. In addition, there is absolutely no need to make a hole, directly during assembly it forms independently.
In most cases, a self-tapping screw is used to connect structures made of materials such as low carbon steel,
aluminum and copper
alloys, and 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 it into a metal or plastic.
GOST 1478-93 and GOST 2702-93 standards regulate the quality of products and production technology. Technical specifications for galvanized self-tapping screws with countersunk and half-countersunk heads are in general form. Cross-head screws with a cylindrical head are also available. The self-tapping screw has quite a few types, besides the ones 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 they have no standards. Although speaking of build quality, they are much more advanced than standard screws.
A self-tapping screw belonging to one of the new types cannot be used in Russian production. The reason lies in the mismatch of thread sizes. The fact is that screw-shaped fasteners with a star-shaped drive, a shaped head and a flange, although more advanced than domestic ones, but they have a completely different thread. In addition, they completely do not meet the currently applicable three standards that regulate product quality and production technology. The design and size of the screws also do not meet Russian standards.
The international standard ISO 1478-2005 has already acquired a new form, involving the production and use of screws with a rounded end. Perhaps in the near future such a self-tapping screw will appear in Russia, as well as appropriate standards will 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, galvanic and black.