Self-tapping screw, also known as "self-tapping screw", is one of the most popular types of construction fasteners, which is used on large-scale construction sites, in production, and in home repairs.
Despite the fact that there is the concept of a "universal" self-tapping screw, in any situation it is advisable to take exactly the hardware that is ready to fully cope with the tasks assigned to it, taking into account specific operational nuances. Self-tapping screws differ according to the following criteria:
- length and thickness
- material and form
–Appointment
Almost all fasteners of this class are produced with corrosion protection, either by galvanizing (yellow hardware) or phosphating and oxidation (black hardware).
Material is the key difference
If you do not take into account the dimensional differences, the main parameter of a self-tapping screw is its purpose, then for what material and in what cases it is ideal.
Wood. Fasteners for wood (or plastic) have their own "chips". Usually this is a countersunk head, which allows you to visually hide a self-tapping screw, as well as a relatively rare thread, due to the qualities of the products being fastened. If the thread is frequent, then the material in the place of drilling is more likely to splinter.
The yellow wood screws are suitable for fastening with a pre-drilled hole, and the black ones for fastening without drilling.
Metal. As well as "wooden" screws, fasteners for metal either require preliminary drilling of a hole (products with a partial thread pitch), or they can drill the material themselves (self-tapping drills with a press washer).
For metal profiles. Self-tapping screws for fastening metal profiles to each other and to metal bases are also called "bugs" or "seeds". They are small in size, can be with or without a drill, with a semi-cylindrical head.
For concrete. Self-tapping screws for fastening wood and metal products to a concrete or brick base are also called pins. They can be with different heads and different lengths, and they are distinguished from other hardware by an uneven thread along the entire length.
Specialized self-tapping screws. There are also more specialized fasteners. For example, self-tapping screws for roofing work (with a drill and a rubber gasket), self-tapping screws for sandwich panels (they drill through metal up to 14 mm thick), self-tapping screws for PVC profiles, furniture fasteners (for a hexagon), strong self-tapping screws.
Universal self-tapping screws are a kind of "golden" mean, which will relatively reliably contain the elements. They can be from 12 to 220 mm in length, from 3 to 6 mm in diameter, the thread frequency is medium. They are not suitable where specialized hardware is needed.
Important! The type, length and number of self-tapping screws are selected, including based on the load indicators for one fastener. For the calculation, special tables are used.
Why a self-tapping screw and not a screw?
On the "body" of a self-tapping screw, that is, on its cylindrical part, there are much more threads than on a screw - it covers either the entire length of the product or most of it. The "nose" of a self-tapping screw, as a rule, is sharper than that of a screw, but it is made from a harder steel.
The right tool
Please note that different types of fasteners require their own tools. Firstly, suitable for the head ("cross", hex, funnel-shaped under the hex key). Secondly, with the limitation of the force in some cases, so as not to deform the fasteners. Third, for pre-drilling when needed.
