Choose tapping screws – a kind of screws to attach the modified material to the substrate without pre-drilling. Screws are different in many ways: type of socket screws Conical – Cone with notches – Crow – Loopback – Galetnaya – Hemispherical – Hex – Flat Types of screws Slots: – The cross – “Starlet” – slotted – Square – Hex (external, internal) Differences in the thread and turn the corner at the top of the profile with a few screws and thread pitch angle at the top of the profile of less than 45 degrees are used to fairly soft materials such as wood, particle board, drywall and more. For screwing the same screws in metal or concrete screws must be used with the frequent pitch thread and steep angle of inclination. Tip type – hot tip – tip – drill – tip – drill with wings from tip type depends on ease of screwing screw into the material.
Screw for screwing into the metal is better to use self-tapping with the tip-drill, the diameter of the rod. The protective coating can distinguish the type of screw cover screw the easiest way for its color. The black color screw means that it does not have the protective coating, and it is most exposed to the environment. Most often to create a protective layer of zinc coating is used. Safety properties of this coating depends on its thickness and application method. Another common protective covering – is oxidized.
Color screw coated with an oxide coating (depending on the mode of its application), dark gray to shiny black. Oxide coating with properties inferior to zinc. If you use screws with oxide coated to their coloration in all conditions. You can also find colored screws. More often all – it’s roofing screws for fixing roofing materials. Universal dimensions of screws screws have a range of lengths from 7mm to 300mm. Self Other lengths are specialized. Diameter screw diameter of the circle is determined by its projections thread. The most common range from 1.6 mm to 12mm. Source: Construction site Nizhny Novgorod.