Tapping screw

Self-tapping screw is a kind of screw with a drill bit, through the construction of special electric tools, drilling, tapping, fixing and locking in one time. Self-tapping screw is mainly used for the connection and fixation of some thin plates, such as the connection between color steel plate and color steel plate, color steel plate and purlin, wall beam connection, etc., its penetration capacity is generally not more than 6mm, the maximum is not more than 12mm.

Self tapping screws are often exposed to the outside world and have strong corrosion resistance. Its rubber sealing ring can ensure that the screw is impermeable and has good corrosion resistance. Tapping screws are usually described by three parameters: screw diameter series, number of threads per inch length, and screw length. There are two types of screw diameter series: level 10 and level 12, whose corresponding screw diameters are 4.87mm and 5.43mm respectively. There are 14, 16 and 24 levels of threads per inch length. The more threads per inch length, the better self-drilling capability.

Product differences: tapping screw hardness high, thread spacing wide, deep thread, surface is not smooth, wood screw on the contrary, another difference is more obvious, wood screw back segment without thread. Wood screw threads are fine, obtuse and soft. Self tapping screw threads are thick, sharp and hard.

Although there are many types of tapping screws, they all have the following main characteristics :(1) they are generally made of carburized steel (99% of the total product). It can also be made of stainless steel or non-ferrous metals. (2) products must undergo heat treatment. Carbon steel self tapping screw must be carburized, stainless steel self tapping screw must be solid solution hardening treatment. In order to make self-tapping screw meet the standard requirements of mechanical properties and performance. (3) high surface hardness and good core toughness. Soft inside and tough outside. This is the self tapping screw performance requirements of a major feature. Such as low surface hardness, screw into the matrix; Such as the core toughness, a twist on the broken, can not be used. So "soft inside and tough outside" is self-tapping screw to meet the requirements of performance. (4) all surfaces of products need surface protection treatment, usually electroplating treatment. Some surfaces need phosphate treatment (phosphating). Such as: wall since tapping screws for phosphating. (5) production by cold heading process. High speed cold heading machine, high speed thread rolling machine or high speed planetary thread rolling machine are recommended to ensure product quality. The head of the tapping screw produced in this way is well formed and the thread quality is high.