What are the applications and characteristics of self-tapping screws?


Locking self-tapping screws are used for non-metal or s […]

Locking self-tapping screws are used for non-metal or soft metals, without drilling and tapping; locking self-tapping screws are pointed, so that they can be "locked and self-tapping"; ordinary screws are flat-headed and thick Consistent. Tightening the self-tapping screw means: the drilled hole is a hole that does not need to be tapped. The screw used is different from the general ones. The tip is pointed and the pitch is relatively large. It is a bit like a chipless tap, and it can be directly tapped Screw in, metal and plastic usually use this method. It can "tap-drill, squeeze, and press" the consolidated body into corresponding threads on the material to be consolidated by its own threads, so that they can be closely matched with each other.
Although there are many types of self-tapping screws, they all have the following main characteristics:
(1) Generally, they are made of carburized steel (accounting for 99% of the total products). It can also be made of stainless steel or non-ferrous metals.
(2) The product must undergo heat treatment. Carbon steel self-tapping locking screws must be carburized, and stainless steel self-tapping locking screws must be solid solution hardened. In order to make the self-tapping lock screw meet the mechanical performance and use performance required by the standard.
(3) The product has high surface hardness and good core toughness. That is "soft inside and rigid outside." This is a major feature of the performance requirements of self-tapping locking screws. If the surface hardness is low, it cannot be screwed into the matrix; if the core has poor toughness, it will break once screwed and cannot be used. Therefore, "flexible inside and rigid outside" are self-tapping locking screws that meet the performance requirements.
(4) The surface of the product needs surface protection treatment, generally electroplating treatment. Some products require phosphate treatment (phosphating) on ​​the surface. For example, self-tapping locking screws for wall panels are mostly phosphated.
(5) Produced by cold heading process. It is recommended to use high-speed cold heading machine and high-speed thread rolling machine or high-speed planetary thread rolling machine to ensure product quality. The head of the self-tapping locking screw produced in this way is well formed and the thread quality is high.
Therefore, all self-tapping locking screws generally have the above-mentioned main features.