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Characteristics of self tapping screws


Self tapping screws, also known as quick tooth screws, are steel quick fit fasteners that have been galvanized and passivated on the surface. Self tapping screws are commonly used for connecting thin metal plates (steel plates, saw plates, etc.). When connecting, first make a threaded bottom hole for the connected part, and then screw the self tapping screw into the threaded bottom hole of the connected part.

Although there are many types of self tapping screws, they all have the following common features:

(1) Generally, it is made of carburized steel (accounting for 99% of the total production). It can also be made of stainless steel or non-ferrous metals.

(2) The product must undergo heat treatment. Carbon steel self tapping screws must undergo carburization treatment, while stainless steel self tapping screws must undergo solution hardening treatment. To achieve the mechanical and service performance required by the standard for self tapping screws.

(3) The product has high surface hardness and good core toughness. That is, 'internal softness and external hardness'. This is a major feature of the performance requirements for self tapping screws. If the surface hardness is low, it cannot be screwed into the substrate; If the toughness of the core is poor, it will break once twisted and cannot be used. So "internal flexible external steel" is a very important requirement for self tapping screws to meet their performance requirements.

(4) The surface of the product requires surface protection treatment, usually electroplating treatment. Some products require phosphate treatment (phosphating) on the surface, such as wall panel self tapping screws that are mostly phosphating.

(5) Produced using cold heading technology. It is recommended to use high-speed cold heading machines, high-speed wire rolling machines, or high-speed planetary wire rolling machines for production. The emphasis on high-speed here is to ensure product quality. Only self tapping screws produced by high-speed machines have good head formation and high thread quality.