Self-drilling metal screws are usually classified as self-tapping screws. They are also self-tapping screws. The tail is different from ordinary screws. It is not a pointed tail, but like a drill.

This tail can be drilled by itself, and the tail of the self-drilling screw is drilled. Holes or pointed ends do not require auxiliary treatment. It can be drilled, tapped and locked directly on the fixed and basic materials, which greatly saves construction time.

Compared with ordinary screws, it has higher toughness and fixing power, and the combined length will not relax after a long time, and it is easy to punch and tap with one key.

They are called self-drilling metal screws or self-drilling metal screws in daily life. Most of the materials used are carbon steel. At present, there are not many manufacturers of self-drilling nails on the market, and the quality is better.

• 

• 

Choose the yuan produced by Shanghai Hangtou Standard Parts Factory. Leng brand is better, quality packaging and price are more economical in all aspects.

People have done statistics: among the ten items that constitute the total assembly cost, the highest includes the processing of holes. In actual applications, self-tapping screws need to be processed for prefabricated holes.

And in order to make the prefabricated holes perform well in practical applications As a result, the size of these holes must be controlled within a fairly strict range. In the early 1960s, self-drilling and self-tapping screws appeared.

Since there is no need to process pre-made holes, it is a big step forward to reduce assembly costs. In a nutshell, self-drilling and self-tapping screws realize one operation of drilling, tapping and tightening.

Classification

The classification of self-drilling metal screws is relatively simple. Mainly divided by the head type, there are: cross recessed countersunk head self-drilling nails, cross recessed pan head self-drilling screws, slotted pan head self-drilling nails, slotted countersunk head drill tailing screws .

Eleven-character compound grooved pan-head self-drilling nails, cross wafer head self-drilling nails, hexagonal head washer-faced self-drilling nails, hexagonal slotted full-faced self-drilling nails, etc.

Standard

Self-drilling metal screws are the same as other types of screws, and there are standard points, but the most commonly used are the German standard and the American standard. Models are: DIN7504K, DIN7504P, DIN7504N, etc.

Features

Although there are many types of self-drilling metal screws, they all have the following common points:
(1) Generally, it is made of carburized steel (accounting for 99% of total output). It can also be made of stainless steel or non-ferrous metals.

(2) The product must undergo heat treatment. Carbon steel tapping screws must be carburized, and stainless steel tapping screws must be solid solution hardened. In order to make the self-tapping screw meet the mechanical properties 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 self-tapping screws performance requirements.

If the surface hardness is low, it cannot be screwed into the matrix; if the core toughness is poor, it will break when screwed and cannot be used. Therefore, the “inner flexible outer steel” is a very important requirement for self-tapping screws to meet the performance.

(4) The surface of the product needs surface protection treatment, generally electroplating treatment. The surface of some products must be phosphated (phosphated), such as wallboard self-tapping screws are mostly phosphated.

(5) It is produced by cold heading process. It is recommended to use high-speed cold heading machine, high-speed thread rolling machine or high-speed planetary thread rolling machine.

High speed is emphasized here to ensure product quality. Only the heads of self-tapping screws produced by high-speed machines are well formed and the thread quality is high.