The head of the self-tapping screw is pointed and can be used normally without drilling. Widely used in doors and windows and iron sheet.

So do you know what are the forms of self-tapping screws? Let’s take a look at the thread types of self-tapping screws together.

The thread forming of self-tapping screws has A, AB, B, BP, C and other types. At present, it has gradually been replaced by thread rolling, so it is not recommended to use in new designs.

The differences between AB, B, and BP are only in the shape of the tail. AB has a threaded tapered tail, B has a blunt tail, and BP has a threaded tapered tail.

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The center of the pointed tail enters the pre-drilled hole and begins to form the thread.

Thread cutting has BF, BP, D, F, G, T and other forms, BF, BP are wide threads, the rest are mechanical threads.

The difference between the recognition characters is the cutting tail. Each type of cutting tail has a shape that can collect the scrap under cutting.

If a self-tapping screw is screwed into a blind hole (a hole that does not penetrate), its fragments will remain and seal at the bottom of the hole.

However, when tapping into a through hole, The waste will fall on the other side of the workpiece.

Therefore, you must consider this when choosing this type. The waste may cause pollution, fall into running parts or make the electronic substrate inoperable.

Standard recognition characters, including symbols representing the shape of lines and tails.

One or two characters of a self-tapping screw represent a thread, representing a mechanical or wide thread. For example, the character “B” is a wide threaded screw.

Those without “B” are mechanical lines. The characters at the end are used to distinguish self-tapping screws, such as thread forming, cutting, rolling or self-drilling.

Mechanical thread：

The thread angle and pitch of the mechanical thread are the same as the 60-degree thread and the British-American unified thread.

If the screw is lost or needs a screw after removal, standard threaded fasteners can be used.

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Wide thread：

The pitch angle of a wide thread is 60 degrees, but the pitch is wider, and because the pitch is wider, the thread is steeper and the thread lead is larger than that of the mechanical thread.

There is another type of thread dedicated to plastic. Its thread angle is 48 degrees, and it is usually called a PT screw.

Type of self-tapping thread:

There are two types of self-tapping screws for cutting wide threads BSD and mechanical threads CSD. There are also special thread types, including high and low double threads, and various tapping tails are also applicable.

Due to the nature of tapping tails and threads, tail drilling screws are not suitable For blind hole operations.

When assembling self-drilling screws, the drill tail must completely penetrate the workpiece before cutting or forming the thread.