How does the screw distinguish between machine tooth and self-Tapping tooth?

Many friends because of work needs, will contact with many kinds of machine tooth screws and self-tapping tooth screws.
In the face of these two screws, from the appearance of the different, but also want to know more professional knowledge.
Only by further mastering the relevant knowledge can we use them more ideally at work.
So, let's briefly talk about the accurate and quick grasp of the common way to distinguish between the two screws.
The screw rod is a machine screw (mechanical screw), which is the flat head type at the front end. The screw pitch is small and uniform. It is generally used to fasten metal and machine parts.
From a professional point of view, mechanical teeth are also known as mechanical teeth, the size of the tooth.
The size of the gap and the bottom of the tooth, the tooth distance is relatively small, the standard Angle of tooth type is 60, and the thread is marked as M * / *.
When using machine tooth screws must be matched with the right nut or prefabricated inner wire lock, in a wide range of applications.
 In most cases, the use of special machinery can replace the manual to complete the machine tooth screw link between the relevant accessories.

The tooth front of the self-tapping tooth screw is very sharp, and the tooth bottom plane is wide, while the standard Angle of the tooth type is less than 60, and the thread is marked as ST * / *.
No nut or tapping when we need it.
Make the matching hole in advance, and tighten the hole directly with a screwdriver. In the process of rotation, the thread will be drilled inside the hole, so as to play the expected fastening role. From its name, we can also understand that it needs to be installed manually.
Finally, let's talk about the use scenario of these two screws, in the non-ferrous metal parts or non-metallic materials can freely use the self-tapping tooth screws, the stability is more ideal.
The application scope of the dental screw is not constrained, also mentioned above, belongs to a very flexible use of a screw.
In short, these two screws each have their own advantages and disadvantages, and they are highly used in all walks of life.