What are the characteristics of self-tapping screws?

The main difference between the thread parameters of self-tapping screws and machine screws is that the pitch is large, the height of the thread is high, and the shape of the end is favorable for screwing. However, if the ordinary machine screw is screwed into a low-strength material such as plastic, the thread will break, which is not suitable.
Some new self-tapping screws have also been further improved in terms of tooth shape angle, number of thread heads, screw shape, etc., so that self-tapping screws can better adapt to the characteristics of thread "self-tapping" and have better mechanical connection performance.
Compared with the connection using metal insert, the self-tapping screw connection saves the metal insert, which not only reduces the cost, but also simplifies the mold structure, greatly improving the production efficiency and cost during injection.
Self-tapping screw connections are a suitable choice for occasions where the connection strength is average and less disassembly is required, such as mobile phones, TVs, DVDs, small appliances, and other products.
The self-tapping screw connection is a detachable connection. Experiments have shown that correct assembly and disassembly can be repeated dozens of times, and still ensure good connection strength. However, the best use of self-tapping screw connections is not to disassemble or to disassemble less. In the case of mass assembly, it is particularly important to consider the inconsistency of assembly.
Compared with the clamping, the self-tapping screw connection does not have assembly gaps (there is a loose phenomenon), and the bonding (glue) does not have air pollution unlike the latter. Compared with the ultrasonic welding, the latter assembly The equipment is more expensive.
For plastic connections that require high strength, self-tapping screw connections can provide less strength than connections made of metal inserts and machine screws. Self-tapping screw connections should not be used.
The self-tapping screws have a small diameter distance. This is to use a larger one when sliding teeth, to avoid the phenomenon of scrapping parts due to the sliding of one pillar.