What are the varieties and uses of self-tapping screws?

Self-tapping screws are mostly used for the connection between thin metal plates (steel plates, saw plates, etc.). When connecting, first make a threaded bottom hole for the connected piece, and then screw the self-tapping screw into the threaded bottom hole of the connected piece. Since the threaded surface of the self-tapping screw has high hardness (≥HRC45), the internal thread can be tapped in the threaded bottom hole of the connected part to form a connection.
Self-tapping pin screws are also mostly used for connection between thin metal plates. The thread is an ordinary thread with an arc-shaped triangular cross-section, and the thread surface also has high hardness. Therefore, when connecting, the screw can also tap an internal thread in the threaded bottom hole of the connected part to form a connection. This kind of screw is characterized by low screwing torque and high locking performance. It has better working performance than ordinary self-tapping screws and can be used instead of machine screws.
Wallboard self-tapping screws are used for the connection between gypsum wallboards, etc. and metal keels. The thread is a double-head thread, and the thread surface also has a high hardness (≥HRC53), which can be quickly screwed into the keel without making a prefabricated hole to form a connection.
The difference between self-drilling and self-tapping screws is that ordinary self-tapping screws must go through two processes of drilling (drilling the bottom hole of the thread) and tapping (including fastening the connection) when connecting; while self-drilling and self-tapping When the screws are connected, the two processes of drilling and tapping are combined and completed at one time. It first uses the drill bit in front of the screw to drill, and then uses the screw to tap (including the fastening connection), which saves construction time and improves construction efficiency.
Pan head and hexagon head tapping screws are suitable for occasions where the drill bit is allowed to be exposed. Hexagon head tapping screws can follow a larger torque than pan head tapping screws. Countersunk head and hexagon socket tapping screws are suitable for occasions where the nail head is not allowed to be exposed. Hexagon socket head tapping screws can bear a larger torque than countersunk head self-tapping screws; semi-recessed countersunk head tapping screws are suitable for slightly exposed nail heads. Occasions. When assembling and disassembling self-tapping screws, slotted self-tapping screws need flat-blade screwdrivers, cross-recessed self-tapping screws need cross-shaped screwdrivers, and internal hexagonal flower-shaped self-tapping screws need internal hexagonal flower-shaped wrenches. To tap the screws, a flat wrench, box wrench, socket wrench or adjustable wrench is required.