What is a self - cutting self - tapping screw?

Self-cutting self-tapping screw (thread cutting self-tapping screw)

Self - cutting self - tapping screw referred to as self - cutting screw. Generally used in materials that do not wish to produce destructive internal stress, or in situations where the torque of self-tapping screws is considered excessive. Its main feature is that it has a cutting groove or opening at the end. So when you screw into the prefabricated hole, you can cut out the matching internal thread like a tap. There are six types :BF, BT, D, F, G and T.

It is hereby introduced as follows:

(1)BT type: the threads of BF type and BT type self-cutting and tapping screws are the same as those of type B, which are ordinary self-tapping threads (wide-tooth threads) and have the same flat end as those of type B. The taper threads of BF type can be complete or incomplete and have one or more cutting edges and chip grooves. BT taper threads are incomplete taper threads. These screws are mainly used in plastics, asbestos products and similar products.

(2) type D, type F, type G and type T: the threads of these four self-cutting and tapping screws are machine threads, i.e., United States thread, with flat ends and tapered feed into the threaded portion. The tapered feed into the threaded portion has one or more cutting edges and chip slots. F - shaped tapered feed threads may be complete or incomplete. Other types are incomplete threads. Threads of D, F, G and T cutting screws need not be measured as normal machine threads. These screws are mainly used in aluminum, zinc and lead die castings, thin steel and section steel, cast iron, brass, plastic and other materials.

3) self-squeezing and self-tapping screws

The thread of the self-extruding screw is similar to the United States thread, having a diameter pitch combination of machine threads and having a blunt end and tapered feed into the threaded portion. There are special circular grooves in the rod and/or tapered feed portion of the thread that allow the screw to be machined out of matched internal threads without chip generation.