SELF TAPPING SCREW

Intro：Generally fingertip, coarse teeth, hard wood screws, also aluminum alloy, plastic. A special self-tapping screw for opening metal holes is called a tap.

Self-tapping screws are used for non-metallic or softer metals, without bottom holes and tapping; Self-tapping screws are pointed, so as to "self-tapping"; Ordinary screws are flat headed, the same thickness.

Self-tapping screw means that the hole is drilled without tapping the hole, the screw is different from the general, the head is pointed, the tooth distance is relatively large, and the chip free tap is a bit like, you can screw directly into the hole without tapping the teeth, metal and plastic are usually used this method.

It can be consolidated on the material, relying on its own thread, the consolidated body will "attack - drill, squeeze, press" out of the corresponding thread, so that they are closely matched with each other.

Thread forming：(Thread Forming Tapping Screws) - is directly developed from the iron sheet screw, thread forming tapping screws must be drilled in advance when using, and then screw into the hole, strong extrusion with female thread, and the original female thread position of the material will be squeezed between the male thread, this is called thread forming tapping screws. It can only be applied to thin and plastic materials, so it has been developed; Thread Cutting Tapping Screws - One or more cutting holes are cut at the end of the thread, so that the tail and teeth of the screw can be used to cut the matching female thread in a similar way to the tap when the pre-drilling is done. It can be used on thick plates, relatively hard or fragile materials that are not easy to shape.

Structural element：From beginning to end, the self-tapping screw is composed of three parts: the head, the rod and the end of the rod. The composition of each self-tapping screw has four major elements: head shape, screw mode, thread type and end type. Head shape - There are a variety of head shapes. There are round head (half round head), flat head, round head flange (with pad), flat head flange (with pad), pan head, pan head flange (with pad), countersunk head, semi-countersunk head, cylindrical head, spherical cylinder head, horn head, hexagonal head, hexagonal flange head, hexagonal flange (with pad) and so on. Wrench mode - Wrench mode is varied. External wrench: hex, hex flange, hex flange, hex flower, etc.; Internal screw: Single slot, cross slot H type (Phillips), cross slot Z type (Pozidriv), cross slot F type (Frearson), square slot (Scrulox), composite slot, internal spline, hexagonal flower shape (club slot), internal triangle, hex, internal 12 Angle, clutch slot, six blade slot, high torque cross slot and so on. Thread types - There are many kinds of threads. There are self-tapping thread (wide tooth thread), machine thread, drywall screw thread, fiberboard screw thread, and some other special thread. In addition, the thread can be divided into single lead (single head), double lead (double head), multiple lead (multiple) and high and low teeth double head thread. End type - The end type mainly has saw end and flat end. However, according to the function of use, grooves, notches or parts similar to drill bits with cutting functions can be machined. In some standards, the same saw end or flat end, there are also different forms. From the above introduction, it can be seen that there are various changes in the head shape of the tapping screw, the way of pulling and screwing, the type of thread and the end type of the rod. They can be combined with each other to release a large number of different products belonging to the category of self-tapping screws.