The head of the tapping screw is pointed and can be used normally without the need for drilling.Widely used in doors and Windows and iron sheet.So, do you know what the form of self tapping screw is?Let’s take a look at the thread types of self-tapping screws.

There are A, AB, B, BP, C and other types of thread forming of tapping screw.At present, it has been gradually replaced by rolling wire, so it is not recommended to use in the new design.The only difference between AB, B and BP is the shape of the tail.AB has a threaded tapered tail, B has a blunt tail, and BP has a threaded tapered tail.The center of the tip enters the pre-drilled hole and begins to thread.Thread cutting has many forms such as BF, BP, D, F, G, T, etc. BF, BP is wide thread, the rest is mechanical thread.

The screw production equipment required by the whole screw production process can be roughly divided into: drawing machine, cold heading machine, rubbing machine, etc.;

The production process is described as follows:

First, screw production technology – wire drawing

Also known as pumping wire, pumping wire to the cold heading machine.Generally, there is a process before drawing is pickling, in order to get rid of the oxide film on the surface of the wire, so that the surface forms a layer of phosphate film, and as far as possible to reduce the scratches on the mold caused by the rough appearance of the wire and sundries.

Two, screw production process — molding (nail embryo)

For ordinary self-tapping screws, the first is to head molding, generally after a mold and two punching process.Head molding can be countersunk head, round head, large flat head, outer hexagonal, inner hexagonal and so on;

Three, screw production process – rubbing teeth

Generally, the self-tapping screw embryo is made into threads. Two tooth plates are needed, one tooth plate is fixed, the other one is moved by rolling semi-finished products, and the product is plastic deformed by kneading to form the required thread.

Four, screw production process — heat treatment

Self-tapping screw as a screw with hardness requirements, heat treatment (influence factors) is necessary, so that the surface hardness and core hardness of self-tapping screw can meet certain requirements, in order to smoothly tap hole and not too soft to tap.

Five, screw production technology – surface treatment

Appearance disposal is a process of forming a covering layer on the surface of the workpiece through a certain method. Its intention is to give the product a beautiful appearance and anti-corrosion effect