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Custom Self Tapping Screw Production Process

Oct. 19, 2020

A custom Self Tapping Screw is simply a screw that can be tapped by itself. The difference between self-tapping screws and ordinary screws is that ordinary screws must have a machined screw hole to be screwed in. Self-tapping screws do not need to be tapped while screwing in. In order to achieve the purpose of self-tapping, this kind of hexagonal self-drilling screws is generally pointed to facilitate squeezing into the object to be screwed.

The screw production equipment required for the entire screw production process can be roughly divided into a wire drawing machine, cold heading machine, thread rolling machine, etc.


01


Drawing

Wire drawing: also known as wire drawing, the wire is pumped to the cold heading machine. Generally, there is a pickling before wire drawing. In order to remove the oxide film on the surface of the wire, a phosphate film is formed on the surface to minimize the roughness of the wire and the scratches on the mold caused by the debris. After the wire coil is pickled, it is cold drawn to the required wire diameter by the wire drawing machine. Suitable for large screws, nuts, and self-tapping screws with the required length of wire.


02


Forming (nail embryo)

For ordinary self-tapping screws, the first step is to form the head, usually through the process of one die and two punches. The head forming can be the countersunk head, round head, big flathead, outer hexagon, inner hexagon, etc.

1. Blocking: Cut the wire stuck in the cutting die into the required blank after moving the movable scissors in one direction

2. First punch: The mold is fixed, and the product head is formed by a punch so that the next stroke can be completely formed. When the product is a straight groove, one punch is a concave or elliptical groove, and when the product is a cross groove, the other punch is a concave square groove.

3. Second punch: After the first punch, all the punches work, the second punch moves to the front of the punch, and the second punch work forward to form the end of the product. Afterward, the blank is pushed out by the back punch.


03


Thread Rolling

Generally, the self-tapping screw nail embryo is made into a thread, which requires two tooth plates, one tooth plate is fixed, and the other rolling semi-finished product is moved. The product is plastically deformed by kneading to form the required thread.


04


Heat treatment

As a screw with hardness requirements, heat treatment (influencing factors) is necessary for self-tapping screws. After the surface hardness and core hardness of the self-tapping screws can meet certain requirements, the holes can be tapped smoothly and not too soft. 

Self Tapping Screw

Self Tapping Screw


05


Surface treatment

The surface treatment is the process of forming a covering layer on the surface of the workpiece through a certain method. The intention is to give the product a beautiful appearance and anti-corrosion effect. The appearance treatment methods carried out are attributed to the following methods: electroplating, hot-dip galvanizing, Mechanical plating, etc.

Commonly used electroplating includes galvanizing, black/white nickel, blackening, phosphating, etc.; for export products that have environmental quality requirements, the phosphorus removal treatment of trivalent white zinc is required, also known as environmentally friendly white zinc.

After the first five processes are completed, the self-tapping screws will come out. Of course, the selection and drying of defective products must be carried out. After that, it is packaging and labeling for delivery.

Although the whole process has more than a dozen steps, it can be used as the winning screw (core product) for the professional production of screws. The control of each link is important, and every detail is not neglected.

 

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