The complete production process of conventional self tapping screws？

The so-called conventional self-tapping screws are screws that can be self-threaded. The difference between this screw and a regular screw is that a suitable screw hole needs to be drilled before tightening, while this screw does not require a screw hole. It can be self-threaded while being screwed in, greatly saving installation steps and time. So do you know the production process of this screw? Today, the technical personnel of Hualong Fasteners have compiled a complete production process document.
Firstly, it is necessary to understand the equipment required for the production of self-tapping screws, including wire drawing machines, cold heading machines, and tooth rolling machines.
Below is a detailed introduction to the complete production process:
1. Wire drawing
Wire drawing: also known as wire drawing, this step mainly involves drawing the wire to the cold heading machine. Usually, there is also a process before wire drawing, which is acid washing. In order to remove the oxide film on the surface of the wire and form a layer of phosphate film on the surface, the main purpose of acid washing is to remove impurities on the surface of the wire as much as possible and avoid surface roughness causing scratches on the mold. After acid washing, the surface of the wire needs to be cold drawn by a wire drawing machine to meet the required wire diameter. The length of the wire diameter should be the length required for the produced screw.
2. Forming (nail embryo)
For screws, forming is a very important step. Generally, head forming is required first. After the process of the first mock examination and two punches, the head can be formed. There are many head shapes, such as hexagonal sockets, countersunk heads, round heads, large flat heads,s, and outer hexagons. During the molding process, the following processes are also required:
① Blocking: Generally, it is necessary to use movable scissors for one-way movement to cut the wire stuck in the cutting mold into the desired shape, making it a blank material.
② One stroke: This step mainly involves fixing the mold, allowing the head of the blank to start forming, but this stroke cannot fully form. If the head shape of the screw is a straight-cut groove, the content of a die is mainly concave and elliptical grooves. If the head of the screw is a cross groove, the content of a die is mainly concave and square grooves.
③ Second punching: After passing through the first punching, the punching tool needs to work completely. The second punching die moves towards the front of the mold, and the second punching die works forward to completely shape the screw. Then, the punching rod can push out the blank material.
3. Rubbing teeth
In this process, the nail blank can be made into a thread sample. Two tooth plates need to be prepared, one of which is fixed and the other is used to roll the semi-finished product. By using kneading, the screw can undergo plastic deformation to form the required thread.
4. Heat treatment
In many situations, there are requirements for the hardness of screws, so heat treatment is the main step to ensure the hardness of screws. After heat treatment, the surface hardness and core hardness can meet the requirements, making it easy to use and smoothly drill holes.
5. Surface treatment
By treating the surface of screws, their anti-corrosion function can be improved and their appearance can be more beautiful. Generally, there are three methods for surface treatment: electroplating, hot-dip galvanizing, and mechanical plating.
After the above five processes are completed, the finished products of conventional self-tapping screws are produced. Of course, quality inspection, defect screening, and drying are also required in the later stage. After these stages are completed, the screws can be packaged into boxes and sold. Every step requires strict supervision so that the quality of the screws delivered to the user's hands is qualified.