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How are screws and nuts made?


How are screws made? Walk into the factory to understand the whole process of manufacturing, the original technical content is so high

To the new science and technology

2 months ago

Screws may seem like insignificant little parts, but they are essential to everything from national treasures to household goods. It has a wonderful name -- screw. Can you imagine something so simple? How is it made? All this is due to a small screw around us! A screw is also called a nut. Do you know how screws are made?

Don't underestimate it. There are six steps in the production process alone. 1. Wire selection. It is necessary to have a preliminary understanding and knowledge of the materials required before proceeding with wire drawing. Wire sort is a lot of, can choose corresponding material according to different use pledges. 2. Rough drawing processing. There are two main steps. It is the processing of wire above all, choose diameter 5-19mm wire as raw material commonly. The second step, rough drawing processing. The wire is heated for a period of time and then cooled slowly to adjust the crystalline structure, reduce the hardness of the wire, remove particles and improve the wire's workability at room temperature, a process we call annealing.

The second is acid pickling phosphating, the metal surface formed phosphate film oxide film from the surface of the wire removal. After the phosphating film, the wire is easier to process and form, but also reduce the wear and loss of the worker mold in the subsequent processing process, such as wire drawing and cold heading. Finally, the annealing process, through the heat treatment of coarse wire drawing, so that its internal structure changes, so as to improve the role of tensile strength. (3) According to different specifications of products, select the corresponding rough drawing process. In simple terms, the purpose of rough drawing is to purify the oxidized skin that wire produces in the process of production and storage, the surface of wire after rough cutting presents original color.

The third step, fine drawing processing. This step needs according to the requirement of different product, pull wire to the thickness of corresponding wire diameter. After a certain length of wire is rough-rolled, subsequent processing such as annealing and pickling is carried out. Finally achieve the required dimensional accuracy. In this process, wire surface roughness and surface quality should be further detected and analyzed. Then you can proceed to the fourth step, which is the molding process, which can be roughly divided into three steps.

The first step is upsetting with a cold upsetting machine, cutting the wire to the required length, and adding nuts and marks. In this stage, cold rolled strip steel is processed, including rolling, annealing and pickling. Among them, the most important is to recycle the leftover materials generated in the process of cold rolling. The second step is the tail design, design through the steel plate dovetail shape, this is also very critical step, from the tail to the end of the thread. This is the third step, rubbing silk, also known as grinding teeth. Through the interaction of movable plate floor and fixed plate, the molded semi-finished product is ground into familiar threads. At this point, the implementation is basically in place.

The second step, heat treatment processing, roughly divided into 5 links. The first step, the screw for preliminary treatment. To do this, there are two steps: first remove any moisture and grease from the screws, and then clean them with alcohol or gasoline. The second step is to heat and harden the screws. The first step is cleaning to remove grease from the screw surface. The second step is high temperature carburizing, the core of the heat treatment, which allows carbon atoms to penetrate the surface of the screw and increase its hardness.

The third step is quenching, that is, hardening the carburized screw at high temperature to form a layer of crystals on the surface of the screw to achieve the final hardness. The fourth step is to clean the quenching oil on the screw surface. The fifth step is low temperature tempering to reduce the hardness of the screw core. The sixth link is the detection in the process of installation and use. The seventh link is the inspection and packaging after heat treatment. Because if the screw core is too hard, it will cause the screw to break, and the screw after low temperature tempering will be more ductile.

After the first five screws are finished, they are usually sent to the laboratory, and after checking various parameters, the plating is finally stopped. Through electrochemistry, another metal is made on the surface of the screw, which can reduce the external corrosion of the screw body, prevent rust, prolong the service life of the screw, and also achieve beautiful effect. The steps of screw plating: the first step is to put the screw into the plating tank for pretreatment; The second step is to make threaded holes in the processed screws; The third step is to clean the screw surface with chemical solution after drilling. Normally, this step takes 1.5 to 2 hours. Finally, the screws are packed according to the model and a small screw is produced.

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