What Is The Bolt Production Process & Manufacturing Process?

Bolts are an important fastener used to connect and fix various structures and mechanical parts. They are called the rice of industry, which shows their important role in industrial production. There are many types of bolts, such as hexagonal bolts, square head bolts, round head bolts, etc. There are also some special types, such as U-bolts, anchor bolts, T-slot bolts, etc. Although the shapes and uses are different, their production processes are basically the same. This article will take you to understand the production process of bolts from the perspective of manufacturers, and see what important production processes are there.

Usually, manufacturers will select steel wire materials of corresponding diameter and material according to different specifications of bolts, but to ensure the quality of these raw materials, Jinrui's raw materials usually come from large steel mills, which can provide material reports.

However, these wires need further processing after arriving at the factory. For example, the raw materials of medium carbon steel and medium carbon alloy steel need to be spheroidized annealed to obtain good plasticity and reduce the cracking rate during cold heading.
 

Of course, steel will inevitably rust during transportation and storage, so after the wire is spheroidized, it needs to be chemically pickled. This step is to use an acidic solution to clean the steel surface, remove scale and other impurities, and provide a clean surface for subsequent processes.
 

Don't worry, there is one more step. Because the bolt product specifications required by customers are different, the wire needs to be drawn after pickling to process it to a wire diameter that meets customer needs.
 

After the steel raw materials are thoroughly prepared, the next step can be taken: wire forming. We need to process the wire raw materials into bolt blanks according to customer needs. Common forming schemes include cold heading and hot forging.
Cold heading is a processing method in which the wire is placed in a cold heading machine for cold processing, and the metal volume is redistributed and transferred with the help of a mold to form the required parts or blanks.
Hot forging is to heat the wire raw materials to a certain temperature, and then apply pressure through a forging machine to deform it into a bolt blank.
 

After the forming process, the bolt can only be regarded as a semi-finished product. If you want to have the function of tightening, you still need to match the thread. At this time, thread processing is also required: rolling thread.
Before rolling the thread, the part to be rolled needs to be turned to the thread diameter size.
Rolling (rubbing) thread refers to a processing method that uses plastic deformation to form the thread teeth. It uses a rolling (thread rolling plate) die with the same pitch and tooth shape as the processed thread, squeezes the cylindrical screw blank while rotating the screw blank, and finally transfers the tooth shape on the rolling die to the screw blank to form the thread.
In order to produce the outer diameter of the thread of the final product, the required thread blank diameter is different, because it is limited by factors such as thread accuracy and whether the material is coated. For example, if the thread is to be hot-dip galvanized in the future, the influence of surface treatment on the final size of the thread must be considered during thread processing, and it is necessary to advance when rolling the thread.

Heat treatment is one of the important processes in the manufacture of high-strength bolts. Its purpose is to improve the comprehensive mechanical properties of fasteners. The heat treatment process has a very important influence on the internal quality of fasteners, especially high-strength bolts.
 

There are many materials used to produce bolts, such as carbon steel, alloy steel, and stainless steel. However, the most commonly used and economical material is carbon steel. Carbon steel itself has no corrosion resistance, so it needs to be properly treated on its surface to meet the corrosion resistance requirements, so some customers will require some surface treatment.
Different surface treatment methods have different corrosion resistance levels, and the characteristics of anti-corrosion coatings are also different. The use temperature of different coatings is also different. Common surface treatments include: electrogalvanizing, hot-dip galvanizing, surface phosphating, electrochromium plating, nickel plating, Dacromet, Teflon, etc.
 

The bolts produced need to undergo strict inspection, including dimension measurement, stress testing, material testing, etc., to ensure that their quality and performance meet the standards.
 

The bolts that pass the inspection will be packaged. The packaging method can be packaged according to customer requirements, and then the appropriate transportation method can be selected for delivery.

Through the above steps, the transformation of bolts from raw materials to finished products is completed.
I didn't expect that the production and processing process of a small bolt is so complicated!
To complete each process, advanced production machinery and experienced craftsmen are required for inspection and supervision. Every link is strictly controlled to ensure the quality and performance of the final product to meet the needs of different industrial applications.
Although bolts are a simple fastening component in large-scale construction projects, they are of great importance. Understanding the entire process of bolt production and processing can help you find out the service life of the bolts from the source, replace and repair them in time, avoid accidents, and let them stand firmly in their jobs.