In the forming process of fasteners, cold heading (extrusion) technology is a main processing process. Cold heading (extrusion) belongs to the category of metal pressure processing. In production, external force is applied to the metal at room temperature to form it in a predetermined mold, which is usually called cold heading. In fact, the formation of any fastener is not only achievable through cold heading as a deformation method. During the cold heading process, in addition to upsetting deformation, there are also various deformation methods such as forward and backward extrusion, composite extrusion, punching, rolling, etc. Therefore, the term ‘cold heading’ in production is only a customary term, more precisely, it should be called ‘cold heading’ (extrusion).
There are many advantages of cold heading (extrusion), which is suitable for mass production of fasteners. Its main advantages can be summarized as follows:
a. High utilization rate of steel. Cold heading (extrusion) is a less cutting and non cutting processing method, such as machining hexagonal head bolts and cylindrical head socket head screws for rods. By using cutting processing, the steel utilization rate is only 25% to 35%. However, using cold heading (extrusion) method, its utilization rate can reach up to 85% to 95%, which is only some process consumption of material head, material tail, and cutting hexagonal head edges.
b. High productivity. Compared with general cutting processing, the efficiency of cold heading (extrusion) forming is several tens of times higher.
c. Good mechanical performance. The parts processed by cold heading (extrusion) method have much superior strength compared to those processed by cutting, as the metal fibers are not cut off.
d. Suitable for automated production. Fasteners (including some irregular parts) suitable for cold heading (extrusion) production are basically symmetrical parts, suitable for production using high-speed automatic cold heading machines, and are also the main method of mass production.
In short, the cold heading (extrusion) method for processing fasteners and special-shaped parts is a highly cost-effective processing method that is widely used in the fastener industry. It is also an advanced processing method widely used and developed domestically and internationally.