The molten metal is poured into the hollow mold and cooled to form a product with the desired shape. This method is called “casting”, and the product obtained in theis a casting. Casting can be divided into “ferrous ” and “nonferrous metal casting” according to casting materials. Ferrous metal casting is divided into steel and iron, and nonferrous metals include copper alloy and aluminum alloy. Casting can be divided into “metal mold casting” and according to mold materials. Casting can also be divided into pressure casting and gravity casting according to the process of liquid metal pouring.
Aluminum alloy has good performance, and the best alloy and casting method are determined in combination with the requirements of use purpose, part shape, economic benefit and so on. Aluminum alloy has been widely used in various parts such as engine block and oil pump. There are many forming methods of aluminum alloy casting wheel hub. At this stage, the common methods are casting method and forging method. The foreign process is mainly composed of three forging processes and continuous casting processes. Although this method can ensure good scientific performance, the yield is only 50%. The casting process of aluminum alloy casting hub is squeeze casting, low pressure casting and gravity casting. When gravity casting is applied to products, casting defects such as porosity and shrinkage can appear, and the mechanical properties and yield are relatively low, which has been eliminated abroad. Low pressure casting is a common casting technology for aluminum alloy casting wheels, and low pressure casting is widely used in the production of aluminum alloy casting wheels in other countries. Most manufacturing enterprises in China still adopt low pressure casting technology.
At this stage, the process of refitting the casting hub is squeeze casting, which mainly uses the press to squeeze the aluminum ingot through the die. The main advantage is that the density is relatively average, and the appearance is more smooth and fine. The cast hub not only has thin wall, but also has the advantages of light weight and high strength. The only disadvantage is the high cost. With the method of low-pressure casting, the product quality and yield can be guaranteed, but the process is complex, so the investment of equipment is relatively large. Using the liquid die forging method, the aluminum alloy can crystallize under high pressure and deform in the crystallization process, so as to effectively solve the shortcomings of porosity and shrinkage, and the products show good mechanical properties. In addition, it also has the characteristics of high precision and high efficiency, and the investment cost is relatively low compared with the low-pressure casting method. Under the pressure of 0.1MPa, high-pressure precision casting can implement precision casting, and this method has good workability, relatively uniform density and brighter appearance. It not only has the advantages of lightweight and high strength, but also ensures that the production cost is within the expected range. Aluminum alloy casting wheel hub in car is mainly formed by pressure casting. In order to improve the performance of products, it is developing towards squeeze casting and semi-solid.