The die casting of aluminum castings is a process of injecting molten aluminum under high pressure into metal molds, achieving mass production through rapid filling and cooling. Its characteristics are closely related to mold design and process parameters, and it is suitable for the manufacturing of various industrial components.
Outstanding production efficiency is a significant advantage. The mold can be opened and closed in one go to complete the formation of a casting. The single-mode cycle is usually 30-90 seconds, and the multi cavity mold can produce 2-8 parts at a time, suitable for batch production of more than 100000 pieces per year. After forming, the surface roughness of the casting can reach Ra1.6-6.3 μ m, and in most cases, there is no need for secondary processing and it can directly enter the assembly process.
The structural adaptability has clear boundaries. It can form complex inner cavities and thin-walled structures, with a wall thickness of 0.5-1mm (depending on the casting size), but the wall thickness needs to be uniform, with a deviation of no more than 0.3mm, to avoid shrinkage caused by differences in cooling rate. The design height of the reinforcing bars should not exceed 5 times the wall thickness, and the spacing should be maintained at 3-5 times the wall thickness to enhance structural rigidity without hindering metal flow.
The material selection needs to match the process characteristics. Commonly used aluminum alloys contain 5% -12% silicon, have good fluidity, and are suitable for complex castings; The alloy containing 3% -5% copper has high strength, but it is prone to sticking to the mold during die casting, and the mold temperature needs to be increased to 200-250 ℃. Pure aluminum has poor fluidity and is only used for simple shaped castings, and the die-casting pressure needs to be increased to 80-120MPa.
Process parameters affect the quality of molding. The temperature of the aluminum liquid should be controlled between 650-700 ℃. Excessive temperature can lead to oxidation, while insufficient temperature can result in incomplete filling; The injection speed is divided into slow injection (0.1-0.5m/s) and fast injection (3-8m/s), and higher speed is required in the fast injection stage of complex cavities. The spacing between the cooling water channels of the mold is 15-30mm, ensuring that the casting solidifies to the demolding temperature within 3-5 seconds.
Limitations need to be addressed in a targeted manner. There may be small pores inside the casting, which are not suitable for high temperature (>200 ℃) environments to avoid deformation caused by pore expansion. Cannot form large castings, generally with a single weight not exceeding 50kg and a projected area controlled within 0.5m ². Mold manufacturing has high costs and long modification cycles, making it unsuitable for small batch and multi variety production.
Die casting has an irreplaceable advantage in mass production of complex aluminum castings due to its high-pressure and rapid process characteristics. Clarifying the boundaries of structural design, selecting materials and process parameters reasonably, can fully leverage its efficiency advantages while avoiding potential defects, and meet the requirements of industrial components for accuracy and consistency.