Aluminum castings must not have invasive pores during the casting process. So, how can we prevent such problems?
Firstly, it is necessary to strictly control why gas enters aluminum castings and how to effectively prevent it? Strictly control the content of gas substances that may be emitted from the core sand and molding sand, as well as the moisture content of the wet mold.
Secondly, the compactness and breathability of the sand mold also need to be carefully controlled, because the lower the breathability of the sand mold, the higher the compactness, and the tendency for invasive pores to occur is much greater. Therefore, under the condition that the sand mold has sufficient strength, we should try our best to reduce the compactness of the sand mold. In fact, using coarse back sand in the surface sand is an effective measure to provide breathability of the sand mold.
Further improving the exhaust capacity of the sand mold and core can effectively enhance the exhaust function by adding exhaust holes on the lower mold. However, it is important to keep the exhaust holes in the sand core unobstructed, and it is also advisable to install an exhaust riser at the top of the aluminum casting. Therefore, we can adopt a more reasonable pouring system.
We can appropriately increase the temperature of the entire pouring process, because increasing the pouring temperature can effectively allow sufficient time for the invading gas to be completely discharged. Therefore, during pouring, it is important to control the pouring height and the entire pouring speed, ensuring a smooth and flowing filling of the liquid metal.
Afterwards, we can appropriately improve the quality of the entire smelting process in the liquid metal. Firstly, we can try to reduce the sulfur content in the molten iron as much as possible, effectively improve the overall flow performance of the molten iron, and prevent excessive flying oxidation of the liquid metal. This can effectively reduce the resistance when the entire gas is discharged.