What is vacuum casting（2）

Vacuum casting

Vacuum casting can be divided into vacuum suction, vacuum low pressure casting, and vacuum die casting.

1. Vacuum suction

Figure 1 Schematic diagram of vacuum. As shown in Figure 1, the mold is placed in a closed container. The mold leaves the air, causing the mold to generate a certain negative pressure, causing the molten metal to enter the mold cavity. It solidifies during in-situ casting and removes negative pressure, so that the molten metal without solidification of the runner returns to the swimming pool. The advantage is to improve the capacity of the filling alloy liquid, the minimum wall thickness of the casting can reach 0.2mm, the casting area is 300mm2, while reducing pores, slag and other defects. It is suitable for the production of fine and small precision castings, especially for cast steel (including stainless steel). The advantages are:

(1) Vacuum suction is beneficial to remove the gas in the mold, suppress turbulence and generate gas. It overcomes the shortcomings of low-pressure casting and differential pressure casting, and the filling capacity of metal liquid is significantly improved.

(2) Due to the vacuum suction and the increase of the filling capacity, the melting casting temperature can be lower than that of gravity casting by 20~30℃.

(3) Castings with large, thin-walled, high-quality requirements between the wall thickness difference of castings.

(4) Choose the appropriate rate of change of vacuum degree, control the speed of metal liquid entering the mold cavity, and you can obtain a smooth filling effect.