The process of low-pressure casting is: in the sealed crucible (or sealed tank), dry compressed air is introduced, and the molten metal rises along the riser pipe into the sprue under the action of gas pressure, and smoothly passes through the sprue. Enter the cavity and maintain the gas pressure on the liquid level inside the crucible. Until the casting is completely solidified. Then, the gas pressure on the liquid surface is released, and the unsolidified metal liquid in the liquid riser flows back to the crucible. Reopen and remove the casting.
It can also be said that low pressure casting is a compromise between high pressure casting and gravity casting.