As the molds have many minuscule pores,the vacuum is needed to suck all gas out of the chamber. This allows any molten metal remaining around the gate to return smoothly to the crucible. The mould is set.
Molten metal is poured from above.
As the gate still attaches to the product, it is necessary to cut off the gate. This results in significantly improved quality of thin-wall products as well as greatly lowered rate of defect. Simple production of thin parts. Minimum blowholes and pinholes. No oxdation on surface of products.