Relationship between processing parameters of LFC shell mold casting aluminum alloy with vacuum and low pressure and filling as well as inner quality of castings was investigated. The results show that filling ability is proportional to processing parameters

such as pouring temperature

gas flow

vacuum rate

gas pressure. Compared with vacuum rate and gas pressure

gas flow and pouring temperature is dominant in filling ability of the castings. Filling behavior in thin-walled castings is seriously related to processing parameters than in thick-walled ones. Porosity in the castings is firstly decreased and then increased with increasing in pouring temperature

and it is decreased with increasing in gas flow

gas pressure and vacuum rate

while density is increased with the increase of parameters. The desirable processing parameters are as follows: pouring temperature of 720

7

50 ℃

gas flow of 12

1

9 m3/h

vacuum rate of -0.03

-

0.04 MPa and gas pressure of 0.03

0

.04 MPa.