According to the structural feature and technological characteristics of AC4B aluminum alloy crankcase-lower bedplate

low pressure casting GM-L850 automobile engine crankcase-lower bedplate and its mould design were described.The processing parameters were adopted as follows:filling pressure of 0.02 MPa

approximately 0.5 m/s filling velocity and 5 s filling time

holding pressure of 0.051 MPa for 90s

pouring at（720±10） ℃

and pre-heating mould at 220 ℃ as well as pouring basin temperature of（600±50） ℃.Multi-parting face was adopted in the mould design to ensure the mould-opened smoothly.Mould wall thickness should be rationally considered

in which local cooling was employed at the thick location to realize the heat balance of the mould

meanwhile

various exhausting ways were adopted in the mould design to fill completely.The production shows that the process scheme

parameters and mould structure were feasible

and high qualified production rate was realized.