The indirect squeeze casting process and working principle of mold were determined based on analysis of the structure of gearbox and forming technology.During the stage of trial-mold

cold sandwich and shrinkage porosity were observed in gearbox produced by vertical squeeze casting machine SCV2000.After optimization of squeeze gearbox mold design

the defects such as cold sandwich and shrinkage porosity near sprue can be eliminated by optimizing structure of sprue bush and adding local pressurization core.Then the microstructures and mechanical properties of gearbox have been investigated.The results reveal that tensile strength

elongation and hardness of gearbox reach up to 317 MPa

6.1%

99 HBS

respectively

meeting the use requirement.The X-ray flaw detection shows that the aluminum alloy gearbox exhibits satisfy surface quality with absence of shrinkage porosity and cavity

gas hole.