Aiming at micro-shrinkage of large magnesium alloy casting （e. g. 137 kilogram）

which refers to main housing of helicopter

the influence of both feeder＇ s characteristic and chiller＇ s dimension on micro-shrinkage in flange was investigated in both numerical and experimental way. The reason for the defect was analyzed according to feeding solidification principle. Results show that for flange with 1.3 cm modulus

using disperse φ50 mm sleeves

putting each chiller with its thickness （ 1.5 - 2.0） times of flange＇ s thickness in between

two feed- ers and putting radius on feeder＇ s neck are able to obtain better modulus gradient for melt of ZM6 alloy in a sleeve and make feeding channel available

thus solving the micro-shrinkage which occurs in flange.