| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a high quality thin cast product while using a cold chamber type die casting machine having high injection capacity by holding molten metal temp. in specified range and regulating the filling speed into a cavity in specified range and the increasing pressure after filling not lower than a specified value. SOLUTION: The temp. of molten magnesium alloy is held in 650-750 deg.C and the filling speed into the cavity is regulated in 1/100-10/100 sec and the increased pressure after filling is regulated to >=200 kgf/cm2. The temp. of a die is held in 150-350 deg.C, and the surface temp. of the die so as not to develop a shrinkage crack in the die casting product, is lowered by >=10 k in comparison with the surrounding part. When casting with the die casting, the air pressure in the die is regulated to <=100 mm Hg. As an addition in the releasing agent, at least one kind is used selected from group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide.
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