Abstract
In the low pressure diecasting process, such casting defects as misrun, shrinkage and cold shut are mostly attributed to the way in controlling the rate of pressure increase of the operating air.
The present authors have recently developed an automatic device for the pressure control.
Using water instead of molten metal in a low pressure casting machine equipped with this controling device, it was found :
1) Sprashing and bubbling accur in the case of a too fast increment rate of pressure.
2) The proper increment rate for mild flowing condition depends upon the area-ratio
(= Sectional area of stalk outlet⁄Surface area of molten in a crucible) and the shape of stalk outlet.
3) Vent hole of die is one of the important factors to affect the flowing condition.
