Describing the static pressure generated by the weight of molten metal inside a mould, sprue or ladle. It is calculated based on the density of the specific alloy and the vertical height of the liquid column. High metallostatic pressure is necessary to force metal into thin sections and prevent shrinkage defects, but excessive pressure can cause mould wall failure or metal penetration into the sand.
We need a taller sprue to increase the metallostatic head, otherwise this thin section will never fill.
Insiders usually just say head pressure on the shop floor, reserving metallostatic for engineering calculations.
Related terms
Sprue
The vertical channel through which molten metal enters a mould.
Downsprue
The vertical channel in a mold that carries molten metal down to the runner system.
Gate
The specific channel where molten metal enters the mold cavity.
Chvorinov's rule
A mathematical formula used to predict how long a metal casting will take to solidify based on its volume and surface area.