as for controlling the pressure for gas injection , it shall be first high then low, wherein at the beginning of injection, higher pressure should be preserved so that the fusant can be forced to fill in the mold cavity and form hollow gas cavity. And upon the completion of this action, the pressure of filling gas, as dwell pressure, should be lowered to avoid overflow and internal stress.
Hi please write more about this kind of molding method, I understand this is so called gas-assisted injection molding