A method for manufacturing an inner door panel for a vehicle side door that employs a die casting process. The method includes providing a die cast mold having opposing mold halves that combine to define a die cavity configured to provide the inner door panel having an integrated impact beam. The mold cavity also includes channels that form a runner and gating system that causes the molten material to form an outer frame defining a central opening that allows the mold halves to be separated when the door panel has hardened within the mold.