High pressure die casting (HPDC) is a manufacturing process that uses high pressure and speed to force molten metal into a closed steel die. The die has a stationary and moving half, both of which are mounted to the die casting machine's platens. The die casting machine uses hydraulics and pressurized gas to move a piston forward, injecting the molten metal into the closed steel die. The metal is held in the die until it solidifies, and then the die is unlocked, opened, and the casting ejected