Vacuum pressure process and apparatus for high pressure die casting

A vacuum pressure process for high pressure die casting in a mould comprising a fixed part (1) and at least a movable part (2) defining inbetween a mould cavity (3) and a shot sleeve (6) for feeding the mould cavity (3) with molten metal: The vacuum process comprises the steps of producing a first reduction of the mold cavity pressure to a first vacuum stage, once the molten metal to be casted is inside the shot sleeve (6) and producing a second reduction of the mold cavity pressure from the first vacuum stage to a second vacuum stage lower than the first vacuum stage, after the first vacuum stage is established and before the filling of the mould cavity (3) begins. The second pressure stage is maintained at least until the mould cavity has been filled.