A die casting insert for producing die casted metal parts from liquid metal. The die casting insert has an outer casing shaped to be fixed in the die block of the die casting apparatus. The die casting insert also has a stopper with a purge opening that is adapted to evacuate contaminants topping the liquid metal as pressure is applied to the liquid metal. The stopper, fitted to mate with the hollow inner cavity of the injection sleeve, is constructed to seal the hollow inner cavity of the injection sleeve except at the purge opening when in a first position; and to permit the flow of the liquid metal into at least one molding cavity when the stopper is in a second position. The die casting insert also has an activation mechanism configured to shift the stopper between the first position and the second position.