Nearly two-thirds of the aluminum castings made in North America are produced using high-pressure die casting techniques. This article compares and contrasts traditional high-pressure die casting with an improved version that uses a vacuum to pull air out of the die in order to reduce porosity in as-cast parts. It begins by describing a typical cycle for a traditional cold-chamber die casting machine, using detailed illustrations to show how gas can become trapped in the liquid metal. It then presents various remedies, ultimately focusing on vacuum die casting for the production of high-integrity parts. In addition to vacuum technology,...