Advanced Casting Methodologies

The chapter deals with vacuum casting, a process that refers to the casting and solidification of alloys within low pressure atmospheres which are often purged with inert gas. Pressures set at 0.1 Pa and below are commonly used with vacuum casting technology. This technology is employed where high cleanliness and purity are required during liquid metal processing. Vacuum casting helps to avoid contamination from reaction of the liquid metal with either the environment gases or crucible and mold container materials. In addition, recent advances in the high pressure die casting process, a process where a hydraulically powered plunger injects liquid metal alloys at high speed into a reusable steel mold are described for die castings produced from aluminum alloys, magnesium alloys, and zinc alloys. A review follows of the fabrication of composites by casting techniques, a promising route for manufacturing near net shape parts at relatively low cost and looks at several liquid fabrication techniques available to manufacture composite materials, classified according to the type of reinforcement. Fabrication techniques can vary considerably and include stir casting, liquid metal infiltration, squeeze casting, spray co-deposition, and compocasting. The chapter concludes with a review of both single roller and twin roller roll casting, processes that can cast strip directly from the melt in a one step, promising savings in effort and energy.