Die casting is a manufacturing process in which molten metal is injected, under pressure, into a hardened steel die also called a mold. Dies are often water-cooled. Dies are then opened, and the die castings are ejected many times (thousands of parts each day). Once the tooling is paid for, die casting is a very inexpensive zinc part manufacturing process.
Compared with sand casting, die castings require much less machining, thinner wall sections can be made, almost all holes can be cored to size and can be held to much closer dimensional limits. Sand castings require new cores to be made each time. Parts will have a much rougher surface and will require manual cleaning for parts requiring a good surface finish or close tolerance dimensions.