Investment Casting uses a mold that has been produced by surrounding an expendable pattern with a refractory slurry that sets at room temperature. The pattern (usually of wax or plastic) is then melted or burned out, leaving the mold cavity. Investment casting is also known as the "lost-wax process" and as "precision casting".
In sand casting, wood or metal pattern are used to make the impression in the molding material. The pattern can be re-used, but the mold is expendable. In Investment casting, a metal pattern die is used to produce the patterns, which, in turn, are used to produce ceramic molds. Both the pattern and molds are expendable. Ceramic cores are used, as required, and these also are expendable.
Investment casting is the most flexible of all the precision casting process with respect to attainable intricacy, precision and the variety of alloys that may be cast within its inherent size limitations. Of the various casting techniques, investment casting is both the newest and the oldest, depending on whether you consider it from the standpoint of industrial history or total genealogy.