Pouring molten metal into three-dimensional molds to make metal parts is the basis behind both sand and investment casting. But there are significant differences between these two methods.

Sand-Casting Basics
In sand casting, molten metal is poured into a sand-based two-piece mold.

Molds are created out of sand usually mixed with clay as a bonding agent and moistened with water. The sand is compacted around a full-sized pattern or model of the final product. Technicians split the mold apart and remove the pattern. The two halves of the mold are put back together, leaving a void the exact shape as the pattern. The void gets filled with molten metal and, once it cools sufficiently, the mold is opened, the sand removed and the part taken out. The metals are usually iron, steel, bronze, brass, aluminum, magnesium or other non-ferrous alloys.

Investment-Casting Basics
Investment casting, otherwise known as lost-wax casting, also makes parts from molten metal, but usually stainless-steel alloys, brass, aluminum and carbon steel. The first step in this type of casting is to build a pattern of the final product or part out of wax, which can be done in one of three ways:

Read more: Investment or Sand Casting? Which is Right for Your Application?