Quick Facts

Sand casting is generally considered the simplest and most versatile of the casting processes.  Sand castings are produced by pouring molten metal into sand molds.  Sand molds are made quite easily, and if trial runs show modifications of the mold are necessary, it is relatively simple to change the patterns.  One important reason for using a sand casting is that it provides the opportunity to meet service requirements of the casting at a cost lower than that of other casting methods.  Sand molds may be either "green sand" (binder not cured by heating) or "chemically bonded sand."

The Process

Making a green sand mold involves the proper ramming of molding sand around a pattern within the confine of a flask.  The pattern is made in two "halves", which often are attached to opposite sides of a flat plate.  Hollows and undercut surfaces in the casting are produced by cores, also made from sand.  These cores are placed in position before the mold is closed and held in place by core prints.  After the pattern is removed from the sand and the gating arrangement is completed, the mold cavity is filled with molten metal to form a casting.

Sand Casting Advantages

The sand casting process is best suited to producing parts having hollow cavities and a complex arrangement of ribs, pockets, etc., and to those parts of sizes that make them unsuitable for casting in metal molds (i.e. die cast aluminum parts).  Low to medium production runs are usually associated with the sand casting process, but the process is often used for high production too.  Sand cast tooling is generally easy to produce and relatively inexpensive compared to other casting processes.  Sand molds are made easily, and if trial runs show that modifications of the mold are necessary, it is relatively easy to change the pattern.

Sand Casting Disadvantages

Although tooling is relatively inexpensive, the unit price for the cast part is higher than metal mold casting processes (i.e. die casting).  Additionally, parts made in the sand casting process may require more machine stock added to the part and subsequently machined to the required dimensions.  Also, sand casting surface finishes are not as smooth as many other casting processes.

Alloys

Nearly all ferrous and non-ferrous alloys may be cast using the sand casting process.

Tooling

Sand mold tooling is generally made using wood, plastic or aluminum materials.

Design and Technical Information