Sand Casting Terminology

Chemistry - The composition, structure, properties, and reactions of a particular alloy.

Cope - The top half of a two-part casting flask used in sand casting.

Drag - The bottom half of a two-part casting flask used in sand casting.

Filter - Filters are used to prevent inclusions in a casting. Placed in the gating system leading to the mold, a filter traps any unwanted material or gases when the molten metal is poured into the mold. Ceramic filters are most commonly used in the metal casting industry and typically come in two forms – foam or cellular.

Flask - The flask is the container box that holds the molding sand. Consisting of two parts, cope (the top half of a flask) and drag (the bottom half of a flask), a flask is typically made of aluminum, steel or wood and can be made in any shape and size. To align the cope and drag, an alignment feature is used insuring a more dimensionally accurate casting. Flasks are reusable; some may be used to form a mold and then removed prior to pouring a casting, others contain the mold throughout pouring and are then shaken out.

Gate - The portion of the runner where the molten metal enters the mold cavity. Gates are formed into a mold extraneous of the desired final product and must be removed by machining once casting has cooled. Gates are arranged so molten metal is fed to the casting at a rate consistent with the rate of solidification.

Green sand - Green sand is moist, clay-bonded sand used for creating molds in sand casting foundries. Green sand is made by combining very fine sand such as silica or olivine, with bentonite clay and water.  Molds made out of green sand can support a higher weight than dry sand molds. Green sand is best used for medium-sized castings that are not complex in design and do not require high dimensional accuracy.

Heat - A single furnace charge of metal.

Ladle - A container used to transfer molten metal from the furnace to the mold.

Riser/Feeder - As part of the runner system or gating, the riser/feeder is an extraneous reservoir cavity of molten metal used to feed the casting as the metal solidifies. The riser is used to compensate for losses due to shrinkage as the casting cools. A riser will cool and solidify with the slowest components (usually the thickest and largest parts) of a casting.

Riser Sleeves - Riser sleeves are typically solid cylindrical shapes available in a variety of sizes. Sleeves are made of various refractory powders, high temperature resistant ceramic fibers, a binder system, and for exothermic sleeves, granular aluminum powders. Insulated sleeves provide insulation to reduce heat loss from the riser. Exothermic sleeves generate heat to maintain temperature from lost heat. Sleeves provide consistency by reducing shrinkage and improving overall casting quality. Riser sleeves also reduce labor costs by providing easier riser knock off and a smaller contact area.

Runner - Runners are passages that distribute molten metal from the sprue to gates or risers around the cavity inside a mold. Runners slow down and smooth out the flow of liquid metal and are designed to provide approximate uniform flow rates to the various parts of the mold cavity.

Tap - To withdraw a molten charge from the melting unit.