Editing Sand casting (section)

====Molding box and materials====
A multi-part molding box (known as a [[casting flask]], the top and bottom halves of which are known respectively as the cope and drag) is prepared to receive the pattern. Molding boxes are made in segments that may be latched to each other and to end closures. For a simple object&mdash;flat on one side&mdash;the lower portion of the box, closed at the bottom, will be filled with a molding sand. The sand is packed in through a vibratory process called ramming, and in this case, periodically [[Screed|screeded]] level. The surface of the sand may then be stabilized with a sizing compound. The pattern is placed on the sand and another molding box segment is added. Additional sand is rammed over and around the pattern. Finally a cover is placed on the box and it is turned and unlatched, so that the halves of the mold may be parted and the pattern with its sprue and vent patterns removed. Additional sizing may be added and any defects introduced by the removal of the pattern are corrected. The box is closed again. This forms a "green" mold which must be dried to receive the hot metal. If the mold is not sufficiently dried a steam explosion can occur that can throw molten metal about. In some cases, the sand may be oiled instead of moistened, which makes casting possible without waiting for the sand to dry. Sand may also be bonded by chemical binders, such as furane resins or amine-hardened resins.

{{Anchor|Additive_manufacturing_of_sand_molds}} [[3D printing|Additive manufacturing]] (AM) can be used in the sand mold preparation, so that instead of the sand mold being formed via packing sand around a pattern, it is 3D-printed. This can reduce lead times for casting by obviating patternmaking.<ref name="Donaldson_2017-11-01">{{Citation |last=Donaldson |first=Brent |date=2017-11-01 |title=Foundry Says Robotic Sand Printing a "Game Changer" for Metal Casting |journal=Additive Manufacturing |url=https://www.additivemanufacturing.media/articles/foundry-says-robotic-sand-printing-a-game-changer-for-metal-casting |access-date=2017-11-14 |postscript=.}}</ref> Besides replacing older methods, additive can also complement them in hybrid models, such as making a variety of AM-printed cores for a cavity derived from a traditional pattern.<ref name="Donaldson_2017-11-01"/>