A flask is a type of tooling used to contain a

mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...

metal casting In metalworking and jewelry making, casting is a process in which a liquid metal is delivered into a mold (usually by a crucible) that contains a negative impression (i.e., a three-dimensional negative image) of the intended shape. The metal is ...

. A flask has only sides, and no top or bottom, and forms a frame around the mold, which is typically made of

molding sand Molding sand, also known as foundry sand, is a sand that when moistened and compressed or oiled or heated tends to pack well and hold its shape. It is used in the process of sand casting for preparing the mold cavity. Green sand Green sand is an a ...

. The shape of a flask may be square, rectangular, round or any convenient shape. A flask can have any size so long as it is larger than the

pattern A pattern is a regularity in the world, in human-made design, or in abstract ideas. As such, the elements of a pattern repeat in a predictable manner. A geometric pattern is a kind of pattern formed of geometric shapes and typically repeated li ...

being used to make the sand mold. Flasks are commonly made of steel,

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

or even wood. A simple flask has two parts: the cope and the drag. More elaborate flasks may have three or even four parts.

Flask design

Flasks are often designed with bars that extend to span two opposite sides. The bars act as reinforcement to the molding sand, which is relatively weak in

tensile strength Ultimate tensile strength (UTS), often shortened to tensile strength (TS), ultimate strength, or F_\text within equations, is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials t ...

. The bars help support the sand through the molding and pouring operation. Flasks are designed with an alignment or registration feature, so that the two flasks can be aligned to one another to ensure a

casting Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejected ...

can be more dimensionally accurate and also in small flasks, so that they cannot be fitted together the wrong way. Flasks usually have handles or

trunnions A trunnion (from Old French "''trognon''", trunk) is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannons, they are an important military development. Alternatively, a trunnion is a shaft that positions a ...

designed into their construction, which assist in handling the flasks with cranes or other lifting machinery. Some flasks are used to form a mold and are removed before pouring the casting, so another mold can be made. Other flasks are designed to contain the mold through the pouring operation, and then the casting is shaken out of the mold. The flasks are then used again and again. Flasks are usually (though not always) the property of the foundry making the casting. The number of available flasks of a given size can be a limiting factor in the overall production rate.

References

*. {{Metalworking navbox, castopen Casting (manufacturing)