A chill is an object used to promote solidification in a specific portion of a metal casting

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 ...

. Normally the metal in the mould cools at a certain rate relative to thickness of the casting. When the geometry of the molding cavity prevents

directional solidification Directional solidification (DS) and progressive solidification are types of solidification within castings. Directional solidification is solidification that occurs from farthest end of the casting and works its way towards the sprue. Progressiv ...

from occurring naturally, a chill can be strategically placed to help promote it. There are two types of chills: ''internal'' and ''external'' chills..

Types

''Internal'' chills are pieces of metal that are placed inside the molding cavity. When the cavity is filled, part of the chill will melt and ultimately become part of the casting, thus the chill must be the same material as the casting. Note that internal chills will absorb both

heat capacity Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K). Heat cap ...

and

heat of fusion In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a s ...

energy. ''External'' chills are masses of material that have a high heat capacity and

thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

. They are placed on the edge of the molding cavity, and effectively become part of the wall of the molding cavity. This type of chill can be used to increase the feeding distance of a riser or reduce the number of risers required.

Materials

Chills can be made of many materials, including iron,

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

, bronze,

aluminium 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. I ...

graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on lar ...

, and

silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal s ...

. Other sand materials with higher densities, thermal conductivity or thermal capacity can also be used as a chill. For example, chromite

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...

or zircon sand can be used when molding with

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...

Types

Materials

References

Notes

Bibliography