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Porosity is a fraction between 0 and 1, typically ranging from less than 0.005 for solid granite to more than 0.5 for peat and clay. The porosity of a rock, or sedimentary layer, is an important consideration when attempting to evaluate the potential volume of water or hydrocarbons it may contain.
Pipes form at the surface of the casting and burrow into the casting, while caved surfaces are shallow cavities that form across the surface of the casting. [5] Closed shrinkage defects, also known as shrinkage porosity, are defects that form within the casting. Isolated pools of liquid form inside solidified metal, which are called hot spots ...
This porosity can range in size, from sub-micron to voids greater than 10 mm, depending on the casting. Casting defects caused by porosity can affect the part’s structural integrity, creating a failure point. Porosity can also prevent the part from being pressure tight. This will impact performance if the part is designed to hold gases or ...
A porous medium is most often characterised by its porosity. Other properties of the medium (e.g. permeability , tensile strength , electrical conductivity , tortuosity ) can sometimes be derived from the respective properties of its constituents (solid matrix and fluid) and the media porosity and pores structure, but such a derivation is ...
Molten metal before casting Casting iron in a sand mold. 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.
This is an accepted version of this page This is the latest accepted revision, reviewed on 28 January 2025. Manufacturing processes This section does not cite any sources.
A small transformer potted in epoxy. The surface visible on the right is formed by the potting compound that has been poured into the plastic box. In electronics, potting is the process of filling a complete electronic assembly with a solid or gelatinous compound.
Gases can form in metal castings in one of two ways: by physical entrapment during the casting process or; by chemical reaction in the cast material. Hydrogen is a common contaminant for most cast metals. It forms as a result of material reactions or from water vapor or machine lubricants.