Editing Metal casting (section)

==Non-expendable mold casting==
[[Image:Castingtinsoldiers.jpg|thumb|200px|upright|The permanent molding process]]

Non-expendable mold casting differs from expendable processes in that the mold need not be reformed after each production cycle. This technique includes at least four different methods: permanent, die, centrifugal, and continuous casting. This form of casting also results in improved repeatability in parts produced and delivers [[near net shape]] results.

===Permanent mold casting===
{{Main article|Permanent mold casting|low-pressure permanent mold casting|vacuum permanent mold casting}}

Permanent mold casting is a metal casting process that employs reusable [[Molding (process)|molds]] ("permanent molds"), usually made from [[metal]]. The most common process uses gravity to fill the mold. However, gas pressure or a [[vacuum]] are also used. A variation on the typical gravity casting process, called [[slush casting]], produces hollow castings. Common casting metals are [[aluminum]], [[magnesium]], and [[copper]] alloys. Other materials include [[tin]], [[zinc]], and [[lead]] alloys and [[iron]] and steel are also cast in [[graphite]] molds. Permanent molds, while lasting more than one casting still have a limited life before wearing out.<!-- See main article for references -->

===Die casting===
{{Main article|Die casting}}

The die casting process forces molten [[metal]] under high pressure into mold cavities (which are machined into dies). Most die castings are made from [[nonferrous metals]], specifically [[zinc]], copper, and aluminium-based alloys, but [[ferrous metal]] die castings are possible. The die casting method is especially suited for applications where many small to medium-sized parts are needed with good detail, a fine surface quality and dimensional consistency.<!-- See main article for references -->

===Semi-solid metal casting===
{{Main article|Semi-solid metal casting}}

Semi-solid metal (SSM) casting is a modified die casting process that reduces or eliminates the residual porosity present in most die castings. Rather than using liquid metal as the feed material, SSM casting uses a higher viscosity feed material that is partially solid and partially liquid. A modified die casting machine is used to inject the semi-solid slurry into reusable hardened steel dies. The high viscosity of the semi-solid metal, along with the use of controlled die filling conditions, ensures that the semi-solid metal fills the die in a non-turbulent manner so that harmful porosity can be essentially eliminated.

Used commercially mainly for aluminium and magnesium alloys, SSM castings can be heat treated to the T4, T5 or T6 tempers. The combination of heat treatment, fast cooling rates (from using uncoated steel dies) and minimal porosity provides excellent combinations of strength and ductility. Other advantages of SSM casting include the ability to produce complex shaped parts net shape, pressure tightness, tight dimensional tolerances and the ability to cast thin walls.<ref>10th International Conference Semi-Solid Processing of Alloys and Composites, Eds. G. Hirt, A. Rassili & A. Buhrig-Polaczek, Aachen Germany & Liege, Belgium, 2008</ref>

=== Centrifugal casting ===
{{Main article|Centrifugal casting (silversmithing)}}In this process molten metal is poured in the mold and allowed to solidify while the mold is rotating. Metal is poured into the center of the mold at its axis of rotation. Due to inertial force, the liquid metal is thrown out toward the periphery.

Centrifugal casting is both gravity and pressure independent since it creates its own force feed using a temporary sand mold held in a spinning chamber. Lead time varies with the application. Semi- and true-centrifugal processing permit 30–50 pieces/hr-mold to be produced, with a practical limit for batch processing of approximately 9000&nbsp;kg total mass with a typical per-item limit of 2.3–4.5&nbsp;kg.

Industrially, the centrifugal casting<ref>{{cite web |title=Centrifugal casting |url=https://eminentengitech.com/services/casting-manufacturer/ |website=Eminent Engitech |access-date=2022-05-09 |archive-date=2022-10-04 |archive-url=https://web.archive.org/web/20221004121735/https://eminentengitech.com/services/casting-manufacturer/ |url-status=live }}</ref> of railway wheels was an early application of the method developed by the [[Germany|German]] industrial company [[Krupp]] and this capability enabled the rapid growth of the enterprise.

Small art pieces such as jewelry are often cast by this method using the lost wax process, as the forces enable the rather viscous liquid metals to flow through very small passages and into fine details such as leaves and petals. This effect is similar to the benefits from vacuum casting, also applied to jewelry casting.

===Continuous casting===
{{Main article|Continuous casting}}

Continuous casting is a refinement of the casting process for the continuous, high-volume production of metal sections with a constant cross-section. It's primarily used to produce a semi-finished products for further processing.<ref>{{Cite book |title=Springer handbook of mechanical engineering |date=2021 |editor=Karl-Heinrich Grote |editor2=Hamid Hefazi |isbn=978-3-030-47035-7 |edition=2nd |location=Cham |publisher=Springer |oclc=1246246146}}</ref>{{Rp|page=339}}  Molten metal is poured into an open-ended, water-cooled mold, which allows a 'skin' of solid metal to form over the still-liquid center, gradually solidifying the metal from the outside in. After solidification, the strand, as it is sometimes called, is continuously withdrawn from the mold. Predetermined lengths of the strand can be cut off by either mechanical shears or traveling oxyacetylene torches and transferred to further forming processes, or to a stockpile. Cast sizes can range from strip (a few millimeters thick by about five meters wide) to billets (90 to 160&nbsp;mm square) to slabs (1.25 m wide by 230&nbsp;mm thick). Sometimes, the strand may undergo an initial [[hot rolling]] process before being cut.

Continuous casting is used due to the lower costs associated with continuous production of a standard product, and also increased quality of the final product. Metals such as steel, copper, aluminum and lead are continuously cast, with steel being the metal with the greatest tonnages cast using this method.

==== Upcasting ====
{{See also|Czochralski method}}
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The upcasting (up-casting, upstream, or upward casting) is a method of either vertical or horizontal continuous casting of rods and pipes of various profiles (cylindrical, square, hexagonal, slabs etc.) of 8-30mm in diameter.<ref name=":0">{{Cite web |title=Technologies of continuous casting: horizontal, vertical downward, vertical upward – KMM {{!}} bronze and brass foundry {{!}} vertical continuous casting |url=https://kmmbronze.com/technologies-of-continuous-casting-horizontal-vertical-downward-vertical-upward/ |archive-url=https://web.archive.org/web/20210307141606/https://kmmbronze.com/technologies-of-continuous-casting-horizontal-vertical-downward-vertical-upward/ |archive-date=March 7, 2021 |access-date=2022-05-05 |language=en-GB}}</ref>  [[Copper]] (Cu), [[bronze]] (Cu·[[Tin|Sn]] alloy), [[List of named alloys|nickel alloys]] are usually used because of greater casting speed (in case of vertical upcasting) and because of better physical features obtained. The advantage of this method is that metals are almost oxygen-free and that the rate of product crystallization (solidification) may be adjusted in a crystallizer - a high-temperature resistant device that cools a growing metal rod or pipe by using water.<ref name=":0" />

The method is comparable to [[Czochralski method]] of growing [[silicon]] (Si) crystals, which is a [[metalloid]].