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Casting

Casting

Casting is the process used to replicate three-dimensional prints or marks. It is widely used to obtain the exact replicate of toolmarks, tire tracks , shoeprints , and sometimes teeth. Casting is of paramount importance in forensic sciences as it allows a crime scene investigator to collect an identical copy of a mark or print from a scene, which can then be compared to a seized tool, shoe, or tire in order to establish a link between a suspect and a crime scene.

Casting can only be accomplished on three-dimensional marks or traces. In the case of tool-marks, for example, casting can be used to obtain the perfect copy of the mark of a screwdriver used to force open a door during a burglary. With a shoeprint, it allows for the shoeprint of a thief that was left in the soil outside the window of the apartment he or she exited to be preserved as evidence . A vehicle used to flee the scene of a murder could leave tire tracks in the snow, which can be recorded and saved for later comparison with a suspicious vehicle. Casting is also used to record dental characteristics of a body and compare these characteristics with known dental records in order to make a proper identification .

The choice of casting material depends on the mark to be copied and the surface on which it is found. For most toolmarks, a dental cast polymer is used. It consists of two pastes mixed together right before the cast is taken. Once mixed together, the paste is applied onto the mark and allowed to dry before being removed. With tire tracks or shoeprints, usually a plaster, such as plaster of Paris, is used. This kind of casting material does not provide as many details as the dental polymer, but can cover a bigger surface and will dry very well over surfaces such as soil. On snow, the use of plaster is not ideal, and molten sulfur offers a much better cast. Sulfur is heated until it liquefied and then poured onto the trace. As soon as the sulfur touches the cold snow, it immediately hardens and takes the shape of the print.

see also Crime scene investigation; Microscope, comparison.

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casting

casting or founding, shaping of metal by melting and pouring into a mold. Most castings, especially large ones, are made in sand molds. Sand, mixed with a binder to hold it together, is pressed around a wooden pattern that leaves a cavity in the sand. Molten metal is poured into the cavity and allowed to solidify. Permanent metal molds are used to make many small, simple parts; shell molding gives greater accuracy for a large volume of semiprecision parts. A two-step process, investment casting, produces small, complex shapes. Wax or plastic replicas of the parts are molded in accurate metal molds. These replicas are covered with sand in a box to make the final mold. When the whole mold is heated, the replica melts, leaving behind a cavity into which metal is poured. Large numbers of small, precise parts of metals that have a low melting point, such as zinc, are made by die-casting; in an automatic process, molten metal is forced under pressure into metal molds. Cast iron and cast steel are more brittle than forged iron and forged steel (see forging).

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Casting

2 Casting

Casting Grip 26

Power Stroke 26

Backcast 27

Forward Cast 28

Overall Tips, Points and Advice 28

Physical Conditioning 30

False Casting 31

Tailing Loop/Sudden Stop 31

Stop 32

Follow Through 33

Single Haul 34

Double Haul 35

Types of Casts 36

Posture (Body Position) 40

Distance Casting Trajectories 41

Wiggle Cast 41

Practice Methods 42

Wind Direction In Your Face 44

Wind On Your Back 44

Crosswinds 44

Off Hand Casting 45

Backwards Cast 45

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casting

casting Forming objects by pouring molten metal into moulds and allowing it to cool and solidify. Specialized processes, such as plastic moulding, composite moulding, cire perdue casting and die casting give greater dimensional accuracy, smoother surfaces and finer detail.

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casting

cast·ing / ˈkasting/ • n. an object made by pouring molten metal or other material into a mold.

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"casting." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 17 Aug. 2017 <http://www.encyclopedia.com>.

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"casting." The Oxford Pocket Dictionary of Current English. . Retrieved August 17, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/casting