Casting Processes

Casting processes involve the use of molten material, usually metal. This molten material is then poured into a mould cavity that takes the form of the finished part. The molten material then cools, with heat generally being extracted via the mould, until it solidifies into the desired shape.

Different Types of Casting Processes

Although casting is one of the oldest known manufacturing techniques, modern advances in casting technology have led to a broad array of specialized casting methods.

Sand Casting
Investment Casting
Plaster Casting
Die Casting (Metal Casting Process)
Centrifugal Casting
Permanent Mold Casting

Advantages of Casting Process

Casting can produce very complex geometry parts with internal Cavities.
It can be used to make small (few hundred grams) to very large size part (thousands of kilograms). Any intricate shape can be Produced.
Any Material can be cast ferrous & non-ferrous.
It is economical, with very little wastage: the extra metal in each casting is re-mental and re-used.
Cast Metal is isotropic. It has the same physical and mechanical properties along and direction.
It is a process highly adaptable to the requirements of mass production large number of a given casting can be produced quickly. For Examples: In the automotive industry there is massive production of cast engine blocks and transmission cases.
Necessary tools required for castings are Cheaper & simple.
Certain metals & alloys are produced only by castings.

Casting Services

Permanent Mold Casting

Permanent mold casting shares similarities with die casting and centrifugal casting, notably the use of reusable molds. These can be made of steel, graphite, etc. and are generally used to cast materials such as lead, zinc, aluminum and magnesium alloys, certain bronzes, and cast iron. It is a low-pressure process with pouring usually done by hand using multiple molds on a turntable. As the molds rotate through the various stations, they are successively coated, closed, filled, opened, and emptied. One such method is known as slush casting, where the mold is filled but emptied before the metal fully hardens. Molten metal is dumped from the casting to produce a hollow, cast shell. A similar idea is used in the molding of hollow chocolate products such as Easter bunnies. The use of metal molds induces faster heat transfer through the mold, allowing the shell to harden while the core remains liquid.

Centrifugal Casting

Centrifugal Casting is used to produce long, cylindrical parts such as cast-iron pipe by relying on the g-forces developed in a spinning mold. Molten metal introduced into the mold is flung against the interior surface of the mold, producing a casting that can be free of voids. Originally invented as the de Laved process using water-cooled molds, the method is applied to symmetrical parts such as soil pipe and large gun barrels and has the advantage of producing parts using a minimal number of risers. For asymmetric parts that cannot be spun around their own axes, a variant of centrifugal casting, called pressure casting, arranges several parts around a common sprue and spins the molds around this axis. A similar idea is applied to the casting of very large gear rings, etc. Depending on the material being cast, metal or sand molds may be used.

Sand Casting

Sand casting typically relies on silica-based materials, such as synthetic or naturally-bonded sand. Casting sand generally consists of finely ground, spherical grains that can be tightly packed together into a smooth molding surface. The casting is designed to reduce the potential for tearing, cracking, or other flaws by allowing a moderate degree of flexibility and shrinkage during the cooling phase of the process. The sand can also be strengthened with the addition of clay, which helps the particles bond more closely. Automotive products such as engine blocks are manufactured through sand casting.
Sand casting involves several steps, including patternmaking, molding, melting and pouring, and cleaning. The pattern is the form around which the sand is packed, usually in two parts, the cope and the drag. After the sand is compacted enough to replicate the pattern, the cope is removed and the pattern extracted. Then, any additional inserts called core boxes are installed and the cope is replaced. After the metal has been poured and solidified, the casting is removed, trimmed of the risers and gates that were used in the pouring process, and cleaned of any adhered sand and scale.

Sand casting's main advantages as a casting process include:

Relatively inexpensive production costs, especially in low-volume runs.
The ability to fabricate large components.
A capacity for casting both ferrous and non-ferrous materials.
A low cost for post-casting tooling.
Despite its benefits, sand casting yields a lower degree of accuracy than do alternate methods and it can be difficult to sand cast components with a predetermined size and weight specifications. Furthermore, this process has a tendency to yield products with a comparatively rough surface finish