Centrifugal Casting
Only cylindrical shapes can be produced with centrifugal casting
Centrifugal Casting
In centrifugal casting, a
permanent mold is rotated about its axis at high speeds (300 to 3000
rpm) as the molten metal is poured. The molten metal is centrifugally
thrown towards the inside mold wall, where it solidifies after cooling.
The casting is usually a fine grain casting with a very fine-grained
outer diameter, which is resistant to atmospheric corrosion, a typical
situation with pipes. The inside diameter has more impurities and
inclusions, which can be machined away.
Size limits are u pto 3 m (10 feet) diameter and 15 m (50 feet) length.
Wall thickness can be 2.5 mm to 125 mm (0.1 - 5.0 in). The tolerances
that can be held on the OD can be as good as 2.5 mm (0.1 in) and on the
ID can be 3.8 mm (0.15 in). The surface finish ranges from 2.5 mm to
12.5 mm (0.1 - 0.5 in) rms. Typical materials that can be cast with
this process are iron, steel, stainless steels, and alloys of aluminum,
copper and nickel. Two materials can be cast by introducing a second
material during the process. Typical parts made by this process are
pipes, boilers, pressure vessels, flywheels, cylinder liners and other
parts that are axi-symmetric. Semi-Centrifugal Casting
The molds used can
be permanent or expendable, can be stacked as necessary. The rotational
speeds are lower than those used in centrifugal casting. The center
axis of the part has inclusion defects as well as porosity and thus is
suitable only for parts where this can be machined away. This process
is used for making wheels, nozzles and similar parts where the axis of
the part is removed by subsequent machining.
Centrifuging
Centrifuging is used for
forcing metal from a central axis of the equipment into individual mold
cavities that are placed on the circumference. This provides a means of
increasing the filling pressure within each mold and allows for
reproduction of intricate details. This method is often used for the
pouring of investment casting pattern.
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