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Continuous casting is a process in which molten copper alloy is
fed through an open-ended graphite mold yielding a bar, tube or
shape of the required cross-section. The solidified form is cooled
and withdrawn at a controlled rate from the water-cooled mold
by rollers and the material is cut to length with a traveling
saw.
There are a number of advantages offered by continuous casting.
Since it operates as a true gravity-fed bottom-flow casting method,
the process precludes the possible trapping of casual dirt and
dross in the casting. Lower casting temperatures are possible
and this, combined with the chill mold and the directional solidification
inherent in this process, promotes a homogeneous, fine-grained,
high-density product with high yield.
About 20 different copper alloys are in common use for solid and
hollow round bars, as well as flat, rectangular, square, hexagonal
and other shapes.
Continuous cast bronze bar is used extensively for machining into
bushings, bearings and a variety of mechanical components used
in mining, steel mills, the pulp and paper industry, shipbuilding,
construction, and for other equipment. The principal requirements
of a bronze bearing alloy are compressive strength, fatigue resistance,
temperature endurance, conformity and good seizure, corrosion
and wear resistance. The mechanical properties of bronze continuous
castings should be noted when selecting alloys for particular
purposes, since there may be some differences in values which
should be used to advantage. A higher yield strength is common.
Continuously cast bronze solids and hollows are made in outside
diameters from _” to 16 inches (12 mm to 406 mm) in Canada and
this is believed to be the largest range in North America. Various
inside diameters are produced by using different cores in the
molds. Length is also an important feature. Large-diameter hollow
bars can be continuously cast in lengths up to 105 inches (2670
mm). In some cases, the bars are “sliced” into the lengths required
for components, while in others the length can be used to advantage
for machining a long bearing or bushing, such as may be used for
a propeller shaft.
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