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Investment casting is an industrial process based on lost-wax casting,
one of the oldest known metal-forming techniques.
 The term "lost-wax casting" can also refer to modern investment casting processes.
Investment casting has been used in various forms for the last 5,000 years.
In its earliest forms, beeswax was used to form patterns necessary for the casting process.
Today, more advanced waxes, refractory materials and specialist alloys are typically
used for making patterns.
Investment casting is valued for its ability to produce components with accuracy, repeatability,
versatility and integrity in a variety of metals and high-performance alloys.
The fragile wax patterns must withstand forces encountered during the mold making.
Much of the wax used in investment casting can be reclaimed and reused
. Lost-foam casting is a modern form of investment casting that eliminates certain steps
in the process.
Investment casting derives its name from the pattern being invested
(surrounded) with a refractory material. Many materials are suitable
for investment casting; examples are stainless steel alloys, brass, aluminium, carbon steel and glass.
The material is poured into a cavity in a refractory material that is an
exact duplicate of the desired part. Due to the hardness of refractory materials used,
investment casting can produce products with exceptional surface qualities,
which can reduce the need for secondary machine processes.
The process can be used for both small castings of a few ounces
and large castings weighing several hundred pounds.
It can be more expensive than die casting or sand casting,
but per-unit costs decrease with large volumes.
Investment casting can produce complicated shapes
that would be difficult or impossible with other casting methods.
It can also produce products with exceptional
surface qualities and low tolerances with minimal surface finishing or machining required
Advantages of investment casting
Excellent surface finish
High dimensional accuracy
Extremely intricate parts are castable
Almost any metal can be cast
No flash or parting lines
Disdvantages of investment casting
The main disadvantage is the overall cost, especially for short-run productions
Some of the reasons for the high cost include specialized equipment,\
costly refractories and binders, many operations to make a mould,
a lot of labor is needed and occasional minute defects.
However, the cost is still less than producing the same part
by machining from bar stock; for example, gun manufacturing
has moved to investment casting to lower costs of producing pistols
Investment casting is used with almost any castable metal.
However, aluminium alloys, copper alloys, and steel are the most common.
In industrial use the size limits are 3 g (0.1 oz) to several hundred kilograms.
The cross-sectional limits are 0.6 mm (0.024 in) to 75 mm (3.0 in).
Investment casting is used in the aerospace and power generation
industries to produce turbine blades with complex shapes or cooling systems
. Blades produced by investment casting can include single-crystal (SX),
directionally solidified (DS), or conventional equiaxed blades
. Investment casting is also widely used by firearms
manufacturers to fabricate firearm receivers, triggers, hammers,
and other precision parts at low cost. Other industries
that use standard investment-cast parts include military,
medical, commercial and automotive.