| The basic
technique of investment casting, under its popular name of 'lost wax casting'
has a history of use in the world reaching back 5-6 millennia, indeed, it
is one of the oldest known metal shaping methods.
Anklets in bronze, dating from 4500 BC, have been found in East Asia
and lost wax castings in Mesopotamia from about 4000 BC; the Chinese used
the technique about 2000-3000 BC to cast elaborate bronze objects and
many examples of cast forms with delicate filigree can be dated to the
Shang Dynasty. Knowledge of the process was diffused in the ancient world
and, by the time of Christ, it appears to have been practised in China,
South East Asia, Mesopotamia, Greece, Italy and Northern Europe.
Little is known of the progress of this versatile casting technique
for nearly 1000 years. Remarkable copper statutory, believed to be lost
wax castings from around 900 AD, have been found in India. By the 13th
century, bronze tomb effigies were being investment cast, examples being
those of King Henry III and Queen Eleanor in Westminster Abbey.
In South America, the Quimbaya goldsmiths from the Cauca Valley of
Columbia produced detailed and intricate hollowed cast gold figures and
jewellery by lost wax methods, and the Aztec goldsmiths are known to have
used the method.
Dentists took up the process, at around the turn of the century, to
produce accurate castings for gold fillings and dental inlays and it is
to this industry that much credit must go for developing some of the basic
methods upon which the modern engineering investment casting depends.
In 1932, they developed the lost wax ceramic block mould process (an alternative
to the ceramic shell process) and the cobalt-chromium series of heat resistant
alloys for dental applications and orthopaedic components
Today precision investment castings are used in the following: aircraft,
aerospace, automotives, computers and other electronics, food machinery,
machine tools and accessories, medical and dental equipment, optical equipment,
pumps and air compressors, small arms and rifles, textile machinery, and