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​Investment casting history

Investment casting is also called lost wax casting.Its products are precise,complex and near to final shape.We could use directly with little machining or no machining.So investment casting is a net shaped advanced technology.

Investment casting history can be traced back to 4000 years ago.The earliest origin countries are Egypt,China and India, then spread to other countries in Africa and Europe.

In ancient China, leaving many boutique investment castings, such as the spring and autumn period and the late Wang Ziwu ding, copper banned, warring states, zeng hou b of the plate, han dynasty mixed copper furnace boshan ship, long letter palace lantern, the sui dynasty of Dong Qinzao MiTuo gold statue. Armillary sphere of Ming dynasty, wudang zhenwu sovereigns, qing palace gate of bronze lions, etc.

In west Africa, about the 11th century ago, make a lot of investment castings. In the 16th century, the investment casting process is widely used by artists and sculptors, Perseus fairy and banshee head's statue made by Cai Li ni (Benvenuto Cellini),is one of the most outstanding works.

In the end of the 19th century, dental investment casting process,combines with centrifugal casting technology to produce dental castings. At the beginning of the 20th century,to produce more precise dental castings, people began to study factors affecting the stability of wax pattern and shell size,and some metal and alloy solidification shrinkage performance, In the early 1930 s they adjusted the casting materials used. From 1900 to 1940 in this area up to more than 400 patents. The jewelry industry also widely adopted investment casting technology.

Aviation engine parts worked in a harsh environment , such as turbocharger, if using traditional alloy, it will cannot satisfy the requirement of performance. In the late 1930 s, people found drill base alloy studied by Austenal laboratory has excellent performance in high temperature, can be used for the turbocharger. But this kind of alloy is hard to processing, thus investment casting has become the metal forming process,The it was quick developed into industrial technology, in aviation, national defense industry sector, and quickly applied to other industry sectors.

With the development of technology,investment casting could not only produce small parts,but also could be used for manufacturing large parts. the largest outline of investment castings has nearly reached 2 m, and the minimum wall thickness is less than 2 mm. At the same time also more precision investment castings could be made, in addition to the linear tolerance, parts also can achieve higher geometric tolerance. Surface roughness of investment castings is becoming much smaller, can achieve Ra0.4 um.

In addition, due to the improvement of investment casting material and the development of technology, the mechanical properties of castings is getting better and better. Turbine blade is a good example. The improvement of  turbine blade material and technological progress, make its performance has been greatly improved. From 60s to 90s in 1990, the material of turbine blade (American brand)changed from IN100, B1900 to MM200, MM247, then to PWA1480; 

At the same time, thanks to the development of solidification technology, turbine blades from traditional isometric (EQ) to the directional solidification(DS) of the columnar crystal,finally to the exhibition to single crystal (SC) blade, so that the work temperature of turbine blade improved from 980 ℃ to 1100 ℃.