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The investment casting (or lost wax) process can be traced back to the Neolithic period around 5000BC, when, in China, brass was cast to make personal ornaments. The process can be traced through to 3200BC in Mesopotamia and Israel later spreading around the Mediterranean, through Asia to South America and Africa.
The process becomes well documented from around 1100AD when Theophilus Presbyter wrote a treatise about the process -- some of which was content garnered from other sources. This documentation of the process led to its wider adoption, particularly for non-ferrous metals, and it is believed that his work led to the adoption of the process by Benvenuto Cellini (1500--1571), whose investment cast, bronze statue of Perseus with the Head of Medusa, stands in the Loggia dei Lanzi in Florence, Italy, to this day.
The process continues as a mainstream production route for individual pieces of art and jewellery because the relatively simple pattern making process is both cheap, suitable for the production of individual pieces, and very flexible -- allowing artisans the creative flexibility to alter their piece of work right up to the last moment .
Wider, mass market application of the process starts in the early 20th century, roughly coinciding with the publication of a paper by Dr. William H. Taggart of Chicago in 1907.
He detailed the use of a lost wax process for the production of dental plates and teeth.
The next major development occurs in the 1940's driven by the 2nd World War, and in particular aircraft and munitions production. The need for rapid rates of production, complex (often largely hollow) shapes, and material scarcity, drove development of the lost wax process, the materials used for pattern making etc., and the diversification of the materials cast.
Through this period the process was developed to permit the casting of ferrous alloys (iron, steels and stainless steels), and otherwise difficult to machine materials such as titanium. The ability of the process to produce near net shape products, thereby minimising waste and secondary machining demands offers particular advantages.
From its' early days as a process for the manufacture of relatively small decorative items in non-ferrous materials the ongoing development now sees the process used widely for the manufacture of industrial components in both ferrous and non-ferrous materials.
Later items range in size up to complete aluminium aircraft doors, steel castings weighing up to 300Kg, and aluminium castings up to 66Kg.
Latterly, the process has found widespread application in the production of nickel alloy aero engine turbine blades, and for the mass market with the production of the turbines for turbochargers.
The current processes in use in China have evolved to suit three key market areas...
A. Mid temperature wax (green wax) Silicon Sol processes which give the best tolerances and surface finishes, and can be used with a wide range of materials -- both ferrous and non-ferrous.
B. Low temperature wax (white wax)and Silicon Sol as the combined process for the first layer, This process is only suitable for carbon steels and a limited range of steel alloys -- this process produces improved tolerances and finishes that those of "C" below.
C. Low temperature wax (white wax) sodium silicate process. This variant of the process is only suitable for carbon steels and a limited range of steel alloys.
Investment, or lost wax casting has a long, well established history, particularly in China, and continues to be developed for new applications in new materials.