The process of investment casting has come to occupy a key position in the range of modern casting techniques.
The term investment casting derives from the characteristic use of mobile ceramic slurries, or “investment”, to form moulds with extremely smooth surfaces. However, “Lost Wax Casting”, “Precision Casting”, “Micro Fusion” are also commonly used terms to identify this technique. The technique of investment casting allows the achievement of unparalleled precision with reference to the most important criteria of the modern casting process: dimensional accuracy, surface smoothness and shape details. The ceramic nature of the mould in investment casting is crucial to the process and lends itself to a variety of casting applications and an even wider selection of alloys.
There are, however, certain characteristics of the process which require special attention. In particular, an appropriate choice of the refractory raw materials is necessary in order to meet the requested casting properties. Thermal expansion, shell strength, gas permeability, shell cracking are only few of the properties that can be controlled by an appropriate choice of the refractory flour and stucco.
Imerys manufactures a wide range of minerals and specific product grades in order to meet virtually all requirements of the Investment Casting process.
White fused alumina, white fused mullite and andalusite are recommended as refractory flour and stucco for the face-coat.
In this respect these materials are regarded as a better performing and cost-effective alternative to replace zircon silicate. Molochite, Mulgrain and Chamotte are specifically designed for the shell back-up and Teco-Sil completes the range of products used in this process.
All investment casting grades are produced under carefully controlled conditions in order to provide our customer with the quality and the consistency that is necessary to operate the ceramic moulding process.