In its December edition Casting, Plant and Technology International published the following article about the key role of Kerphalite KF for precision casting written by Joachim Wolff (Imerys Refractory Minerals), Sabine Umla-Latz and Martine Dahlmann (Hüttenes-Albertus).
Complex cast parts such as turbocharger housings play a central role in the design of modern high-performance engines. Due to its particular characteristics, silica sand has its limits as a moulding material when it comes to casting finely structured components, reduced wall thicknesses and perfect surfaces. Thanks to its high temperature load strength and a strong resistance to metal penetration, Kerphalite™ KF, a special sand produced in Brittany for special applications in the foundry industry, has proven itself suitable for these types of applications in many foundries.
In central Europe, silica sand is available in large quantities and in good qualities, and is widely used in foundries as an economical basic moulding material. But it also has negative properties, which may lead to problems when producing sophisticated castings. These particularly include the so-called quartz inversion, i.e. the abrupt expansion of the specific volume at 573°C. It occurs during virtually every casting process and may lead to sand expansion defects, mainly in the form of finning (also called veining). The moulding material can crack under high temperature load, allowing liquid metal to seep into the resulting cracks and cavities. To read the article on pages 14 click on following title “Kerphalite™ KF : high performance moulding material for precision casting”