This paper is concerned with shrinkage porosities in jewelry castings and with a method that helps to reduce them. As shrinkage defects are mainly due to incorrect feeding of components and as some jewelry pieces have a complex geometry, it is sometimes difficult to apply the correct technical casting procedures. A method, based on the creation of a thermal gradient in the mold, was developed, and a statistical analysis of the results proves its ability to help with component feeding and thus reduce shrinkage porosities. This paper deals not only with the defects analysis but also with the ability of the investment material to be able to allow the creation and maintenance of the thermal gradient during the whole casting process.

Author(s): Dr. Filipe Silva