Platinum is a challenging material for casters because of its physical properties that result in possible crucible and flask reactions during melting and casting, high shrinkage porosity, and difficulties in filling of filigree items. This paper describes a collaborative research effort of several industrial partners and FEM on the influence of casting process parameters, initiated and financed by PGI. Based on an analysis of casting defects from industrial practice, experiments at FEM were performed in order to identify optimum casting parameters. Two common Pt alloys (95Pt5Co and 95Pt5Ru) and four different investment materials were used for casting experiments with variation of atmosphere, casting and flask temperature, tree design and centrifugal machine parameters. Detailed sample investigation found shrinkage porosity and surface defects as main problems. Optimized process parameters for heavy and filigree items were identified. Future research on platinum casting should focus on casting simulation in order to reduce experimental efforts and costs.

Author(s): Dr. Ulrich E. Klotz, Tiziana Drago