Characterization of Slurry-Cast Layer Compounds for 3D Printing of High Strength Casting Cores

Abstract

Additive manufacturing of casting cores and molds is state of the art in industrial application today. However, improving the properties of chemically bonded casting cores regarding temperature stability, bending strength, and surface quality is still a major challenge. The process of slurry-based 3D printing allows the fabrication of dense structures and therefore sinterable casting cores. This paper presents a study of the slurry-based fabrication of ceramic layer compounds focusing on the drying process and the achievable properties in slurry-based 3D printing of casting cores. This study aims at contributing to a better understanding of the interrelations between the drying conditions in the 3D printing process and the properties of sintered specimens relating thereto. The drying intensity influenced by an IR heater as well as the drying periods are varied for layer thicknesses of 50, 75, and 100 µm. Within this study, a process window applicable for 3D printing of sinterable casting cores is identified and further indications are given for optimization potentials. At layer heights of 75 µm, bending strengths between ~8 and 11 MPa as well as densities of around 50% of the theoretical density were achieved. Since the mean roughness depth Rz is determined to be <30 µm in plane, an application of slurry-based 3D printing in investment casting is conceivable.

Influence of the Resin System and Sand Type on the Infiltration of 3D-Printed Sand Tools

“…The binder jetting process and the properties of sand cores relevant to the casting process are studied frequently. Sand cores must be strong enough to withstand the thermal and mechanical loads during casting but still be removable from the casting after the solidification of the metal [ 21 ]. Typical flexural strengths are between 2.5 and 5 MPa [ 22 ]—strengths allow only single-use as lost tooling in gravity or low-pressure die casting.…”