Analysis of shrinkage, density and tensile strength of multi-step FLM metal parts depending on the print direction

Additive manufacturing (AM) of metallic parts has great potential for various industrial sectors. The different AM processes can be break down in single-step and multi-step processes. In case of multi-step processes a green body is printed first, which needs to be processed by subsequent steps (debinding and sintering) to become the final part with its final mechanical properties. An affordable approach to print green bodies is to use established metal injection moulding (MIM) materials and process these on a Fused Layer Modeling (FLM) printer. This approach could be a door opener for small and medium-sized companies to get into the topic of 3D metal printing. Especially because common single-stage processes are not economical for many companies due to high acquisition and operating costs as well as strict safety regulations. This paper examines material properties of FLM printed Catamold 316 LA green bodies and the subsequent metal parts. Since the printed parts shrink during the sintering process, the shrinkage behaviour in x-, y- and z-axis is investigated. The data is used to derive a factor that enables the correct scaling of CAD models of the parts prior to the printing process. The study also investigates the density of the printed green body as well as the sintered part and compares them with conventional MIM manufactured parts. Finally, the tensile strength of the final parts is determined for different printing orientation sand compared with conventional MIM manufactured parts.