Powder condition and spreading parameter impact on green and sintered density in metal binder jetting

ABSTRACT

Metal binder jetting is a high throughput additive manufacturing process of growing interest. The progress is driven by improvements in machine technology, enabling the processing of finer powders to produce homogeneous, dense final parts. However, the strong cohesive forces of fine metal powders impair flowability, packing behaviour and thus the properties relevant for powder spreading. This paper investigates the impact of powder condition and spreading parameters on green and sintered density using an Analysis of Variance. Parts from dried and from untreated powder are printed, varying in layer thickness, roller diameter, supply-to-spread ratio, translational and rotational roller speed. Powder drying increases the statistical impact of the spreading parameter and improves the green density, while the sintered density remains unchanged. Layer thickness and roller diameter have the most significant effect. Furthermore, the spreading parameter combinations that resulted in a high green density also provided a high sintered density.

KEYWORDS:

• Additive manufacturing
• metal binder jetting
• powder spreading
• green density
• sintered density
• powder moisture
• powder drying

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Bastian Barthel

Bastian Barthel studied industrial engineering and management as well as production technology, both with a focus on material science, at the University of Bremen. During his studies, he worked for 4 years at IWT Bremen in the Heat Treatment department before joining Fraunhofer IFAM in 2016, to start focusing on Metal Binder Jetting. After graduating in 2017, he became a Project Manager in the Additive Manufacturing group of the Powder Technology department and is pursuing his doctoral thesis on process development in Metal Binder Jetting.

Frederik Janas

Frederik Janas studied medical engineering at the University of Bremerhaven as well as production technology, with a focus on material science, at the University of Bremen. At the end of his bachelor studies, he worked for 1 year at Atesos Medical in the construction department of medical devices. In 2018 during his master he joined the Fraunhofer IFAM, to work on Metal Binder Jetting. In 2019 he completed his studies with a thesis based on the optimisation of the Metal Binder Jetting process.

Sandra Wieland

Sandra Wieland studied material science at Technical University Dresden and is working at Fraunhofer IFAM since her graduation in 2014. Besides her occupation as a project manager, she pursued her doctoral thesis on sintering of magnetocaloric LaFeSi-alloys, which was completed in 2019. Currently, she is the head of the Functional Materials and Components group in the Powder Technology department at Fraunhofer IFAM.