Novel testing device and routine to characterise the spreadability of powders for powder bed fusion processes – a problem-oriented approach

ABSTRACT

Currently there is considerable interest in understanding and quantifying the powder characteristics that affect the quality of the top spread powder layer for processes such as powder bed fusion and binder jetting. For this purpose, a new testing device has been developed in order to assess several aspects of this top spread powder layer. Using different measurement procedures, the roughness of the top layer, the surface coverage of a single spread powder layer and the powder bed density of an entire spreading experiment can be determined. Since the tester is freely programmable, the individual process steps of spreading a single powder layer can also be varied. Using these methods, the influence of different process parameters such as e.g. the spreading velocity or the distance between the blade and the building platform, which is also referred to as gap size in general, on the quality of the top or only a single spread layer and on the powder bed packing density can be examined. This study presents the new test device as well as the corresponding measurement procedures mentioned, the reproducibility of the results, which, depending on the measurement method and the measured parameter, range between 0.24 and 4.81%, and the influence of the spreading strategy, which defines the chronological order of the single steps during spreading.

KEYWORDS:

• Additive manufacturing
• powder bed fusion
• spreading
• spreadability
• testing
• python

Disclosure statement

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

Additional information

Notes on contributors

Marco Mitterlehner

Marco Mitterlehner studied Technical Chemistry at the Technische Universität Wien, Austria, where he also did his PhD thesis. He started working in the field of Additive Manufacturing during his master studies in 2015. Throughout his university research, Mr. Mitterlehner was particularly concerned with the spreadability, storage and processing of AM powders. He is now working as process and product developer for AM powders in the R&D department of voestalpine Böhler Edelstahl GmbH & Co KG in Kapfenberg, Austria.

Herbert Danninger

Herbert Danninger is retired professor for Chemical Technology of Inorganic Materials at Technische Universität Wien, Vienna, Austria. He has been active in powder metallurgy for more than 40 years and is author/co-author of 500+ publications. From 2009 to 2020 he was chairman of the ‘Gemeinschaftsausschuss Pulvermetallurgie', the PM association of the German-speaking countries. He holds honorary doctoral degrees of Technical University Cluj-Napoca (Romania), Universidad Carlos III de Madrid (Spain) and Universitatea din Craiova (Romania) and is Fellow of APMI and EPMA. In 2020 he was awarded the ‘Ivor Jenkins Medal’ of IOM3.

Christian Gierl–Mayer

Christian Gierl-Mayer studied Technical Chemistry at Technische Universität Wien (TU Wien), Vienna, Austria. He got his Master in 1996 and his PhD in 2000 from TU Wien. After 3 years in private research institute (ofi-Austrian Research Institute of Chemistry and Technology) he re-joined the powder metallurgy group of Prof. Herbert Danninger as senior researcher. He got his habilitation in 2019 for ‘Thermoananlytical Investigation of Interactions between Powder Metallurgy Steels and the Atmosphere during Sintering’, and became Associate Professor in 2019. He is currently leading the research group Powder Metallurgy at TU Wien and the Division Chemical Technologies, Institute of Chemical Technologies and Analytics. His publication record is about 260 publications in journals and conference proceedings, 4 book chapters and 7 patents.

Johannes Frank

Since 1999 Johannes Frank is employed at the Technische Universität Wien (TU Wien), Vienna, Austria. He started as technician at the Institute of Materials Chemistry. In 2013 he became leader of the Joint Workshop of the Faculty of Technical Chemistry at the TU Wien. He is responsible for design, construction and fabrication of prototypes and machinery.

Wolfgang Tomischko

Wolfgang Tomischko has worked in the electronics industry since leaving school in 1977. He has worked in this field as a developer in several Austrian medium-sized companies. Since 2007 he has been a technical employee at the Technische Universität Wien, Vienna, Austria. Since 2014, he has also held a lectureship in the field of electrical engineering at the same university.

Harald Gschiel

Harald Gschiel has studied Technical Chemistry at the Vienna University of Technology, where he also did his PhD thesis focusing on Powder Metallurgy and Solid Oxide Fuel Cells. After leaving university in 2015, he has been constantly working in the field of Additive Manufacturing, now employed at voestalpine Böhler Edelstahl GmbH & Co KG. His topics are mainly powder processing, powder characterization and product development.