J. Ceram. Sci. Tech., 08 [01] 155-160 (2017) DOI: 10.4416/JCST2016-00104 available online at: http://www.ceramic-science.com © 2017 Göller Verlag Droplet-Based Additive Manufacturing of Hard Metal Components by Thermoplastic 3D Printing (T3DP) U. Scheithauer * , J. Pötschke, S. Weingarten, E. Schwarzer, A. Vornberger, T. Moritz, A. Michaelis Fraunhofer IKTS, Institute for Ceramic Technologies and Systems, Winterbergstrasse 28, D-01277 Dresden, Germany received November 5, 2016; received in revised form December 25, 2016; accepted January 31, 2017 Abstract Thermoplastic 3D printing (T3DP) is an Additive Manufacturing (AM) technology that cannot only be used for producing ceramic, metal or multi-material components, but for the Additive Manufacturing of hard metal or cemented carbide components, too. This is possible because the technology combines the precise deposition of small droplets of molten thermoplastic hard-metal-containing suspensions and an increasing viscosity resulting from a cooling process as curing mechanism. This paper demonstrates the suitability of the T3DP-process for the AM of hard metal compounds. Using WC-Co suspensions with a solid content of 67 vol%, single droplets were deposited and first components manufactured. After de-binding and sintering, completely dense samples were achieved. Zero porosity was determined in the microstruc- tures analyzed by means of FESEM and optical microscopy. Keywords: Additive Manufacturing, Thermoplastic 3D printing, hard metal, cemented carbide, WC-Co I. Introduction Additive Manufacturing (AM) is a manufacturing pro- cess that allows the build-up of objects layer-by-layer. Formerly, AM was also referred to as rapid prototyping (RP) or Solid Freeform Fabrication (SFF). In popular sci- ence, the term “3D printing” is used as a synonym for Additive Manufacturing. According to ASTM, Additive Manufacturing is a “process of joining material to make objects from 3D model data, usually layer upon layer” 1 . Today, AM of polymers is state-of-the-art. In the field of metals and ceramics, it is possible to process more and more materials. For hard metal materials, the technical application of AM technologies has so far been limited. First investigations were described by Zong et al. in 1992. WC-Co-Ni pow- der mixtures were processed by means of Selective Laser Sintering (SLS) 2 . Laoui et al. used WC-9 wt% Co for SLS and infiltrated the manufactured structures with copper 3 , Kruth et al. made 3D pyramid parts from WC-12 wt% Co using SLS followed by cobalt infiltration and achieved a maximum density of 89.5 % 4 . The manufacturing of WC- Co composite using SLS followed by Cu infiltration was described by Gu et al. 5, 6 . Kumar produced a density of 96 % with non-infiltrated WC-9Co-parts from the SLS- process 7 . The Additive Manufacturing of hard metal components with 3D printing was investigated too. Kelley produced a green density of 52 vol% using a powder-bed-based pro- * Corresponding author: uwe.scheithauer@ikts.fraunhofer.de cess and a particle size between 38 µm and 53 µm by using a special densification process for the powder bed 8 . Ker- nan et al. described a suspension-based 3D printing pro- cess and achieved a green density of about 47 % of theo- retical density for a finer powder mixture, which allowed the realization of a layer thickness of 25 µm 9 . Thermoplastic 3D printing (T3DP) has been developed as an AM technology 10 , which can be used for the pro- duction of dense ceramic components independent of the physical properties of the used powders (e.g. light absorp- tion) 11 as well as for the production of multi-material- components 12, 13 to combine multi-functional properties with freedom in design and construction 14 . The combi- nation of precise deposition of small droplets with the fast deposition of filaments is one of the main advantages of T3DP. The small droplets enable a high resolution in criti- cal volumes and the deposition of filaments guarantees a high production speed for volumes where no change in material occurs. The AM of dense alumina components with the use of T3DP could be demonstrated 10 as well as the AM of multi-material components (zirconia-stainless steel) 11, 12 . Molten thermoplastic feedstocks (=suspensions) are pro- cessed in a dispensing unit with xyz positioning. The melt- ing temperature of the suspensions (approx. 100 °C) and the viscosity are relatively low compared to the thermo- plastic feedstocks that are used in conventional Fused Fil- ament Fabrication (FFF). The main goal of the presented study was to investigate if the T3DP process would also be adequate for the AM of