Dr.

Hein, Sebastian Boris

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  • Publication
    Evaluation of the Processing Capability of Aluminium Alloy 6061 for Metal Binder Jetting
    ( 2021)
    Wieland, Sandra
    ;
    Hein, Sebastian Boris
    ;
    Weber, David
    Sinter-based Additive Manufacturing (AM) processes such as Metal Binder Jetting (MBJ) combine the advantages of AM, such as freedom of design and low material loss, with comparatively high economic efficiency. However, sintering of aluminium and aluminium alloys is challenging due to the stable oxide layer, and is becoming even more difficult by the addition of an organic binder. In this work, several commercially available 6061 powders in a particle size range suitable for MBJ have been investigated regarding their processing capability. After analysing the sinterability of loose powder at different temperatures and atmospheric conditions, MBJ binder was added to study the influence of the organic components and various debinding conditions. The powder which achieved the highest sintered density was selected for MBJ trials, and the resulting green and sintered density of simple test parts was investigated.
  • Publication
    Additive Manufacturing of Functional Metallic Materials
    ( 2019)
    Wieland, Sandra
    ;
    Goossens, Nils
    ;
    Weck, Christian
    ;
    Hein, Sebastian Boris
    Additive Manufacturing (AM) has become increasingly popular during the recent years, but up to now AM research is mainly focused on structural applications. However, the advantages of AM technologies, as the ability to realise optimized designs with reduced material consumption, apply similarly for functional metallic materials. Additionally, for some materials the specific microstructure formed by an AM method can be beneficial for the functional properties or for further processing steps. Utilizing this advantages, AM could significantly promote getting innovative materials which are difficult to produce or machine into practical application. A brief overview on the status of AM of functional materials will be given and potentials and challenges will be illustrated by the cases of Laser Beam Melting of soft magnetic Fe-Ni-alloys and magnetocaloric La(Fe,Si)13-alloys.
  • Patent
    Verfahren zur Herstellung von Wendeln
    ( 2019)
    Wöstmann, Franz-Josef
    ;
    Kramer, Lutz
    ;
    Heuser, Michael
    ;
    Hein, Sebastian Boris
    ;
    Mulser, Marco
    ;
    Hartwig, Thomas
    Die Anmeldung betrifft ein Verfahren zur Herstellung metallischer Wendeln, sowie die in dem Verfahren hergestellten Wendeln. Das Verfahren umfasst die folgenden Schritte: Bereitstellen einer wendelförmigen Kavität (1.1) in einem Spritzgießwerkzeug; Füllen der Kavität (1.1) mit einer ein Pulver aus einem sinterfähigen Material enthaltenden Formmasse; Herstellen eines Grünteils (2) durch Erstarren der Formmasse; Entnehmen des Grünteils (2) aus dem Spritzgießwerkzeug; Entbinderung des Grünteils (2); Sintern des Grünteils (2).
  • Publication
    Influence of Particle Size Distribution in Metal Binder Jetting - Effects on the Properties of Green and Sintered Parts
    ( 2019)
    Barthel, Bastian
    ;
    Hein, Sebastian Boris
    ;
    Aumund-Kopp, Claus
    ;
    Petzoldt, Frank
    In binder jetting, parts are build layer-by-layer in a powder bed by locally printing an organic binder. After curing the binder, the green parts are cleaned of the loose powder. A combined furnace process removes the binder and fuses the particles together. The microstructure of a sintered part depends on powder properties, green part density and sintering parameters. The influence of the particle size distribution (PSD) on the sintering behaviour is widely known. With decreasing particle size, the sintering activity increases. This enables a reduction of the sintering temperature and reduces the distortion potential. Finer powders have higher capillary forces and tend to agglomerate, which affects packing density and flowability. This paper takes a closer look at the influence of PSD and layer thickness on density and dimensional accuracy of the green parts. The effects on shrinkage behaviour and sintering density of binder-jetted parts are also shown.
  • Patent
    Verfahren zum Metallpulverspritzgießen
    ( 2019)
    Wöstmann, Franz-Josef
    ;
    Kramer, Lutz
    ;
    Heuser, Michael
    ;
    Hein, Sebastian Boris
    ;
    Hartwig, Thomas
    ;
    Mulser, Marco
    Die Anmeldung betrifft ein Verfahren zur Herstellung eines Gusskörpers. Das Verfahren umfasst die Schritte: Herstellen eines oder mehrerer Einlegeteile; Bereitstellen des einen oder der mehreren Einlegeteile in einer Gussform eines Spritzgießwerkzeugs, so dass eine Kavität, die der Form des Gusskörpers entspricht, von dem einen oder den mehreren Einlegeteilen oder von dem einen oder den mehreren Einlegeteilen zusammen mit der Gussform, gebildet wird; Füllen der Kavität mit einer ein Pulver aus einem sinterfähigen Material enthaltenden Formmasse; Herstellen eines Grünteils durch Erstarren der Formmasse; Entnehmen eines Zwischenprodukts, bestehend aus Grünteil und dem einen oder den mehreren Einlegeteilen aus dem Spritzgießwerkzeug; Entfernen des einen Einlegeteils oder der mehreren Einlegeteile aus dem Zwischenprodukt; Entbinderung des Grünteils; Sintern des Grünteils.
  • Publication
    Fused Filament Fabrication of Biodegradable Materials for Implants
    ( 2019)
    Hein, Sebastian Boris
    ;
    Reineke, Lea
    ;
    Reinkemeyer, Vincent
    Biodegradable materials receive increasing interest in medical technology, wherever applicable sensibly. Bone-related implant applications can be met with powder technological approaches, if such implants consist of biocompatible metals or ceramics. In case of biodegradable implants, the underlying desire is to omit the need for removal surgeries, which may arise for long-term implants or for children, still in their growth. This spares the patient additional surgical treatment. Of course, patient-specific implants directly relate to 3D printing. We combine the technological possibilities of fused filament fabrication (FFF) with biodegradable materials. Two material concepts, a metal-ceramic composite of iron and tricalcium phosphate, and a bioceramic based on calcium phosphate were used for FFF of sintered parts, applicable e.g. in oral and maxillofacial surgery. Feedstock and process adaptions were carried out and lead to very promising results in both cases. A potential future workflow concept for implant manufacturing was developed on this basis.
  • Publication
    Manufacturing and properties of metal parts made by fused filament fabrication
    ( 2018)
    Andresen, Olaf
    ;
    Riecker, Sebastian
    ;
    Studnitzky, Thomas
    ;
    Hein, Sebastian Boris
    ;
    Lohse, Uwe
    ;
    Kleback, Bernd
    A complete process chain for the additive manufacturing of metal components by means of Fused Filament Fabrication (FFF) is being developed in a joint project. The final goal is to develop a process chain that provides ready-to-use parts of industrial quality at moderate investment cost. This includes a 4-axis milling machine for green and final machining of the as-printed and sintered parts and a compact furnace for debinding and sintering. This paper reports about ongoing work in the funded joint project ""AMCC Line"". A thermoplastic filament with a high metal powder loading of 55 vol% was developed and successfully processed on commercially available FFF printers. In order to achieve near full density metallic parts, a debinding treatment is required that removes the organic constituents. Subsequently, the individual metal particles are joined by diffusion in the solid state (sintering) and a fully metallic part is obtained. It was possible to print and heat-treat different parts in stainless steel 316L. Examples of achievable geometries and a strategy for dimensional and mechanical property monitoring is presented that provides information about the industrial viability of this process chain.
  • Publication
    Lost-form powder injection moulding - combining additive manufacturing and PIM
    ( 2018)
    Hein, Sebastian Boris
    ;
    Otte, Anna- Lena
    Powder injection moulding (PIM) is often characterized by being a process for the mass production of relatively complex parts. When it comes to highly complex parts and lower part numbers, additive manufacturing (AM) is regarded as complementary to PIM. Still, AM processes do not make use of the same material as PIM, or even if, are processed differently, which leads to parts with different properties or the need to adjust processing steps (e.g. sintering conditions). By combining PIM with AM in a sensible way, parts can be realized that make use of the PIM feedstock but have considerably increased complexity and can be produced with cheap moulds, thus enabling an economical production of small series in production quality. To demonstrate this approach, we produced sacrificial mould inserts of a suitable polymer by digital light processing (DLP), placed them in a simple mould, injected a metal-ceramic feedstock and thermally degraded the AM structures prior to the sintering of the powder-containing parts. The design of the AM part and its material properties (strength, thermal behaviour) are crucial for the success of the process. The successful production of metal-ceramic parts verified the applicability of the lost-form PIM process with AM parts.
  • Publication
    Additive Manufacturing of Stainless Steel/Zirconia Ceramic Composite Parts by Fused Filament Fabrication and Sintering
    ( 2018)
    Godlinski, Dirk
    ;
    Müller, Y.
    ;
    Hein, Sebastian Boris
    Motivation of this work is to demonstrate the combination of additive manufacturing andpowder technology for individual metal-ceramic composite parts. 316L-zirconia composites areproduced by extrusion of a powder filled thermoplastic feedstock through a hot nozzle (fused filamentfabrication, FFF) followed by a debinding and sintering step. The formulation and optimization of differentfeedstocks to printable filaments and the subsequent debinding and sintering cycles are described. Testparts have been fabricated and characterised in terms of geometrical quality, sinter shrinkage, density,mechanical strength, hardness, and microstructure. A suitable material-process combination has beendeveloped that gives similar microstructure and properties of parts compared to powder injectionmoulding (PIM) of the same material system. Areas of applications like individual and small series ofmedical parts are addressed.
  • Publication
    Effects of the composition of stainless steel / zirconium dioxide metal-ceramic composites on the material performance
    ( 2016)
    Hein, Sebastian Boris
    ;
    Kalka, Sebastian
    ;
    Busse, Matthias
    Combining the properties of metals and ceramics is challenging, mostly due to differences in physical properties (e.g. thermal expansion) and the required processing conditions. Nonetheless, property profiles are achievable that neither pure component shows. Thus, new applications or improvements for existing ones may result. This work deals with the system 316L-ZrO2 and the influence of the composition on the material performance. A thorough investigation of composites over the complete range of composition was carried out. The transition from particle composites to interpenetrating phase composites (IPCs) on both sides of the composition window could be correlated to percolation theory and the change of microstructure and material properties (hardness, compression and bending behaviour) was analysed. Some properties changed erratically, others more steadily, leading to interesting property combinations. Our study furthermore showed the possibility to use those composites in two- and three-component PIM parts, bearing great potential for positive substance joining during sintering.