TY - THES

T1 - Development of feedstocks for extrusion based additive manufacturing for catalytic debinding

AU - Hentschel, Lukas

N1 - embargoed until 29-04-2024

PY - 2019

Y1 - 2019

N2 - Additive manufacturing gained attraction over the last years, especially for the metal industry. Usually, selective laser sintering (SLS) or other high energy deposition methods are used to fabricate parts made out of metal materials. Such devices are expensive due to the high energy systems needed for those technologies. New developments concerning polymer based feedstock systems enable the possibility to produce full dens metal parts with the fused filament fabrication (FFF) method. The whole process chain is adapted from the powder injection molding technique. Thus, the process chain includes compounding, filament production, shaping, debinding, and sintering. However, the method is still in its infancy, and only a small variety of filaments are commercially available, especially for catalytic debinding. A new formulation of a catalytic debindable binder system was developed within this thesis. Therefore, the materials are compounded with different techniques and mixed with a stainless steel powder up to 55 vol%. Filaments were produced out of this feedstock, which were further used for 3D-printing. The processability and the influence of the previous processing steps on the materials were studied by thermogravimetric analysis. The scope of this thesis is to define a compounding method for the feedstock, producing of filaments, and to study the processability of the filaments with a desktop 3D-printer. It is shown that the materials show chemical interactions and water sensitivity. Thus, a suitable compounding procedure was defined to avoid chemical degradation. Therefore, the compounding was divided into three individual steps. Some deviations of the differently produced filaments could be detected, but those are not critical for this application and are more related to homogeneity. Further, a study of different processing settings was performed to determine a suitable range for various parameters. Consequently, recommendations concerning the printing bed, temperatures and printing speed are given. An examination showed the influence of processing settings on the weight and printing accuracy of the printed geometry, which was related to the final porosity or density of the sintered part.

AB - Additive manufacturing gained attraction over the last years, especially for the metal industry. Usually, selective laser sintering (SLS) or other high energy deposition methods are used to fabricate parts made out of metal materials. Such devices are expensive due to the high energy systems needed for those technologies. New developments concerning polymer based feedstock systems enable the possibility to produce full dens metal parts with the fused filament fabrication (FFF) method. The whole process chain is adapted from the powder injection molding technique. Thus, the process chain includes compounding, filament production, shaping, debinding, and sintering. However, the method is still in its infancy, and only a small variety of filaments are commercially available, especially for catalytic debinding. A new formulation of a catalytic debindable binder system was developed within this thesis. Therefore, the materials are compounded with different techniques and mixed with a stainless steel powder up to 55 vol%. Filaments were produced out of this feedstock, which were further used for 3D-printing. The processability and the influence of the previous processing steps on the materials were studied by thermogravimetric analysis. The scope of this thesis is to define a compounding method for the feedstock, producing of filaments, and to study the processability of the filaments with a desktop 3D-printer. It is shown that the materials show chemical interactions and water sensitivity. Thus, a suitable compounding procedure was defined to avoid chemical degradation. Therefore, the compounding was divided into three individual steps. Some deviations of the differently produced filaments could be detected, but those are not critical for this application and are more related to homogeneity. Further, a study of different processing settings was performed to determine a suitable range for various parameters. Consequently, recommendations concerning the printing bed, temperatures and printing speed are given. An examination showed the influence of processing settings on the weight and printing accuracy of the printed geometry, which was related to the final porosity or density of the sintered part.

KW - additive manufacturing

KW - 3D printing

KW - catalytic debinding

KW - sintering

KW - FFF

KW - fused filament fabrication

KW - POM

KW - Polyoxymethylene

KW - Feedstocks

KW - TGA

KW - filament

KW - Additive Fertigung

KW - 3D-Druck

KW - Katalytisch Entbindern

KW - Sintern

KW - FFF

KW - Fused Filament Fabrication

KW - POM

KW - Polyoxymethylen

KW - Feedstock

KW - TGA

KW - Filament

M3 - Master's Thesis

ER -