Systematic evaluation of the part properties through combination of different greyscales in one part in High Speed Sintering

Titelangaben

Pezold, Daniel ; Schorzmann, Johann ; Waldmüller, Paula ; Kemnitzer, Jan Felix ; Döpper, Frank:
Systematic evaluation of the part properties through combination of different greyscales in one part in High Speed Sintering.
In: Procedia CIRP. Bd. 118 (2023) . - S. 729-734.
ISSN 2212-8271
DOI: https://doi.org/10.1016/j.procir.2023.06.125

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Abstract

High Speed Sintering (HSS) belongs to the Additive Manufacturing processes of powder bed fusion of polymers (PBF-P).and is known for its high productivity and scalability. The process of part production in HSS follows a combination of infrared
absorbing ink, which is selectively applied to the powder bed surface by print heads, and an infrared (IR) lamp. Compared to other PBF-Processes the layer time is independent on the fill level of the build space due to the two-dimensional application of the ink or the irradiation of the powder bed surface. This characteristic of HSS is discharging in the possibility of specific adjustment of local part and material properties through the variation of the energy input by variation of the ink application quantity. In General the ink application quantity can be controlled by adjusting the greyscale (GS 1-5). In this case there are no existing studies in additive manufacturing, that investigate the combination of different GS for HSS in one part and its’ effect on the part properties. The combination of different GS in one part offers a big potential for the HSS because it allows to targeted and locally adjust the part properties – such as mechanical properties, density and form and dimensional accuracy. By allowing new combinations of GS, the parts can be specifically matched to the desired application and optimize also the HSS process.
For Evaluation the influence of ink application quantity in form of different GS combinations in one part specimens are
manufactured from PA12 polymer by using the voxeljet VX200 HSS. To assess the influence of the ink application quantity in form of GS combination on the part properties specimens are evaluated with regard to the criteria flexural strength, modulus and strain, density, and form- and dimensional accuracy. The GS are combined by printing stripes with a defined Layer Width (LW 1, 3, 5, 7 px) in a defined area. The evaluation of the results showed that the part properties can be influenced positively by GS combinations comparing to uniform GS for mechanical properties and density. For form- and dimensional accuracy a uniform GS is beneficial for part manufacturing. Concerning the LW the highest values are at LW 1 and lowest at 7 px. This can be explained by increasingly LWs are leading to inhomogenities in the specimens resulting in material weak points.