Simulation of the shrinkage behavior in Fused Deposition Modeling
Final Report Abstract
Additive manufacturing is a manufacturing process and is characterized by the layer-by-layer generation of components. The layer-by-layer principle enables almost unlimited accessibility to every area of the component to be manufactured during the manufacturing process. This results in new potentials with regard to the design of complex component structures that cannot be produced economically by conventional methods such as machining. The Fused Deposition Modeling (FDM) process is a widely used additive manufacturing process. Here, a thermoplastic polymer filament serves as the raw material. The filament is fed into the so-called FDM-head by a feeder unit, which is located in the heated build chamber, where it is plasticized in a heated nozzle. A plasticized plastic strand is discharged from the nozzle, forced by the following material being pushed into the heated nozzle. In the system used in the project, a "Fortus 400mc large" from Stratasys, the strand is deposited in the respective layer in a defined manner by the movement of the nozzle in the XY-plane. For this purpose, first, the contour and then the filling of the cross-sectional area of the respective layer of the component is applied. The build platform is then lowered by one layer thickness and the deposition process begins for the subsequent layer. The successive build-up of the component from individual, plasticized polymer strands results in complex cooling processes. These cooling processes result in anisotropic shrinkage of the final component. In previous investigations, KNOOP showed that the linear shrinkage factors established in practice only apply to specific nominal length ranges for the test specimens investigated. Until now, components have been adjusted in an iterative process of repeated manufacturing and measuring to achieve better dimensional accuracy. Due to the long process times, this procedure is not economical. From this, the need for research was derived to develop a possibility to apply different shrinkage factors to different areas of the component already in the CAD-file. Within the scope of the project, the approach envisaged in the application was initially pursued. In the course of the investigations, however, the approach considered proved to be unsuitable. Instead of the proposed cooling simulation, modeling (DOE) of the shrinkage behavior of raster lines and the geometry-specific volumetric shrinkage of components was resorted to in the further course of the project. This model is applied locally by a software developed within this project according to the situation and depending on the process parameters to be used in the subsequent manufacturing process. The results show that with the developed methodology, the dimensional accuracy of simple geometries can be improved beyond the results obtained by applying linear scaling factors.
Publications
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Investigation of the Process Parameter Dependent Shrinkage Behavior of Raster Lines in the Fused Deposition Modeling Process, Proceedings of the 33rd Annual Solid Freeform Fabrication Symposium, Austin, Texas, USA, 2022.
E. Moritzer & F. Hecker
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Validation and Comparison of FEM-Simulation Results of the Fused Deposition Modeling Process under Consideration of Different Mesh Resolutions, Proceedings of the 33rd Annual International Solid Freeform Fabrication Symposium, Austin, Texas, USA, 2022.
E. Moritzer & F. Hecker
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Adaptive Scaling of Components in the Fused Deposition Modeling Process. Macromolecular Symposia, 411(1).
Moritzer, Elmar & Hecker, Felix
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Compensation of the Shrinkage Behavior Occurring in Cylindrical Components in the FDM Process. Macromolecular Symposia, 411(1).
Koers, Thorsten & Magyar, Balázs
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Compensation of the shrinkage behaviour occurring in cylindrical components in the FDM process, 6th International Conference Polcom, Bukarest, Rumänien, 2022.
Koers, Thorsten & Magyar, Balázs
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Investigation of the deposition velocity related temperature deviations for high temperature materials in the FDM process. AIP Conference Proceedings, 2884, 170001. AIP Publishing.
Moritzer, Elmar; Hecker, Felix; Wächter, Julian & Knaup, Felix
