Fused Deposition Modelling (FDM) is one of the most widely used additive manufacturing processes. As with other additive manufacturing processes, components are created layer by layer in FDM. This offers the advantage of great design freedom, which cannot be realised with conventional manufacturing processes, or only with great effort. In addition, the components are produced directly from a prepared CAD file. Layer generation in FDM is achieved by depositing a plasticised thermoplastic strand. For this purpose, the starting material, a filament, is fed through a heated nozzle in the FDM head and melted. For the defined deposition of the melted material, the nozzle is moved in the X-Y plane. Overhangs are supported with a backing material, which is processed with another nozzle. After completion of a layer, the build platform is lowered relative to the nozzle by a layer thickness in the Z direction and the deposition process begins again.
The production of components in FDM usually takes place in a heated build room. The build room temperature is far below the melting temperature of the material to be processed in order to ensure the stability of the already deposited component areas. As a result, the deposited plastic strands cool down and shrink shortly after they are deposited. Thus, each component area shrinks separately. The resulting inhomogeneous shrinkage can cause residual stresses in the component, which in turn lead to distortion and thus to geometric deviations. The shrinkage is currently compensated for in the data preparation prior to production by linear scaling of the component along the three spatial directions. However, previous investigations have shown that this is not a generally valid solution. Therefore, further approaches to shrinkage compensation are to be investigated in this project.
First of all, the possibility of assembling a component from elementary cells is examined in this project. The scaling factors for individual elementary cells are determined and then applied to the entire component. In addition, the FEM simulation of the manufacturing process of components with suitable software will be examined. Accompanying investigations are carried out to determine boundary conditions such as the material exit temperature from the nozzle.