# Review and New Aspects in Combining Multipoint Moulding and Additive Manufacturing
## 3 Possible Additive Manufacturing Methods
### Plastic-Based Processes
For a better prediction of this anisotropic behaviour, [PERSON] and [PERSON] [42] develop a simulation model of the connection between the extrusion strands. [PERSON] et al. [43] and [PERSON] et al. [44] can also determine a clear dependence of the mechanical characteristics on the position of the component in the building space. Figure 11: Schematic representation of fused filament fabrication (based on the work in [37]). [PERSON] et al. [45] compare the mechanical properties of the components produced by fused filament fabrication with those of components produced by injection moulding. The conclusion is that the additively manufactured components achieve strengths close to those of the injection-moulded components along the extrusion strands. In contrast, components produced using fused filament fabrication perform significantly worse under bending stress. [PERSON] et al. [46] extend the strength approach by the aspect of construction costs and try to derive an optimum from it. [PERSON] and [PERSON] [47] make targeted use of this anisotropy and show a formalism for the targeted reinforcement of highly stressed areas by corresponding planning of the extrusion paths. [PERSON] et al. [48] identify not only the screen angle, but also the layer thickness, the nozzle spacing and the number of contour paths as important factors influencing creep resistance. [PERSON] et al. [49] show that components produced in weightlessness have significantly better mechanical properties than those produced on earth. The exact reasons for this behaviour remain unclear. The group of stereolithographic processes (SLA) rely on a liquid and light-sensitive resin as a base material. As shown in Figure 12a, one option is to use a laser beam for exposing a construction chamber filled with liquid resin along the component contours and thus activating the solidification of the polymer in these areas. Alternatively, the contours of an entire layer are exposed to light and thus cured by a mask process, as shown in Figure 12b. In the next step, the construction platform is lowered and the next layer is created. This process achieves very high accuracies and especially the mask processes achieve good production speeds. The downside is that in the first process step only green parts are produced which have to be cured afterwards [28; 30]. The laminated layer manufacturing (LLM) or laminated object modelling (LOM) (see Figure 13) has to be mentioned as a process with plate- or film-shaped raw materials. For each layer of the part, a new film layer is glued to the lower layer and cut out along the component contours. The produced part can be removed from the waste material hackled by a crosshatch after all layers have been produced [28; 30]. Figure 12: Schematic representation of stereolithographic processes: (**a**) vector scan SLA, (**b**) mask projection SLA (based on [30]). However, the disadvantage is that the individual film layers create clearly visible and comparatively sharp-edged transitions between the layers on component slopes, the so-called staircase effect. For a significant increase in production speed and simultaneous improvement in surface quality [PERSON] et al. (2018), [PERSON] et al. (2018), [PERSON] et al. (2018) and [PERSON] et al. (2018) present a process based on thicker layers. At the same time, a cut deviating from the vertical is made possible, so that the staircase effect can be reduced.