# Review and New Aspects in Combining Multipoint Moulding and Additive Manufacturing
## 5 Summary and Conclusions  
Overall, it could be shown that vacuum-assisted multipoint moulding adds flexibility in production of prototypes or small series, as there is no need for mould production. In addition, resources and costs can be saved in the production, as there are no low-use moulds to be recycled. At the same time, the structure of the production technology also has some disadvantages. The biggest disadvantage is the limited detail accuracy due to the necessary interpolation layer. This means that very small structures and larger structures with strong transitions cannot be produced. The solution to this could be an integrated process called enhanced vacuum-assisted multipoint moulding with additive attachments that integrates the details that cannot be depicted in the vacuum assisted multipoint mould using corresponding attachments. These attachments are to be produced directly on the interpolation layer using additive manufacturing. It could be shown that with enhanced vacuum-assisted multipoint moulding with additive attachments a larger amount of part shapes can be depicted with this process. A number of challenges were identified in this paper. A large block of topics is the selection of the additive manufacturing process. In this study, it could be shown that the powder bed-based processes and the processes based on resin baths are not suitable for production directly on the vacuum-assisted multipoint mould. This is due to the raw materials, which could damage the existing system, as well as to the temperatures required for these processes, which can cause damage to the interpolation layer. Overall, it could be shown that the extrusion-based fused filament fabrication is most suitable for this application, although the plastics used in fused filament fabrication lead to restrictions for the component materials that can be processed. Further challenges arise from the interpolation layer as a building platform. In contrast to the usual fused filament fabrication, which relies on a flat building platform made of glass, the interpolation layer can form a curved building platform. In addition, the interpolation layer is made of silicone. This raises the question of the adhesion of the attachments on the interpolation layer. This study has shown that the challenges of a curved building platform have already been examined in literature. It could be shown that there are two possibilities for layer generation, on the one hand the classical process with flat layers, and, on the other hand, the extrusion along curved layers. In principle, both methods are also suitable for use on curved building platforms. However, the comparisons carried out in the literature clearly show that curved layers along the outer contours of the component bring clear advantages in terms of surface quality and the tolerable load. The first tests carried out in the literature for additive production on a silicone platform showed that this is a challenge. Although a solution could be presented there using an additional intermediate layer, the actual implementation must still be verified for the application outlined in this paper. The following investigations have to answer the question of the ideal combination of process parameters of the additive manufacturing process for production on the curved silicone platform. In this context, it should also be examined whether a corresponding intermediate layer can be dispensed by varying process parameters. In addition, the influence of the nozzle angle to the construction platform and on the component properties has to be explored. In this context, it must be clarified which design (portal or delta machine, robot arm, etc.) is ideal for the system. The achievable production accuracy of the additively manufactured attachments must also be clarified.