## 6 Conclusions and Final Results (Cost Analysis)  
The innovations of this work are:  
1. Freedom of design and function-driven design
2. Speed of production of the product (just six hours for complete printing)
3. Better quality than other additive technologies thanks to the use of detailed agents
4. Possibility to reduce costs by optimizing design  
In this last paragraph, an economic feasibility will be performed in order to consider the costs of the components and the workings. The processing costs are (Table 6):  
- 0.08 \(\upmu\)/g for variable costs (material). - 0.20 \(\upmu\)/g for service cost or cost allocated by amortization. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Lattice Structure** & **Full Structure** \\ \hline Total Weight [g/px] & 253 & 320 \\ DC Engine [\(\upmu\)/px] & 6 & 6 \\ LED [\(\upmu\)/px] & 0.45 & 0.45 \\ Electrical Components [\(\upmu\)/px] & 2 & 2 \\ Service Cost [\(\upmu\)/px] & 50.6 & 64 \\ Power Cost [\(\upmu\)/px] & 20.24 & 25.6 \\ Total Cost [\(\upmu\)/px] & 79.29 & 98.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Cost analysis. Figure 21: Final result achieved. Figure 20: Sandblasting machine used to clean the fan. The components have the following costs:  
* DC motor from supplier: 8 \(\upxi\)/pcs, without considering the discounts for larger lots. * Led: 2 \(\upxi\)/m from supplier catalogue. On the inner circumference of the sphere = \(\upxi\) 0.45
* Electrical components: a cost of 2 \(\upxi\)/fan is estimate. Neglecting labor costs and electricity costs, it can be noted that, simply by adopting the lattice structure, it is possible to reduce production costs by several tens of euros. The most significant component is that linked to the company's service cost (0.20 \(\upxi\)/g). However, companies who have purchased this technology are able to allocate fixed costs to higher production volume, thus lowering costs. Nevertheless, production costs remain very high and the real challenge in the next few years is to reduce them considerably to allow for real mass production. The main advantage of this technology is the ability to reduce costs simply by reducing the amount of printed material. In fact, starting from the basic 3D model, better solutions could be adopted (topology optimization), such as reducing the thickness of the walls or creating pockets in the housings. This, in addition to the lattice structure, would have allowed to further reduce the amount of material required and, therefore, to reduce costs. However, in this article, no further structures or design variants have been developed. In the validation phase, the emerging multi jet fusion technology presented several advantages including:  
* Processing speed (six hours). * Accessible costs for the machines (300.000 \(\upxi\)). * Better quality due to the detail agents. * Freedom of design, in fact the fan body would have been particularly difficult to achieve with conventional techniques. * Possibility to reduce costs simply by printing less material. The better the design, the lower the cost  
However, it is essential to discuss also the main drawbacks we came across in this case study: to begin with, costs are relatively high if we consider service cost. Moreover, some components were deformed by the cooling process: the fan hole (2 mm) does not fit the motor shaft. Therefore, tolerances are not precise. Furthermore, only few materials were allowed in Multi Jet Fusion, such as PA 12 or PA11. To resume, only two solutions were developed: a full structure as per design and a lattice structure. By adopting the latter, we managed to reduce the costs by a few tens of euros. Unfortunately, in this article, it was not possible to design a better solution that would optimize costs (by topology optimization). For this reason, it would be interesting to push the design for additive to the limit in a future case study, perhaps creating pockets, reducing the thicknesses to a minimum or generating different topologies thanks to the generative design software and algorithms.