# Optimization of Brake Calipers Using Topology Optimization for Additive Manufacturing
## 6 Topology Optimization for Manufacturing  
The TO is mainly used as a design tool. However, its utilization in manufacturing is possible but challenging. There are many parameters that should be taken into account, such as the overall optimization method, the manufacturing method as well as the TO approach, and its applied software. The TO procedure is dependent on the overall optimization method and cannot be seen separately. The followed optimization method in this paper was implemented in three levels: the development of new caliper design concepts using less and downsized components, the exploration of lighter and stiffer materials in the production of the calipers' housings, and the removal of unwanted material from them by using TO. First, the modifications and changes made in the caliper assemblies could optimize the structures and save material without any loss in their performance. For example, the reduction of the pistons in the front caliper from four to two could reduce its weight. Secondly, material exploration was conducted for the housings. The AlSi10 Mg was the lightest material among the available options; however, the Ti6 Al4V was instead used due to its exceptional yield strength, even in high temperatures. In addition, the 3D printing preparation of the models should take into account the 3D printing material. For example, it is recommended \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Diameter [mm]** & **Depth [mm]** & **Pad Distance [mm]** \\ \hline CAD of Front housing & 25 & 59 & 10 \\
3D printed Front housing & 24.87 & 59.01 & 9.93 \\ CAD of Rear housing & 17 & 49.5 & 10 \\
3D printed Rear housing & 16.93 & 49.58 & 9.95 \\ Average Deviation & \(-0.47\%\) & \(0.09\%\) & \(-0.60\%\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Geometric deviations between the CAD models and the 3D printed parts of the housings. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Component/Assembly** & **Weight (g)** & **Max Stress (MPa)** & **Total Displacement (mm)** & **Displacement in Y** \\ \hline \multirow{8}{*}{FRONT CALIPER} & \multirow{4}{*}{Housing} & ISR 22-048 & 320 & 425 & 0.663 & 0.516 \\  & & Optimized (raw model) & 185.75 & 434 & 0.47 & 0.39 \\  & & Optimized after redesign & 189.64 & 400 & 0.27 & 0.25 \\  & & Optimized after 3D & 228.58 & 350 & 0.33 & 0.29 \\  & &printing preparation & 230.6 & - & - & - \\ \cline{2-6}  & \multirow{4}{*}{Caliper} & SR 22-048 & 483 & - & - & 0.5 \\  & & assembly & 2285 & 73 & 0.041 & 0.037 \\  & & Optimized & 304.7 & 400 & 0.27 & 0.25 \\ \hline \multirow{8}{*}{REAR CALIPER} & \multirow{4}{*}{Housing} & ISR 22-049 & 210 & 465 & 0.543 & 0.461 \\  & & Optimized (raw model) & 74.10 & 312 & 0.47 & 0.36 \\ \cline{1-1}  & & Optimized after redesign & 83.37 & 447 & 0.45 & 0.33 \\ \cline{1-1}  & & Optimized after 3D & 112.4 & 405 & 0.37 & 0.36 \\ \cline{1-1}  & & printing preparation & 3D printed & 119.2 & - & - \\ \cline{1-1}  & & ISR 22-049 & 320.8 & - & - & 0.4 \\ \cline{1-1}  & & Design space assembly & 1254 & 44 & 0.012 & 0.009 \\ \cline{1-1}  & & Optimized & 165.11 & 447 & 0.45 & 0.33 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The results from the validation studies. to use support material for an overhang angle bigger than 20-30\({}^{\circ}\) for titanium parts, while this angle limit is increased to 45\({}^{\circ}\) for parts made by aluminum. Third, the TO procedure focused on the housings, which were the heaviest components of the calipers. A small change in the overall optimization procedure could also have a high impact on the TO procedure. For example, the number and the spatial placement of the caliper's components could affect the design space of the housings, and thus the results of the conducted TO. The manufacturing method of the housings has been decided from the beginning of this optimization work and was the SLM 3D printing. The reason for that was to avoid the time-consuming redesign step of the optimized solutions.