## 2 Materials and Methods
### Metal 3D Printing  
A temperature management system with an implemented cooling circuit requires a manufacturing process that enables the fabrication of complex and fragile structures. In addition, a heat-resistant material is required to withstand temperature fluctuations within or around the system. Therefore, Direct Metal Laser Sintering (DMLS) is selected to be a suitable manufacturing technology for this application. DMLS is an additive manufacturing technology for fabricating metal components out of powder particles and it is assigned to the Laser Powder Bed Fusion (LPBF) technology. The DMLS printing system consists of three different chambers as schematically shown in Figure 6. These chambers are flooded with inert gas (Nitrogen/Argon--depending on the powder material) to create an oxygen-free atmosphere during the printing process. There is one movable platform in each of the chambers. First, the powder material is filled on the dispenser platform. Here, the powder material must be manually compacted with the help of spatulas to avoid cavities that could lead to problems during the print job. Then, the recoater arm including the recoater blade moves across all three platforms, starting on the right (dispenser platform). Here, the recoater blade (steel, ceramic, or soft brush--depending on the powder material and on the geometry) takes away a certain amount of powder material which is then applied on the build platform. The excessive powder material is pushed onto the collector platform. After the first layer of powder material is applied, a high-power Ytterbium fibre laser beam fuses the individual powder particles together according to a two-dimensional section of the computer-aided design (CAD) model. Splashes from the laser beam are blown away by a continuous gas flow across the build platform. After the powder layer is exposed, the next powder layer is applied by the recoater arm. This iterative process lasts until the structure to be printed is finished [9; 10; 11; 12; 13]. \begin{table}
\begin{tabular}{l l} \hline Volume extension [\%] & 12.5 \\ \hline Flashpoint [\({}^{\circ}\)C] & 140 \\ \hline max. operation temperature [\({}^{\circ}\)C] & 40 \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._  
Figure 6: Principle of DMLS printing system [14]. Due to the high process complexity of DMLS, the number of influencing factors (e.g., direction of the gas flow and direction/movement of the recoater arm) can have a significant impact on the buildability, the quality, and also the process costs. To keep the risk of adverse effects from influencing factors low, the entire printing process should be considered, including the individual steps as shown in Figure 7.  
The first step in the printing process is _part design_. A 3D model of the component is created using CAD software, considering process and material-dependent design guidelines. These design guidelines contain relevant information regarding geometric constraints (maximum pin diameter, minimum wall thickness, etc.). A well-thought-out design saves support structures and helps reduce process costs. This step has been given special attention and is described in more detail in Section 2.3. At the end of the part design, the 3D model is transferred into a standard transformation language (STL) file. The second step is called _pre-processing_. In this step, the STL file is loaded into software that represents a virtual build platform (e.g., Materialize Magics). This is where the part orientation is defined, and the support structure is generated. Part orientation has a significant impact on part quality and process costs. After this step, the STL files are transferred to the slicing software (e.g., EOSPRINT). Within the slicing software, the 3D model in the STL file is divided into 2D sections, so-called'slices'. This step is necessary because the printing system processes one layer at a time during the process. Additionally, appropriate printing parameters are selected in the slicing software.