## 2 Materials and Methods
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Method** & **Alloy Type** & **Challenge/Limitations** \\ \hline \multirow{3}{*}{Powder Bed Fusion (PBF)} & \multirow{3}{*}{Al-Si-Mg} & Most mature AM methods for Al alloys. \\  & & Challenges limited to the lack of \\  & & standardization, high cost, and limited \\  & & alloy type. \\ \hline \multirow{3}{*}{Electron beam additive manufacturing (EBAM)} & All weldable & Not ideal for aluminum. Because of \\  & & the vacuum \\  & & aluminum, e.g., 4043 & chamber, there is a need to add other \\  & & compositions with Al material, \\  & & essentially creating a new alloy. \\ \hline \multirow{3}{*}{Ultrasonic additive manufacturing (UAM)} & \multirow{3}{*}{Aluminum 6061} & More efficient for dissimilar metal \\  & & combinations and embedding sensors \\  & & or fiber optics into the part and/or have \\  & & complex internal channels. \\ \hline Laser hybrid welding (MIG, & All weldable & Requires machining to obtain the \\  & & aluminum & final geometry. \\ \hline Laser metal deposition (LMD) & All weldable & No available service provider for \\  & & aluminum & aluminum alloys. \\ \hline Laser Engineered Net Shaping (LENZ)-DED & Al 4047 & Requires machining to obtain the \\  & & final geometry. \\ \hline \multirow{3}{*}{Binder jetting} & Al-Si-Mg & Size limitation. \\  & & Al-Si \\  & & 6061 & At the R\&D level. \\ \hline Reactive additive manufacturing (RAM) & \multirow{3}{*}{A6061-RAM2} & Same as PBF but a different alloy, which \\  & & results in faster printing and higher \\  & technology & & mechanical properties. \\ \hline Material jetting (aluminum & 4008 & \\  & liquid metal AM) & A356 & At the R\&D level. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Evaluation of the AM market and available technologies for aluminum printing. According to the proposed flowchart, if the part complexity is medium and the size is smaller than 155 cm *155 cm *110 cm, two options can be considered. One option is the Directed Energy Deposition (DED) method with consideration of any necessary heat treatment and the selection of alloy type due to the required electrical/mechanical properties. The second option is printing by PBF-based methods and considering any potential heat treatment, machining, or post-processing. The example in Table 3 shows the path through the flowchart for one part, and the red arrows show the direction of selection due to the technical specifications and requirements. Other examples are summarized in Table 4. \begin{table}
\begin{tabular}{c c|c c} \hline
\begin{tabular}{c c} \hline \end{tabular}
\end{table} 
Table 2: Decision chart of AM feasibility for aluminum parts in GIS products. \begin{table} \begin{tabular}{c c} \hline
**Geometry Complexity** & **Size Limitations and Post-Processing Requirements** & **Final Decision** \\ \hline \hline \end{tabular} 
\begin{tabular}{c c}  
Figure 1: Decision flowchart to analyze the printability of the case study’s aluminum parts. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Part** & **Weight (kg)** & **Challenge** & \multicolumn{2}{c}{**Decision Based on the Flowchart**} \\ \hline  & & & & \\  & & 1. & Multiple threads. & 1. & DED. \\  & 2. & Surface roughness below & 2. & Hybrid solutions \\  & & 6.3 microns. & & (PBF + machining). \\ \hline  & & 1. & High electrical & 1. & PBF with Al-Si-Mg + HT + PP. \\  & & 2. & Surface roughness below & 2. & DED with aluminum \\  & & 6.3 microns. & & 5 XXX + HT. \\ \hline  & & 1. & Internal gear. & 1. & DED with aluminum \\  & & 2. & Mechanical properties and & 5 XXX. \\  & & & fine surface roughness of & 2. & Hybrid solutions \\  & & & printed gears. & (PBF + machining). \\ \hline  & & & 1. & DED. \\  & & 2. & Hybrid solutions \\  & & & (PBF + machining). \\ \hline  & & 1. & High mechanical/electrical & 1. & Hybrid solutions \\  & & & (PBF + HT + machining). \\ \hline  & & 2. & Including thread. & 5 XXX + HT. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Some of the evaluated aluminum parts in GIS-ELK-04/145 kV.