## 3 Results and Discussions  
### Findings from DOE 1, 2 and 3  
Table 5 shows the thermal and structural results obtained from DOE 1, 2 and 3. The results are in terms of cooling time and maximum von Mises stress at the time of ejection. The objective is to obtain the minimum cooling time and minimum stress, as previously mentioned in Table 3.  
In Table 5 column 2, it is seen that for DOE-1, the minimum cooling time is 14.32 s in case 1.1, whereas the minimum value of the maximum von Mises stress occurs in case 1.10 (column 3, row 12), which is 107 MPa. Similar phenomena are observed for DOE-2 and DOE-3, too. In DOE-2 (Table 5 column 5), the minimum cooling time, i.e., 21.39 s, occurs in case 2.7, whereas the minimum stress 161 MPa occurs in case 2.5 (column 6). In DOE-3, case 3.13 and case 3.6 have the best thermal (27.47 s) and best structural (162 MPa) results, as found in column 8 and 9, respectively. Hence, a trade-off is necessary in order to define the best design solution. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**DOE Number** & \begin{tabular}{c} **Shape of** \\ **Plastic Part** \\ \end{tabular} & \begin{tabular}{c} **Part Thickness** \\ **(mm)** \\ \end{tabular} & \begin{tabular}{c} **Part Height** \\ **(mm)** \\ \end{tabular} & \
\begin{tabular}{c} **Part Larger** \\ **Diameter (mm)** \\ \end{tabular} &
\begin{tabular}{c} **Part Smaller** \\ **Diameter (mm)** \\ \end{tabular} \\ \hline DOE-4 & cylindrical & 1 & 60 & 80 & 80 \\ DOE-5 & cylindrical & 3.5 & 60 & 80 & 80 \\ DOE-6 & cylindrical & 6 & 60 & 80 & 80 \\ DOE-7 & conical & 1 & 60 & 80 & 50 \\ DOE-8 & conical & 3.5 & 60 & 80 & 50 \\ DOE-9 & conical & 6 & 60 & 80 & 50 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Plastic part dimensions for DOE 4, 5, 6, 7, 8 and 9. Figure 1: CAD models of six different plastic parts. It is notable that the value of the minimum cooling time increases from DOE-1 to DOE-3. This is an expected behavior, as the thickness of the plastic part also increases. Although the cooling time increases, in each case, they show better results than their respective traditional mold design scenario. This comparison is conducted by creating three traditional mold designs with straight drilled cooling channels and analyzing their thermal and structural performance. These cases are named as 1-conventional, 2-conventional, and 3-conventional. These design cases are created for plastic parts with thicknesses of one mm, 3.5 mm, and six mm, respectively, in order to be comparable with their conformal design cases. Table 6 shows the cooling times for these conventional cases along with the respective conformal design cases, which indicate positive improvement with the application of conformal cooling channels in all of the cases. The thermal analysis results for the design cases mentioned in Table 6 are shown in Figure 2. It shows the temperature distribution of the respective plastic parts at the time of ejection. The selected top three design cases are listed in Table 7. This selection is based on a trade-off between the best thermal results and best structural results in DOE 1, 2 and 3. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**DOE Number** & \multicolumn{3}{c}{**Coinormal Cooling Time (s)**} & **Conventional Cooling Time (s)** & **Conformal Max. von Mises (MPa)** & **Conventional Max. von Mises Stress (MPa)** \\ \hline DOE-1 & 14.32 & 28.04 & 159 & 153 \\ DOE-2 & 22.37 & 28.32 & 203 & 167 \\ DOE-3 & 27.47 & 35.55 & 176 & 168 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparative thermal and structural results from DOE 1, 2 and 3 with conformal and conventional cooling channels. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**DOE-1**} & \multicolumn{3}{c}{**DOE-2**} & \multicolumn{3}{c}{**DOE-3**} \\ \hline
**Case** & **Cooling Time (s)** & **[PERSON] Time (s)** & **Case** & **Cooling Time (s)** & **[PERSON] Time (MPa)** & **Case** & **Cooling Time (s)** & **[PERSON] Time (MPa)** \\ \hline  
\hline \hline \end{tabular}
\end{table}