## 4 Case Study
### The Method Employed in this Study Is Illustrated in Figure 7
#### 4.1.2 Phases 2 and 3: Do and Check
A sample of 27 armatures showed a significant change in the mean detachment force on the short side compared to the last change (epoxy layer thickness adjustment). This conclusion can be explained by the \(p\)-value shown in Table 10. This significant improvement suggests superior adhesion, potentially eliminating the previously encountered hipot failures. In addition to the positive outcomes observed on the short side, inverting the lamination also produced favorable results for the long side as well. The test conducted on the long side, as shown in Table 10b, revealed no statistical evidence to reject the hypothesis of equal means before and after inverting the faces of the laminations. This indicates that there was even a small change in the mean breaking force values on the long side. This can be explained because this improvement was mainly focused on improving the breaking force on the short side. Inverted lamination proved to be highly beneficial, as evidenced by the marked improvement in terms of meeting specifications. Table 11 and Figure 23 illustrate a notable increase in the short side's Ppk, which surged from 0.05 to 1.06, bringing it closer to the minimum target of 1.32. Conversely, Table 11 and Figure 23 also indicate that the long \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**(a)**} & \multicolumn{6}{c}{**(b)**} \\ \hline  & **N** & **Mean** & **StDev** & \multicolumn{2}{c}{**SE**} & \multicolumn{2}{c}{**N**} & **Mean** & **StDev** & \multicolumn{2}{c}{**SE**} \\  & & & & **Mean** & & & & & & **Mean** \\ \hline C5 & 30 & 61.3 & 15.5 & 2.8 & C6 & 30 & 114.4 & 27.0 & 4.9 \\ \hline C7 & 27 & 291.4 & 73.3 & 14 & C8 & 27 & 105.2 & 23.1 & 4.5 \\ \hline \multicolumn{8}{c}{C5 = Data before 3 rd experiment} & \multicolumn{6}{c}{C6 = Data before 3 rd experiment} \\ \hline  & C7 = Data after 3 rd experiment & \multicolumn{6}{c}{C8 = Data after 3 rd experiment} \\ \hline  & Difference = \(\mu\) (C5)—\(\mu\) (C7) & \multicolumn{6}{c}{Difference = \(\mu\) (C6)—\(\mu\) (C8)} \\ \hline  & Estimate for difference: \(-230.2\) & \multicolumn{6}{c}{Estimate for difference: 9.23} \\ \hline
95\% CI for difference: \((-259.7,-200.7)\) & \multicolumn{6}{c}{95\% CI for difference: \((-4.09,22.54)\)} \\ \hline  & T-Test of difference = 0 (vs \(\
eq\)) & \multicolumn{6}{c}{T-Test of difference = 0 (vs \(\
eq\))} \\ \hline T-Value = \(-16.00\) & \multicolumn{6}{c}{T-Value = 1.39} \\ \hline \(p\)-Value = 0.000 DF = 28 & \multicolumn{6}{c}{\(p\)-Value = 0.170 DF = 54} \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Mean difference test results for breaking force before and after rotating the lamination faces 180\({}^{\circ}\): (a) short-side armature; (b) long-side armature. Figure 22: Detailed view of the commutator and its winding, together with the stack. side experienced negligible change. However, the overall result is that both sides now demonstrate significantly enhanced process capability. This achievement strongly indicates that inverted lamination could serve as a pivotal solution to address the detachment force issue previously identified in the manufacturing process. Differential Scanning Calorimetry Test  
To conclude these two phases of the PDCA cycle and ensure the epoxy's performance with the implemented modifications, a DSC study was conducted. This study aimed to investigate the behavior of the epoxy powder during changes in curing temperature. Specifically, the study focused on determining whether the epoxy degraded under these conditions, as this directly impacts the functionality, quality, and durability of the reinforced motor. The DSC analysis compared a virgin epoxy sample to a cured sample, as depicted in Figures 24 and 25. The results revealed a curing percentage of 84.23%.