## 4 Case Study
### The Method Employed in this Study Is Illustrated in Figure 7
#### 4.1.2 Phases 2 and 3: Do and Check
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Process Data:** & \multicolumn{3}{c}{**Overall Capability**} \\ \hline  & **Short-Side Armature** & \begin{tabular}{c} **Long-Side** \\ **Armature** \\ \end{tabular} & \begin{tabular}{c} **Short-Side** \\ **Armature** \\ \end{tabular} & \begin{tabular}{c} **Long-Side** \\ **Armature** \\ \end{tabular} \\ \hline LSL & 58.8399 & 58.8399 & PPL & 0.05 & 0.69 \\ \hline Sample mean & 61.2592 & 114.412 & Ppk & 0.05 & 0.69 \\ \hline Sample N & 30 & 30 & Potential (within) capability \\ \hline Overall StDev & 15.5159 & 26.9718 & CPL & 0.05 & 0.67 \\ \hline StDev (within) & 15.2593 & 27.5506 & Cpk & 0.05 & 0.67 \\ \hline Performance: & & & & & & \\ \hline \multicolumn{6}{c}{Observed} & Expected Overall & Expected within \\ \hline  & \begin{tabular}{c} Short-Side \\ Armature \\ \end{tabular} & \begin{tabular}{c} Long-Side \\ Armature \\ \end{tabular} & \begin{tabular}{c} Short-Side \\ Armature \\ \end{tabular} & \begin{tabular}{c} Long-Side \\ Armature \\ \end{tabular} & \
\begin{tabular}{c} Short-Side \\ Armature \\ \end{tabular} &
\begin{tabular}{c} Long-Side \\ Armature \\ \end{tabular} \\ \hline PPM \textless{} LSL & 500,000 & 33,333.33 & 43,8046.75 & 19,681.94 & 437,013.53 & 21,843.95 \\ \hline PPM total & 500,000 & 33,333.33 & 43,8046.75 & 19,681.94 & 437,013.53 & 21,843.95 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Detachment force capability response to epoxy coating thickness increase. Evaluating the Impact of Rotating the Lamination Faces 180\({}^{\circ}\) on the Compatibility of the Armature Body with the Epoxy Coating  
Maintaining the voltage range (3.0-3.1 kV) and epoxy thickness (0.200-0.350 mm), a third experiment focused on the lamination rotation based on the observed higher break force on the long side. Rotating the laminations 180\({}^{\circ}\) consists of flipping all laminations to the other side throughout the entire length of the armature. Analysis revealed the lamination has two distinct sides: one flat and one with a raised edge (burr) where the detachment force is applied. Figure 21a shows a lamination side with a prominent burr, while Figure 21b depicts a burr-free side. These burrs caused insufficient insulation, allowing cable insertion to reach the lamination and creating an electrical path between the cable and the metal (continuity). This situation is particularly evident on the short side of the armature because the face with the burr is positioned towards the side where the commutator bar is located (Figure 22). The commutator has to be accurately associated by the stack slots whenever pushed on top of the shaft because the wires from every coil will appear from the slots, as well as attaching to the commutator bars. This is where the winding experiences a higher force, as it is where the coil turns are generated. This generates higher pressure, pushing the wire against the epoxy coating. The presence of a burr on this side of the laminations may further contribute to these stresses, potentially explaining the occurrence of hipot failures, and highlights the need for a solution to burr formation during lamination. Rotating all the laminations 180\({}^{\circ}\) proved to be a successful solution. This is because the long side of the armature lacks a collector, resulting in less tension on the cable winding compared to the short side. Figure 3 illustrates the perspective of the long side of the armature. It can be observed that the cable is only routed from one slot to another. Despite the presence of a burr due to the rotation of all the laminations, there is no tension to press the cable against the epoxy coating. This helps to prevent hipot failures. A t-test for mean differences  
Figure 21: Lamination face (**a**) with burr and (**b**) without burr. Figure 20: Histograms of detachment force capability response to epoxy coating thickness increase: (**a**) short-side armature; (**b**) long-side armature. was performed using the same parameters as the previous tests performed in this study.