## 4 Case Study
### The Method Employed in this Study Is Illustrated in Figure 7
#### 4.1.1 Phase 1: Plan
**ROOT CAUSE**  
Non-uniform coating distribution during the manufacturing process led to a significant decrease in epoxy thickness on the lamination walls. Detection  
Why? The tester measured a detachment force (the resistance to peeling), falling within the acceptable range with a minimum value of 58.8399 N (6 kgf). Why? For the adhesion test, the armature sample must be tilted to an angle between 80\({}^{\circ}\) and 90\({}^{\circ}\) from the vertical to simulate the stress conditions experienced by the cable during winding. **ROOT CAUSE**  
For the adhesion test, the armature sample must be tilted to an angle between 80\({}^{\circ}\) and 90\({}^{\circ}\) from the vertical to simulate the stress conditions experienced by the cable during winding. Systemic  
Why? This failure mode was not identified as a potential risk in the PFMEA or addressed in the control plan. **ROOT CAUSE**  
\begin{table}
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**Issue Description:** \\ \hline The production line for the armature subassembly came to a halt due to failures in the hi-pot tests. \\ \hline Details: During the specific process of checking armature resistance and varistor function and conducting a hipot test, the machine triggered the alarm due to a detected defective part, \\ prompting a subsequent investigation. \\ \hline The high-potential tester’s alarm blared, alerting operators of a part that failed the crucial insulation test. \\ \hline Why? \\ \hline The high-potential test detected unintended leakage current, indicating a direct electrical path between the armature cable and the laminated core. \\ \hline Why? \\ \hline The stress event compromised the epoxy coating, leading to a breach in cable insulation and contact with the lamination. \\ \hline Why? \\ \hline Non-uniform coating distribution during the manufacturing process resulted in a significant decrease in epoxy thickness on the lamination walls. \\ \hline
**ROOT CAUSE** \\ \hline Non-uniform coating distribution during the manufacturing process led to a significant decrease in epoxy thickness on the lamination walls. \\ \hline Detection \\ \hline Why? \\ \hline The tester measured a detachment force (the resistance to peeling), falling within the acceptable range with a minimum value of 58.8399 N (6 kgf). \\ \hline Why? \\ \hline For the adhesion test, the armature sample must be tilted to an angle between 80\({}^{\circ}\) and 90\({}^{\circ}\) from the vertical to simulate the stress conditions experienced by the cable during winding. \\ \hline
**ROOT CAUSE** \\ \hline For the adhesion test, the armature sample must be tilted to an angle between 80\({}^{\circ}\) and 90\({}^{\circ}\) from the vertical to simulate the stress conditions experienced by the cable during winding. \\ \hline
**ROOT CAUSE** \\ \hline Non-uniform coating distribution during the manufacturing process led to a significant decrease in epoxy thickness on the lamination walls. \\ \hline
**ROOT CAUSE** \\ \hline Two-dimensional coating distribution during the manufacturing process led to a significant decrease in epoxy thickness on the lamination walls. The following conclusions were drawn from the first two phases of the proposed methodology:  
1. The armature production line frequently halts due to hipot issues, resulting in costly stoppages and the generation of scrap. Unwanted continuity in the pieces renders them unusable in electric motors, necessitating their disposal. 2. Thin or uneven epoxy coating, crucial for preventing contact between the cable and lamination, is identified as a significant factor contributing to the hipot failures. 3. The validation process for the epoxy coating addition process is deemed unreliable. Given these findings, the \"Do\" phase should prioritize improvement strategies aimed at ensuring the insulation of the lamination and wire winding.