*4.3. Results for Dipping an Iron Sheet*

From the results of the filling process (Table 5), it can be seen that the resin emerges first from the right side, then the middle of the left side, and finally from the two sides of

the left T-shape. There is obviously more resin on the right side than that on the left side. The emerged resin in the plate is numerically extracted, and then the resin is used as the initial condition for the dipping analysis. The simulation result of the dipping process is shown in Figure 11. The distribution of resin is uneven, which will reduce the adhesion quality of the iron sheets, and there is an over-flow on the right side, which will cause bumps when the iron chips are stacked on each other (the resin area exceeds the size of the iron sheet) (see Figure 12). the left T-shape. There is obviously more resin on the right side than that on the left side. 265 The emerged resin in the plate is numerically extracted, and then the resin is used as the 266 initial condition for the dipping analysis. The simulation result of the dipping process is 267 shown in Figure 11. The distribution of resin is uneven, which will reduce the adhesion 268 quality of the iron sheets, and there is an over-flow on the right side, which will cause 269 bumps when the iron chips are stacked on each other (the resin area exceeds the size of 270 the iron sheet) (see Figure 12). 271

From the results of the filling process (Table 5), it can be seen that the resin emerges 263 first from the right side, then the middle of the left side, and finally from the two sides of 264

3 sec 4 sec

272

274

284

, 291

) times the resin thickness (0.002 288

(Figure 14), and the volume was 0.644 mm<sup>3</sup>

*Polymers* **2021**, *13*, x FOR PEER REVIEW 12 of 18

48 sec 289 sec

**Figure 11.** Top view of the dipping process results. 273 **Figure 11.** Top view of the dipping process results.

**Figure 12.** Schematic diagram of bumps caused by resin overflow. 275 **Figure 12.** Schematic diagram of bumps caused by resin overflow.

#### *4.4. Air Traps Results* 276 *4.4. Air Traps Results*

mm) is 0.64 cm<sup>3</sup>

The simulation was very important not only in terms of predicting the flow of resin 277 during the dipping process but also in terms of predicting the occurrence of air traps. The 278 occurrence of air traps may reduce the adhesive area. In addition to insufficient adhesion, 279 the subsequent heating process for the iron sheet may also produce a popcorn effect, 280 which may decrease product quality. From Figure 13, it can be seen that most of the air 281 traps are located on the right half. This phenomenon is due to too much resin on the right 282 half, which causes the gas to not discharge smoothly during the dipping process. 283 The simulation was very important not only in terms of predicting the flow of resin during the dipping process but also in terms of predicting the occurrence of air traps. The occurrence of air traps may reduce the adhesive area. In addition to insufficient adhesion, the subsequent heating process for the iron sheet may also produce a popcorn effect, which may decrease product quality. From Figure 13, it can be seen that most of the air traps are located on the right half. This phenomenon is due to too much resin on the right half, which causes the gas to not discharge smoothly during the dipping process.

**Figure 13.** Position of air traps. 285

*4.5. Comparison of the Target Value and the Simulation Results* 286 Since it is not easy to measure the resin volume in the experiment, the resin volume 287

Image analysis software (ImageJ) was used to analyze the resin area associated with 290

resulting in a simulation error of 0.6%. 292

, which can be used as a comparison basis for simulation. 289

can be obtained by the estimated resin area (320.8 mm<sup>2</sup>

the dipping results, which was 322.021 mm<sup>2</sup>

**Figure 12.** Schematic diagram of bumps caused by resin overflow. 275

*4.4. Air Traps Results* 276 The simulation was very important not only in terms of predicting the flow of resin 277 during the dipping process but also in terms of predicting the occurrence of air traps. The 278 occurrence of air traps may reduce the adhesive area. In addition to insufficient adhesion, 279 the subsequent heating process for the iron sheet may also produce a popcorn effect, 280 which may decrease product quality. From Figure 13, it can be seen that most of the air 281 traps are located on the right half. This phenomenon is due to too much resin on the right 282 half, which causes the gas to not discharge smoothly during the dipping process. 283

274

284

, 291

**Figure 13.** Position of air traps. 285 **Figure 13.** Position of air traps.

#### *4.5. Comparison of the Target Value and the Simulation Results* 286 *4.5. Comparison of the Target Value and the Simulation Results*

Since it is not easy to measure the resin volume in the experiment, the resin volume 287 can be obtained by the estimated resin area (320.8 mm<sup>2</sup> ) times the resin thickness (0.002 288 mm) is 0.64 cm<sup>3</sup> , which can be used as a comparison basis for simulation. 289 Since it is not easy to measure the resin volume in the experiment, the resin volume can be obtained by the estimated resin area (320.8 mm<sup>2</sup> ) times the resin thickness (0.002 mm) is 0.64 cm<sup>3</sup> , which can be used as a comparison basis for simulation.

Image analysis software (ImageJ) was used to analyze the resin area associated with 290 the dipping results, which was 322.021 mm<sup>2</sup> (Figure 14), and the volume was 0.644 mm<sup>3</sup> resulting in a simulation error of 0.6%. 292 Image analysis software (ImageJ) was used to analyze the resin area associated with the dipping results, which was 322.021 mm<sup>2</sup> (Figure 14), and the volume was 0.644 mm<sup>3</sup> , resulting in a simulation error of 0.6%.

**Figure 14.** ImageJ measurement results.

#### **5. Conclusions**

This article was focused on the gluing technology used in the stamping process. The gluing method was relatively similar to other joining methods (welding, riveting), but it had advantages including lowering iron loss, smoothing the magnetic circuit, and obtaining higher overall rigidity. In this study, Moldex3D mold flow analysis software was used to predict the flow of the resin due to the design of the module and runners and the process used to stick the iron sheet during the motor core die-bonding process, in order to observe the resin flow. In this research, the flow of the plastic in the module was simulated first, and then the flow results were taken as the condition before dipping in order to predict the plastic dipping process under specific conditions.

Based on the research results, the following conclusions could be drawn:


**Author Contributions:** Methodology, Y.-J.Z., S.-J.H., Y.-D.L., C.-S.H.; validation, S.-J.H.; formal analysis, Y.-J.Z.; writing—original draft preparation, Y.-J.Z.; writing—review and editing, Y.-J.Z. and Y.-J.Z.; supervision, S.-J.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **Appendix A**


**Figure A1.** *Cont*.

**Figure A1.** The detail dimensions of the filling model. (Unit: mm) (**a**) The Teflon block; (**b**) The resin pool.

**Appendix B**

**Figure A2.** The flow rate is 0.02 cm3/s. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 70%.

**Figure B3.** The flow rate is 0.04 cm<sup>3</sup> /sec. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 329 **Figure A3.** The flow rate is 0.03 cm3/s. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 70%.

70%. 330

70%. 332

70%. 332

70%. 330

/sec. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 331

/sec. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 331

(**c**) (**d**) **Figure B3.** The flow rate is 0.04 cm<sup>3</sup> /sec. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 329 **Figure A4.** The flow rate is 0.04 cm3/s. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 70%.

**Figure B4.** The flow rate is 0.05 cm<sup>3</sup>

**Figure B4.** The flow rate is 0.05 cm<sup>3</sup>

(**a**) (**b**)

(**c**) (**d**)

(**a**) (**b**)

(**c**) (**d**)

/sec. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 329

70%. 330

70%. 332

**Figure B3.** The flow rate is 0.04 cm<sup>3</sup>

**Figure B4.** The flow rate is 0.05 cm<sup>3</sup> /sec. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 331 **Figure A5.** The flow rate is 0.05 cm3/s. (**a**) Filling 10%; (**b**) Filling 30%; (**c**) Filling 50%; (**d**) Filling 70%.

#### **References**

