## 4 Conclusions  
Problems that appear in the mold design stage for implementing a rapid heating process using CNT web film as a heat source were identified by designing variables. When applying CNT web film to multilayer structure molds, processing and assembly errors may cause non-contact areas called flush, damaging the CNT web film when heated. 1. CNT web film was applied by setting flush of 0 mm, 0.1 mm, and 0.3 mm through a flush test mold, and the damage to CNT web film after heating was measured through changes in resistance and Raman spectroscopy. 2. When 0.1 mm flush was applied, the resistance change and \(D/G\) peak did not show much difference from the 0 mm flush sample, confirming that the flush was within the allowable value. However, when applying a 0.3 mm flush, the resistance change rates in the repeated experiment were highest in the low- and high-temperature ranges, and the \(D/G\) peak value of Raman spectroscopy was also highest. It was confirmed that it is inappropriate to apply CNT web film as a heat source in a multilayer structure with a flush of 0.3 mm or above. As the flush increases, the non-contact area of the CNT web film becomes more extensive, and it is relatively overheated during heating, confirming that the effect of oxidation is more significant than in other areas. For the stable implementation of a rapid heating multilayer structure mold with a CNT web film, it is necessary to design the flush level of the multilayer structure to be less than 0.3 mm. 3. Optimization analysis was performed by combining the thicknesses of each material. The thicknesses of the CNT web film were 5 \(\upmu\)m, 10 \(\upmu\)m, 24 \(\upmu\)m, and 37 \(\upmu\)m. Insulator thicknesses were 0.25 mm, 0.5 mm, 1 mm, 5 mm, and 10 mm. The thicknesses of the electrical insulator were 0.25 mm, 0.5 mm, 1 mm, 2 mm, and 4 mm. As a result of the analysis, heat-transfer performance increased as the thickness of the CNT web film and electrical insulator decreased, and heat-transfer performance increased as the thickness of the insulator increased. The heat-transfer performance of the CNT web film converged below 10 \(\upmu\)m, and that of the insulator converged above 5 mm. Electrical insulators show better performance as they decrease. However, a thickness of at least 0.5 mm was selected for insulation safety. Heat-transfer performance in the direction of the cavity surface varies depending on the thickness of the insulator to block heat-transfer to the back of the mold and the electrical insulator located between the cavity surface and the CNT web film. The heat flow direction was toward the cavity surface when the electrical insulator was thinner than the insulator. That caused maximum heat-transfer performance to be observed. 4. When comparing RHCM and CIM using cartridge heaters, the heating performance of the multilayer structure mold (RHCM) was heated more than four times faster than with CIM. The maximum heating rates in the RHCM mold and CIM mold were 21 \({}^{\circ}\)C/s and 5 \({}^{\circ}\)C/s, respectively. RHCM mold temperature uniformity was also higher by more than 10% for RHCM, with an average of 98% compared to 88% for CIM. The rapid heating injection mold with the multilayer structure designed in this study has the advantage of a faster heating rate compared to the existing rapid heating technique. It also has significant advantages in production and cost, with low facility investment costs. In the future, the main variables of the rapid heating mold required for application to the injection process will be identified and reflected in the mold design to increase the durability and stabilization of the technology. Conceptualization, Y.K. ; Formal analysis, H.L. ; Investigation, H.L. ; Methodology, Y.K. and W.C.; Validation, H.L. ; Writing--original draft, H.L. ; Writing--review and editing, Y.K. and W.C. All authors have read and agreed to the published version of the manuscript. This work was supported by the Technology Innovation Program (Grant No.