## 5 Conclusions
Main screw pressure control: Speed set at 480-500 rpm\", \"B. Polymer temperature control at 200-240 \({}^{\circ}\)C\", \"C. T-die lips adjustment thickness is controlled at 0.45-0.69 mm \", \"D. Cooling rolls pressing stability pressing control at \(\pm\)0.05 mm \", \"E. Cooling rolls temperature stability is controlled at 20-45 \({}^{\circ}\)C\", \"F. Extruder main screw geometric design adopts American style. Standard\", \"G. Heating controller is stable controller at 230-250 \({}^{\circ}\)C\", \"H. Thermostatic control error of molding heating \(\pm\)1 \({}^{\circ}\)C\", \"I. Stability of molding vacuum pressure \(\pm\)0.01 MPa\", \"J. Mold forming area design between the mold and the area is designed from 60% to 90% of the size\". In the production of food packaging, to reach a good result in production quality control by using isobutane or CO\({}_{2}\) as a blowing agent injected in the extruder to increase the foaming ratio under the physical foaming process can result in less material usage, better isolation purpose, and higher heat resistance, as long as the extruded die and cooling mandrel, etc., are changed. The study can correspond to the key factor in the quality of thermoforming processing. It is confirmed in practical manufacture processing in the experimental factory for an obvious quality and energy-saving improvement. The production processing of the regrind recycling system is assisted in conveying scrapped material from the edge trimmer or crusher back to the extruder loading system in collocating with the automatic volumetric dosing device. The returned recycled material mixes with new material. At the present, the extruder and thermoforming system with precise vacuum forming molds is intelligent automatic machinery. The division of management and procurement are most concerned about having reliable quality and less error. As there are few related literature reviews of the Delphi technique, this study applied science to actual operators engaging in plastic production or clients with plain and specific key factors or data. Worldwide polypropylene sheet production is over 30 million metric tons. The key to the market competition is the condition that the percentage raises up in 1-2% for certified products and regrind recycling material to produce polypropylene coffee cups. Nonetheless, the findings indicated that the manufacturing quality and energy savings could be improved effectively in the experimental plant. The study findings are expected to improve intelligent manufacturing and quality for production engineers and researchers, enhance the market competitiveness of products, and reduce enterprise management costs. As a result, the findings may contribute to achieving sustainable development, environmental protection, energy savings, and carbon reductions. **Author Contributions:** All authors contributed meaningfully to this study. [PERSON]-[PERSON] and [PERSON]-[PERSON], research topic; [PERSON], [PERSON]-[PERSON] and [PERSON]-[PERSON], data acquisition and analysis; [PERSON], [PERSON]-[PERSON] and [PERSON]-[PERSON], methodology support; [PERSON], [PERSON] and [PERSON], original draft preparation; [PERSON] and [PERSON], writing--review and editing. 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:** Not applicable. **Conflicts of Interest:** The authors declare no conflict of interest.