## 5 Conclusions  
According to the statistical results, the key factors in PP extrusion molding quality control had the following ten key subitems: (1-2) PP extrusion driving screw feed pressure control (correction: PP extrusion driving screw discharge pressure control), abbreviated as A. Main screw pressure; (1-3) PP extrusion resin temperature change control, abbreviated as B. Polymer temperature; (1-4) T-die lips adjustment sheet stability (correction: die lips adjustment depends on sheet thickness), abbreviated as C. T-die lips adjustment thickness; (1-5) mirror wheel pressing stability, abbreviated as D. Cooling rolls pressing stability; \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**No.** & **Item** & **Mo** & **M** & **SD** &
\begin{tabular}{c} **K-S** \\ **Z-Test** \\ \end{tabular} & **Choice** \\ \hline \hline
**3. Key Factors of Polypropylene Forming and Mold Manufacturing** & & & & & \\ \hline
3-5 & Forming heating controller element stability & 4 & 4.46 & 0.499 & 1.941 ** & Keep \\ \hline
3-6 &
\begin{tabular}{c} The deviation of forming heating constant \\ temperature control area \\ \end{tabular} & 4 & 4.23 & 0.421 & 2.774 ** & Keep \\ \hline
3-7 & Near to scenic sport or night markets & 4 & 4.46 & 0.499 & 1.941 ** & Keep \\ \hline
**4. Key Factors of Mold and Thermoforming Line Equipment Design** & & & & & \\ \hline
4-5 &
\begin{tabular}{c} The maximum clamping force of the \\ thermodformer and mold forming area design \\ \end{tabular} & 4 & 4.23 & 0.421 & 2.774 ** & Keep \\ \hline \hline \end{tabular}  
**\(p\) < 0.01.**  
\end{table} 
Table 7: _Cont._  
Figure 7: Important key factors affecting the quality of polypropylene extrusion molding. (1-7) mirror wheel temperature stability, abbreviated as E. Cooling rolls temperature stability; (2-3) extrusion driving screw geometric design, abbreviated as F. Extruder main screw geometric design; (3-5) molding heating controller element stability, abbreviated as G. Heating controller is stable; (3-6) molding heating thermostatic control area error value, abbreviated as H. Thermostatic control; (3-7) molding vacuum and compressed air system stability, abbreviated as I. Vacuum pressure; and (4-5) molding machine maximum clamping force and molding area relationship design, abbreviated as J. Mold forming area design. Therefore, the key factors in the PP extrusion molding production quality are abbreviated to \"A. Main screw pressure\", \"B. Polymer temperature\", \"C. T-die lips adjustment thickness\", \"D. Cooling rolls pressing stability\", \"E. Cooling rolls temperature stability\", \"F. Extruder main screw geometric design\", \"G. Heating controller is stable\", \"H. Thermostatic control, \"I. Vacuum pressure\", and \"J. Mold forming area design\", totaling ten key control factors in quality. The said key quality factors had a few differences in setting the technical parameters of real production due to different specifications of manufacturing machines and molds. Through the manufacturing and production of S company's intelligent modern extrusion molding machine, with the chain restaurant McDonald's drinks the cup lid as a production case, its production efficiency is more than 1.5 times that of injection molding products, and the production cost is only injection molding. The market price of molded products is about 60%. At present, the innovative and optimized automatic machinery and production technology are not comparable to the general traditional semi-automatic extrusion and cutting molding machines. According to the product weight, the plate thickness is about 0.45 mm\(\sim\)0.65 mm, corresponding to the key control factors of fishbone diagram quality: \"A.