Preform gate stringing

In the stretch '2079851475616104457 production process, the product exhibits the quality defect of "Preform gate stringing". The specific manifestation is that stringing appears at the preform gate. This defect is relatively common when processing materials such as PET, PP, PC, and its occurrence conditions are usually related to the unreasonable settings of stretching temperature, stretch ratio, blowing pressure, and preform heating uniformity. When the "Preform gate stringing" situation is severe, it will cause a series of chain quality defects in the product in terms of appearance, dimensional accuracy, mechanical properties, etc., which not only reduces the functionality and safety of the product in use, but also directly increases the scrap rate and production cost. Therefore, this problem requires systematic diagnosis and optimization from multiple dimensions such as material selection, the status of the stretch '2079851475616104457 machine, heating oven, stretch rod, and blow mold, and stretching temperature, stretch ratio, blowing pressure, and preform heating uniformity.

1. Hot runner gate temperature too high. Temperature is the core factor affecting melt fluidity and viscosity. A temperature set too high will cause the melt viscosity to decrease, insufficient melt strength, and even thermal degradation; a temperature that is too low results in poor melt fluidity and insufficient plasticization, making it impossible to fill or form smoothly. A reasonable temperature window should be optimized and determined within the recommended range according to the melting characteristics and thermal stability of the material. 2. Holding pressure time too long. This factor causing the problem reflects that certain process conditions or material characteristics in stretch blow '2079851475616104453ing have not met the optimal molding requirements. Such problems are often cumulative and hidden, and should be investigated and verified as key focus items during process debugging and finalization to ensure that hidden dangers are eliminated at the source. In addition, the insufficient overall coordination of preform heating uniformity and biaxial stretch orientation control is also a factor that cannot be ignored; there are complex interactions and coupling relationships among the process parameters, and the deviation of any one parameter may aggravate the degree of "Preform gate stringing" through chain effects. In terms of equipment maintenance, the regular overhaul and precision confirmation of the stretch '2079851475616104457 machine, heating oven, stretch rod, and blow mold are not in place, causing the actual operating parameters of the equipment to deviate from the process requirements, which will also become a potential inducement of the "Preform gate stringing" problem.

1. Reduce the gate temperature. Adjustments should follow the principle of gradual progress; the amplitude of each adjustment should not be too large, and it is recommended to decrease by 5%~15% of the current value. After each adjustment, observe the product quality changes stably for at least 5~10 mold cycles, and continue adjusting only after confirming that the improvement direction is correct; avoid one-step excessive adjustment. 2. Shorten the holding pressure time. Adjustments should follow the principle of gradual progress; the amplitude of each adjustment should not be too large, and it is recommended to decrease by 5%~15% of the current value. After each adjustment, observe the product quality changes stably for at least 5~10 mold cycles, and continue adjusting only after confirming that the improvement direction is correct; avoid one-step excessive adjustment. 3. Optimize the valve gate timing. Optimization work must be based on an accurate diagnosis of the root cause of the problem, and blind attempts must be avoided. It is recommended to first determine the key influencing factors and their interactions through the process DOE test method or historical production data analysis, and then carry out parameter optimization and structural improvement in a targeted manner to achieve twice the result with half the effort. In terms of material management, incoming inspection of raw materials upon arrival and in-process inspection of work-in-progress should be strengthened, and the key performance indicators of PET, PP, PC should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the "Preform gate stringing" problem can be attributed to the combined action of multiple factors such as Hot runner gate temperature too high, Holding pressure time too long. Solving this problem requires starting from aspects such as Reduce the gate temperature, Shorten the holding pressure time and adopting systematic governance measures. In actual production, it is recommended to establish a prevention and rapid response mechanism for this problem, and achieve stable production and continuous improvement through preform heating uniformity and biaxial stretch orientation control.