Uneven bottle mouth threads

In the stretch '2079851475616104457 production process, the product exhibits the quality defect of "Uneven bottle mouth threads". The specific manifestation is that the bottle mouth threads are incompletely filled or the thread pitch is uneven. 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 "Uneven bottle mouth threads" 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. Preform mouth temperature too low. 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. Poor precision of the mold thread cavity. The mold is the core tool that gives the product its shape and surface quality. Unreasonable mold design, such as improper runner/gate dimensions, insufficient venting, and inadequate draft angle, will directly cause molding defects. The machining accuracy, surface treatment quality, and daily maintenance status of the mold also directly affect product quality. 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 "Uneven bottle mouth threads" 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 "Uneven bottle mouth threads" problem.

1. Increase the preform mouth temperature. When implementing adjustments, it is recommended to adopt the single-factor variable method, adjusting only one parameter at a time and fully evaluating the effect, to avoid simultaneous changes of multiple parameters making the cause of the problem untraceable. The adjustment amplitude should be small rather than large; each adjustment is recommended to be controlled within 5%~10% of the original value, and after adjustment, run stably for at least 3~5 mold cycles to observe the effect. 2. Repair the thread cavity. Polishing operations should be carried out step by step from coarse to fine; each time a finer abrasive is changed, the polishing direction should be changed to eliminate the texture traces of the previous step. The final surface roughness should be tested with a roughness meter to confirm it meets the standard. After polishing is completed, it should be thoroughly cleaned to remove abrasive and grinding agent residues to prevent them from entering the melt and contaminating the product. It is recommended to formulate a preventive checklist for the "Uneven bottle mouth threads" problem, incorporate preform heating uniformity and biaxial stretch orientation control into the daily inspection scope, and conduct online monitoring of key parameters through the SPC statistical process control method to achieve early warning and rapid response to the problem. 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 "Uneven bottle mouth threads" problem can be attributed to the combined action of multiple factors such as Preform mouth temperature too low, Poor precision of the mold thread cavity. Solving this problem requires starting from aspects such as Increase the preform mouth temperature, Repair the thread cavity 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.