Excessive flash at the bottle bottom

During the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Excessive flash at the bottle bottom". Specifically manifested as abundant and large-sized flash residue after edge trimming at the bottle bottom. This defect is relatively common when processing materials such as HDPE, PP, PVC, and PC, and its occurrence conditions are usually related to unreasonable settings of melt temperature, extrusion speed, blowing air pressure, and mold temperature. When the Excessive flash at the bottle bottom situation is severe, it will cause a series of chain-reaction quality defects in the product in terms of appearance, dimensional accuracy, mechanical properties, etc., which not only reduces the usability and safety of the product, but also directly increases the scrap rate and production cost. Therefore, this problem requires systematic diagnosis and optimization from multiple dimensions, including material selection, the condition of the extruder, die head, die, mold clamping mechanism, and blowing system, as well as melt temperature, extrusion speed, blowing air pressure, and mold temperature.

1. Parison diameter too large. This factor leading to the problem reflects that certain process conditions or material properties in extrusion blow '2079851475616104453ing have not met the optimal molding requirements. Such problems often have cumulative and hidden characteristics, and should be investigated and verified as key focus items during process debugging and finalization to ensure that hidden dangers are eliminated from the source. 2. Improper pinch-off design. Unreasonable structural design or process layout is often the systemic root of the problem. Runner design defects causing uneven flow, unreasonable cooling water channel layout causing temperature differences, insufficient venting structures causing air entrapment, etc., are all fundamental problems that need to be solved with emphasis during the design and development stage. 3. Parison temperature too high. Temperature is the core factor affecting melt fluidity and viscosity. Setting the temperature too high will cause the melt viscosity to decrease, insufficient melt strength, and even thermal degradation; if the temperature is too low, the melt fluidity is poor and plasticization is insufficient, making it impossible to fill or mold smoothly. A reasonable temperature window should be optimally determined within the recommended range according to the melting characteristics and thermal stability of the material. In terms of equipment maintenance, inadequate regular overhaul and accuracy confirmation of the extruder, die head, die, mold clamping mechanism, and blowing system cause the actual operating parameters of the equipment to deviate from the process requirements, which can also become a potential inducement of the Excessive flash at the bottle bottom problem.

1. Reduce the parison diameter. Adjustments should follow the principle of gradual progress; the magnitude of each adjustment should not be too large, and it is recommended to decrease in steps of 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; one-step excessive adjustment must be avoided. 2. Optimize the pinch-off dimensions and angle. 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 targeted parameter optimization and structural improvement to achieve twice the result with half the effort. 3. Appropriately lower the parison temperature. Adjustments should follow the principle of gradual progress; the magnitude of each adjustment should not be too large, and it is recommended to decrease in steps of 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; one-step excessive adjustment must be avoided. In terms of material management, incoming inspection of raw materials and in-process inspection of work-in-progress should be strengthened, and the key performance indicators of HDPE, PP, PVC, and PC should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the "Excessive flash at the bottle bottom" problem can be attributed to the combined action of multiple factors such as parison diameter too large and improper pinch-off design. Solving this problem requires starting from aspects such as reduce the parison diameter and optimize the pinch-off dimensions and angle, and adopting systematic governance measures. In actual production, it is recommended to establish a prevention and rapid response mechanism for this problem, achieving stable production and continuous improvement through parison wall thickness control and parison temperature uniformity.