Silver streaks on the parison surface

During the injection '2079851475616104457 production process, the product exhibits the quality defect of "Silver streaks on the parison surface". Specifically manifested as silvery-white streaks appearing on the parison surface. This defect is relatively common when processing materials such as PET, PP, HDPE, and PS, and its occurrence conditions are usually related to unreasonable settings of injection pressure, parison temperature, blowing air pressure, and mold temperature. When the Silver streaks on the parison surface 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 injection '2079851475616104457 machine, core rod, parison mold, blow mold, and transfer mechanism, as well as injection pressure, parison temperature, blowing air pressure, and mold temperature.

1. High moisture content of the raw material. The selection and handling of materials is the foundation of molding quality. The intrinsic characteristics of the resin, such as molecular weight, molecular weight distribution, and melt index, determine its processing window and final performance. Factors such as excessive moisture content of the raw material, mixing in of impurities, and improper proportion of regrind will all trigger various defects during processing. 2. Melt temperature too high causing decomposition gases. 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. 3. Poor screw venting. Mold venting is a basic condition to ensure smooth filling of the melt. When venting is poor, the air in the mold cavity is compressed to form a high-pressure air cushion, which hinders melt flow and causes problems such as insufficient filling, burnt, and weld lines. A reasonable venting design should consider the venting position and venting gap to ensure that air is discharged in time. In terms of equipment maintenance, inadequate regular overhaul and accuracy confirmation of the injection '2079851475616104457 machine, core rod, parison mold, blow mold, and transfer mechanism cause the actual operating parameters of the equipment to deviate from the process requirements, which can also become a potential inducement of the Silver streaks on the parison surface problem.

1. Fully dry the raw material. Raw '2079851475616104451 should select a matching type of drying equipment according to the resin type and water absorption characteristics, and reasonably set the drying temperature, drying time, and dew point indicators. The dried raw material should be put into production use as soon as possible; if temporary storage is required, it should be kept in a sealed container in a dry environment (dew point below -30℃). Regularly test the drying effect to ensure that the moisture content meets the standard. 2. Lower the melt 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. 3. Check the screw venting section. Inspection work should establish a standardized inspection checklist, clarifying the inspection items, technical standards, inspection frequency, and responsible persons. Key equipment components should be regularly disassembled to inspect the condition of hidden parts, and judgment should not be based solely on operating appearance. Inspection results should be recorded in detail and a trend analysis mechanism established to predict potential failures. 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 PET, PP, HDPE, and PS should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the "Silver streaks on the parison surface" problem can be attributed to the combined action of multiple factors such as high moisture content of the raw material and melt temperature too high causing decomposition gases. Solving this problem requires starting from aspects such as fully dry the raw material and lower the melt temperature, 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 uniformity and transfer temperature control.