Bamboo-node marks on the parison surface (elastic turbulence)

In the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Bamboo-node marks on the parison surface (elastic turbulence)".The specific manifestation is Regularly spaced bamboo-node-like fluctuations appear on the parison surface.This defect is more common when processing materials such as HDPE, PP, PVC and PC, and its occurrence is usually related to unreasonable settings of melt temperature, extrusion speed, blowing pressure and mold temperature.When the Bamboo-node marks on the parison surface (elastic turbulence) situation is severe, it will cause a series of chain quality defects in the product's appearance, dimensional accuracy, mechanical properties and other aspects, which not only reduces the product's functionality and safety 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 extruder, head, die, mold clamping mechanism and blowing system, and melt temperature, extrusion speed, blowing pressure and mold temperature.

1. Excessive extrusion rate triggering elastic unstable melt flow.This factor causing the problem reflects that certain process conditions or material properties in extrusion '2079851475616104457 do not meet the optimal forming requirements.Such problems are often cumulative and concealed, and should be investigated and verified as key focus items during process debugging and finalization to ensure hidden dangers are eliminated at the source. In addition, the insufficient overall coordination of parison wall thickness control and parison temperature uniformity is also a factor that cannot be ignored; there are complex interactions and coupling relationships among the process parameters, and the deviation of any parameter may aggravate the degree of Bamboo-node marks on the parison surface (elastic turbulence) through chain effects.

1. Reduce the extrusion rate.Adjustments should follow the principle of gradual progress; each adjustment should not be too large, and a decrement of 5%~15% of the current value is recommended.After each adjustment, stably observe the product quality changes for at least 5~10 mold cycles, and continue adjusting only after confirming the improvement direction is correct; never make excessive one-step adjustments. 2. Raise the die temperature to reduce elastic effects.When implementing adjustments, it is recommended to use 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. 3. Replace with a resin with narrow molecular weight distribution.When replacing parts, original manufacturer spare parts of the same or higher specification should be selected to ensure installation accuracy and fit tolerances meet equipment technical requirements.After replacement, relevant parameters need to be recalibrated and trial runs conducted to verify the effect; normal production can only be resumed after confirming expectations are met.It is recommended to establish a spare parts life cycle management ledger. In terms of material management, incoming inspection of raw materials and in-process testing of work-in-progress should be strengthened, and key performance indicators of HDPE, PP, PVC and PC should be strictly controlled to ensure the stability of forming quality from the source.

In summary, the causes of the "Bamboo-node marks on the parison surface (elastic turbulence)" problem can be attributed to the combined action of multiple factors such as Excessive extrusion rate triggering elastic unstable melt flow.To solve this problem, it is necessary to start from aspects such as Reduce the extrusion rate, Raise the die temperature to reduce elastic effects and take 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.