Regular ripples on the parison surface (elastic instability)

In the injection '2079851475616104457 production process, the product exhibits the quality defect of "Regular ripples on the parison surface (elastic instability)".The specific manifestation is Regularly spaced ripples appear on the parison surface.This defect is more common when processing materials such as PET, PP, HDPE and PS, and its occurrence is usually related to unreasonable settings of injection pressure, parison temperature, blowing pressure and mold temperature.When the Regular ripples on the parison surface (elastic instability) 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 injection '2079851475616104457 machine, core rod, parison mold, blow mold and transfer mechanism, and injection pressure, parison temperature, blowing pressure and mold temperature.

1. Excessive injection speed triggering elastic unstable melt flow.Speed parameters affect the flow state and time allocation of the melt during the forming process.Too slow speed leads to premature cooling and insufficient filling; too fast speed causes melt fracture, air entrapment and shear overheating.Optimization of the speed curve should make the melt flow smoothly and orderly in the cavity. In addition, the insufficient overall coordination of parison wall thickness uniformity and transfer temperature 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 parameter may aggravate the degree of Regular ripples on the parison surface (elastic instability) through chain effects.

1. Reduce the injection speed.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 melt temperature.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. Adopt multi-stage injection.Before introducing new tools, new materials or new methods, sufficient applicability evaluation and small-batch verification should be carried out.It is recommended to first conduct offline tests or simulation analyses outside production conditions, and introduce them into the formal production line only after confirming effectiveness and safety.Keep proper change management records to facilitate subsequent traceability and experience accumulation. 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 PET, PP, HDPE and PS should be strictly controlled to ensure the stability of forming quality from the source.

In summary, the causes of the "Regular ripples on the parison surface (elastic instability)" problem can be attributed to the combined action of multiple factors such as Excessive injection speed triggering elastic unstable melt flow.To solve this problem, it is necessary to start from aspects such as Reduce the injection speed, Raise the melt temperature 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 uniformity and transfer temperature control.