Die head screen pack clogging

During the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Die head screen pack clogging". Specifically manifested as screen pack clogging causing increased extrusion pressure and decreased output. 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 Die head screen pack clogging 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. High impurity content in 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. Screen mesh count too high or used for too long. 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. In addition, insufficient overall coordination between 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 various process parameters, and the deviation of any single parameter may aggravate the degree of Die head screen pack clogging through chain effects. 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 Die head screen pack clogging problem.

1. Regularly replace the screen pack. When replacing parts, spare parts of the same or higher specification from the original manufacturer should be selected to ensure that the installation accuracy and fit tolerances meet the technical requirements of the equipment. After replacement, the relevant parameters need to be recalibrated and a trial run performed to verify the effect; normal production can only be resumed after confirming that the expectations are met. It is recommended to establish a spare parts life cycle management ledger. 2. Improve raw material cleanliness. 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 multiple parameters changing simultaneously making the cause of the problem untraceable. The adjustment magnitude 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. Use an automatic screen changer. Before introducing new tools, new materials, or new methods, a full applicability assessment and small-batch verification should be carried out. It is recommended to first conduct offline tests or simulation analysis outside of production conditions, and introduce them into the formal production line only after confirming effectiveness and safety. Keep change management records to facilitate subsequent traceability and experience accumulation. 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 "Die head screen pack clogging" problem can be attributed to the combined action of multiple factors such as high impurity content in the raw material and screen mesh count too high or used for too long. Solving this problem requires starting from aspects such as regularly replace the screen pack and improve raw material cleanliness, 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.