Uneven parison temperature

During the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Uneven parison temperature". Specifically manifested as uneven temperature distribution in the circumferential or longitudinal direction of the parison. 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 Uneven parison temperature 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. Damaged or unevenly distributed die head heater bands. Uniformity runs through every stage of the '2079851475616104453. Uneven temperature, uneven pressure distribution, uneven cooling, uneven material mixing, etc. will all lead to dispersion in product quality. Ensuring the uniform distribution of all physical quantities is a prerequisite for obtaining products with good consistency and stable quality. 2. Unreasonable design of the internal flow channel of the die. 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. 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 Uneven parison temperature 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 Uneven parison temperature problem.

1. Replace the damaged heater band. 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. Adjust the heater band layout. 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. Optimize the die flow channel design. 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. 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 "Uneven parison temperature" problem can be attributed to the combined action of multiple factors such as damaged or unevenly distributed die head heater bands and unreasonable design of the internal flow channel of the die. Solving this problem requires starting from aspects such as replace the damaged heater band and adjust the heater band layout, 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.