Uneven parison wall thickness (wall thickness control)

During the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Uneven parison wall thickness (wall thickness control)". Specifically manifested as large differences in the circumferential wall thickness of the parison, which the wall thickness controller cannot effectively correct. 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 wall thickness (wall thickness control) 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. Uneven die gap. 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. Wear of the inner surface of the die. Mechanical wear and loosening during long-term equipment operation will cause clearance changes, accuracy degradation, and unstable operation, thereby triggering various process and quality problems. Establishing a regular inspection and preventive maintenance system for equipment operating conditions, and promptly repairing or replacing worn parts, is a necessary measure to maintain equipment accuracy and process stability. 3. Improper parameter settings of the wall thickness controller. The uniformity of wall thickness distribution is directly related to the mechanical properties of the product and the consistency of cooling shrinkage. Excessive wall thickness differences will cause inconsistent cooling rates, with sink marks and warpage occurring in thick-walled areas and insufficient strength in thin-walled areas. Wall thickness design should follow the principle of uniform wall thickness, and wall thickness changes should transition smoothly. 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 wall thickness (wall thickness control) problem.

1. Adjust the die gap. 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. 2. Replace the worn die. 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. 3. Optimize the wall thickness control curve. 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 wall thickness (wall thickness control)" problem can be attributed to the combined action of multiple factors such as uneven die gap and wear of the inner surface of the die. Solving this problem requires starting from aspects such as adjust the die gap and replace the worn die, 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.