Preform eccentricity (uneven wall thickness)

During the stretch '2079851475616104457 production process, the product exhibits the quality defect of "Preform eccentricity (uneven wall thickness)". Specifically manifested as uneven circumferential wall thickness of the preform, with axis deviation. This defect is relatively common when processing materials such as PET, PP, and PC, and its occurrence conditions are usually related to unreasonable settings of stretching temperature, stretch ratio, blowing air pressure, and preform heating uniformity. When the Preform eccentricity (uneven wall thickness) 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 stretch '2079851475616104457 machine, heating oven, stretch rod, and blow mold, as well as stretching temperature, stretch ratio, blowing air pressure, and preform heating uniformity.

1. Core rod of the injection mold eccentric. This factor leading to the problem reflects that certain process conditions or material properties in stretch 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. 2. Wear of the mold guide pins. The mold is the core tool that imparts shape and surface quality to the product. Unreasonable mold design, such as improper runner/gate dimensions, insufficient venting, inadequate draft angle, etc., will directly cause molding defects. The machining accuracy, surface treatment quality, and daily maintenance condition of the mold also directly affect product quality. 3. Gate eccentricity. This factor leading to the problem reflects that certain process conditions or material properties in stretch 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 terms of equipment maintenance, inadequate regular overhaul and accuracy confirmation of the stretch '2079851475616104457 machine, heating oven, stretch rod, and blow mold cause the actual operating parameters of the equipment to deviate from the process requirements, which can also become a potential inducement of the Preform eccentricity (uneven wall thickness) problem.

1. Correct the alignment of the core rod. Calibration work should use standard instruments that have been verified as qualified by legal metrological verification institutions, and be carried out strictly in accordance with the specified cycle and method. The calibration results should form a written technical report, giving the deviation value and expanded uncertainty. Out-of-tolerance equipment should be immediately taken out of service and marked for repair, and can only be restored to use after passing recalibration. 2. Replace the worn guide pins. 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. Check the gate position. Inspection work should establish a standardized inspection checklist, clarifying the inspection items, technical standards, inspection frequency, and responsible persons. Key equipment components should be regularly disassembled to inspect the condition of hidden parts, and judgment should not be based solely on operating appearance. Inspection results should be recorded in detail and a trend analysis mechanism established to predict potential failures. 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 PET, PP, and PC should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the "Preform eccentricity (uneven wall thickness)" problem can be attributed to the combined action of multiple factors such as core rod of the injection mold eccentric and wear of the mold guide pins. Solving this problem requires starting from aspects such as correct the alignment of the core rod and replace the worn guide pins, 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 preform heating uniformity and biaxial stretch orientation control.