Preform contamination (foreign matter)

In the stretch '2079851475616104457 production process, the product exhibits the quality defect of "Preform contamination (foreign matter)". The specific manifestation is that there is foreign matter inside or on the surface of the preform. This defect is relatively common when processing materials such as PET, PP, PC, and its occurrence conditions are usually related to the unreasonable settings of stretching temperature, stretch ratio, blowing pressure, and preform heating uniformity. When the "Preform contamination (foreign matter)" situation is severe, it will cause a series of chain quality defects in the product in terms of appearance, dimensional accuracy, mechanical properties, etc., which not only reduces the functionality and safety of the product 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 stretch '2079851475616104457 machine, heating oven, stretch rod, and blow mold, and stretching temperature, stretch ratio, blowing pressure, and preform heating uniformity.

1. Unclean injection environment. This factor causing the problem reflects that certain process conditions or material characteristics in stretch blow '2079851475616104453ing have not met the optimal molding requirements. Such problems are often cumulative and hidden, and should be investigated and verified as key focus items during process debugging and finalization to ensure that hidden dangers are eliminated at the source. 2. Impurities 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 properties. Factors such as raw material moisture content exceeding the standard, impurity mixing, and improper regrind ratio will all cause various defects during processing. 3. Mold not clean. The mold is the core tool that gives the product its shape and surface quality. Unreasonable mold design, such as improper runner/gate dimensions, insufficient venting, and inadequate draft angle, will directly cause molding defects. The machining accuracy, surface treatment quality, and daily maintenance status of the mold also directly affect product quality. In terms of equipment maintenance, the regular overhaul and precision confirmation of the stretch '2079851475616104457 machine, heating oven, stretch rod, and blow mold are not in place, causing the actual operating parameters of the equipment to deviate from the process requirements, which will also become a potential inducement of the "Preform contamination (foreign matter)" problem.

1. Improve the cleanliness of the injection environment. 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 parameter optimization and structural improvement in a targeted manner to achieve twice the result with half the effort. 2. Filter the raw material. Filtration and sieving are the basic physical means of removing foreign impurities. The filtration accuracy and sieving mesh should be reasonably selected according to the cleanliness requirements of the product and the type and size of the impurities. Filtration devices should be regularly inspected and replaced to prevent failure due to clogging or damage. Multi-stage filtration in series can balance filtration effect and service life. 3. Regularly clean the mold. Cleaning work should be incorporated into the equipment preventive maintenance plan, and the cleaning frequency should be reasonably determined according to the actual conditions of the processing materials and operating cycle. Use dedicated cleaning tools and cleaning materials to avoid scratching the cavity surface or electrolytic corrosion caused by improper operation. After cleaning, recheck and confirm that the key clearances are accurate. In terms of material management, incoming inspection of raw materials upon arrival and in-process inspection of work-in-progress should be strengthened, and the key performance indicators of PET, PP, PC should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the "Preform contamination (foreign matter)" problem can be attributed to the combined action of multiple factors such as Unclean injection environment, Impurities in the raw material. Solving this problem requires starting from aspects such as Improve the cleanliness of the injection environment, Filter the raw material and adopting systematic governance measures. In actual production, it is recommended to establish a prevention and rapid response mechanism for this problem, and achieve stable production and continuous improvement through preform heating uniformity and biaxial stretch orientation control.