High preform haze

In the stretch '2079851475616104457 production process, the product exhibits the quality defect of "High preform haze". The specific manifestation is that the preform has poor transparency and the haze exceeds the standard. 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 "High preform haze" 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. Raw material moisture content too high. 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. 2. Mold surface not smooth. 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. 3. Improper melt temperature. Temperature is the core factor affecting melt fluidity and viscosity. A temperature set too high will cause the melt viscosity to decrease, insufficient melt strength, and even thermal degradation; a temperature that is too low results in poor melt fluidity and insufficient plasticization, making it impossible to fill or form smoothly. A reasonable temperature window should be optimized and determined within the recommended range according to the melting characteristics and thermal stability of the material. 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 "High preform haze" problem.

1. Strictly dry the raw material to a moisture content of <50ppm. Raw '2079851475616104451 should select a matching drying equipment type according to the resin type and water absorption characteristics, and reasonably set the drying temperature, drying time, and dew point indicators. The dried raw material should be put into production use as soon as possible; if temporary storage is required, it should be stored in a sealed container in a dry environment (dew point below -30°C). Regularly test the drying effect to ensure the moisture content meets the standard. 2. Polish the mold. Polishing operations should be carried out step by step from coarse to fine; each time a finer abrasive is changed, the polishing direction should be changed to eliminate the texture traces of the previous step. The final surface roughness should be tested with a roughness meter to confirm it meets the standard. After polishing is completed, it should be thoroughly cleaned to remove abrasive and grinding agent residues to prevent them from entering the melt and contaminating the product. 3. Optimize the melt temperature. 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. 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 "High preform haze" problem can be attributed to the combined action of multiple factors such as Raw material moisture content too high, Mold surface not smooth. Solving this problem requires starting from aspects such as Strictly dry the raw material to a moisture content of <50ppm, Polish the mold 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.