Product Embrittlement in Low-Temperature Environments

In the rotational molding production process, the product exhibits the quality defect of 「Product Embrittlement in Low-Temperature Environments」. The specific manifestation is that the product embrittles during low-temperature use. This defect is relatively common when processing powder materials such as LLDPE, HDPE, PVC, and PA, and its occurrence conditions are usually related to unreasonable settings of heating temperature and time, rotation speed ratio, cooling rate, and mold wall thickness. When the Product Embrittlement in Low-Temperature Environments situation is severe, it will cause a series of chain quality defects in the product in terms of appearance, dimensional accuracy, and mechanical properties, which not only reduces the product's use functionality and safety, but also directly increases the scrap rate and production cost. Therefore, this problem needs to be systematically diagnosed and optimized from multiple dimensions such as material selection, the rotational molding machine, the heating oven, the rotating arm, the cooling station status, and heating temperature and time, rotation speed ratio, cooling rate, and mold wall thickness.

1. Poor low-temperature toughness of the resin. Material selection and handling are the foundation of molding quality. Intrinsic properties of the resin such as molecular weight, molecular weight distribution, and melt index determine its processing window and final performance. Factors such as excessive raw material moisture content, impurity mixing, and improper proportion of recycled material will all cause various defects during processing. 2. Insufficient wall thickness. 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 lead to inconsistent cooling rates, sink marks and warpage in thick-walled areas, and insufficient strength in thin-walled areas. Wall thickness design should follow the uniform wall thickness principle, and wall thickness changes should transition smoothly. 3. Crystallinity too high. This factor leading to the problem reflects that certain process conditions or material properties in rotational '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 from the source. In terms of equipment maintenance, the regular overhaul and accuracy confirmation of the rotational molding machine, heating oven, rotating arm, and cooling station are not in place, causing the actual operating parameters of the equipment to deviate from process requirements, which will also become a potential inducement of the Product Embrittlement in Low-Temperature Environments problem.

1. Select a low-temperature-resistant resin. Before introducing new tools, new materials, or new methods, adequate applicability evaluation and small-batch verification should be carried out. It is recommended to first conduct offline tests or simulation analysis outside production conditions, and introduce them into the formal production line only after confirming effectiveness and safety. Make good change management records to facilitate subsequent traceability and experience accumulation. 2. Increase the wall thickness. When implementing adjustments, it is recommended to use the single-factor variable method, adjusting only one parameter at a time and fully evaluating the effect, to avoid simultaneous changes of multiple parameters making the problem cause untraceable. The adjustment amplitude should be small rather than large; each adjustment is recommended to be controlled within 5%~10% of the original value, and after adjustment, run stably for at least 3~5 cycles to observe the effect. 3. Add toughening agent. Formula and ratio adjustments should be determined on the basis of laboratory small-scale tests, and then verified in online pilot tests. Any change in the formula should be recorded and evaluated for its comprehensive impact on product performance. Automatic metering and batching devices can effectively reduce manual batching errors and batch-to-batch fluctuations. In terms of material management, incoming inspection of raw materials and in-process inspection of work-in-progress products should be strengthened, and the key performance indicators of powder materials such as LLDPE, HDPE, PVC, and PA should be strictly controlled to ensure the stability of molding quality from the source.

In summary, the causes of the 「Product Embrittlement in Low-Temperature Environments」 problem can be attributed to the combined effects of multiple factors such as poor low-temperature toughness of the resin and insufficient wall thickness. To solve this problem, it is necessary to start from aspects such as selecting a low-temperature-resistant resin and increasing the wall thickness and take systematic treatment 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 powder melting uniformity and product wall thickness control.