Powder Getting Damp

In the rotational molding production process, the product exhibits the quality defect of 「Powder Getting Damp」. The specific manifestation is that moisture in the powder causes bubbles or defects in the product. 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 Powder Getting Damp 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. Humid powder storage environment. Moisture is one of the variables that need to be controlled with emphasis in plastic processing. Moisture in hygroscopic resin evaporates rapidly during high-temperature melting to produce bubbles and silver streaks, and can also trigger hydrolysis reactions leading to molecular weight reduction. Adequate drying treatment and strict moisture-regain prevention management are the basic prerequisites for ensuring melt quality. 2. Not stored sealed. 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 addition, insufficient overall coordination of powder melting uniformity and product wall thickness control is also a factor that cannot be ignored. There are complex interactions and coupling relationships among various process parameters, and the deviation of any parameter may aggravate the degree of Powder Getting Damp through chain effects. 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 Powder Getting Damp problem.

1. Store the powder sealed. The storage conditions of materials and products directly affect their processing adaptability and use performance. The temperature, humidity, and lighting conditions of the storage environment should be controlled according to material characteristics, avoiding high-temperature high-humidity and direct sunlight areas. For hygroscopic materials, sealed moisture-proof packaging or dry environment storage should be adopted. 2. Dry before use. 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. 3. Improve storage conditions. Optimization work needs to be based on accurate diagnosis of the root cause of the problem, and blind attempts should be avoided. It is recommended to first determine the key influencing factors and their interactions through process DOE test methods 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 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 「Powder Getting Damp」 problem can be attributed to the combined effects of multiple factors such as humid powder storage environment and not being stored sealed. To solve this problem, it is necessary to start from aspects such as storing the powder sealed and drying before use 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.