Embrittlement and cracking of the product in low-temperature environments

In the extrusion '2079851475616104457 production process, the product exhibits the quality defect of "Embrittlement and cracking of the product in low-temperature environments".The specific manifestation is The product brittle-cracks in winter or cold-chain environments.This defect is more common when processing materials such as HDPE, PP, PVC and PC, and its occurrence is usually related to unreasonable settings of melt temperature, extrusion speed, blowing pressure and mold temperature.When the Embrittlement and cracking of the product in low-temperature environments situation is severe, it will cause a series of chain quality defects in the product's appearance, dimensional accuracy, mechanical properties and other aspects, which not only reduces the product's functionality and safety 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 extruder, head, die, mold clamping mechanism and blowing system, and melt temperature, extrusion speed, blowing pressure and mold temperature.

1. Insufficient low-temperature toughness of the resin.Material selection and handling are the foundation of forming quality.The 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 moisture content of raw materials, mixed impurities and improper regrind ratios will all cause various defects during processing. 2. Wall thickness too thin.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 cause 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. In addition, the insufficient overall coordination of parison wall thickness control and parison temperature uniformity is also a factor that cannot be ignored; there are complex interactions and coupling relationships among the process parameters, and the deviation of any parameter may aggravate the degree of Embrittlement and cracking of the product in low-temperature environments through chain effects. In terms of equipment maintenance, the regular overhaul and accuracy confirmation of the extruder, head, die, mold clamping mechanism and blowing system 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 Embrittlement and cracking of the product in low-temperature environments problem.

1. Select low-temperature impact-modified resin.Before introducing new tools, new materials or new methods, sufficient applicability evaluation and small-batch verification should be carried out.It is recommended to first conduct offline tests or simulation analyses outside production conditions, and introduce them into the formal production line only after confirming effectiveness and safety.Keep proper change management records to facilitate subsequent traceability and experience accumulation. 2. Increase product 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 cause of the problem 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 mold cycles to observe the effect. It is recommended to formulate a preventive checklist for the Embrittlement and cracking of the product in low-temperature environments problem, incorporate parison wall thickness control and parison temperature uniformity into the daily inspection scope, and conduct online monitoring of key parameters through the SPC statistical process control method to achieve early warning and rapid response to problems. In terms of material management, incoming inspection of raw materials and in-process testing of work-in-progress should be strengthened, and key performance indicators of HDPE, PP, PVC and PC should be strictly controlled to ensure the stability of forming quality from the source.

In summary, the causes of the "Embrittlement and cracking of the product in low-temperature environments" problem can be attributed to the combined action of multiple factors such as Insufficient low-temperature toughness of the resin, Wall thickness too thin.To solve this problem, it is necessary to start from aspects such as Select low-temperature impact-modified resin, Increase product wall thickness and take 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 parison wall thickness control and parison temperature uniformity.