How to choose the appropriate conical screw barrel aspect ratio for different process requirements?

In industrial production, the aspect ratio of conical screw barrel is very important.
For processes that require high mixing and plasticization, such as the production of high-quality plastic products, a larger aspect ratio is the right choice. A large aspect ratio means that the heating area of ​​the screw and the material residence time increase, which is conducive to the full mixing and plasticization of the material in the screw, can increase the melt pressure, reduce backflow and leakage losses, and make the quality of the final product more uniform and stable. For example, when producing high-performance engineering plastics, a conical screw barrel with an aspect ratio of 20-27 can fully melt and mix the plastic particles, thereby producing products with good mechanical properties and appearance quality.
For some polymer processing processes with poor thermal stability, the aspect ratio should not be too large. Because a screw that is too long will cause the material to stay at high temperature for too long, it is easy to cause thermal decomposition and affect product quality. For example, when processing certain heat-sensitive plastics, if the aspect ratio is not properly selected, it may cause problems such as plastic discoloration and performance degradation. At this time, a relatively small aspect ratio, such as 15-20, should be selected to shorten the residence time of the material in the screw and avoid overheating and decomposition.
In addition, for some processes with high output requirements, it is necessary to improve production efficiency while ensuring product quality. A smaller aspect ratio can speed up the conveying speed of the material in the screw, thereby increasing output. But this may sacrifice some mixing and plasticizing effects to a certain extent. Therefore, it is necessary to find a balance between output and quality and select a suitable aspect ratio based on specific process requirements and product quality standards. For example, in some daily plastic product production that does not require particularly high quality of plastic products but has a large demand for output, a conical screw barrel with an aspect ratio of 18-22 can be selected, which can not only ensure a certain production efficiency, but also meet basic product quality requirements.