Understanding polymer flow properties is important for profile setting and quality control of injection molding. In view of the shortcomings of the characterization method currently used, an improved method has been proposed considering the estimation of polymer power law index through air-shot injection molding. The entire research project is divided into three aspects: theoretical framework, experimental validation and error analysis.

In the theoretical part, the improved model that describes polymer flow conditions during the air-shot injection molding process is firstly derived. The improved model considers the geometry of the injection nozzle. Based on this model, the estimation of polymer power law index is discussed.

In the experimental part, experiments with fou...[ Read more ]

Understanding polymer flow properties is important for profile setting and quality control of injection molding. In view of the shortcomings of the characterization method currently used, an improved method has been proposed considering the estimation of polymer power law index through air-shot injection molding. The entire research project is divided into three aspects: theoretical framework, experimental validation and error analysis.

In the theoretical part, the improved model that describes polymer flow conditions during the air-shot injection molding process is firstly derived. The improved model considers the geometry of the injection nozzle. Based on this model, the estimation of polymer power law index is discussed.

In the experimental part, experiments with four different materials are conducted to calculate the power law index based on the derived model. The results are then compared with the actual values of power law index measured by laboratory capillary rheometer. Differences between the estimated and actual value of the power law index are compared.

In the error analysis part, the discrepancy of the estimated power law index caused by measurement error of the transducer is discussed. Afterwards, the influence of simplification during theoretical derivation is also investigated. It was found that the estimation of power law index was slightly influenced by the measurement error of the transducer and simplification procedure.

In conclusion, the proposed method provides a quick and convenient way for the power law index estimation.