Study on wall slip behavior of polymer melt in ultrasonic-assisted micro-injection molding (UμIM)

摘要

Wall slip of polymer melt in micro-injection molding process has a significant impact on the melt flow behavior.Based on the study of the mechanism of ultrasonic-assisted micro-injection molding (UμIM), the action of ultrasonic vibration on the wall slip of the melt in the micro scale cavity is analyzed in this paper.Comprehensive considering the wall slip equation of polymer melt and the influence mechanism of ultrasonic vibration on the wall slip of melt, the theoretical model of wall slip in UμIM is expounded.The wall slip behavior of polymer melt under the action of ultrasonic vibration is experimental verified by using capillary rheometer.Through the analysis of the critical shear stress changes of wall slip, the influence of ultrasonic vibration on the melt wall slip behavior during micro cavity filling is clarified.The results show that during the UμIM process, critical shear stress of melt in micro cavity under the action of ultrasonic decreases or becomes zero, the melt viscosity under ultrasonic vibration is significantly reduced, thereby the mold filling capability in micro cavity is enhanced and the molding quality of micro plastic parts is improved.