The Effect of Two‐Dimensional Ultrasonic Vibration on the Filling Performance of the Polymer Melt in Injection Molding for Thin‐Walled Parts

ABSTRACT During the injection molding process of thin‐walled parts, the polymer melt encounters significant flow resistance within narrow mold cavities, which easily results in short‐shot defects. A two‐dimensional ultrasonic‐assisted injection molding (2DUIM) method is proposed and used to improve the melt filling performance in thin‐walled injection molding under normal process parameters. A 2DUIM mold that can directly exert two‐dimensional (2D) ultrasonic vibration on the polymer melt in the cavity is developed to fabricate an accelerometer pendulum with complex thin‐walled structures. The 2DUIM experiments for the accelerometer pendulum demonstrated that the introduction of 2D ultrasonic vibration markedly enhanced the melt filling performance. Specifically, the filling area of the cavity corresponding to the mass block increased by up to 18.1 mm 2 relative to that without ultrasonic assistance, accounting for 19.7% of the total filling area of the C2 cavity. Meanwhile, 2D ultrasonic vibration reduces the surface flatness and residual stress of the mass block, improving the molding quality of the accelerometer pendulum. This study presents a novel and effective strategy for overcoming the inherent difficulties in the injection molding of thin‐walled parts.