Research On The Injection Molding Of Micro Plastic Components With High Aspect Ratio

Micro injection molding(μIM)is one of the technologies for fabricating miniature plastic components,especially for the parts with complex geometrical shapes.It has the advantages of low cost,abundant raw materials,short cycle and high replication precision and can realize automatic batch manufacturing,receiving extensive attention.It is a difficult problem for μIM to ensure the filling integrity and molding quality of micro plastic parts or local microstructures and to obtain micro plastic parts with high aspect ratio.In this paper,ultrasonic-assisted μIM method and vacuum-assisted μIM method were proposed and applied in the injection molding process of micro cylinder arrays with high aspect ratio,making full use of ultrasonic vibration and vacuum to ameliorate the filling performance of polymer melt and improve molding quality of plastic parts.On the basis of analyzing the flow behavior of polymer melt in the μIM process of micro cylinder arrays,the vacuum-assisted μIM method and ultrasonic-assisted μIM method were researched respectively.Firstly,the vacuum-assisted μIM system was designed and developed.The μIM experiments under the system were performed to verify its effects on the filling property of the polymer melt.The filling height of the cylinder array increased by 16.40% and the shrinkage rate decreased by 41.57%.Secondly,the ultrasonic-assisted μIM system was designed and developed.The ultrasonic-assisted μIM experiments of micro cylinder arrays were carried out to explore the influences of ultrasonic vibration on the filling performance of polymer melt.The filling height of micro cylinder array was improved by 11.65% and the shrinkage rate decreased by 12.36%.Finally,the μIM technology and process of micro cylinder array with high aspect ratio were optimized with the combined assistance of vacuum and ultrasonic vibration to achieve efficient production of micro cylinder array with high quality.