Research Of Injection Molding For The Micro Fluidic Chip By Introducing Ultrasonic Vibration To Overall Cavity

With the development of the MEMS technology, the microstructure parts have been applied in many fields. At present, although the micro injection molding process has many advantages such as low cost, short cycle and mass production, a single forming method has been unable to meet the increasing requirements for molding quality of the microstructures. On the basis of rapid development of ultrasonic technology, many scholars have started to think the application of ultrasonic vibration in the field of micro injection molding, and confirmed that the ultrasonic vibration can reduce viscosity of polymer melt and then increase the flow property to a certain extent. So the micro-fluidic chip which has a broad application prospect was chosen as the object of this research, aiming to explore the influence of the ultrasonic vibration on the forming quality of injection molding microstructures.Firstly, after discussing the manners of filling mould microstructure in injection molding, the influence of the angel between the mold filling direction and the mould microstructure distribution direction on molding quality of micro-fluidic chip micro groove was analyzed. Then the micro groove distribution style of the micro-fluidic chip was designed in order to study the influence of ultrasonic vibration on molding qualities of microstructures with different sizes and distributing areas.Secondly, on basis of summing up previous study works, the influences of ultrasonic vibration with different vibrating directions and covering areas on molding quality of micro structures were analyzed for injection molded microstructure parts. A proposal was put forward that ultrasonic vibration was introduced to overall cavity. And the injection mould containing different vibration directions of cavities was designed, in order to investigate results of molding qualities of micro-fluidic chips generated with different cavity vibrating directions.Finally, the influences of ultrasonic vibration parameters on molding qualities of material PMMA micro-fluidic chips were studied by ultrasound-aided micro injection molding experiments. The experimental results showed that the molding qualities of micro-fluidic chips appeared different levels when introducing ultrasonic vibration to the overall cavity in the different phases of molding process. When the vibrating process was in the filling phase, the opening width of the micro groove reduced constantly with increasing of ultrasonic power and extending of vibration time within a certain range. However, the opening width of the micro groove started to appear enlargement after the vibration time extended to post-stage after the holding phase. With increasement of ultrasonic power, vibration marks appeared on the plastic parts surface gradually gathering together from edges of the part to the centre. When the ultrasonic vibration was applied in post-stage after the holding phase, the vibration marks also appeared on the plastic parts surface changing with the same rule. A series of phenomena indicate when ultrasonic vibration is introduced to molding process, the imposing moment and duration time are very important on molding qualities of micro-structure parts.