Quality Research For Injection Molding Of Ultrasond-based Microfluidic Chip

The ultrasonic technology is recognized as one of the advanced technologies and future industries in both academic and engineering field. With the rapid development of physics, material science, biomedicine, and mech-electronic technology, the application of ultrasonic technology in various industrial fields has attracted wide concern. As a new kind of polymer molding process method, micro injection molding with ultrasound has combined ultrasonic field and micro injection molding together. It has become the research hotspot because of its obvious advantages such as reducing the polymer viscosity, increasing the melt flow property, improving the products internal micro-structure and controlling the crystallization and orientation of molecular.The filling flow difficulty of the melt and the filling dissatisfaction of micro-mold cavity are the main problems caused by mincroscale effect in injection molding of the microfluidic chip. To solve these problems, this paper put forward a new method using the high frequency activation of ultrasond on the polymer melt to eliminate the adverse effects of the microscale effect. With this method, the activity ability of the molecular and the flow property of the melt in mold filling have been improved. A micro injection mold with the function of vacuum and ultrasonic vibration was designed and manufactured. Based on the Taguchi experimental design method, the coupling effects of the five factors, including ultrasonic power, vibration time, melt temperature, mold temperature and injection speed, on the activity ability of macromolecules, the chain structure and morphological changes in the flow field of the micro-mould were explored, and their interactions on the quality of micro molding part were investigated. The inlfuence sequence of prcess parameters on the micro part quality property and optimal combination of process parameters were obtained. Based on the orthogonal experiment, the effects of the nine fators, including vacuum, ultrasonic power, vibration time, melt temperature, mold temperature, injection speed, injection pressure, packing pressure and parking time, on the law of polymer melt flow property and micro plastic quality property were studied. Multi-factors coupling effects of microscale effect, ultrasonic parameters and process conditions on the internal law of polymer melt flow property and micro plastic quality property in the microscale effect based on the superposition of ultrasonic field effect were studied. Internal relationship between ultrasonic parameter, process conditions of micro injection molding and the quality property of micro plasic part in microscale were also established. A new process method for the injection molding of micro parts was provided.