| The processing technology of micro-injection molding can be adopted in mass-produce of micro size and local micro-structures plastic parts. However, the molding defects such as filling shortage happens constantly due to the micro global or local size of micro plastic parts, seriously affecting the broad application of micro plastic parts in the field of micro systems. Therefore, the research on effective and high-quality molding techniques and methods of micro plastic parts is one of the importance. In this paper, a micro-column arrays with6x16micro columns uniformly distributed on the substrate was chosen as the research object. The diameter and height of the micro columns were (?)200μm and280μm respectively. Filling properties and molding quality of micro-column arrays assisted by ultrasonic vibration and mold vacuum were researched.First, aiming at the structural characteristics of micro-column arrays, the ultrasonic vibration and vacuum assisted micro-injection mold was designed. Single micro wire electrode and micro-column arrays electrode were made by the methods of WEDG and HSM (High-Speed Milling) respectively to fabricate micro mold cavity. The blind holes of micro-column arrays was processed by MEDM machine to get mold cavity for micro-column arrays parts. Detection result shows that the micro-column cavity fabricated by micro wire electrode was high in process precision, low in efficiency, but using the method micro-column arrays electrode, the micro-column cavity was high in efficiency and low in process precision.Then, the orthogonal and short shot molding experiment of micro-column arrays with different polymer materials was carried out by precise injection machine using the designed and made micro injection mold. The filling properties of micro-column arrays cavity were researched with and without the effect of ultrasonic vibration in different injection process conditions. By Analysing the effect factors of blind micro-column hole filling of polymer melt, the rule of the effect of ultrasonic parameters changing on filling quality of micro-column arrays parts and best ultrasonic parameters as well as combination of process parameters molding qualified micro-column arrays parts were obtained.At last, X-ray diffraction (XRD), scanning electron microscope (SEM) and infrared spectroscopy (IR) were adopted to realize the micro structure observation of micro-column arrays parts. By analysing the independent effect and co-effect of mold vacuum and ultrasonic vibration, acquiring the deep relation between internal crystal structure and type, condensed state forming and plastic parts quality, the main factors of effect on filling properties of micro-column cavities were achieved. |
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