A Study of Super Precise Injection Molding Technique Assisted by Radiation Energy

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In this research project, usage of infrared radiation energy was proposed to significantly improve the total quality of the injection molded polymer products. CO2 laser provided from the outside of the mold cavity was introduced through an optically transparent window of Zinc-selenide installed in the mold to prevent temperature drop of the molded polymer melt during the filling stage. Feasibility and effectiveness of this method was investigated and discussed through the experimental molding as well as the numerical heat transter analysis. In the first year, improvement of the residual birefringence (one kind of optical strain) in the products and transcription ability on product surface was experimentally studied by using the method. In the second year, temperature distribution within the molded polymer melt under irradiated was numerically estimated to make the characteristics clear, and improvement of the flow limitation in a thin flow path was experimentally studied. In the third year (final year), thin disk molding that simulates the practical process was performed according to the results obtained in the previous two years to give a general discussion for this method. And usage of a halogen lamp was tried and studied to propose a cheaper system that seemed to be desirable for the practical use. The results obtained in this research project are summarized as below :1. This method can significantly decrease the residual birefringence within the products.2. This method can considerably improve the transcription ability on the molded polymer surface that followed the fine mold wall geometry.3. This method can maintain flow ability in a quite thin flow path.4. This method can realize above advantages without considerable elongation of the process cycle time.5. This method can be achieved with some other radiation source by choosing appropriate molding material and transparent mold window.