A new concept of active temperature control for an injection molding process using infrared radiation heating

This paper deals with an innovative injection molding process that uses infrared radiation heating for active temperature control of the molded polymer. The feasibility of the proposed technique was investigated through numerical simulation and experimental study. By directly heating the molded polymer with radiation energy, precise and rapid temperature control and a small effect on the cooling duration were expected. Zinc-selenide and a CO2 laser were used as a transparent mold window and radiation energy source, respectively. In the numerical simulation, temperature distribution both in the molded polymer and the mold wall was evaluated for various molding conditions. The results showed that the heating extent of the molded polymer varied with radiation intensity, radiation absorption coefficient, and melt flow rate. It was also estimated that extension of the cooling duration with the present technique was much shorter than that of a conventional conductive heating technique. In the experimental study, the present technique was applied to actively control the melt temperature and to improve the quality of molded products. As a result, apparent reduction of the residual molecular orientation and considerable improvement of the surface transcription were successfully realized.