Papers by Keyword: Viscous Heating

Abstract: Since the fiber drawing speed continues to increase in the modern mass manufacturing of optical fibers, the effects of viscous heating on the coating liquid flow could be significant in the capillary coating die of optical fiber coating applicator. Present study investigates the viscous coating resin flows in the micron-sized channel of coating die with temperature dependent viscosity. The computational results find the substantial temperature increase near the die wall and plug-like velocity distribution due to localized viscous heating. Also, final coating thickness is affected by the change of coating die diameter when the fiber drawing speed is high. Thus, the design of glass fiber coating process at high drawing speed requires careful consideration of several key operational parameters.

Abstract: In manufacturing optical fibers, there has been intense research efforts of continually increasing fiber drawing speed to improve productivity. However, higher speed fiber drawing poses new challenge in many areas of optical fiber manufacturing. In this paper, thermal effects on coating resin flow in an unpressurized coating applicator are studied numerically. Present simulation results found that higher fiber drawing speed leads to severe viscous heating in coating resin flow and significant increase of resin temperature, which in turn leads to substantial viscosity decrease. These thermal effects profoundly alter the resin flow patterns and velocity profiles in the coating die and they should be considered in controlling the final coating thickness.

Abstract: This study investigates the flow characteristics of microinjection-molded lightguiding plates. This study also analyzes the position of melt fronts on lightguiding plates. Viscous heating, temperature and velocity distribution are utilized to analyze delay or advancement of the melt front experimentally and using three-dimensional (3D) numerical simulation. A slow injection speed reduces viscous heating. As viscous heating decreases, the temperature distribution decreases and plastic viscosity increases. A high plastic viscosity increases flow resistance and melt plastic velocity decreases. The advancing melt front of a lightguiding plate is delayed in this situation. The key of this research is that the plastic melt front can arrive the end position at the same time on filling stage of lightguiding plate for microinjection molding. In this research, the authors find increasing the injection speed can help the previous situation. Experimental results demonstrate that filling in the experiment is very close to that in 3D numerical simulation.