Injection Molding Of Microlens Array To Copy Evaluation And Optimization Of Process Parameters

Micro injection molding provided a new approach for mass production of micro components. The study of molding process is one of the important contents in micro injection molding. In order to provide a new method of improving the replication fidelity for micro-feature structure parts in injection molding, taking microlens array as an application case, this paper studied the effects of processing parameters on the replication fidelity of micro-feature structure parts using part weight as a quantitative evaluation criterion.Microlens arrays were simplified into an experimental model of 5×16 micro columns array (200μm in diameter, 300μm in height). A nickel mold insert was made using LIGA process. The experimental mold was designed and manufactured, which provided an experiment platform for the research of micro injection molding and development of plastic microlens array.Firstly, according to DOE scheme based on Taguchi's method and single factor experiment scheme, MPI /Flow-fusion simulations were done to study the effects of processing parameters on the part weight and runner system weight at the same time. The results showed that the simulation reflected the variation regularity of the flatted part weight and the runner system weight; the micro-feature structures were ignored. To investigate the filling of micro-feature structures, high quality tetrahedron FEM model meshed by Hypermesh software package was input into MPI to carry out Flow 3D simulation of the part without runner system. The results showed that the mold temperature and the injection time have important effects on the filling of micro-feature structures; According to the curves between mold temperature and part weight, injection time and part weight respectively, we can determine the optimal mold temperature and injection time for better replication fidelity.Experiments were done to study the effects of processing parameters on the injection molding of micro columns array. Part and the runner system were weighed and analyzed respectively. The results showed that the increase of melt temperature and mold temperature can make the packing pressure transfer to micro cavity more effectively through runner system, and increasing the part weight, which is different from the phenomenon that part weight decreased with the increasing of temperature in conventional injection molding. From the observation results of the image measuring apparatus, it was discovered that the higher the part weight, the better the filling of the microstructures. The molding weight of the part can evaluate the replication fidelity of micro-feature structured parts primarily, and this method can be used to improve the replication fidelity of micro-feature structures parts.