Development of the Two-Stage High Precision Replication Process Assisted by Infrared Radiation

Abstract

The development of a novel precision replication procedure having two stages: a molding process and a replication process assisted by an infrared radiation from an external source is described in this paper. As a preliminary process, an injection molding system is used to process blank components by a conventional procedure; the components in this stage not always require a high degree of accuracy. A component molded in the first stage is inserted into the cavity, and is covered with an infrared-transparent glass plate. An infrared radiation is applied to heat the inserted resin components for a certain duration about a few tens seconds. Since the temperature of the thin layer of resin near surface rises due to absorption of radiation, the fluidity of polymer consequently increases. The information on the window is replicated onto the work piece by means of heat supplied with the external radiation. In this replication process, the system is able to be in a low temperature, and therefore cooling is rapidly accomplished. Further, it is expected that the residual birefringence remained within the injection molded products by such a reheating process. In this process, two kinds of precise mold were adopted; a ZnSe mold wall on the surface of which a few precise fine grooves were formed and a thin metallic stamper plate for CDs pasted on the surface of ZnSe were used for replication. The temperature distributions within the plastics were obtained by numerical calculation in order to estimate the validity of the proposing experimental system. The proposed process showed remarkable performance on the micro-and sub-micro-scale replication keeping rapid cooling after heat supplying with the external radiation.