Improvement in Cooling Characteristics of Injection Molds Using Microcellular Cooling Structures

In the injection molding process, cooling channels are usually manufactured as straight shapes and hence have low cooling efficiency for curved-shape molds. Recently, additive manufacturing technology has been applied to design conformal cooling channels close to the curved mold surfaces, which requires additional postprocessing for surface finish improvement. In this study, a milled-groove mold core is fabricated by assembling a core insert that contains conformal cooling channel, and the relevant cooling performance is analyzed through numerical simulation and experimental considerations. In addition, a composite mold is developed by inserting a cooling structure based on a triple periodic minimum curved surface (TPMS) using additive manufacturing technology, and the relevant heat transfer characteristics are experimentally compared with the results of machining-type conformal cooling channel. Injection molding experiments are performed using the composite mold assembled with the TPMS cooling structure, and the cooling time is observed be reduced to 1/4 or less compared to those of existing molds with straight cooling channels.